Way back with my first version of my 540, it made 732HP on a Superflow engine dyno. That was open headers, no carb spacer and using the belt driven water pump and stock pulleys. Installed in my car it made 615 RWHP with open headers and the only differences were that it had an alternator in the mix now. I removed the 7 blade flex fan for that test..but it actually only killed 3-5 RWHP at the worst and that's almost within run to run variations. It only made 565 RWHP with 3" crimp bent pipes and Flowmaster 2 chamber mufflers. That exhaust killed it.

This was using stock 3.36 rear differential and a Doug Nash street 5 speed. I was also using 4th (underdrive) to keep the tire speed down since they were plain BFG street radials and they get pretty weird looking at 150 mph plus! So I was losing a little through the trans multiplication. From our tests it's about 5-8 RWHP difference on that trans between 4th and 5th (one to one).

We've also got data showing that Drag radials and or slicks can kill 20-25 RWHP on a high HP car too as compared to regular tires. Lots of heat and friction there!

Another buddy tested a G-Force 5 speed, a Richmond 5 speed and an Autogear M-22 and found they all were awful similar despite the straight cut gears of the G-Force. Maybe rotating mass made up for reduced friction?

Light flywheels, wheels, driveshafts, lightened ring gears etc etc will all show up on a chassis dyno as more HP. Lots of C-2/C-3 stuff is pretty chunky compared to C-5/C-6 stuff.

Just think what my Dana 60 IRS hybrid and 3.5"x.134 wall halfshafts and similar driveshaft are eating up? I don't really care because that's what it takes to survive when I drop the hammer on them!

JIM

 

16% on a manual transmission.

Here is a stock 2001 MN6

295 rwhp, 346 on the flywheel