LS3 dyno.

[Quiggs]

LS3 is the engine going in the 2008+ Corvettes. Beastly.

[fisetdavid26]

*awaiting badda to reply to this thread*

Nice specs, loads of power and torque too. I wonder if there's going to be a LS8 too?

[baddabang]

LS3>All.

Seriously though, I want one for the Cobalt. My B-Day is in March just so you guys know what to get me.

[coolieman1220]

LS3>All.

Seriously though, I want one for the Cobalt. My B-Day is in March just so you guys know what to get me.

haah imagine what taht would be like. ricing to the extreme. like putting a 2JZ or RB26 in like a civic or sentra or celica

[johnnynumfiv]

How would that be ricing? It would be pure awesomeness.

[Quiggs]

This man speaks troof.

[my porsche]

Isn't 390hp a step down...?

[johnnynumfiv]

Isn't 390hp a step down...?

That is 390 at the wheels.

[rev440]

Im pretty sure this is a mildly modded LS3 with a different intake and some other stuff.

[Slicks]

Im pretty sure this is a mildly modded LS3 with a different intake and some other stuff.

Nope, those are baseline numbers, pretty sure its for the six speed auto too. 390rwhp ~ 448FWHP (rated at 436hp).
These are after headers, air filter and no tune:
http://lgmotorsports.com/gallery/albums/userpics/10001/LG%20pro%20LT%20Headers%20LS3.JPG

[KingNothing]

Is this going in the the base or the Z06/BD/whatever? Im hoping base...

[Bob]

LS3 is for base vettes. LS7 is for the Z06 currently, but it's possible we'll see improvements to that in the future.

[rev440]

Nope, those are baseline numbers, pretty sure its for the six speed auto too. 390rwhp ~ 448FWHP (rated at 436hp).
These are after headers, air filter and no tune:
http://lgmotorsports.com/gallery/albums/userpics/10001/LG%20pro%20LT%20Headers%20LS3.JPG

Headers on these cars make a pretty large difference and an airfilter can sometimes add 10rwhp.

[my porsche]

yeah seriously, headers and filter will easily give you the 36hp more that it's rated at...

[F1_Master]

So, you're saying the 380Bhp actually means 430Bhp for the new Vettes as GM said?

Phew.

[Slicks]

yeah seriously, headers and filter will easily give you the 36hp more that it's rated at...

I guess you missed where someone already corrected you, its REAR WHEEL power, NOT fly wheel power, which cars are rated at. You lose power through the drivetrain, roughly 15%, which makes 390RWHP = 448 Fly wheel HP. And this is with under 100 miles on the engine. So like all previous LSx engines, this one is underrated in power as well.
And with the LTs and the air filter, its making roughly 486 fly wheel hp... And thats without a tune yet...

[Slicks]

So, you're saying the 380Bhp actually means 430Bhp for the new Vettes as GM said?

Phew.
Its not BHP, its RWHP.

[rev440]

Slicks whats the CI on this engine? Thats still extremly impressive exspecially with an auto.

[monaroCountry]

430fwhp = 380rwhp. ALL manufacturers use fwhp.

[roosterjuicer]

i love how gm usually underrates their ls series of engines. pretty much every ls motor has been a beast and gm just keeps em rolling.

[my porsche]

Slicks whats the CI on this engine? Thats still extremly impressive exspecially with an auto.

Even if it's the 6L like the current 'vette, with 430hp that's only 70hp per liter...good, but hardly impressive, especially when you consider the Carrera S makes 93hp/liter and is also naturally aspirated.

[roosterjuicer]

its a 6.2 litre. i think that comes out to about 380 or so...prolly just a little smaller than the ole 383 stroker ehyo!

[rev440]

Even if it's the 6L like the current 'vette, with 430hp that's only 70hp per liter...good, but hardly impressive, especially when you consider the Carrera S makes 93hp/liter and is also naturally aspirated.

The Carrera also revs alot higher and the LS2 is hardly even close to its full potetional in its out of the box form. Its not unheard of for a N/A corvette to be high 500hp low 600hp in N/A form while running on pump gas. This is all in a old school OHV engine. HP/L is a ricer argument at best. I can show you mutiple cars with less ci then a 911 but also produce more horse but whats the point? Its all about torque under the curve. I did a little math just for you MP my friends car put out 490rwhp in a vette which equates to about 576 crank horse with a 15 percent drivetrain loss. But it turned out to be a porsche smashing 101 hp/l who would of thunk it? This is also in a 346CI LS1 so you could expect LS2 and LS3 results to be even higher.

[roosterjuicer]

well said rev440. it doesn't matter how you make the power, all that matters is that the power gets made, and its usefull. specific output is pretty much just an excuse made by ricer's and a lot of euro car fans because they have a lack of power.

[my porsche]

Yeah but with a higher hp/L it will weigh less, so the total car weighs less. Ricer argument at best? wtf...

[Bob]

Even if it's the 6L like the current 'vette, with 430hp that's only 70hp per liter...good, but hardly impressive, especially when you consider the Carrera S makes 93hp/liter and is also naturally aspirated.

93 hp/liter... Yes the carrera S is impressive... until you consider it costs more, revs higher, breaks more, is more complicated, cannot be repaired except by a dealer, has higher costs for replacement parts.......

[roosterjuicer]

Yeah but with a higher hp/L it will weigh less, so the total car weighs less. Ricer argument at best? wtf...

vette is faster.

[Bob]

Yeah but with a higher hp/L it will weigh less, so the total car weighs less. Ricer argument at best? wtf...
False. People always bring this up, it's always wrong. If I bore and stroke my 305 (5L) to a 383(6.2L) I don't increase its mass at all... pistons and rods are more massive, as well as the crank, but the block itself is the same size. There's no significant change in mass.

Now consider this- Engines like Porche's use DOHC... that's 4 cams compared to the LS3's 1. That's all extra weight, and much worse, extra rotating weight. They also use vvt mechanisms of some sort, which add more weight. Etc. etc.

The facts are that the LS engine family does without expensive systems, while still delivering lots of power (and the potential for literally >1000 hp when turbo'd) and good stock fuel consumption.

[Kitdy]

Yeah but with a higher hp/L it will weigh less, so the total car weighs less. Ricer argument at best? wtf...

That is untrue. A higher hp/L actually means nothing - view this chart (http://en.wikipedia.org/wiki/Power-to-weight_ratio) to see. If you are talking about horsepower and engine ratings, it is all about hp/lb.

You'll see that the larger (in displacement) engine of the LS7 weights less than some of its performance-oriented contemporaries and maintains a very good hp/lb. ratio.

hp/L is dumb and useless. I am a little confused about the relationship between hp and torque on performance, but if torque is more important than maybe lb.-ft/lb. is more important than hp/lb.

