I remember a discussion about "drive-line" HP loss a while ago..

[Pokageek]

FYI - Follow up. Several of you said depending on the drive-train..anywhere from a factor of .80 - .85 should be used on average. One guy said that he knows some experience dude that said no matter what car it was there was only like a 15hp difference between whp and rwhp. I thought that was BS. Well, here's the dyno on the new zr-1...guess what...REAL close to the 15-20 PERCENT drive-line loss NOT 15HP.

"It always happens this way. Shortly after a new performance car is released to the public, it will find its way to a dyno shortly thereafter. When that new vehicle is the new performance king of the automotive world, aka the 2009 Corvette ZR1, our collective interest is piqued. So, how does it fare on the rollers? Two separate 'Vettes were tested, and the average output was about 535 horsepower at the rear wheels. After factoring in the normal 15-percent drivetrain losses for a rear-wheel drive car, that's pretty darn close to the claimed 638. " - corvette blogger.com

 

[SN95StangMan]

some experience dude that said no matter what car it was there was only like a 15hp difference between whp and rwhp. I thought that was BS.

That guy is an idiot, plain and simple

 

[ProKiller]

its always good to know this number for when building a combo. most people shoot for rwhp without thinking of the power that the block has to support to reach that number and boom...

 

[revhead347]

I think someone should have explained this concept to the guys at "Top Gear," before they markered "almost" on a brand new GT500. That show is funny as ****, but those guys don't know **** about cars.

Kurt

 

[5spd GT]

For a typical AOD (not AODE), there is an extra 4-5% loss.

One guy did a T5 swap, from a fox AOD, and doing the math, the AOD was sitting in the high 18% drivetrain loss, assuming the 5spd is taking 15%.

NASCAR is in the 5-6% drivetrain loss range.

It is always a percentage, not a HP/TQ value.

 

[Black95GTS]

Engine dynos are where it's at. Chassis dyno's are useful for tuning but don't mean squat except on LS1tech.com.

I don't know many pro drag teams that boast about RWHP!

Adam

 

[Dino Dino Bambino]

The AOD has a drivetrain loss of 24% so I expect it should be the same with the AODE. You'll find this article interesting and yes, drivetrain HP/TQ loss is a fairly constant percentage across the rpm range:

Drivetrain Power Loss - Car Craft Magazine

 

[revhead347]

Engine dynos are where it's at. Chassis dyno's are useful for tuning but don't mean squat except on LS1tech.com.

I don't know many pro drag teams that boast about RWHP!

Adam

What difference does it make. All you are doing is getting a measurement from which to judge performance adjustments. Doesn't matter if it's from the crank or the tires. Most pro drag teams don't use chassis dynos because there are no chassis dynos that measure that kind of power. The dyno used by John Force's funnycar team uses a rebuilt generator from the Hoover damn. The generator is driven up to speed with a 3000hp diesel engine, then they clutch in the funny car engine, and apply a load to the generator to measure the hp. You know you're the man when you have to design your own dyno to measure the power output of your engine.

Kurt

 

[Black95GTS]

What difference does it make. All you are doing is getting a measurement from which to judge performance adjustments. Doesn't matter if it's from the crank or the tires. Most pro drag teams don't use chassis dynos because there are no chassis dynos that measure that kind of power. The dyno used by John Force's funnycar team uses a rebuilt generator from the Hoover damn. The generator is driven up to speed with a 3000hp diesel engine, then they clutch in the funny car engine, and apply a load to the generator to measure the hp. You know you're the man when you have to design your own dyno to measure the power output of your engine.

Kurt

That this thread even exists proves you are wrong. My uncle's Grand National stalls at 5500. It measured 712HP on an engine dyno, and on chassis dynos (which he uses for tuning only) it makes in the low 500s to high 400s.

Are you telling me he loses 35-40% through the drive train? I will laugh at you all the way to low 10 second passes.

Adam

 

[revhead347]

That this thread even exists proves you are wrong. My uncle's Grand National stalls at 5500. It measured 712HP on an engine dyno, and on chassis dynos (which he uses for tuning only) it makes in the low 500s to high 400s.

Are you telling me he loses 35-40% through the drive train? I will laugh at you all the way to low 10 second passes.

Adam

No, you are proving me right. You said that he uses the chassis dyno to tune. That's exactly what you use a dyno for, to tune with. I know that it would be a pain in the ass to pull my engine out and get it running aside from the car. Doesn't sounds like an effective way to tune to me.

Kurt

 

[5spd GT]

The dyno has many less variables to consider compared to a track.

I would rather see manual transmission dyno's.

Engine dyno's do not simulate what accessories you will have, drivetrain, or type of load.

If you are at the track, look at MPH, not ET for power.

The comment about the top-notch drag teams not dynoing because of the power, that is true.

 

[final5-0]

I find this thread interesting

I like to use dyno results to judge things because it takes the driver and his
skill ... or ... lack of skill out of the mix

then again

Dyno techs can fudge the results

soooooooo ... whatever method one uses to judge

NONE of em are totally or 100% accurate or without draw backs

I look for trends in the results myself

I DO NOT understand but have seen this trend in auto trans dyno pulls

They are all over the place

Almost every time ... they are a good bit less than a stick
and some of the time
They are a whole lot less than a similar stick combo

Just a few random thoughts

Grady

 

[final5-0]

double post

 

[BlackVert]

The AOD has a drivetrain loss of 24% so I expect it should be the same with the AODE. You'll find this article interesting and yes, drivetrain HP/TQ loss is a fairly constant percentage across the rpm range:

Drivetrain Power Loss - Car Craft Magazine

ouch. i have an AOD. good thing my build is not about racing

 

[Dino Dino Bambino]

ouch. i have an AOD. good thing my build is not about racing

But there are ways that you can lower the drivetrain loss with an AOD/AODE such as:

Shift kit
Lighter torque converter
Aluminium driveshaft
'98+ 4R70W internals