Flywheel to Rear wheel HP conversion

[Bernica]

These cars weigh between 2,300 and 2,600 pounds. When you think about it, even 300 HP at the wheels is pretty damn good. Beyond that, like in the 400+ range. is just plain sick and off the charts for a car as small as we all drive. I think chasing a big RWH number on these cars is more vanity than common sense. And, yes, I have this sickness. Next car will be the "common sense" car, I promise.

[Tommy]

I saw the point made by CSXDreamer illustrated on one of those half hour car shows where they hop up cars. They took a showroom stock import sedan and prepped it for road racing. They started by taking dead stock dyno readings and lap times. Next they upgraded the wheels, tires and brakes, and did some intake and exhaust improvements before putting it back on the dyno. They were surprised and befuddled when the modified HP at the wheels was lower than the baseline. They later figured out that the upgraded wheels, tires and brakes had more angular inertia than the stock equipment. Ultimately, all the improvements they did to the engine served only to restore the HP at the wheels to what it had been when the car was stock.

[CobraDan]

Rear Wheel Horsepower to Flywheel Horsepower Conversion
Convert rear wheel figures to estimate flywheel figures.

Flywheel Horsepower = FHP; Rear wheel Horsepower = RHP

FHP = RHP + 17% (auto trans)

FHP = RHP + 25% (man trans)

RHP = FHP - 15% (auto trans)

RHP = FHP - 20% (man trans)

Example: 312.25 FHP = 249.8 RHP + 62.45 HP*

* Manual trans: +25%

http://www.cobranet.com/calcs.htm

[Dwight]

Keith Craft told me 20% for a Cobra. He has dyno'ed motors and then installed them in Cobras. Dyno'ed the Cobra.

Dwight

[danc30]

Also depends on how loose your converter is in an auto. Ask me how I know.....