[Bob]

This argument has been had over and over, and until people understand a few things it probably will keep happening. Not trying to be rude MP but a few false assumptions...
1. More Displacement does not mean more mass.
2. More displacement does not mean greater fuel consumption.
3. An engine that is more complex, is not always (or usually) lighter
4. An engine that is less complex, and uses displacement to make up for it, doesn't need to be heavier.

To produce a given amount of power, you can use complicated engines with less displacement and/or turbochargers, etc., or you can use more displacement and keep it simple, cheap, and still effective. It all depends on the application.

[my porsche]

vette is faster.
I never said it wasnt...it has 100 more horsepower and probably 100+ lbft more...

[Bob]

That is untrue. A higher hp/L actually means nothing - view this chart (http://en.wikipedia.org/wiki/Power-to-weight_ratio) to see. If you are talking about horsepower and engine ratings, it is all about hp/lb.

You'll see that the larger (in displacement) engine of the LS7 weights less than some of its performance-oriented contemporaries and maintains a very good hp/lb. ratio.

hp/L is dumb and useless. I am a little confused about the relationship between hp and torque on performance, but if torque is more important than maybe lb.-ft/lb. is more important than hp/lb.Good post. Concerning the last part (don't get ht involved please.)

Power is what's important, not peak power, which is not very meaningful at all, but avg. power over the rev range that the engine is designed to operate in.

This means that peak torque numbers are useful, because a high peak torque at a lower rpm than peak power signifies that an engine has a flatter power curve over the important rev range, and thus a higher avg. power

Avg. power over the rev range is the only thing that matters.

[my porsche]

I'm not knocking the LSx engine series, just pointing out that 430hp from a huge V8 isn't impressive.

[roosterjuicer]

it is when it can spank porsche's that cost twice as much.

[Bob]

To (hopefully) clear up the whole power/torque thing once and for all...
Two engines, both make 350 peak hp at 5280 rpm.
Engine A has peak torque of 500 ft lbs at 3000 rpm.
Engine B has a peak torque of 350 ft lbs at 5280 rpm.

Engine A is a much stronger engine. Not because it has a higher peak torque, but because it has a high torque at a low rpm, which equates to 320+ hp from 3000 to 5500 rpm. This means a very high avg power.

Engine B is not so strong, because even with a very flat torque curve, its power at 3000 rpm will be only 200 hp. This equates to a much lower avg power over the rev range (3000-5500 rpm)

In this way we see that all that matters is avg power, but large torque number at low rpms give us flatter power curves, that, when combined with high peak hp numbers, give high avg hp.

[rev440]

I'm not knocking the LSx engine series, just pointing out that 430hp from a huge V8 isn't impressive.

How bout 600hp with still running on pump gas and still getting 30+mpg on the expressway? Thats hardly a huge v8 thats still a small block my friend.

[baddabang]

I'm not knocking the LSx engine series, just pointing out that 430hp from a huge V8 isn't impressive.

Yes it is considering this "huge" V8 is no place close to its full potential.

[Kitdy]

Now consider this- Engines like Porche's use DOHC... that's 4 cams compared to the LS3's 1. That's all extra weight, and much worse, extra rotating weight. They also use vvt mechanisms of some sort, which add more weight. Etc. etc.

However, do those extra camshafts not help make the engine more powerful at the expense of being heavier?

[Kitdy]

Good post. Concerning the last part (don't get ht involved please.)

Power is what's important, not peak power, which is not very meaningful at all, but avg. power over the rev range that the engine is designed to operate in.

This means that peak torque numbers are useful, because a high peak torque at a lower rpm than peak power signifies that an engine has a flatter power curve over the important rev range, and thus a higher avg. power

Avg. power over the rev range is the only thing that matters.

I heard form another memeber that the torque curve influenced acceleration? Is that true or is it ultimately hp that matters - the flatter the torque curve being better as it gives more horsepower at a lower rpm and across a band?

[Fleet 500]

Yes it is considering this "huge" V8 is no place close to its full potential.
Right. A lot of people "forget" that many V-8s are not built to their full hp potential.

I wonder... if a 6.2 L/380-cu-in V-8 is "huge," what are 7.5 L/454-cu-in, or 7.7 L/472-cu-in, or 8.2 L/500-cu-in engines? Maybe "giant?" :D

[The_Canuck]

Right. A lot of people "forget" that many V-8s are not built to their full hp potential.

I wonder... if a 6.2 L/380-cu-in V-8 is "huge," what are 7.5 L/454-cu-in, or 7.7 L/472-cu-in, or 8.2 L/500-cu-in engines? Maybe "giant?" :D

....uh...yeah...

[Bob]

However, do those extra camshafts not help make the engine more powerful at the expense of being heavier?Yes, by allowing more valves per cylinder and timing event variations, they can allow more performance and more efficiency. The point I'm trying to make is that the most complex route is not always the best, and that simple engines with large displacement are in some ways better than complex engines with less displacement. Again, it all depends on application. But, as many know, hp/L figures mean nothing.


I heard form another memeber that the torque curve influenced acceleration? Is that true or is it ultimately hp that matters - the flatter the torque curve being better as it gives more horsepower at a lower rpm and across a band?Yes, this is the basis of the whole argument that went on in the tech thread between HT, Slicks, Revetec, Matra, etc. I will kindly ask others not to begin that argument again in this thread ;)

But as a short answer, both sides were right. Power is all that matters, because speed is really just kinetic energy. However to ignore torque entirely is a mistake, because torque is irrelevant only from a theoretic point of view.

In reality, what matters is average power. Sometimes in magazines you'll see that a car makes peak power at 6000 rpm, and the article states "over 80% of peak power is available from 3000 rpm onward."

This would mean the engine has a fairly flat power curve, resulting from high torque at low rpms.
And it is true that a car will accelerate on its torque curve.




Basically, when you look for an engine, what you want is avg. power over a specific rev range. It would be better if manufacturers gave power numbers at the two ends of the rev range used for performance driving, but since they don't, high torque at low rpm and high power at high rpm means a nice flat hp curve with a high avg power.

[Kitdy]

And it is true that a car will accelerate on its torque curve.

If that is true, then how is horsepower important at all?

I would say then the average torque would be the thing that you want then, right?

[Bob]

If that is true, then how is horsepower important at all?

