Pushrod or OHC

[Matra et Alpine]

Originally Posted by Slicks

All depends on the car. Torquey cars, you can and generally do (f-bodies, corvettes, mustangs etc.) Even when I drove that Celia GT I let the clutch up before 1000RPMs and was fine.

Not black and white, just an overexhaduration. Its still not conveinient (under normal driving) to have to rev higher before slipping the clutch.

Missed the POINT completely.

You DO have to slip the clutch anyway.
Or you lurch off.
So it's actually NO EXTRA effort.
The point I was making was that in the teaching of driving they dont' go ontothe throttle until the person understands about clutch bite point. THEN they teach about balancing the car on throttle and clutch.
If a driver does not learn that skill and it become second nature then they cannot do effective steep hill starts, or starts towing heavy trailer or BOTH !!!
Once the skill is properly learned then there is NO difference.
To suggest otherwise is forgetting that there is more to driving a car than starting off on a flat road

Stop thinking in a racing POV.
Think about he statement "gears are to stay in the powerband". That alone just says nothing about acceleration (not saying racing acceleration, but just to get from a to b). Like I said, if that were the case, then only one gear would be necesary, since it says nothing about acceleration. Gears are for acceleration, AND match the powerband(really depends on the car, like trucks are going to have gears for towing, and economy cars are going to be geared for economy.)

I wasn't just and don't assume I was.
In ANY car the wider powerband means you can stay in the same gear longer and hence do NOT need to change gear so often when at the extremities of a narrower power band you would have had to change down or up.
Have you driven a range of manuals with varying power bands ?
If you had then you will have experienced that surely ????
So gears are about MATCHING the power band to give the speed - I've said it often enough for the penny to have dropped surely

Yes, width of the band matters, I know. But in normal driving (stop thinking racing, cars were not made in the intension to race, think model T, made for transport) the lower the RPM the power comes at the easier it is to drive.

ONLY if you can't drive a manual.
ANY driver who does not balance throttle and clutch on takeaway is incapable of driving with a heavy load, heavy trailer or starting on steep hills.
At some point there is not enough torque to move the vehicle.
So learning the skill it is no hassle to execute.
Drivers don't ever actually THINK the activity.
It becomes a learned response.
So not any more difficult.
If it was, then all cars would be built with a first gear and enough torque NEVER to need the throttle to drive off.
They aren't. Consider why not
Be careful, I am NOT saying that lack of torque at low end is a godd thing. Of course the balancing of throeel and clutch is an easier exercise with a torquier engine - unless you'r on snow and ice and then the OPPOSITE is true

Ah, but wouldnt taking an LS (keeping 5.7L) and making it rev to, say, 8000RPMs to produce the 600hp be "enough"? Larger dispaced engines produce more torque, and usually a better torque curve, and that is what matters.

I've proven the last comment not true with LINGENFELTERS own facts.
In the balance of things lots more torque is better than a tiny increase in bandwidth.
Equally HUGE bandwidth can make up for not having much torque.
and LOTS of gears can make up for narrow bandwidth. Don't know about US trucks, but Eureopan trucks and motorway buasses can have 12+ gears.
Gears are torque multipliers.
What matters to a cars performance is the torque it delivers at the wheels.
How it makes it is irrelevant to the fact of moving the car - though does make a difference in many other areas
as you say, taking a nice torquey engine and expanding it's rev AND matching power band WOULD be enough.
That has been said all along.
Except some cars do it in different ways and not just the height, but employ the width

Reprogramming the LS1 to eliminate the rev limiter does NOT increase the powerband, becuase the LS1 was NOT made to make power at that high an RPM. If it were re-tuned than yes, but taking the rev limiter away on a stock engine is just asking for trouble.

duh, you would normally reprogramme because you have changed something else.

Ah OK, I'll write to Lingenfelter and tell them they're wrong cos Slicks on UCP says you're wasting your time
Also, I dont' know about the LS1 but many older OHV engines had limiters on because they broke above certain revs, NOT because they lost power !!! BDAs, 1380s would all throw parts before they ran out of steam

So then more revs do NOT mean better powerband, a point Ive been trying to get across. BUT they CAN mean a better powerband, that doesnt mean they always will though.

