Pushrod or OHC

[NAZCA C2]

You gotta like pushrod engines for their superior performance for the money. You can get a 550+ hp fordracing crate motor for well under $10,000. If you want a dohc motor with that much power your gonna have to spend a lot more. If money is no object then the dohc motor is definately the better choice.

[henk4]

Originally Posted by NAZCA C2

You gotta like pushrod engines for their superior performance for the money. You can get a 550+ hp fordracing crate motor for well under $10,000. If you want a dohc motor with that much power your gonna have to spend a lot more. If money is no object then the dohc motor is definately the better choice.

That is because they are based on mass produced engines, the marginal costs for tuning them are relatively low. If the Northstar was produced in similar numbers as the small block Chevy, your costs figures would more or less correspond. It has nothing to do with the having pushrods or ohc's, it is just about the numbers

[targa]

i think i have made my views of pushrods clear

[henk4]

Originally Posted by targa

i think i have made my views of pushrods clear

but not in this thread. Enlighten us please

[90ft]

The overiding factor between the two has always been COST.
Performance wise DOHC are superior.
Over head make the heads much more expensive to manufacture.
It's what you get for your money. That's what drives car companies at the end of the day. Money.
Corvette is different when tradition has overtaken sense on all fronts.
Has to be designed and built in Detroit and has to be push rod. No exceptions made.
So they do their push rod engines with magnesium and titanium bits everywhere. Stupid!
Like harleys, has to run like shit and rattle your teeth out. Not because they can't make better engines but because of tradition.
GM make some great DOHC engines. The Northstar V8 for example. And their racing engines.
It's just a cost issue.
Bang for your buck.
You want a better engine and cost isn't a factor - DOHC.

[henk4]

Originally Posted by 90ft

The overiding factor between the two has always been COST.
Performance wise DOHC are superior.
Over head make the heads much more expensive to manufacture.
It's what you get for your money. That's what drives car companies at the end of the day. Money.
Corvette is different when tradition has overtaken sense on all fronts.
Has to be designed and built in Detroit and has to be push rod. No exceptions made.
So they do their push rod engines with magnesium and titanium bits everywhere. Stupid!
Like harleys, has to run like shit and rattle your teeth out. Not because they can't make better engines but because of tradition.
GM make some great DOHC engines. The Northstar V8 for example. And their racing engines.
It's just a cost issue.
Bang for your buck.
You want a better engine and cost isn't a factor - DOHC.

If cost is an issue why are then all engines of smaller cars, where costs are much more critical due to the lower margins, being fitted with S-or DOHC engines?

[Matra et Alpine]

I wonder if the cost issue is as big as it once was.
The heads used to need more machining which USED to be a manual task.
Now with semi-automated casting and fully automated machining I wonder if the price is significant anymore.

[Slicks]

Originally Posted by 90ft

Corvette is different when tradition has overtaken sense on all fronts.
Has to be designed and built in Detroit and has to be push rod. No exceptions made.

Gm already tried DOHC in a Corvette, it failed immensely, it gained 200lbs over the same year LT1 engine'd Corvette, and the LT5 was 100lbs heavier than the OHV LT1, and 200lbs heavier over the current LS1, and even more so heavier than the LS6/LS2 (and probably LS7).

So they do their push rod engines with magnesium and titanium bits everywhere. Stupid!

What engine is using magnesium? And only the LS7 is using titanium, and thats only on the pushrods. Even with that its STILL cheaper than most same power'ed DOHC engines.

Like harleys, has to run like shit and rattle your teeth out. Not because they can't make better engines but because of tradition.

How do Harleys "run like shit"? They "rattle" because of the lobey cams they have, and long stroke for nice torque and a beautiful exhaust not. Its not about tradition, its about what people want, they want that "rattle."

GM make some great DOHC engines. The Northstar V8 for example. And their racing engines.
It's just a cost issue.
Bang for your buck.
You want a better engine and cost isn't a factor - DOHC.

The Northstar is a great engine, but the LS1 is smaller, lighter, more powerful, more gas efficient, and most of all cheaper, so which do you want in your car?

[henk4]

Yes Slicks the Corvette is using pushrods, virtually all other constructors for high revving, low revving and very competitive cars all use OHC, my god are these people stupid.