I would say then the average torque would be the thing that you want then, right? Close but no. Because torque at the engine does not move the car, torque at the wheels does. Wheel torque has the same shape as engine torque, it is multiplied by the gearbox and rear. The end effect is that you gain wheel torque at the expense of wheel rpm. Now, if engine A produces 10,000 ft lbs of torque, but at only 100 rpm, (this works out to 180 hp) you need to use your gearbox trade torque for rpm, so that your wheels are spinning at a decent speed. On the other hand, If engine B makes 1,000 ft lbs of torque at 5,000 rpm, (this works out to ~1000 hp) you do not need to gear up at all.

Practical example, your accelerating out of a turn from 20 mph. (assuming same size wheels with a circumference of 3 ft to keep it simple.)
Both cars wheels are turning at 587 rpm. [ 20*5280/60/3 ]

Therefore the gearing for engine A needs to be about 5.9:1, to make the 100 rpm engine speed into 590 rpm wheel speed.
This means that its wheel torque is only 1695 lb-ft. [ 10,000 / 5.9 ]

Engine B needs a gears of 1:8.5, to make the 5000 rpm of engine speed into only 587 rpm of wheel speed.
This means that its wheel torque is 8,500 ft-lbs [ 1,000*8.5 ]

So at any given vehicle speed, the vehicle producing more power will always be producing more torque at the wheels, even if engine torque is lower, because of gearing.

Which is why Formula One car's are so fast even with very little torque. However, in the real world, its impractical to run an engine at 20k rpm, and impractical to gear that high, so torque must be high in order to produce power in a suitable rev range.

[Bob]

To further clarify, a car's acceleration curve is always the same shape as it torque curve (aside from wind resistance, etc.,) but it is power production that determines gearing, which multiplies torque at the wheels, and thus more power always make more torque to the wheels (other things equal) at a given vehicle speed.

[monaroCountry]

I'm not knocking the LSx engine series, just pointing out that 430hp from a huge V8 isn't impressive.


So do you also think that the Bugatti Veyrons 8L and 4 turbos isnt impressive?........given that it only has 1000fwhp.

Theres a single turbo kit out in Australia thats designed to handle 1000hp using the 6L.

[Slicks]

I'm not knocking the LSx engine series, just pointing out that 430hp from a huge V8 isn't impressive.

hp/l is irrelivent. What is impressive is the LS3 makes 430hp/428ft.lbs out of an engine that weighs less than 400lbs, and is in a very low state of tune. For comparison, the competition's engines are not only heavier, but physically bigger as well...

[charged]

So do you also think that the Bugatti Veyrons 8L and 4 turbos isnt impressive?........given that it only has 1000fwhp.

Theres a single turbo kit out in Australia thats designed to handle 1000hp using the 6L.

Alloy Block or cast ???

Theres a guy on PF that has just installed a twin turbo gt2876 with .63 housings, housing definetley undersize, too much back pressure. He thinks 800 hp will be the limit with a twin turbs set up, 1000hp with a single turbo would definetley be quite laggy and doubting a lsX stock block would handle that much FI

http://www.performanceforums.com/forums/showthread.php?t=67210431

[rev440]

Alloy Block or cast ???

Theres a guy on PF that has just installed a twin turbo gt2876 with .63 housings, housing definetley undersize, too much back pressure. He thinks 800 hp will be the limit with a twin turbs set up, 1000hp with a single turbo would definetley be quite laggy and doubting a lsX stock block would handle that much FI

http://www.performanceforums.com/forums/showthread.php?t=67210431

Stock block is not unheard of. Stock rods and pistons no chance. There is a guy on LS1tech who has a TT LS1 Trans Am that did mid 800rwhp on a turbo setup he desighned.

[Bob]

Just as a note- LS1, LS2, LS3, LS6, and LS7 are all alloy blocks (I think?)
But there is a new block named the LSX which is cast iron, and capable of over 2000 hp.

We should stop referring to the whole series as the lsx. The lsx is specifically the cast iron block. If you want to talk about the whole series say LS- or LS series or something. Just a suggestion for less confusion.

[Kitdy]

To further clarify, a car's acceleration curve is always the same shape as it torque curve (aside from wind resistance, etc.,) but it is power production that determines gearing, which multiplies torque at the wheels, and thus more power always make more torque to the wheels (other things equal) at a given vehicle speed.

I don't understand what you mean by saying that the acceleration curve is the same as the torque curve. IF that is true, then it would ALWAYS be better to have very, very high torque at extremely low rpm, but then you also say that gearing changes it so that torque at the wheels is what matters.

By torque curve, do oyu mean torque at the wheels torque, or torque at the engine (flywheel? wherever the hell they measure torque from) torque?

I am trying to learn and your example has confused me slightly as I am not sure how you calculated all this stuff and what gearing is exactly and how you calculated that the wheels are spinning at 587 rpm in your example.

I think I am close to understanding roughly what is going on but not quite there.

[Bob]

I don't understand what you mean by saying that the acceleration curve is the same as the torque curve. IF that is true, then it would ALWAYS be better to have very, very high torque at extremely low rpm, but then you also say that gearing changes it so that torque at the wheels is what matters.

By torque curve, do oyu mean torque at the wheels torque, or torque at the engine (flywheel? wherever the hell they measure torque from) torque?

I am trying to learn and your example has confused me slightly as I am not sure how you calculated all this stuff and what gearing is exactly and how you calculated that the wheels are spinning at 587 rpm in your example.

I think I am close to understanding roughly what is going on but not quite there.The acceleration curve is the same shape as the torque curve. In a given gear, if you are making twice as much torque at 500 rpm than at 1000 rpm, then you will be accelerating twice as hard at 500rpm.

The reason this is so confusing is that kinetic energy varies with the square of speed. This means it is "harder" to accelerate from 20mph to 30mph, than it is to accelerate from 10mph to 20 mph.



By torque curve, I was referring to the graph of torque vs rpm at the flywheel. However, torque at the wheels is equal to torque at the flywheel, multiplied by the gearing, subtracting friction. Both torque curves have the same shape as the acceleration curve; that is, twice as much torque always yields twice as much acceleration. (In one gear.)

I'll go through my example in detail in the next post.

[Bob]

Practical example, your accelerating out of a turn from 20 mph. (assuming same size wheels with a circumference of 3 ft to keep it simple.)
Both cars wheels are turning at 587 rpm. [ 20*5280/60/3 ]
Therefore the gearing for engine A needs to be about 5.9:1, to make the 100 rpm engine speed into 590 rpm wheel speed.
This means that its wheel torque is only 1695 lb-ft. [ 10,000 / 5.9 ]
Engine B needs a gears of 1:8.5, to make the 5000 rpm of engine speed into only 587 rpm of wheel speed.
This means that its wheel torque is 8,500 ft-lbs [ 1,000*8.5 ]
Power (h.p) = Torque (ft*lbs) x engine speed / 5252
(I got that constant 5252 wrong in my example by a bit, didn't feel like looking up) go here (http://auto.howstuffworks.com/question622.htm) for more in depth on this.

