Future for Pushrod engines in sportscar racing?

[chernaudi]

Is there a future for pushrod engines in protoype sportscar racing? Panoz had some pretty good sucess for a while( until the R8 showed up!). I asked Mulsanne Mike about this at his site( I asked in specific about the Panoz Elan 6.0L Ford based V8), and he said that the EEP engine's biggest problems were its size, weight, and fuel econmomy. Mike said that the size could be reduced, as well as weight, but not by much. Simply put, the Elan V8 was too tall and heavy to be really competitve with the R8's 3.6L twin turbo FSI V8. The Panoz' front end areo didn't help much neither, as the front end was as big as singer/actress Cher's lips( whether or not you think they're artifically inflated or not!).

The old 302 cubic in./5.0L Ford Windsor V8( as used in the pre-2003 Ford Falcon, the Falcon V8 Supercars, pre-1996 Ford Mustang, and the current AC Cobra replicas) could work( it was also used, in 5.0 and 5.5L guises, in the old IMSA WSC cars).

So do pushrod OHV V8's have any future in prototype sportscar racing?

[Psychoman]

I recall a project where someone attempted to convert Lee Brayton/John Menard's stillborn turbo pushrod V8 (originally designed for Indianapolis) to sportscar purposes, with promising test results... not sure how far off the ground this got though.

Had a thread at the Speed Channel boards, but the IRL/CART tech boards have since been shuttered, so this is the best link I can find:

http://sundoulos.us/motor.html

[Bob Riebe]

An all iron short deck SB Ford weighs 460 lbs., plus or minus depending exactly which block and head is used.
An all alloy short deck SB Ford weighs 360 lbs, again depending on exactly which block and head is used is used.

A 351 Windsor block is apprx., again depending on exact components, 50 lbs. heavier, so an ally one would weigh 410 lbs. plus or minus X amount depending on components chosen.

----------------------------- Length Width Height
Ford-Cosworth V-8 1995---------22.2 21.7 21.9

Ford Windsor V8 sd------ 28 21 22 with street water pump set-up

Chevy SB ----------------28 25 22 " " " " "

[MulsanneMike]

It's the weight that's the big problem of the pushrods, compare:

AER P32 T V8: 250 lbs. (this number is highly optimistic I think though "official")
Judd GV5 S2: 303 lbs.
Judd GV4: 297 lbs.

[chernaudi]

I think that the big problem is that these Ford, GM, and Chrylser small block pushrod engines were designed in the '50s and '60s. A new engine could probably be lighter. And, just for comparison's sake, the 4.6/5.4 Ford Modular V8 is taller and nearly as heavy( dispite being all aluminum) as the cast iron 5.0 engine, due inpart to it being an OHC engine. OHC engines are also sightly more expensive to build.

[Bob Riebe]

Originally Posted by chernaudi

I think that the big problem is that these Ford, GM, and Chrylser small block pushrod engines were designed in the '50s and '60s. A new engine could probably be lighter. And, just for comparison's sake, the 4.6/5.4 Ford Modular V8 is taller and nearly as heavy( dispite being all aluminum) as the cast iron 5.0 engine, due inpart to it being an OHC engine. OHC engines are also sightly more expensive to build.

The Ford mod. engine is similar in size to the Boss 429, which is bad for such a small engine, but good as one can install a Boss in the same engine bay if desired.

One reason for the small size of many OHC engine is limited amount of cubes they are capable of being built to; therefore tack on a blower, the poor mans substitute for building an engine of larger architecture.
Ford thought they could get away with it with the Mod. engine, but the success of the LS and Hemi, plus blowerless short comings of the Mod.,have forced them to build the new Hurricane.

Trouble with that is the last OHC Chevy was both heavy, apprx. 600 lbs, even in all alloy that put it fifty over a ZL-1 BB, and large, so if the new Hurricane is OHC, physics say it will be larger than the small Mod. engine.
I would bet on it probably being a Push-Rod, but you never know.

It is the rules that limit the push-rod engines, not the engine type.

[veeten]

but then again, it was during the 50's-60's that small-block engines, ranging between 221-302 C.I., were manufactured by all three auto companies. With a little modern interpretation, these engines can be used in sportscar racing.

It was Ford's 260-289 engines that brought about the end of Ferrari's domination in GT racing, and since the all-up weight of modern Prototype chassis are far lighter than anything used back then, it would make for a perfect combination.

While it may be the rules that limit pushrod engines, at least as how Bob sees it, it is the "bigger is better" mentality that has proven unnecessesary to many in sportscar racing when it comes to engineering.

[HORNDAWG]

Originally Posted by chernaudi

I think that the big problem is that these Ford, GM, and Chrylser small block pushrod engines were designed in the '50s and '60s. A new engine could probably be lighter. And, just for comparison's sake, the 4.6/5.4 Ford Modular V8 is taller and nearly as heavy( dispite being all aluminum) as the cast iron 5.0 engine, due inpart to it being an OHC engine. OHC engines are also sightly more expensive to build.

So which is it? Push rod or OHC that is no good? As per the example's given, neither are good. So what a reed valve assembly? I think it is mostly architecture (to accomodate c.i.) and metallurgy that are the challenges.