[Matra et Alpine]

Originally Posted by Slicks

How do Harleys "run like shit"? They "rattle" because of the lobey cams they have, and long stroke for nice torque and a beautiful exhaust not. Its not about tradition, its about what people want, they want that "rattle."

having ridden one, the comment was about rattling your teeth out, not valvetrain rattle.
"not tradition" -- "what people want" erm that IS tradition isn't it ??
it's what Harley have alwys sold on.
Harley are the only bike maker to have patented their engine sound they feel ThAT sstrongly it's why people buy there product. The famous "potato-potato" sound
Like the big cars on US freeways, if I had to sit on a bike at 55 for 4 hours I would prefer the Harley. Anywhere else and it's not the favourite.
The engines run fine, they are designed to maintain the harley sound and good on the company for identifying their unique selling point and adhereing to it. Shame that British bikes in the 60s USP was leaking oil and they satayed with that till they went bust

The Northstar is a great engine, but the LS1 is smaller, lighter, more powerful, more gas efficient, and most of all cheaper, so which do you want in your car?

What are the relative sales volumes of these respective engines.
It was previously raised that the LS1 is cheap because of volume.
You're never going to get a cheap Ferrari engine for as long as they stay with low volume and hand-engineered/built.
It woudl be interesting to conjecture WHAT-IF on a Ferrari or Lambo or BMW engine if it coudl be made in the same numbers and factory costs as the LS1

[megotmea7]

This has been a point of discussion all the time when the corvette C6 was
being set off against european cars.

the corvette uses pushrod motors because that is the best solution for that car, its what the buyer wants. in that car it is a more compact, lighter design which produces all the torque and power that is required(well mabe a smidget more... ) for cheap. i cannot think of a better motor to go in a corvette. and sure heritage is part of it. the LT5 was DOHC and it was a good motor, but as slicks said it was heavier and cost kept it from being much of a success. pushrod may not be the best design alone but it is the best solution in many sitations, such as the corvette. especially considering the corvette is one of the best high end sports car values today compared with the likes of the viper, M3, 911, etc.

So both modern high revving and low revving engines produced in Europe (and Japan) are fitted with OHC's. In my opinion this means that for choice options you describe OHC's provide the best option.

best option no, as i described above with the vette "best option" is a reletive term. "best" for a bimmer or a civic doesnt mean its "best" for a corvette or GTO. im under the impression that modern diesels use OHC designs because of the more precise control needed for a more efficient combustion process. and the inherent design of diesel blocks makes weight pretty much a non-issue. at least not enough of an issue to justify not using an OHC design.

cost is also an issue. pushrods are cheaper, possibly both for the reasons henk posted and for the manufacturing process. it is more expensive to have a OHC head ported than a pushrod head, it cheaper to cast/grind one cam than 4. 16 valves/springs as oposed to 32. and with advancements in pushrod head design such as those used on modern chevy LS engines the advantages of OHC are hardly worth the cost(both monetary cost and weight/volume)

engines such as the DOHC northstar and the SOHC/DOHC ford modualr motor have been mass produced for over a decade now. they can be had for reletivly cheap. and are used in replacement for the likes of LS and LT motors. but the fact still remains that it is easier and cheaper to buy an LT1 or LS1, build and make power out of than it is for en equivelent mass produced DOHC motor such as the mod' or northstar. its just the way things are....

[henk4]

Originally Posted by megotmea7

pushrod may not be the best design alone but it is the best solution in many sitations, such as the corvette.

Interesting contribution Meg, I won't dwell on all your points, but I would like to be told more about why the Corvette is so unique that a pushrod is better there. Aren't there any other comparable sportscars that could also benefit from the perceived advantages of the pushrod? Or is it still the case that the engine can be made cheap because the majority of the LS engines is being sold in truck in less tweaked form.

I am not downplaying the qualities of the C6, in fact I just read a comparison between the C6 and the 911S done by the French magazine Echappement, whereby the Porsche was a tat faster in all departments (including the 1/4 mile) but that was due to a much better gearbox which really has 6 gears while the C6 has a 5 plus 1. Also the C6 engine picked up slightly less alert than the Porsche. With a price of more than 30000 US$ less in Europe this is not a thing that prospective C6 buyers would worry about.