Correct. but more torque does not mean better performance AT THE WHEELS THROUGH GEAR CHANGES either.
You can't take a single item and make it the prima-face of engine performance. And that's why you're stuck in theis "old-thinking" mindset.
As I'd said way way back. Much more torque/power is better than a little extra bandwidth.
BUT an engine that has reasonable usable torque AND a wide powerband means the car has to do less gear changes to travel a set course be it on track in town or tootling about !!
UNLESS if has insufficient torque to get the thing rolling to start with - ie no point putting a bike engine in a 1960s muscle car. it wont go anywhere. Equally little point in putting a 1200hp tuned LS1 in a Lotus 7. ( 500bhp seems to be the max before it's the tyres adhesion is THE big limiting factor on a car so light - it needs MU values way above 1.0 to even work then )

Good read, im sure Ive posted it before:
http://www.caranddriver.com/article....&page_number=1

In that article, Winegarden admits that DOHC is used for MARKETING, rather than a "better" engine. Yes, he says that it has its advantages, in which it does, but I made an earily point even more true now.

Actually at NO POINT in that article does he say it's marketing.
Could you review it please and point it out.
I may have missed it.

Your right, revving higher for an OHV engine would most likely start to bend the rods. But it is true that they don't NEED to, because if you have a powerband as big as another cars powerband, whats the point?

aha. you've got it --- so it HAS been worthwhile !!!
"as big as" -- bang on. If powerbands are equal then the one with more power/torque wins.
If powerbands are NOT equal then it becomes a "depends" - how much power, how much weight to move, how many gears and a dozen others
Look back a few dozen posts, this was given to you on a plate

Again, your thinking racing. Increasing revs does not always lead to a better powerband, and more certainly not a more "usable" one. Remember street driving, you are switching up at lower RPMs, your not racing at WOT near redline.

HAVE to remind you again that racing is NOT about being on the redline either. If race casr spent all the time on the redline they woudl expire within about 10 minutes MAX.
I suspect watching too much NASCAR and Demolition Derby has addled the brain

Most of the time you have the gas peddle 1/10th of the way down from WOT, if even that much (depends on car).

And having learned the skill to press the pedal at all, how is it harder, more complicated etc etc to use it properly ??
So I drive with the throttle probably 1/4 way down most of the time.
Each of our feet have moved, HOW is one different than the other ? Same physical act, just a different postion

[Matra et Alpine]

Originally Posted by henk4

This is not the story I am hearing from Germany, where old cars are being run properly without any changes to the engine. At least they don't mention it but I have to check that.

Maybe it depends on how good the engine management settings are and also how much of a 'mix' is run.

In the early days you could mix cold diesel with gasoline to prevent gelling, but it seems that high pressure TDi and HDI engines don't allow this any more. Therefore winterdiesel has some additives to prevent gelling.
I am sure for biodiesel they will be able to find a similar thing.

Guaranteed they could, IF the oil companies invest in it

[Matra et Alpine]

Originally Posted by Slicks

A couple problems, your using torque, which actually if you think about it should be the one being used.

I know torque is really what SHOULD be used because power is an application over time. Torque is what we USE of an engine at any instant.

But I used hp, in which if that was wrong, you should have corrected me, you wanted the right formula right? (or do you want your formula....
Actually funny enough, the 25% formula can come close here.

Look at the thrird dyno:
Peak torque = 410
410 * 75% = 307 (you had 340)

And using 15% instead of 25%
Peak torque = 410
410* 85% = 348, much closer to your calculation.

Looks like my mental calculations failed me there, sorry
yeah, this is the best point to remind us that these things are "rules of thumb", most cases, etc. There are bound to be configurations where they don't work out quite that way.
It's important NOT to get too hung up about ONE number - be it lb/ft OR bhp there are too many variables that affect either

Just an example, but for the most part, it seems that the 20% formula "works" here. Really it just seems to show revs here, like the 3rd one again for example, 5200RPMs *20% is 1040RPMs, so is that supposed to be the powerband then? The peak torque occurs at about 3800RPMs, what does that have to do with the formula? How does it really show the "powerband?"