First, we are assuming same size wheels to simplify things. In reality, they are just another factor of gearing. So, with wheels that have a three foot circumference, one turn gives three feet of distance. 1 rpm at the wheels gives 3 feet per minute, or 180 ft per hour.

To convert our example speed of 20 mph into wheel rpm, first we convert into feet per minute. 20 mph * 5280 feet/mile * 1 hour/60minutes = 1760 ft/min at the wheels. Since 1 rpm equals 3 ft/min, 1760 ft/min * 1rpm/3(ft/min) = 587 rpm. At the wheels.

After that, figuring out gearing ratios and multiply torque by them is fairly straightforward. Gearing multplies torque and rpm accordingly. Since engine A is spinning at 100 rpm, and the wheels are spinning at 587 rpm, the overall gear ration must be about 5.9 wheel rpm : 1 engine rpm. This means is multiplied by a factor of 1/5.9.

Same goes for engine B. Since the engine is spinning at 5000 rpm, its gearing is about 5000 engine rpm : 587 wheel rpm. This means that torque is multiplied by a factor of almost 8.5, or 5000/587.



Now that you know how to do it, make up your own engine numbers. You'll find that as long as two engines are makng the same power, they make the same torque at the wheels, even when the make different amounts of torque at the flywheel.

[Kitdy]

So with all the cards dropped, the main statistic of a good engine is not torque but hp across a broad range, correct?

[Bob]

So with all the cards dropped, the main statistic of a good engine is not torque but hp across a broad range, correct?
For racing or all out speed, yes. Any racing vehicle you look at will have a power curve optimized for hp in the top end. F1 and Top Fuel come to mind most notably.

However, the more you move towards "everday" cars, the more you want low end torque&power, because people can't start their cars moving by dropping the clutch at 6000 rpm, and they don't want to run their car anywhere near redline on a day to day basis.

[culver]

I'm not knocking the LSx engine series, just pointing out that 430hp from a huge V8 isn't impressive.

Just to throw up one of my old posts...
http://www.ultimatecarpage.com/forum/showpost.php?p=276347&postcount=219

It's not definitive but it certainly suggest there may be some flaws in assuming displacement equals engine size and weight. More so when looking at cam arrangements.

BTW, sometimes there are reasons we might be happier with less HP/lb.

[henk4]

Just to throw up one of my old posts...
http://www.ultimatecarpage.com/forum/showpost.php?p=276347&postcount=219

It's not definitive but it certainly suggest there may be some flaws in assuming displacement equals engine size and weight. More so when looking at cam arrangements.

BTW, sometimes there are reasons we might be happier with less HP/lb.

I read your link (the page for the 4-valve OHV engine has gone missing).

It looks like a fair treatment of things (except using the word "perception")

now apparently the main benefits of DOHC engines lay in the rev department, which is logical as the pushrods are the limiting factor. You could also have brought forward that the revving capability a larger engine with relatively few cylinders will also be limited by the absolute piston speed. (Check for instance the old 4.2. liter DOHC Jaguar inline 6 which had a 106 mm stroke and was redlined at 5500)

However, this being the case, I would like your views about why diesel engined cars, which run out of steam at about 5000 revs are nowadays also fitted with at least one, but in many cases (like my car) 2 OHCs. Also the new Peugeot and Audi V12 racing engines for their prototypes have DOHC and still don't run over 5000.

You mention that OHV engines are cheaper to produce, which I would actually doubt. An OHC block does not need any channels for the pushrods, so the block does not need to be holed for that. There will still be a camshaft in an OHV engine, the only difference with an OHC engine will be the cam drive. The cambelts are not really the most heavy part of an engine.

The fact that the American produced engines are relatively cheap also results from the shear numbers in which they are produced. About 50% of the GM small block engines ends up in trucks of which millions are sold each year.

[culver]

I read your link (the page for the 4-valve OHV engine has gone missing).

It looks like a fair treatment of things (except using the word "perception")

now apparently the main benefits of DOHC engines lay in the rev department, which is logical as the pushrods are the limiting factor. You could also have brought forward that the revving capability a larger engine with relatively few cylinders will also be limited by the absolute piston speed. (Check for instance the old 4.2. liter DOHC Jaguar inline 6 which had a 106 mm stroke and was redlined at 5500)

However, this being the case, I would like your views about why diesel engined cars, which run out of steam at about 5000 revs are nowadays also fitted with at least one, but in many cases (like my car) 2 OHCs. Also the new Peugeot and Audi V12 racing engines for their prototypes have DOHC and still don't run over 5000.

You mention that OHV engines are cheaper to produce, which I would actually doubt. An OHC block does not need any channels for the pushrods, so the block does not need to be holed for that. There will still be a camshaft in an OHV engine, the only difference with an OHC engine will be the cam drive. The cambelts are not really the most heavy part of an engine.

The fact that the American produced engines are relatively cheap also results from the shear numbers in which they are produced. About 50% of the GM small block engines ends up in trucks of which millions are sold each year.

I can only speculate about the diesels but I will give it my guess. I suspect the larger V block diesels are used for two reasons; first they have heads which are architecturally similar to an in line motor, second, they are likely smoother.
Most of the diesels in Europe, are in line engines. Just like with an inline gasoline engine, you don't gain much of anything with an OHV inline motor. So your volume motors are going to be OHC in Europe (diesel or gas). I suspect when looking at the V block motors they largely would go with head designs similar to what they had done in their smaller inline motors. Another possibility could be clearance for the pushrods in the heads. In all engines but especially 4 valve models you need to weave intake, exhaust, injectors and valves into a small space. It is possible that most of that with the smaller displacement motors it is simply easier to package all those parts with OHCs rather than pushrods (which are one more thing that must occupy space in the heads.
Also, while I do believe that pushrod motors can be very smooth and refined (having driven a few that were) I can also buy into the notion that OHC still offers the potential to be smoother yet. As the V block diesels in Europe are often in luxury cars I suspect they are willing (or customers demand) the OHC architecture.
Again, this is speculation. I do have not had the chance to ask various engineers at various automakers what they think so I can only put together a series of assumptions that seem to plausibly fit the facts.

I can’t speculate about the race engines. The design criteria for race engines are much different than those of production automobiles.


Cost: Well the best source I can cite would be GM who’s representatives have publicly stated that an OHV V6 costs approximately the same to manufacture as an 16V OHC I4. I have to assume they are comparing their costs and may or may not be based on real vs theoretical motors. I can believe the claim based on the number of machining operations and the complexities of those operations based on what I know of the two engine architectures. Given that GM has claimed the I4 cost about the same to make as the pushrod V6, I can not believe that adding 12 more valves (assuming the comparison was 12V vs 24V) and three more cam shafts wouldn’t significantly increase the cost of the motor.

