FAQ Regarding Cobra Drivetrain Setups

[Dominik]

Brent,
while you are inquiring for hp values most engines on your side are still rated SAE, aren't they?

Example: my 496cui had 500Hp at the wheels, translating in 565Hp DIN at the flywheel with 12% losses in the drivetrain (in 4th, "direct" gear).

An US calculation resulted in 700Hp due to 20% losses and 80Hp for auxillary components and inefficient exhaust (assumed losses for exhaust).
700-80=620Hp
620x0,8=496Hp

With BfG the wheels were spinning endlessly in the 1/4-mile, with Hoosier AutoCrosser I was okay (in 2000). The cam was very torquey 0.560 lift mech roller, but using 1.8 ratio (Chev BB). The springs I had allowed for only 0.600" lift.

In a nutshell, you rely on rear wheel hp (rwhp) for your assessment?

[blykins]

No, I go by flywheel horsepower only. A Cobra has a terrible amount of parasitic losses through the driveline and through the exhaust. Some here have stated that they have removed the sidepipes and gained 100 rwhp. Some sidepipes are very restrictive.

It's easier for me to know what's going on when flywheel horsepower is mentioned. There are way too many variables when someone quotes rear wheel horsepower.

In my line of work, I get a lot of guys talking about 600hp small blocks and 700hp big blocks. I always ask to see the dyno sheets....and even then I take them with a grain of salt.

[Dominik]

Flywheel hp, makes sense...

After all, we ask you for advise for what comes right after the flywheel: the clutch!
And not what comes after the tires: the road ;-)

[undy]

No insinuations here Brent, but big number sell engines for builders.

Unlike the major auto mfrs the small guys typically dyno their engines under ideal conditions, perfect equal length headers, ideal mufflers (if any), electric water pumps, no restrictive (Cobra typical) air cleaners, etc, etc. Take the LS7 for instance... In the Z06 it's rated @ 505 hp (SAE "J" I believe). I've seen the LS7 "crate motors" dyno'd locally and they typically dyno 570 to 580 fwhp, SAE) They're running identical motors as the Z06 is running too. A lot of people don't understand all the variances in dynoing the engines and assume apples to apples. I don't entirely buy or subscribe 100% to the "inherent" Cobra dyno inadequacies. IMHO, the engines would also dyno lower in a Moosetang or another "typical" car, not just the Cobra. My 505hp Z06 develops more rwhp than my 600hp 482 Cobra. I honestly believe, given an "optimal" installation it would still fall waaaaay short of it's 600hp rating.