The 3rd calculation for example (im using this because its 20%, not 12% like the first) seems incorrect. Sorry if I missunderstood this but:
410 peak * 80% is 328, not 340.
Or is it 5200RPMS * 80% = 4160RPMs, which is roughly where the peak torque occurs. So are you saying 4160RPMs - 5200RPMs is the "20%" powerband? Because from 3500-4000RPMs the torque is pretty much the same, shouldnt that be "usable" then, since its the same at 3500 as 4160?

I think it IS confusing as even I'm not sure of which numbers you're quoting and I know we had the mix up with that before. So I'll go over it again.

Find the point in the rev band that the peak is.
For the torque or power at that peak calculate a -20% point for it.
Then look along the graph to find where the powerband crosses that torque/power figure. THAT is the +-10% point for the curve.
SO a curve that peaked at 150hp would have +-10 points at 120hp.
If the peak was at 4500 revs and the curve crossed the 120hp line at 1500 and 5500 then the "usable powerband" would be 1500 to 5500 a total of 4000 revs. NOTE that where the peak occurred doesn't come into it. Also that we do NOT calculate the revs we read them straight from the curves.
The same for torque.


Actually let mo go over the theoretical usage as it is slightly different but involves the mean and averaging over time. I've avoided that till now as the how the average is taken over can have a dramatic impact on the results seen Usually an industry agrees on one. What is normally done is a mean is taken over the main powerband and that mean comes out to GIVE the +-10% points. Except now the mean power is in the middle. So the peak is 10% ABOVE the means and the lower limits at the left and right of the curve are the -10% limits. As engines follow a typical arc then it's usually accepted that the area above and below within the +-10% points are the same so taking the peak to be the +10% point is acceptable. PLEASE dont' ask me to go over the statistical theories for that. I can for the electronics and it will take a LOT more time than I have here given how long it's taken to get the simplified "practical" usage over

[Matra et Alpine]

Originally Posted by henk4

Matra, I got news for you, I do let the clutch up at idle, very convenient in slowly moving traffic jams. I can shift through to second and then to third without even touching the throttle and still the engine won't stall.

In fact when Wouter was having his official driving lessons in an Honda Accord, his instructor told him not to drive my car anymore, because it was too easy. (another free benefit of the diesel, with one OHC )

A good instructor.

Yeah, but is it really "easier" ?
Isnt' your foot on the throttle ready to accellarate ?
So it's the differecne between 1/4" up or down of your right toe

I do it as well, but I'm alwasy on the throttle ready to apply more gas when needed. Part fo my advanced driving training. Your foot is either on the throttle ready to accelerate or is already accelerating or is on the brake or already braking. Anywhere else is "bad". You may wish to accelerate out of or brake to avodi a possibel incident.

Glad to see Wouter's instructer making sure. Otherwise the first steep hill and he'd be in trouble. Mind you you coudl drive most of the day and not fidn anything worse than 1 in 20 at a bridge over a canal OR towing.

[targa]

wow, this has gotten super technical

[henk4]

Originally Posted by Matra et Alpine

A good instructor.

Yeah, but is it really "easier" ?
Isnt' your foot on the throttle ready to accellarate ?=

In traffic jams my right foot is hanging above the brake pedal . The fact that I can accelarate without moving the throttle does not mean I always do it.
It also comes very handy under slipperry and snowy conditions where you can take off without wheelspin.

[Slicks]

Originally Posted by Matra et Alpine

Missed the POINT completely.