I do not believe the cost difference is just due to numbers. At a certain volume you don’t gain much by increasing production volume. While you might see savings in producing 100,000 vs 5,000, you may not see a per unit savings when moving from 100,000 to 200,000 (purely example numbers). GM also produces OHC motors in very high quantities. Chrysler produces OHV and OHC V6 motors in high quantities. Toyota, Nissan and to a lesser degree Honda produce high volumes of OHC V block motors largely for the US market. I don’t think it is fair to assume an American OHV motor is cheaper than OHC motors just because of volume. Again, if you look at the number of parts and the number of and complexity of the machining operations for the parts you will find that OHV V-block motors will cost less than a similar configuration DOHC motor. They will also generally be more compact. The issue in the end is how do you balance those trade offs.

Again, for full disclosure, the only pushrod powered car I’ve ever owned was manufactured in Europe and had a 1.6L I4 (’79 Ford Fiesta). It was also my only car with Webbers :D

[henk4]

I can only speculate about the diesels but I will give it my guess. I suspect the larger V block diesels are used for two reasons; first they have heads which are architecturally similar to an in line motor, second, they are likely smoother.
Most of the diesels in Europe, are in line engines. Just like with an inline gasoline engine, you don't gain much of anything with an OHV inline motor. So your volume motors are going to be OHC in Europe (diesel or gas). I suspect when looking at the V block motors they largely would go with head designs similar to what they had done in their smaller inline motors. Another possibility could be clearance for the pushrods in the heads. In all engines but especially 4 valve models you need to weave intake, exhaust, injectors and valves into a small space. It is possible that most of that with the smaller displacement motors it is simply easier to package all those parts with OHCs rather than pushrods (which are one more thing that must occupy space in the heads.
Also, while I do believe that pushrod motors can be very smooth and refined (having driven a few that were) I can also buy into the notion that OHC still offers the potential to be smoother yet. As the V block diesels in Europe are often in luxury cars I suspect they are willing (or customers demand) the OHC architecture.
Again, this is speculation. I do have not had the chance to ask various engineers at various automakers what they think so I can only put together a series of assumptions that seem to plausibly fit the facts.

I can’t speculate about the race engines. The design criteria for race engines are much different than those of production automobiles.


Cost: Well the best source I can cite would be GM who’s representatives have publicly stated that an OHV V6 costs approximately the same to manufacture as an 16V OHC I4. I have to assume they are comparing their costs and may or may not be based on real vs theoretical motors. I can believe the claim based on the number of machining operations and the complexities of those operations based on what I know of the two engine architectures. Given that GM has claimed the I4 cost about the same to make as the pushrod V6, I can not believe that adding 12 more valves (assuming the comparison was 12V vs 24V) and three more cam shafts wouldn’t significantly increase the cost of the motor.

I do not believe the cost difference is just due to numbers. At a certain volume you don’t gain much by increasing production volume. While you might see savings in producing 100,000 vs 5,000, you may not see a per unit savings when moving from 100,000 to 200,000 (purely example numbers). GM also produces OHC motors in very high quantities. Chrysler produces OHV and OHC V6 motors in high quantities. Toyota, Nissan and to a lesser degree Honda produce high volumes of OHC V block motors largely for the US market. I don’t think it is fair to assume an American OHV motor is cheaper than OHC motors just because of volume. Again, if you look at the number of parts and the number of and complexity of the machining operations for the parts you will find that OHV V-block motors will cost less than a similar configuration DOHC motor. They will also generally be more compact. The issue in the end is how do you balance those trade offs.

Again, for full disclosure, the only pushrod powered car I’ve ever owned was manufactured in Europe and had a 1.6L I4 (’79 Ford Fiesta). It was also my only car with Webbers :D

Interesting, just a couple of comments. You attribute one of the reasons for using OHC in European (diesel) engines as related to the space in the cylinder head. I am not aware that a diesel would need more space there, also because of the absence of sparkplugs. ( I run a 2.2 liter I-4 with 16 valves and DOHC)

I have my doubts about GM's claims regarding the production costs of a OHV V6 vs a DOHC I4. It could well be the case if for the current range of OHV V6 engines they can use the existing tooling and for an OHC V6 they have to go for new stuff. Also the calculation only seems to be valid in the USA as all GM V6 engines in Europe are DOHC. (I am not sure about Australia, but the new Alfa V6 DOHC engine is coming from Holden, a result from the brief involvement of GM with Fiat)).
Chrysler has an interesting mixed bag of V6 engines, the OHV ones according to my source book only offered in the Voyager, while all the other models get the OHC versions, and comparing the performance figures of both engine types, it is easy to understand why. (and the OHC engines are not Mercedes designs).

[2ndclasscitizen]

I am not sure about Australia, but the new Alfa V6 DOHC engine is coming from Holden, a result from the brief involvement of GM with Fiat

Holden dropped the old Buick OHV V6 maybe 2 years ago now, with the DOHC, VCT Alloytec V6 replacing it. It's not exactly a Holden engine, but they did have a bit of engineering involvement, and the one Holden uses has a quite a lot of the parts manufactured in GM's Mexico plants then assembly is done here IIRC. The Alloytec, along with the Zeta chassis, are meant to be Global GM products.

[henk4]

The Alloytec, along with the Zeta chassis, are meant to be Global GM products.

would that mean that the days of the old V6 are numbered?

[2ndclasscitizen]

would that mean that the days of the old V6 are numbered?

Don't know. Certainly outside the US, but I don't know if any GM US domestic cars use it anymore. Cadillac has been using the Alloytec for a while now but I don't know about any others.

[henk4]

Chevrolet uses both the old one (LZ4/LZ8) for the Impala and the Monte Carlo, and the 2007 Malibu model, while the new engine (LY7) is fitted in the 2008 Malibu. Pontiac uses the LZ4/8 for all models except the G6 GTP, which uses the LY7.
(I have not looked at SUVs and the like)

[roosterjuicer]

the good ole pushrod v6 is still used somewhat, although its slowly being replaced by what gm is calling the "high feature" DOHC v-6's in some of the higher end trim levels. But the pushrod 3500 is currently the base "high value" v6. there is also the pushrod 3900. Both can be found in cars like the impala, monte carlo, malibu, g6, grand prix, buick lacrosse/lucerne, and some of the smaller crossover suv's.

the 3500 is comparable although slightly better than the venerable 3800. and the 3900 is the equivalent of the supercharged 3800.

personally i wish they would never get rid of the pushrod v-6's but times are changing and gm's gotta get with the times good or bad.

