LS6 now you are bringing back memories! And the buick 455, 360hp and probably 550 tq!

 

I really think the 928 engine dose a great job for the limited ci that it is.

Back in the day I would have never bothered with a 5L engine.
The 350/5.7L gave just that little bit more with a good intake and cam and a larger carb you could get around the 350HP area.

If you had the money to spend on porting and more exotic upgrades like roller rockers and lifters, then the thought was why not start with a big block and get those few extra horse for free.

Making the heads breath with porting and big big over size valves is the way to go. Dose anyone build heads for the 928? Big Heads.
Then open those valves with a cam that wont idle under a 1000 rpm and you have some flow baby.
The big exhaust you guys seem to have.
The blowers you have
The technology you have.

I would say it is up to one of the 928 racer/machinist like Simard to build those big heads.
The problem is he will not sell a 1000 of them so the price will not be as cheap as the chevy.

Just my 2 cents

Brad

 

can't help but thinking about a 413 max wedge or 396 hemi, those were good days! Ray

 

Or how about chop up two 968 blocks and weld them together for a 6.0 liter V8

Dan
'91 928GT S/C 475hp/460lb.ft

 

Here is a 1000 HP 6 cylinder

http://www.youtube.com/watch?v=n8ey8N1eFnc

 

How about 8000hp from a V8 when it comes to Horsepower its USA built.
Its loud!
http://www.youtube.com/watch?v=gUVmGTJFoNw

 

can anyone explain to me why push rod engines havent evolved into overhead cams...do the overhead cams limit the head design, or is the timing belt length the issue.....just wondering but you still see the push rod engine design making gobbs of hp

 

There are advantages with push-rods at high rpm's. Some engines use little helper push rods (BMW M-engines).
Another advantage is engine height, push-rod setup takes up less space.

 

Pushrod engines and overhead cam multi valve engines both evolved around 100 years ago. Pushrod engines on the negative side have more parts, valve train flex and less sexy valve covers. On the plus side they aren't limited to valve lift, don't need lengthy cam chains or belts and don't need tensioners. I would also suspect them to be less subject to massive failure. We have a timing belt failure we have almost lost an engine. A pushrod engine looses a pushrod and it runs on seven.

 

I think it goes back to the "if it ain't broke don't fix it" theory...considering the huge investment required to make a new overhead cam engine it also makes sense..

Also they are making around 1.2hp per cubic inch and pass smog..not to mention they are much lighter, have only 1 cam and a more compact package...

I think the main advantage of overhead cam is HIGH rpm operation, for greater valve control...but it appears that benefit doesn't come into play until north of 10,000rpm for a built engine.... & don't forget metal valve springs are good until about 13k anyway....thats why F1 runs air springs....

 

One of the reasons I think, it was said earlier in this thread too, that the Chevy made more power at 8psi was efficiency.
Temperature effects volume. 8psi at 150deg is less volume of air than 8psi at 100deg. The turbo with the lowest air temp will make more power assuming the exhaust sides are the same. Now these are different power adders, supercharged and turbos.
I'm not sure about Carl's but the Chevy in this example had two large turbos feeding into an air/water IC. I've had IAT below ambient before on motors and they LOVED it!
Of course, this is separate from all other factors too, like heads, cams and other stuff Greg spoke about.

 

GM has I4, V6, and V8 DOHC engines . Those heads designs could easily be carried over to LS blocks. HFV6 heads and cams on a 6.2L would make 525 hp. The 6.2 is currently making 430hp or 480 with the factory cam upgrade. For 10% more power you now have double the valves and springs, 3 more cams, direct injection, cam phasers, more sensors, more work to calibrate, and a much bigger engine.

 

Unless the push rod bends and gets wedged in the head holding the valve open while the piston relentlessly hammers itself into confetti.
Moral to the story: Don't rev a 351 Winsor to 6K rpms in the parking lot and then suddenly chop the throttle.
Don't ask me how I know, and no it wasn't me, but I was a witness.

 

I let a college buddy drive a Pantera I had about 25 years ago. He downshifted into 2nd at about 80 mph. Blew the clutch so badly that the clutch lining was imbedded in the undercoating in the engine compartment. It also left me with a collapsed lifter that had the car running on seven cylinders. Those old pushrod V8's were tuff.