[Marty McFlew]

Originally Posted by ChevyRules

HP/liter is heavily biased towards DOHC vs OHV. The engine breathes better due to 4 valves vs 2 valves in the OHV setup and can rev more than the OHV. Thus you don't need to have a big of a displacement to make the power. But you do need to rev the engine out to make such power( the Voodoo V8 is a perfect example of this) and is a physically bigger motor thus creating packaging issues( the Coyote V8 will not be able to fit in the Corvette).

The OHV design can't breath as well nor can rev as high as the DOHC architecture, so need displacement to make power. The benefit of using displacement to make power is a ton of torque being made down low. Also, an OHV engine is physically compact. How the LT1 can fit in the Corvette. Heck its the reason why the Small Block V8 is such a popular crate engine. Can throw it in a Porsche, Miata, etc with very little mods.

Not only that but the 5.0/DOHC engines in general have a higher center of gravity which effects handling. The OHV Crankshaft sits low in the block allowing the crank to sit lower than the wheel axles giving the vehicle better balance. The last I heard the 5.0 can not be mounted low enough to have the crank sit lower than the axles yet they have done a great job at still making compromises for a great handling package but still as of 2017 not on Par with the Camaro. Don't know about the 2018s. Quite frankly I would not be surprised if Ford came back out with another performance OHV. But to do so may be admitting the DOHC 5.0 was not good enough.

[KyBoy]

Holy multiple posts Batman!

Heath

[Marty McFlew]

Originally Posted by KyBoy

First is my M6. Second is my wife's A8.

Yeh but I bet she doesn't step into hers like you do yours.

[KyBoy]

Originally Posted by Marty McFlew

Yeh but I bet she doesn't step into hers like you do yours.

No...no she doesn't.

Heath

[MakCamaro]

Thread revival! Why did you stop the discussion?

[95 imp]

Originally Posted by formare

Fuel economy has a lot to do with the body style and overall weight. Kind of a strange request in this conversation...

Fuel economy as in BSFC.

[6spdhyperblue]

Useless metric

[chaospiece]

~WHAT IF~
we compared engines by power being produced at specific rpms...

Lol I'm kidding. I love my lt1, I love my coyote.
Definitely prefer my lt1, I think hp/liter and dependability have been well covered here already.

[avalonandl]

The LT1 does with 1 cam what most engines require 4 cams for.

[triggerjerk]

I think what the OP is getting at is that the LT1 is leaving some power potential on the table. The LT2 is proof of that and even that engine isn't very radical.

[Rlhay2]

Originally Posted by Ryephile

If you want to compare engines across configurations, use BMEP, BSFC, external size, and weight.

The HP/L thing is nice bench-racing but it's certainly not the whole picture.

And then there are those thermodynamic principles that always come into play. I.E. an engine's efficiency decreases with an increase in engine size...

[DorkMissile]

Well - if HP/Liter was the only thing that mattered, then we would all be driving Wankels

[oldman]

Originally Posted by formare

So hear me our before you judge the title.

The 3.7 liter engine makes 90.5hp per liter. Its efficient and reliable. So why is the LT1 so far behind in development. By my math, a 6.2 liter engine should make 561hp. That's a metric crap tone of HP.

Suppose you could make the argument that with the GM performance cam and heads IE "hot cam" kit it could get close to the 561hp. But why not include it from the factory. Why so much evolution difference between the platforms?

Try HP per cam 455 HP for one cam, your V6 is only producing 89 HP per cam
Try HP per Valve, that would be 13.95 for your V6 and
28.7 for the LT1

HP per liter is not a design constraint, HP per external size is, OHV wins, HP per unit cost is OHV wins, that is why Ford's new truck engine is OHV. HP per longevity is (see Ford's new truck engine).

HP per liter, that is for guys that ain't got the goods. My Integra Type R at 2.05 liters puts out 275 HP NA, bout 135 HP per liter... Tell Porsche bring it.... Just kidding as I'm mighty impressed that Porsche FINALLY is producing the same HP as my stock 22 year old Honda... The Mugen Civic I believe was 260 HP from 2.2 liters or 118 per liter for 2008 ish. 1996 JDM Type R was 200 from 1797 cc or 111.3 HP per liter, which was broken by the 60 units production of the Mugen RR and then I believe a Ferrari took the HP per liter lead at 120 ish (forget now) and finally Porsche has an engine that can do it. I don't know if Porsche engine uses their version of VTEC (Variocam plus) which is very elegant. GM uses a similar setup on the 4 banger:

https://media.gm.com/media/us/en/gm/...takevalve.html

The article does seem to imply that GM uses their VTEC on the V6 also, I don't think so... but who knows

Sill 500 HP for 4.0 finally (125 HP per liter)for Porsche at 150gs....




https://www.kingmotorsports.com/blog...vanced-Concept

[cmitchell17]

Originally Posted by Rlhay2

And then there are those thermodynamic principles that always come into play. I.E. an engine's efficiency decreases with an increase in engine size...

Where did you get this info from?

My recollection of thermodynamics is that a model of the Otto cycle is that thermodynamic efficiency (how much mechanical work we can get out of heat flowing from hot to cold) is only dependent on the compression ratio and specific heat of the fluid (air and combustion gases) and is completely independent and has nothing to do with displacement.

Of course this is only a model, and yes bigger bore and longer stroke also mean more work done by friction, but I can guarantee this any efficiency savings from this is negligible. Also others have pointed out the fact you will get less friction from one cam instead of 4, although this is also probably negligible.

Most of this inefficiency you think "big" engines have is from pumping losses (parasitic). Friction is a parasitic loss, but the biggest lost comes from the engine being throttled, since its a larger displacement, for the same RPM as a smaller displacement engine, you will have to close the throttle more to get the same torque output. A lot of this is fixed by gearing the engine down when high torque is not required and with AFM/DOD by artificially changing the displacement during load load.