You DO have to slip the clutch anyway.
Or you lurch off.
So it's actually NO EXTRA effort.
The point I was making was that in the teaching of driving they dont' go ontothe throttle until the person understands about clutch bite point. THEN they teach about balancing the car on throttle and clutch.
If a driver does not learn that skill and it become second nature then they cannot do effective steep hill starts, or starts towing heavy trailer or BOTH !!!
Once the skill is properly learned then there is NO difference.
To suggest otherwise is forgetting that there is more to driving a car than starting off on a flat road

Alright I understand, but like Henk4 commented, say your sitting in traffic, its much more convienent to slip the clutch and not have to worry about your car dieing from being at too low of an RPM.

I wasn't just and don't assume I was.
In ANY car the wider powerband means you can stay in the same gear longer and hence do NOT need to change gear so often when at the extremities of a narrower power band you would have had to change down or up.
Have you driven a range of manuals with varying power bands ?
If you had then you will have experienced that surely ????
So gears are about MATCHING the power band to give the speed - I've said it often enough for the penny to have dropped surely

Ive driven a decent range of cars with varying powerbands, and found it much more convienient to drive the ones with power at the low RPMs. It was also alot more fun, the slightest touch of the gas got you going.
Gear DO match the powerbands, but thats not what they're about. Think about in a drag racing sence. Let say you have a stock car, you change out the gears for smaller ones, this increases acceleration. WHy? Because gear manipulate torque. You stay in the powerband for a shorter amount of time now (beacuse the gears are smaller you engine revs faster through them), but you are going quicker.

I've proven the last comment not true with LINGENFELTERS own facts.
In the balance of things lots more torque is better than a tiny increase in bandwidth.

How so? I didnt see anything prooven.

Equally HUGE bandwidth can make up for not having much torque.
and LOTS of gears can make up for narrow bandwidth. Don't know about US trucks, but Eureopan trucks and motorway buasses can have 12+ gears.

True, because you can put in small gears and manipulate the torque more.
I dont know about our semis, but I know from experience in riding the school bus in the early years of high school that they have 4 or 5 gears.
Oh yeah, and the "U hauls" (moving trucks) are usually 5 speeds.

duh, you would normally reprogramme because you have changed something else.

Ah OK, I'll write to Lingenfelter and tell them they're wrong cos Slicks on UCP says you're wasting your time
Also, I dont' know about the LS1 but many older OHV engines had limiters on because they broke above certain revs, NOT because they lost power !!! BDAs, 1380s would all throw parts before they ran out of steam

Notice lingenfelter isnt making a STOCK LS1 rev higher. Yes, they will mostlikley bend a rod(or more ).

Actually at NO POINT in that article does he say it's marketing.
Could you review it please and point it out.
I may have missed it.

"So if the pushrod design makes such a good V-8, why does GM make a DOHC V-8 Northstar? "I'm not going to touch that one," laughs Winegarden. GM's party line is that some customers want what it calls "high-feature engines." Winegarden does admit there are some refinement benefits to the DOHC layout, but personally, I don't find the Vette's engine to be a bit unruly."
They want the "high tech" DOHC engines. So in other words, if the people didnt want the "high tech" engines, GM wouldnt bother with making them.

aha. you've got it --- so it HAS been worthwhile !!!
"as big as" -- bang on. If powerbands are equal then the one with more power/torque wins.
If powerbands are NOT equal then it becomes a "depends" - how much power, how much weight to move, how many gears and a dozen others
Look back a few dozen posts, this was given to you on a plate

Ive known that all along...

HAVE to remind you again that racing is NOT about being on the redline either. If race casr spent all the time on the redline they woudl expire within about 10 minutes MAX.
I suspect watching too much NASCAR and Demolition Derby has addled the brain

Ok, not at redline, but close to it. Definetly not close to idling RPMs.
Nope, dont watch NASCAR or demolition derby(although thats kind cool), if im watching racing(which is rare) its usually F1, WRC, or LeMans. And for the most part I dont watch more than like 10 minutes(with the execption of WRC), gets boring watching the same thing over and over.

And having learned the skill to press the pedal at all, how is it harder, more complicated etc etc to use it properly ??
So I drive with the throttle probably 1/4 way down most of the time.
Each of our feet have moved, HOW is one different than the other ? Same physical act, just a different postion

Wouldnt you like it if it were easier to get the car moving with less throttle?