[henk4]

the good ole pushrod v6 is still used somewhat, although its slowly being replaced by what gm is calling the "high feature" DOHC v-6's in some of the higher end trim levels. But the pushrod 3500 is currently the base "high value" v6. there is also the pushrod 3900. Both can be found in cars like the impala, monte carlo, malibu, g6, grand prix, buick lacrosse/lucerne, and some of the smaller crossover suv's.

the 3500 is comparable although slightly better than the venerable 3800. and the 3900 is the equivalent of the supercharged 3800.

personally i wish they would never get rid of the pushrod v-6's but times are changing and gm's gotta get with the times good or bad.

well if you compare the pushrod 3.9 with the DOHC 3.6 we see the following:
243/256 BHP and more importantly 326@4600 vs 340@3200 NM of torque, I can understand GM's decision...figures taken from the 2007 and 2008 Malibu specs, source: Automobil REvue Catalogue, (Swiss)

[roosterjuicer]

im not saying the 3.6 isn't better than the 3900. i just like the gm pushrod v6's cause they are cheap, simple, and easy to work on.

ive also never driven a car with the 3.6 but i have driven my fair share of 3800 equipped cars and for some reason that motor felt so much stronger than the numbers said they were. ive never really got that feeling driving many DOHC cars...haha i remember i once smoked an integra gsr in a 3800 equipped oldsmobile acheiva pos, you shoulda seen the look on his face.

but the truth is that in reality i know the 3.6 is a better motor, im just stuck in my ways.

[henk4]

im not saying the 3.6 isn't better than the 3900. i just like the gm pushrod v6's cause they are cheap, simple, and easy to work on.

ive also never driven a car with the 3.6 but i have driven my fair share of 3800 equipped cars and for some reason that motor felt so much stronger than the numbers said they were. ive never really got that feeling driving many DOHC cars...haha i remember i once smoked an integra gsr in a 3800 equipped oldsmobile acheiva pos, you shoulda seen the look on his face.

but the truth is that in reality i know the 3.6 is a better motor, im just stuck in my ways.

I bet if you wold have had the same choice 60 years ago, you would have sworn with the Ford flathead V8:)

[roosterjuicer]

I bet if you wold have had the same choice 60 years ago, you would have sworn with the Ford flathead V8:)

haha id hope i wouldn't be that bad, i mean there was a huuuuge leap between the flathead and the ohv small block although hindsight is 20/20 i suppose:D

[culver]

well if you compare the pushrod 3.9 with the DOHC 3.6 we see the following:
243/256 BHP and more importantly 326@4600 vs 340@3200 NM of torque, I can understand GM's decision...figures taken from the 2007 and 2008 Malibu specs, source: Automobil REvue Catalogue, (Swiss)

The 3.9L is physically smaller (thought not likely lighter due to the iron block and head(?)). The 3.9L is cheaper to make.

[henk4]

The 3.9L is cheaper to make.so are life rear axles.....but do you have comparative production cost figures to support this, or will you stick with the statement of GM?

[culver]

so are life rear axles.....but do you have comparative production cost figures to support this, or will you stick with the statement of GM?

As I've said, I will trust GM on this one. A quick assessment of the number of parts and the number of machining operations for the various parts certainly suggests that OHC engines will cost more.

You have 4 cam shafts to grind rather than 1
You have 4 cam journals to grind rather than 1
You have 2 times the number of valves and their associated assemblies (though I suspect each pushrod-valve assembly costs more than each OHC assembly).
You have twice the number of valve seats to grind

How many items can you name that would tend to make a 2 valve pushrod motor cost more?

[henk4]

As I've said, I will trust GM on this one. A quick assessment of the number of parts and the number of machining operations for the various parts certainly suggests that OHC engines will cost more.

You have 4 cam shafts to grind rather than 1
You have 4 cam journals to grind rather than 1
You have 2 times the number of valves and their associated assemblies (though I suspect each pushrod-valve assembly costs more than each OHC assembly).
You have twice the number of valve seats to grind

How many items can you name that would tend to make a 2 valve pushrod motor cost more?

and what would be the marginal cost of an additional camshaft? Just the metal?
off course you will need 12 pushrods.....(very little metal though)...
Does it take more time to put together an OHC engine?

and of course costs should always be seen in relation to revenues, which in this case is a better performing engine....all new constructions were once more expensive than what they replaced, like disc brakes over drums, four speed box over a three speeder etc, but in the en d the result was better. This is investment theory, and the simple production cost of an engine is only part of that....

[Slicks]

so are life rear axles.....but do you have comparative production cost figures to support this, or will you stick with the statement of GM?

Logically if the 3.9L were more expencive, and a "worse" engine, why wouldn't they bother ditching it?

[2ndclasscitizen]

the good ole pushrod v6 is still used somewhat, although its slowly being replaced by what gm is calling the "high feature" DOHC v-6's in some of the higher end trim levels.

The "High Feature" V6 is what Holden calls the Alloytec.


The 3.9L is cheaper to make.

That's probably due more to the fact that it's been around for a quite a while and GM already returned it's investment in the development and tooling.

[culver]

That's probably due more to the fact that it's been around for a quite a while and GM already returned it's investment in the development and tooling.

While that certainly helps, again see my posts about the number and complexity of the parts and machining operations used to make the motors. There are simply fewer of the expensive parts that required expensive machining or grinding operations.

[henk4]

Logically if the 3.9L were more expencive, and a "worse" engine, why wouldn't they bother ditching it?

sometimes it takes a while to change the whole model range...the have started ditching the 3.5 so it will be only be a matter of time...

just another issue. As one of the advantages of OHV it is often mentioned that they are easier to work on...now what exactly is it that you do then? Adjusting valves? Setting the timing or what. Just wondering because I never have felt the need to work on my engine, ever since electronic motor management systems have taken over...

[henk4]

While that certainly helps, again see my posts about the number and complexity of the parts and machining operations used to make the motors. There are simply fewer of the expensive parts that required expensive machining or grinding operations.

Once the tooling is in place the costs are sunk fund. As long as you don't have figures that would indicate that an OHC engine requires more expensive tooling (and by how much) I think your assumption lacks some fundamentals. Why would a robot that has to drill holes in the engine block to have the pushrods go through be cheaper than a robot that grinds the camshafts?
Do you have any figures that would indicate that constructing an OHC engine takes more time than an OHV? (Time equals money:) )

[culver]

They don't drill holes for the pushrods. However, cam shafts are comparatively expensive because they require a grinding operation. Same it true for all the cam shaft fluid bearings. Again, those operations are costly and a DOHC motor have 4 vs 1.