Cost issues need to be further investigated, if all cost advantages that pushrod engines appear to have (if what you said is correct) then I really don't understand why so few engines still run on pushrods. Can you name one new design less than 10 old that is running OHV? (not the small block derivatives)

[megotmea7]

I would like to be told more about why the Corvette is so unique that a pushrod is better there. Aren't there any other comparable sportscars that could also benefit from the perceived advantages of the pushrod?

no, the corvette is not unique at all. there are comparable cars, such as the 911 and the M3. both using more "advanced" DOHC 6 cylinder powerplants and producing comparable power to a vette. the main reason i see however that the vette still uses a big OHV V8 aside from heritage is the fact that it gains nothing by going to an OHC engine aside from a couple hundered pounds and a more cramped engine bay. im sure the M3 could (and has in some cases) benifit from a small compact OHV V8 but who wants their ultimate driving machine to be pushrod powered? im sure it would shed a few pound but it wouldnt be a bimmer. the small block is a better motor for the vette not only from a engineering perspective(light weight, good power, good torque, good gas mileage, cheap to build) but from a buyers perspective (power/torque, ease of driving, gas mileage, ease of moding, vette heritage, etc.). just as the case with the M3 owner, he/she wants a high tech motor to go along with his/her cutting edge chassis design and overacheiving handling. but what advantages do you see the M3's I6 having over an LS2 or even an LS1 smallblock fitted in the vette?

I just read a comparison between the C6 and the 911S done by the French magazine Echappement

ive not actually seen a comparison between the C6 and the new 911 but ive heard from a friend (who happenes to be a big porsche and german car fan, he loves the E30 bmw) where those 2 cars were compared, and the C6 beat out the porsche in every criteria, but the porsche won in overall because of its more inspiring feel and being more controlable and stable, making you want to pushn it further than you'd want to in the vette(which i can apreciate). but im not going to argue the vaildity of either claim. they are both great cars, and has their individual merits; price, performance, and feel.

Cost issues need to be further investigated, if all cost advantages that pushrod engines appear to have (if what you said is correct) then I really don't understand why so few engines still run on pushrods. Can you name one new design less than 10 old that is running OHV? (not the small block derivatives)

im no engine manufaturer, im giving my opinion based on what ive seen when it comes to cost of engine building, theres a reason the LT5 failed miserably, and it was ebcause of price, beacuse they could make the OHV engines for cheaper and acomplish the same thing while taking up less space and weight. i too would like to know why pushrod motors are dying out but my theory is its the consumer. ppl want high tech, they want cutting edge, even on their base model econo boxes. OHC is a better design, more can be done with it in terms of economy(in a world where economy is becoming more and more important), just ebcause the vette has better gas mileage than a comparible sports car doesnt mean any car will get better gas mileage out of a pushrod motor. OHV also has a negitive stigma about it, esp. outside of the US. such as in the first supercar project, ppl wanted to see a 4.3 liter OHC lexus motor or a turbo 4 liter OHC I6 instead of the LS1 regardless of the increased weight/size from either of those motors. i belive its because they dont think pushrod motors are "good enough", their "old tech" even when the numbers prove them supirior for a given purpose. its just the way things are. like a diesel ferrari, if ferrari developed a diesel 4 cylinder that outperformed their V8 and V12's in every way, while sipping fuel and weighing about the same and put it in their next flagship, most ppl would have a heart attack(esp in the US where opinions on diesels are even lower than in europe, esp. in the performance dept). and it wouldnt be just because of ferraris history of high revving V12's either, it would be just because its a deisel, visions of huge big rigs whistling by on the free way come to mind. like with pushrods, big muscle cars that cant really handle come to mind. and unfortunatly ppl dont realize alot has changed since the 60's pushrods included. well thats my theory anyway.

and about the new example of a pushrod only one i cn think of off the top of my head is the 4 cylinder used in the ford ranger. not sure where/when it came from tho. just know it is used in rangers to this day. but leaving out small block derivatives leaves out alot of new motors coarse theres the new 8.1 liter big block used in chevy trucks

[henk4]

Basically it is therefore a psychologic issue, which I can understand on the supercar and luxobarge market. However, if you would ask the average
Joe in the street about the valve drive of his car you would be met with a blank stare. A mass produced engine could do very well without OHC's for image purposes, but obviously there are other technical advantages which even exceed the perceived cheaper construction costs. Matra has mentioned a few and it is difficult to understand why these advantages would not be vaid for any engine.

I don't know what the price differences were at the time, but what was the additional costs of the ZR1 compared to the pushrod version? Was the difference substantial enough to prevent the ZR1 from becoming a commercial success?

A ferrari 4-pot diesel I could probably afford. , and you may have heard that Maserati is developing a V8 version of the Fiat multijet diesel engine to be installed in the QP. The Brera will have a 5 pot 200 BHP diesel, you can buy BMW 3 coupe with the 330d engine, Audi delivered its previous A4 cabrio with a diesel and the list is endless.

[targa]

i prefer DOHC...i will leave it at that

i cried when a pontiac powered DP won daytona