[Slicks]

Originally Posted by Matra et Alpine

Looks like my mental calculations failed me there, sorry
yeah, this is the best point to remind us that these things are "rules of thumb", most cases, etc. There are bound to be configurations where they don't work out quite that way.
It's important NOT to get too hung up about ONE number - be it lb/ft OR bhp there are too many variables that affect either

No big deal.
My confusion is here: lets say that an engine maker makes a non performace engine, its power(generally) will be in the lower RPMs for street driving. How do you measure its band?
The point of actually taking the torque band (instead of revs) and multiplying that by a % is that not all cars rev to the same RPM, and not all powerband are setup the same. But, all cars do make torque, use that to find its powerband.

I think it IS confusing as even I'm not sure of which numbers you're quoting and I know we had the mix up with that before. So I'll go over it again.

Definetly confusing :P

Find the point in the rev band that the peak is.
For the torque or power at that peak calculate a -20% point for it.

The RPM or the peak torque?

Then look along the graph to find where the powerband crosses that torque/power figure. THAT is the +-10% point for the curve.

Im assuming its the RPM multiplied by 20%, in that case:
http://www.compcams.com/Technical/Dy...56H-10_001.asp
with this the peak torque is at 4000RPMs, 4000RPMs (20%) = 800RPMS???
Or 4000RPM (80%) = 3200RPMS???


I gtg, Ill reply to the rest later.

[henk4]

Originally Posted by Slicks

Ive driven a decent range of cars with varying powerbands, and found it much more convienient to drive the ones with power at the low RPMs. It was also alot more fun, the slightest touch of the gas got you going.
Gear DO match the powerbands, but thats not what they're about.

you now show the right mindset to switch to the new generation of powerful diesel engines, now just hope they will make it to the USA. (and they all have OHC's )

[Matra et Alpine]

Originally Posted by Slicks

Ive driven a decent range of cars with varying powerbands, and found it much more convenient to drive the ones with power at the low RPMs. It was also a lot more fun, the slightest touch of the gas got you going.

We'll just need to let that one drop because you focus on the first 1/4" of movement on the throttle as giving you that movement, I say its the 1/4" to 1/2" point. Frankly don't see the difference when you are actually DRIVING a car and not just mind-masturbating about it So much of what has been typed here NEITHER of us gives one fraction of a seconds thought to when we are actually in our cars

Gear DO match the powerbands, but thats not what they're about. Think about in a drag racing sence. Let say you have a stock car, you change out the gears for smaller ones, this increases acceleration. WHy? Because gear manipulate torque. You stay in the powerband for a shorter amount of time now (beacuse the gears are smaller you engine revs faster through them), but you are going quicker.

You're thinking drag racing where you just go up through a gear.
Think street driving and road racing where the longer you can stay IN a gear and have usable torque at the wheels the better it is.
Thinking acceleration is only one side of a complex cube

True, because you can put in small gears and manipulate the torque more.
I dont know about our semis, but I know from experience in riding the school bus in the arly years of high school that they have 4 or 5 gears.
Oh yeah, and the "U hauls" (moving trucks) are usually 5 speeds.

SERIOUSLY, busses only have 4/5 gears ??
SHOCKED.
I did a quick qoogle and a 95 Freighlineer had 10 gears !!
I think that is passage of time Your school bus isn't really representative of what happens today.

"So if the pushrod design makes such a good V-8, why does GM make a DOHC V-8 Northstar? "I'm not going to touch that one," laughs Winegarden. GM's party line is that some customers want what it calls "high-feature engines." Winegarden does admit there are some refinement benefits to the DOHC layout, but personally, I don't find the Vette's engine to be a bit unruly."
They want the "high tech" DOHC engines. So in other words, if the people didnt want the "high tech" engines, GM wouldnt bother with making them.

That's a long way from "Winegarden admits that DOHC is used for MARKETING, " which implies DOHC is a marketing ploy with no technical merit. NOT what is said.

