seems a little wierd to me thatyou lose so much horsepower...must be something wrong with that machine

 

found a good write-up on drivetrain loss....

"15-17% for manual transmissions and 20-25% for automatics."

"HP loss in auto vs stick is mostly related to the converter slip (there is always some slip in a normal converter). However, even with a mechanically locked up converter, in the planetary gear system used in autos, there are more gear meshes occurring, which increases HP losses since each gear mesh results in a HP loss (relates back to statement 1). And don't forgot, in an auto, you have direct pumping losses from the oil pump (you don't have this in a manual trans). And the higher the line pressure, or fluid flow rate, the greater the pumping losses.

In an Automatic transmission you will find several factors that determine power requirements: Weight, Lockup/non-lockup, Stall speed, Torque converter design, Valve Body"

full write-up can be found here:
http://www.superstang.com/horsepower.htm


Also found this in another online article... "Most experts agree that a 10 to 15 percent loss is normal." and their test vehicle (a FWD Neon) actually lost 22%.


and from yet another article I found:

"The worst scenario case for a rear drive setup is on the order of 12.5% in 4th gear, not the 20 -25% often published. If 25% was being lost in the drive train, the oil would boil in the differential housing in short order and aluminum transmission cases would fatigue and break from the temperatures generated. On a 200 hp engine, something on the order of 37,000 watts would have to be dissipated out of the transmission and differential housings. Obviously, this is not the case.[align=left]
[/align] [align=left] Transverse, front drive transaxles usually have no direct lockup gears and no 1 to 1 ratio, however, since the torque path is never turned 90 degrees as in the rear drive setup and efficient helical gears are usually employed for the final drive set, losses are more on the order of 6 to 9 percent in the upper ratios.[/align][align=left]
[/align] [align=left] Tire pressure and wheel alignment can have very significant effects on losses at the rollers. Tire pressures should be set the same between each test. Tire rolling resistance varies inversely with speed, another factor not taken into account by most chassis dynos when applying phantom flywheel hp formulas.

In one recent independent test, hp figures varied by 11% simply by doing the runs in different gears and in another test, results varied by almost 4 % by doing the runs with a different wheel/tire combination. Tire alignment has been shown to affect results up to 3% as well."



[/align]

 

i figure there dyno would be calibrated right they just had it installed last week

 

i was hoping that something was wrong with the dyno until i read 06MonteSSwrite up that makes me sad

 

anyone have any different numbers for FWD drivetrain loss??