So what we have is GM saying they are cheaper and I've put forth reasons why. You many not understand those reasons but I don't think just saying legacy tooling is sufficient.
Consider that GM could have replaced the small block V8 with an OHC engine. They had an OHC V8 at the time but they decided to make a new pushrod family of motors (LSx). Chrysler also chose to make a new pushrod V8 instead of an OHC motor (HEMI). The changes in the HEMI head means that Chrysler likely had to invest in quite a bit of new tooling to make it instead of a wedge head like their older V8s.

Sorry, you may not believe it but that doesn't make it not true.

[henk4]

They don't drill holes for the pushrods. However, cam shafts are comparatively expensive because they require a grinding operation. Same it true for all the cam shaft fluid bearings. Again, those operations are costly and a DOHC motor have 4 vs 1.

So what we have is GM saying they are cheaper and I've put forth reasons why. You many not understand those reasons but I don't think just saying legacy tooling is sufficient.
Consider that GM could have replaced the small block V8 with an OHC engine. They had an OHC V8 at the time but they decided to make a new pushrod family of motors (LSx). Chrysler also chose to make a new pushrod V8 instead of an OHC motor (HEMI). The changes in the HEMI head means that Chrysler likely had to invest in quite a bit of new tooling to make it instead of a wedge head like their older V8s.

Sorry, you may not believe it but that doesn't make it not true.

Is grinding a manual process? Why are these operations "costly" and by how much more than say the construction of the OHV valve mechanisms?

As long as the words from GM are not supported by visible and controllable calculations we only have the words, and words by any factory need to be judged critically at any the time, even if you can come up with construction aspects which look to be more expensive...

In the same vein you are asking me the questions about the GM policies regarding the V8 engines, I could ask you the same questions regarding the V6 engines (both for Chrysler and GM0, where the DOHC versions clearly prove to be a significant leap forward in terms of peak power and low-end torque.
It looks like there is a tendency to go for a DOHC V6 and an OHV V8, and I would not be surprised that at a time when the DOHC V6 is the common norm, also in the USA, the marginal costs for extending such an engine into a V8 will be offset by the increased performance ("benefits") in the same way the new V6 surpassed the old OHV versions.

[culver]

I can no more provide you with financial data regarding GM's V6 engines than I can provide you with financial data proving that a leaf sprung live axle is cheaper than a double A-arm IRS system. The difference is you don't dispute the IRS claims. Asking for that information is a red herring.

Grinding operations are slower than other machining operations. They take time and time equals money in manufacturing. Precision operations equal money. If you don't understand these things I'm not sure you are qualified to judge the potential costs of the two engines.

As for the decline of the pushrod vs OHC motors, I think I provided a number of reasons which almost all come down to these:

OHV has less HP/L which is important in markets which control displacement (or in markets where buyers place a lot of weight on engine displacement).

OHV is not quite as refined (generalization vs in all cases) as OHC. Thus in displacement limited markets a larger displacement motor is at a premium. As it is a premium motor buyers will demand the full premium status (the extra power and refinement allowed by OHC).

In the US the market supports the conditions which would allow a buyer to choose between an OHV or similar priced but smaller displacement/cylinder count OHC motor. Both motors being choices in moderately priced vehicles.

The factors that make OHV engines a poor choice in Europe do not apply in the US. It would be incorrect to assume that factors that affect choices in Europe must apply equally in the US.

[henk4]

I can no more provide you with financial data regarding GM's V6 engines than I can provide you with financial data proving that a leaf sprung live axle is cheaper than a double A-arm IRS system. The difference is you don't dispute the IRS claims. Asking for that information is a red herring.

Grinding operations are slower than other machining operations. They take time and time equals money in manufacturing. Precision operations equal money. If you don't understand these things I'm not sure you are qualified to judge the potential costs of the two engines.

As for the decline of the pushrod vs OHC motors, I think I provided a number of reasons which almost all come down to these:

OHV has less HP/L which is important in markets which control displacement (or in markets where buyers place a lot of weight on engine displacement).

OHV is not quite as refined (generalization vs in all cases) as OHC. Thus in displacement limited markets a larger displacement motor is at a premium. As it is a premium motor buyers will demand the full premium status (the extra power and refinement allowed by OHC).

In the US the market supports the conditions which would allow a buyer to choose between an OHV or similar priced but smaller displacement/cylinder count OHC motor. Both motors being choices in moderately priced vehicles.

The factors that make OHV engines a poor choice in Europe do not apply in the US. It would be incorrect to assume that factors that affect choices in Europe must apply equally in the US.

Having graduated as an economist (almost 30 years ago:) ) makes me interested in cost aspects. The fact that IRS is more expensive to produce than leaf springs is offset by the benefits of better handling and safer ride. I would not call that a red herring. It is the basic principle of any cost-benefit analysis:)

I think my comparison of the performance of the new GM V6 (LY4) versus the old LZ4 and the gradual introduction of the LY4 into the bread and butter GM cars indicates that your statement about Europe (and Japan) being the more suitable markets for OHC engines does not fully hold truth anymore. The fact that the LY4 performs better than the LZ4 may offset the assumed higher production costs.

[2ndclasscitizen]

Chrysler also chose to make a new pushrod V8 instead of an OHC motor (HEMI). The changes in the HEMI head means that Chrysler likely had to invest in quite a bit of new tooling to make it instead of a wedge head like their older V8s.

That'd be because they chose to make the new engine a HEMI, which is incredible complicated, possibly impossible to make with an OHC configuration.

[culver]

That'd be because they chose to make the new engine a HEMI, which is incredible complicated, possibly impossible to make with an OHC configuration.

Not hard in the least. The HEMI combustion chamber design was evolved from what Chrysler saw in the air cooled 911 motor.

[henk4]

Not hard in the least. The HEMI combustion chamber design was evolved from what Chrysler saw in the air cooled 911 motor.

I think the original HEMIs were from the fifties, the 911 6 cylinder engine dates from the early sixties, and I am not sure that the Fuhrmann 4 cylinder Carrera engine was the inspiration for the HEMI.
But anyway, with a hemispheric combustion chamber, there is more space for 4 valves.....

[P4g4nite]

But anyway, with a hemispheric combustion chamber, there is more space for 4 valves.....
Hemispheric? A 4 valve hemi sounds like a nightmare of packaging. I though the only real advantage a Hemi gave was that it allowed for 2 huge valves.

[henk4]

Hemispheric? A 4 valve hemi sounds like a nightmare of packaging. I though the only real advantage a Hemi gave was that it allowed for 2 huge valves.