Ok, not at redline, but close to it. Definetly not close to idling RPMs.

No even close to it. Repeat - any race car that sits on OR CLOSE to redline has limited life.
A race car ACTUALLY is geared up to spend MOST of its' time at peak power for speed, torque for twisties.
Yep, nobody sits close to idle - even on launch == that is meant to raise a SMILE

Wouldnt you like it if it were easier to get the car moving with less throttle?

The exception is the busy city traffic as henk suggested where with an engine torquey enough you can NEVER touch the throttle whilst starting/stopping moving VERY slowly. BUT as soon as you need to touch the throttle I struggle to see how you can make the "benefit" tangible.
As I'd said, for a light car it doesn't' need a LOT of torque to handle those situations anyway. Heavy load a different matter

[Matra et Alpine]

Originally Posted by Slicks

Im assuming its the RPM multiplied by 20%, in that case:
http://www.compcams.com/Technical/Dy...56H-10_001.asp
with this the peak torque is at 4000RPMs, 4000RPMs (20%) = 800RPMS???
Or 4000RPM (80%) = 3200RPMS???

NO.

It is peak then take off 20% and then LOOK ON THE GRAPH FOR WHERE THAT LINE crosses the graph.

NEVER multiply revs or take 5ages or anything.

just READ the revs from the graph axes.

I'll try and get the time to draw it later

[zeta]

I hope GM stays orginal with OHV motors, thats a good american tradition instead of flowing the Euro (F1) tricked out cam OHC style (all the time) "high tech". I they think should develop on pushrod engine technology- like figgerout how to improve the disadvantages over OHC(). Aside from all the other advantages , the OHV most importantly gets much better fuel mileage and is lighter weight, then OHC. The 6L LS2 gets the gas mileage of V6's, and the GM 3.8 series III (OHV) V6 gets the mileage or better of some (29city/32hwy) 4bangers This defeats the purpose of small engines for better fuel economy in (most cases) or that big motors pointlessly just waste fuel. Making american style performance and American trademark big motors, reasonable to exists. That comment on OHV valvetrain having reliable disadvantage because of 3 more moving parts or rocker arms not as quick as OHC set up , is rubbish

If some ever decides to make camshaftless motors it going to change the game forever, Slicks reminded me, the ECU/PCM controlling timing and lift duration, instead of the mechanically imperfect complex cams, the computer would balance out everything to almost endless revs- if its programmed (without factoring engine heat and motor endurance)

GM makes a large line of deseils the Duramax. in 6.2L, 6.4L, 6600 (they should put those as options in full sized trucks like the H2 and sclade, like the pick-ups.

*Realized. the GM 3.8 V6 is the most fuel efficent V6 in the world? what other V6 gets 29city/32-34hwy?

[Alastor]

Originally Posted by zeta

thats a good american tradition instead of flowing the Euro (F1) tricked out cam OHC style (all the time) "high tech".

...

the ECU/PCM controlling timing and lift duration, instead of the mechanically imperfect complex cams, the computer would balance out everything to almost endless revs

Perhaps I am miss-understanding the technology, but aren’t F1 engines cam-less and operate as described above (although with hydraulic actuation)? So does that mean F1 is actually "a good American tradition?"

[CdocZ]

Originally Posted by Alastor

Perhaps I am miss-understanding the technology, but aren’t F1 engines cam-less and operate as described above (although with hydraulic actuation)? So does that mean F1 is actually "a good American tradition?"

American tradition is also low revvers. F1 cars rev like VERY few others.

[MetA]

Originally Posted by Alastor

Perhaps I am miss-understanding the technology, but aren’t F1 engines cam-less and operate as described above (although with hydraulic actuation)? So does that mean F1 is actually "a good American tradition?"

Nope.
Here's the Ferrari V10

They still cannot make the actuator small and light enough to fully replace the cams. Renault played with it but cou;dn't get the thign smaller than a coke can Someday though

Anyway, THIS is what they currently do ....


The almost perfect 'cube' of the M-B ingine