L.P.

[chernaudi]

I'm saying that OHC engines are more expensive and heavier than comparable pushrod engines made out of the same stuff. As far as engine capcacity, as long as you don't bore out too much metal, you can make it nearly any capcity you want by playing with bore and stroke as long as you don't bore too much metal out of the engine block. The 4.6/5.4 Ford engines are nearly as big as Ford's old NASCAR big block 7liter engines. Even a cast iron 5.8 Cleveland engine( like in the DeTomaso Pantera) is smaller than the Ford Modular engines and for sure the Modular based Boss/Hurricane engines. The aluminum 5.8 engine( which is what Panoz used in their LMP cars) is also far lighter.

And even then, the Audi R8/Bentley Speed 8 3.6-4.0 aluminum twin turbo V8s weigh about 390lbs. And the aluminum 5.0-5.8 Ford engines aren't much heavier.

[HORNDAWG]

Lets not also forget that these engines are designed and built to be mass produced. And worked on by your corner mechanic. Its not that the person at the corner shop isn't any good,its just a little to high tech to be expected everywhere. And we know that a LMP engine isn't designed to go 1/4 million miles in its service life!!

L.P.

[AU N EGL]

Originally Posted by chernaudi

The 4.6/5.4 Ford engines are nearly as big as Ford's old NASCAR big block 7liter engines. Even a cast iron 5.8 Cleveland engine( like in the DeTomaso Pantera) is smaller than the Ford Modular engines and for sure the Modular based Boss/Hurricane engines. The aluminum 5.8 engine( which is what Panoz used in their LMP cars) is also far lighter.

Lets not get too carried away here. The NASCAR motors are 351 ci iron ( ~5.6L) blocks. Depending on the track configurations, and if it is a restrictor race or not, run betwwen 750-900 bhp. Bucsh GN cars run 600-750 BHP. Granted they use the engines one race then rebuild them.

I would not be suppreised that if some of the NASCAR race shops were free to build Grand AM DP engines they could come up with a very formatible and reliable motor.



Personlly I like my 5.7L V8 aluminum block, alumium head push rod, 460 bhp, 466tq motor. Very easy to work on and very very reliable.

[JHamilton]

I'd be interested to know if the weights y'all are posting are for a fully trimmed engine?

The current GM smallblock would be the best choice for a prototype as it is very compact for a large displacement V8. A Ford modular won't make it into any racecar as it's friggen ginormous.

On the OP's orginal question......I don't care if it's the slowest prototype on the track, if Panoz came out with another front engined, V8 prototype, I'd follow it around like it was the Greatful Dead.

EDIT....fwiw Nascar engines are 358ci

[chernaudi]

It would also help if the 6.0 Elan/Ford V8 were rear mounted in stead of front mounted. The Panoz's nose was as big as Cher's before she had her nose job( not to rip on her-I'm a fan of her's). Front engined prototypes will probably have the poorest areo of any racing prototype.

[JHamilton]

Originally Posted by chernaudi

It would also help if the 6.0 Elan/Ford V8 were rear mounted in stead of front mounted. The Panoz's nose was as big as Cher's before she had her nose job( not to rip on her-I'm a fan of her's). Front engined prototypes will probably have the poorest areo of any racing prototype.

I've only been watching sports car racing for 6 years. How many front engined proptypes have there been in the "modern" era?

I loved the LMP-01 and really miss it. That car was the whole reason I got into sports cars.

[Hammerdown]

No doubt someone will put me right if I'm wrong here, but don't pushrod engines have a problem with high revs? And aren't they limited to two valve heads? The more direct and precisely controlled your valve actuation, the higher your rev limit, and the better your breathing, the more power.

Having said that, however, a large capacity engine breathing through (say it quietly!) restrictors, might work quite well. Should certainly be torquey. I'm staggered by the power NASCAR engines can produce.

[AU N EGL]

Originally Posted by Hammerdown

No doubt someone will put me right if I'm wrong here, but don't pushrod engines have a problem with high revs? And aren't they limited to two valve heads? The more direct and precisely controlled your valve actuation, the higher your rev limit, and the better your breathing, the more power.

Having said that, however, a large capacity engine breathing through (say it quietly!) restrictors, might work quite well. Should certainly be torquey. I'm staggered by the power NASCAR engines can produce.

torque is word my freind. Dont need 8,000 rpms when you have 600 ft lbs of tq at 3,000 rpms.

HP or power is just a calcualted function of tq and RPM.

HP =[[ tq (ftlbs) x rpms] / 5252]

HP= TQ at 5252 ( or approimtly the same)

NACAR 358ci do spin up to 9,000 rpms.

Each engine design has it's purpose.

I personnly like BIG torque monster motors that allow one to coming out of a low speed corner at 35 mph, as your right foot goes to the floor as the car flys forward then when you shift from 3rd to 4th at 120 mph the tq just pushes you deep into the seat as your head snaps back to the head rest and the car speed acclerates up to 150+ mph. Ohh Better toss a bucket of cold water on me.

[Hammerdown]

Sounds good to me.