I am just as we speak looking at a picture of the cylinder head of a Ferrari 355, Hemispheric combustion area, 5 valves....:)

one of the first cars to use the Hemispeheric principle was the Peugeot GP car of 1912, otherwise famous because of its use of DOHC....

[culver]

The current HEMI motor doesn't really have a hemispherical chamber. What is does share with the old HEMIs is the valve train layout (above and beyond just being pushrods). When Chrysler designed the current HEMI they started off with what they thought to be the best two valve head on the market, the late model, air cooled 911. I'm sure they looked at other motors but they specifically started with the Porsche chamber shape. The shape evolved and the current shape isn't the same as the 2 valve 911 but it did start there.

As for the benefits of the hemi head, there were several. One was putting the valves on opposite sides of the combustion chamber. This did allow for larger valves when compared to a wedge head motor.

I'm not sure if the Ferrari 355 uses a hemispherical head. I only know of 1 4 valve motor that uses a hemi head. The 5 valve Ferrari head is more likely a variation of the penta-roof head used on basically all 4 valve heads. Among other criteria the valve stems of a hemi head should all point inward to the center of the combustion chamber. BMW made a 4 valve race motor where this actually did happen. The valves were arranged around the top of the chamber. The two intake valves were actually across from each other. The intake charge came in between the intake and exhaust cams and exited on BOTH sides of the cylinder head (in the top, out both sides). It made for a very strange motor.

Anyway, penta-roof heads are used on basically all 4 valve heads because they are MUCH easier to make than a true 4 valve hemi. They also have largely the same combustion properties.

One more thing, none of the Chrysler "hemi" motors had hemispherical heads. Even the old ones had only semi-hemispherical heads. The top of the combustion chamber wasn't a hemisphere, more like a hemisphere with a weight on top. A true hemispherical head required a very domed piston to get enough compression.

[henk4]

thanks for the further explanation, nice reference to the BMW Apfelbeck cylinder head, which was tried during the second part of the sixties in formula 2 cars and in this Brabham BT7 record car. Yes, this is a 4 cylinder engine

[culver]

That's the one I was thinking of. I read about it in a book about racing engines. Hell of an interesting motor. It took me a while to understand the section views of the head!

[henk4]

That's the one I was thinking of. I read about it in a book about racing engines. Hell of an interesting motor. It took me a while to understand the section views of the head!

I read about it when it was being developed (in German:) ). I think I never fully grasped the concept.....

[culver]

I read about it when it was being developed (in German:) ). I think I never fully grasped the concept.....

The section views eventually make it clear. Think of it this way, if you look straight down on the engine the valves all point to the center of the combustion chamber. From that same view the intake valves are inline with the crank. You have one intake valve in front and one behind the spark plug. The exhaust valves are to the left and right of the spark plug. The center lines of the plug and all four valves intersect at the center of the chamber. The valve train uses a series of rockers to actuate the valves.

One more note, I actually can remember if the intake valves were exactly in line or if they were at 45 degrees from the engine centerline when viewed from the top. If so the exhaust valves were also moved. From the top the valve stems were 90 degrees from each other.

[culver]

http://www.moto-histo.com/4t_4sp/4t_4sp.htm

A google search found this site. I'll have to find a translation so I can see what they are talking about.

[Matra et Alpine]

ah th Apfelbeck radial head :) Phenomenal performance from a small block for it's day.
Great sound (http://www.02-club.de/technik/motor/radial.mp3)too :)
http://www.02-club.de/technik/motor/radialmo.jpg
The idea was that all valves were equidistant from a focal point in the cylinder head. This meant some unusual valve angles and with 4 valves per head Apfelbeck decided that having an input trumpet per VALVE would give better performance than trying to have inlet manifolds and branches.
EDIT: Here's the valve arrangement ....http://www.02-club.de/technik/motor/apfelbe.jpg

[henk4]

http://www.moto-histo.com/4t_4sp/4t_4sp.htm

A google search found this site. I'll have to find a translation so I can see what they are talking about.


Good site, inside is also a picture of a Honda single cylinder 500 cc engine, with radial valves (1983)

[henk4]

ah th Apfelbeck radial head :) Phenomenal performance from a small block for it's day.

Indeed, BMW quoted 310 bhp from 1990 cc....

[Kitdy]

Indeed, BMW quoted 310 bhp from 1990 cc....

Why is it not used? Complexity? Cost? Mass?

[culver]

It was very complex and needed two sets of rockers per valve. It also adds a good bit of height to the top of the motor. It's an example of a solution that increases specific power at the expense of increased engine mass, volume and cost. Odds are these days there are more effective methods to gain the extra power. Or conversely, the extra size of the motor presented a packaging problem that made it uncompetitive. When it comes to race engines (which the BMW motor was) sometimes it's not issues with the engine but issues with integrating the motor into the chassis that cause problems. Ferrari stopped doing flat 12s for this reason (they hurt underbody aero).

BTW, I am speculating though I strongly suspect the cost benefit ratio just didn't favor this solution.

[Lets Gekiga In]

LS3 is the engine going in the 2008+ Corvettes. Beastly.
Yep, I cannot wait. No better time than now to get a convertible Vette! :D

[Matra et Alpine]

It was very complex and needed two sets of rockers per valve.
Only for the very fiurst bversion where he laid out the valves in perfect hemispherical angles. Later versions they went for the more common and successful parallel pairs.

It also adds a good bit of height to the top of the motor.
No. Not a "lot" and in later versions the cam sat in the middle of the valves :)

It's an example of a solution that increases specific power at the expense of increased engine mass, volume and cost.
It wasa race development to maximise the output from a fixed capacity......

Odds are these days there are more effective methods to gain the extra power.
........ so the answer is pretty much NO :)

Or conversely, the extra size of the motor presented a packaging problem that made it uncompetitive. When it comes to race engines (which the BMW motor was) sometimes it's not issues with the engine but issues with integrating the motor into the chassis that cause problems.
But they weren't :)
reliability really ended the efforts -- and better understanding of x-flow head design :)

BTW, I am speculating though I strongly suspect the cost benefit ratio just didn't favor this solution.
In reality it was a step along the way of head design, much of which still stays with us.
A dutch team are producing a modern version to test out the hp/l efficiency claims he calculated. Looks a nice pieve of kit too :)

[FikseGTS]

the same guys who dyno'd the first LS3 (LG) are now getting 507hp and 457 tq with some decent mods:

» 2008 Chevrolet Corvette LS3 Dyno Results (http://www.dragtimes.com/blog/2008-chevrolet-corvette-ls3-dyno-results)

[Quiggs]

Mother of God...

[Lets Gekiga In]

And the Corvette keeps kicking ass.