Future for Pushrod engines in sportscar racing?

[AU N EGL]

Originally Posted by 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.

But isnt that the reason for the two differnt engines?? DOHC uses the smaller displacement vs the pushrod. One has larger and one has smaller displacement for approx the same HP. two differnt ways for the same results. Does not necessarly make one better then the other, just differnt.

Then the driving styles are differnt too with a high RPM engine, vs a lower rpm engine.

[Bob Riebe]

John:
Yes I was referring to the ZR1 engine, or LT-5 as was engine name.

A fellow in Germany has the Rippey GT1, ZR1 Corvette and spent the money to make it run right.
Bob

[johnh875]

Thanks Bob, I could not think of what else it could be!

Originally Posted by AU N EGL

But isnt that the reason for the two differnt engines?? DOHC uses the smaller displacement vs the pushrod. One has larger and one has smaller displacement for approx the same HP. two differnt ways for the same results. Does not necessarly make one better then the other, just differnt.

It is a bit chicken-and-egg here - if you have a more efficent engine you can make it smaller capacity which usually has benefits in a production/road car context. Then again if you have an engine with adequate power/efficiency etc then a cheaper to produce engine would be attractive. Apart from the GM LS1/2 and Chrysler "Hemi" engines what other ohv engines have been designed in the last decade?

In the racing world it is more common for a straight capacity limit (without air restrictor allowances) so you would be mad to use a less efficient engine.

What rev range the power/torque occurs is more affected by cam/port/manifold design than valve actuation method.

[AU N EGL]

Originally Posted by johnh875

Thanks Bob, I could not think of what else it could be!


It is a bit chicken-and-egg here - if you have a more efficent engine you can make it smaller capacity which usually has benefits in a production/road car context. Then again if you have an engine with adequate power/efficiency etc then a cheaper to produce engine would be attractive. Apart from the GM LS1/2 and Chrysler "Hemi" engines what other ohv engines have been designed in the last decade?

Different ways at achivine the same efficiancy.

Porsche has a wonderful powerplant that producs +/-400 bhp. The Chevy LS6 and LS2 again 400 bhp. Two differnt engines to produce the same output. Each has diffent HP and TQ curves and should be driven differently. The Porsche works best at high RPMs in lower gears, vs the Corvette at Lower RPMs and high gears.

The Porsche and Corvette drive much different then each other. I have driven both extensivly. I have not had the pleasure of driving 996 RS or RSRs let alone the new 997 configurations.

I have driven lots of 996 GT2 and GT3s and they are wonderful cars. I have been a passanger in a 996TT, but not driven.

Also driven many many corvettes of differnt LS1/6 and LS2/7 configuartions and modifications.

If there is a main difference between the two is fuel economy. "economy" kind of an oxymoron though. . Under normal street driving fuel milage is appox equal. Under WOT and race conditions is a differnt story.

Personlly drive/race have a LS6 modification to 400 rwhp & 405 rwtq or approx 460 bhp.

As far as new ohv engines, Chevy has the new L92 / L76 design out for 2007 plus a new LS9 ( 6.4 Liter supercharged ~ 600 bhp) engine due out in a few years.

So IMHO it is differnet roads to the same destination.