Originally Posted by BobDoLe

what? are you living in the future?
coyote motors run 11:1 compression and use regular old fuel injection.
here's a picture of a coyote head.... http://image.streetrodderweb.com/f/3...otor-5-v8+.jpg
i see there's something there where an injector wants to grow out of. know anything about that?

Originally Posted by 1quickirocz

Based on the quality of GMs OHC engines i hope they never replace the LS engines with a OHC engine. the 3.6 liter is a prime example of GM getting rid of a great proven V6 (3.8) for a DOHC POS thats costing them all kinds of money. Didnt see any issues with the LT5 because nobody ever put any great mileage on them and GM didnt really design it.

Originally Posted by SparkyJJO

To be fair, the 4.2L Atlas inline 6 that GM used in the Trailblazer is a DOHC with VVT on the exhaust cam, and that was easily one of the more durable engines that GM has made.

Originally Posted by Metal Muscle

From experience, given your sig?

Originally Posted by Nowhereman

Actually, I am an engineer by trade with a masters in material science and my major was mechanical engineering.
Your missing the point totally and you need to work on that.
A good design for any "machine" that would be used on a daily basis is that it's moving parts / quantity be held to a minimum... period
More complexity always results in less operational up time.
You can split hairs, you can try an bullshit your way out of it but, it's a truth that's never been faulted.
If I had a motor company and had to design engines for any application, I would go for the best top side in growth and that is an OHC.
I love pushrod motors as they have gone farther than they have should.
OHC motors offer much more flexibility in application.
There are no down sides to OHC applications unless you try to make one up.
You can size one up to run with any push rod app their is.
You can have any valve angle you wish, not to mention port design with a DOHC design.
That cannot be said with push rods.
This post is about GM bringing on OHC designs.
They know it's time and they understand that with small cube applications, OHC is the way to go.

Originally Posted by JD_AMG

I wouldn't assume things too fast here, just because the LS1 had years of engineering and testing put into it doesn't mean GM couldn't figure out how to get an extra ~20hp out of their current (LT1 at the time) production pushrod V8. Id bet GM took their time to get the reliability down, and to ensure they could be made for relatively cheap. Lets not forget the LS1 is very held back in stock form (on purpose, GM only wanted 350hp) - what was to stop them from putting in a different cam and better flowing heads (like the 405hp LS6?). -Their goal was an inexpensive, lightweight and compact 350hp engine, and then a 400hp engine for the Z06.


But being 200+lbs heavier, all around bigger, more complex and significantly more expensive.
If both engines are making the same power, wouldn't you want the lighter, smaller, cheaper one?

Originally Posted by bww3588

this is true, however, saying that GM could have made the LT1 20hp more is not exactly correct. well...it is but it isint. the LT1 was loosely based off the 45 year old GEN I SBC. basically, any way you look at it, the LT1 was a "hold you over" engine until the LS series came out. not saying GM couldnt have squeezed an extra XX amout of power out of the LT1 but this has been done time and time again to an increasingly aging engine that is way outdated.

it would have been totally pointless.

Originally Posted by RPM WS6

I understand and agree with your general sentiment, however GM actually *did* squeeze an extra ~30hp out of the LT1....it was called the LT4.

The fact that people still build ~500hp streetable SBC engines is proof that the the Gen I design still had a lot more in it. But I agree with your line of thinking and understand the challenges that an OE manufacturer faces with emissions/CAFE requirements are not the same as private builders. For this reason, it was infact time for the Gen III clean-sheet-of-paper engine.

Originally Posted by LS1GMCTruck

Well...Not really...lol. I don't know how my thread got sidetracted to overhead cam(OHC) engine discussion? What I was inquiring about, was GM moving/evolving to a direct fuel injection(DFI) cylinder head/LS engine type design. This is where fuel injector(s) are designed directly into the combustion chamber area. Mercury Marine, as an example, has been using this technology for about eight years now, on all their larger horsepower, high-performance engines. Was just curious if anyone else heard of GM switching over to this DFI design in the next couple years on the LS series, as I have?