Can I have a go, please?

[veeten]

and that is where the Audi R10 shines. By using a diesel, designed with racing in mind, it produces similar performance numbers to the R8, but with increases in fuel economy that no gasoline engine can match, N/A or forced induction.

The real trick here is not in the engine, but in the transmission/transaxle. In being able to handle that amount of torque and putting it to the track without trouble is one of the more interesting things about the car.

I'd wager if you can take that transaxle and mate it to nearly any push-rod actuated engine, you would have similar results as american engines creat HP & Torque at sub-9000 RPM levels.

Just a theory, use it as you like...

[FCYTravis]

Originally Posted by AU N EGL

I would not be suppreised that if some of the NASCAR race shops were free to build Grand AM DP engines they could come up with a very formatible and reliable motor.

They already do. Roush-Yates does the Ford overhead-cam modular V8s.

[AU N EGL]

Originally Posted by FCYTravis

They already do. Roush-Yates does the Ford overhead-cam modular V8s.

So Travis, who builds your LSx Pontiac engines??

[FCYTravis]

Cronin Racing Development - CRD. A long-time builder of small-block V-8s for Trans-Am, ARCA, Busch, SCCA, etc. They build the Pontiacs for SunTrust/Wayne Taylor, Howard Motorsports, us and a couple others.

http://crdengines.com/

[johnh875]

Hammerdown – the issue with a pushrod is not revs (well up to practical limits <10,000 anyway) but breathing, specifically valve area. There aren’t many multivalve pushrod engines, which means they give away approx 10% advantage in valve area.

I think a pushrod engine would need a slight hand to be competitive, but then so do n/a engines against turbos, and against turbo-diesel – it is all in the equivalence factor. It really depends on what the sport wants, eg do they want a team to try using a Chev LS2 variant, and the fans/sponsors that would follow? My opinion is that variety is one of the key attractions in sportscar racing. I think JHamilton’s comment re front-engined cars backs this up.

The Ford mod engine’s biggest problem is the ridiculous 90mm bore. We get the 5.4 version in sohc 3v and dohc 4v forms, they have a 105.8mm stroke which means not only a bulky engine (taller block deck height than the 4.6) but also very high piston speeds. On the weekend I saw a 5.4 dohc V8 in a 1971 Falcon (same engine bay as 67-68 Mustang), there was approx ¼” clearance to the shock tower on one side, the other side was slightly better.

For a mid-engine sportscar installation I don’t the cross-sectional area would be a big problem apart from the centre of gravity aspect, although not ideal of course. The coming Hurricane engine will be much better, the length will increase slightly with a wider bore (all things being equal) but the overall width of the engine won’t – the dohc heads are much wider than the block.

Bob is the Chev OHC engine you refer to the Corvette ZR1 engine?

Sorry for such a long post!

[johnh875]

Edit - accidental repost #1

[chewymonster]

Actually pushrods don't make more torque, they are just usually big and run lower RPM. With equal dispacement, DOHC engines make more torque as they make more hp.

[knighty]

Originally Posted by johnh875

Hammerdown – the issue with a pushrod is not revs (well up to practical limits <10,000 anyway) but breathing, specifically valve area. There aren’t many multivalve pushrod engines, which means they give away approx 10% advantage in valve area.

I think a pushrod engine would need a slight hand to be competitive, but then so do n/a engines against turbos, and against turbo-diesel – it is all in the equivalence factor. It really depends on what the sport wants, eg do they want a team to try using a Chev LS2 variant, and the fans/sponsors that would follow? My opinion is that variety is one of the key attractions in sportscar racing. I think JHamilton’s comment re front-engined cars backs this up.

The Ford mod engine’s biggest problem is the ridiculous 90mm bore. We get the 5.4 version in sohc 3v and dohc 4v forms, they have a 105.8mm stroke which means not only a bulky engine (taller block deck height than the 4.6) but also very high piston speeds. On the weekend I saw a 5.4 dohc V8 in a 1971 Falcon (same engine bay as 67-68 Mustang), there was approx ¼” clearance to the shock tower on one side, the other side was slightly better.

For a mid-engine sportscar installation I don’t the cross-sectional area would be a big problem apart from the centre of gravity aspect, although not ideal of course. The coming Hurricane engine will be much better, the length will increase slightly with a wider bore (all things being equal) but the overall width of the engine won’t – the dohc heads are much wider than the block.

Bob is the Chev OHC engine you refer to the Corvette ZR1 engine?

Sorry for such a long post!

I have just checked the ACO rules and sure enough - all normally aspirated 2v engines can run a bigger restrictor than their 4v equivalent in the same capacity - so the ACO are aware of the 2v engines having a 10% flow defecit to 4v heads.........I dont know if this still applies to turbo engines, from the ACO rules it appears not - I know it did in 2001 but not anymore - someone please correct me if I'm wrong.............for the old turbo rules at Lemans - if you run a 2v engine you can run a bigger restrictor too - in the latter days of the Toyota Lemans cars 1999 ish, it was roumoured they converted their V8 turbo engine to 2v cylinder heads in order to take advantage of this rule..........