What's the drivetrain loss for an M6? I've heard anywhere from 15%-30%. Is there really even a specific % or is there just too many variables? Thanks

 

Driverain loss is a combination of friction and rotational inertia. The friction part isn't nearly as dynamic as the rest. The weight of your wheels, tires, rear gears, and driveshaft can all change the drivetrain loss. There are also a few other more detailed issues. This is why you will only read broad generalities about drivetrain loss. Simple answer=10-30%. Detailed answer=Who knows?

 

I have seen some common rules of thumb over the years from reading magazines and talking with knowledgeable folks.

The informal consensus seems to be around 15% for a manual trans equipped car and 18-20% for an automatic.

Common sense tells us that the actual % will vary for every car's particular setup. The only way to get a pretty accurate number would be to dyno your motor, then install it in your car and drive over to a chassis dyno and compare the numbers.

 

That's what I was thinking...

I guess my ZR1's w/ 335 tires don't help at all, lol.

 

I guess that there would be a way to tell. If someone dyno tested their engine and created a computer estimate of how fast it should take to get from 0 to X MPH and compared the real life time you could get an estimate. Keep it in 1st gear and it would be doable.

 

Simple answer is that based off engine dyno testing as compared to chasis dyno, you loose about 50hp from a LS1 or LS2 through a M6...that's about 15-17 % depending on gears, etc...but when you dyno your car and get 500rw, you cannot go saying that your motor makes 600hp - it doesn't work that way. You will still only lose about 50 hp if you have changed nothing but the input power of the motor, + a small percentage for added loss.

There have been quite a few heated discussions on this issue.

 

I think your estimate of 15 to 17 percent sounds about right!

 

Is that 15-17% assuming a 10 bolt? I read recently in Chevy Hi Performance that there is a 3 1/2% loss between a 12 bolt and a 9". Maybe there is a 2-3% loss between a 10 bolt and a 12 bolt. Add in a steel DS and some heavy wheels and tires and you now have a very significant drive train loss.

 

Yes, I didn't want to type a lot. The exact loss depends on a lot of factors.

a few:

1. Driveshaft mass. Steel? Aluminum? Carbon Fiber?

2. What exact type of transmission?

3. rear end? 10-bolt? 12-bolt? 9-inch?

everything in the drivetrain affects it. You could change your clutch and pressure plate out and get a slightly different RWHP.

 

Since when is 50 hp 17% of 400? Yes I am using the outer ends of your estimate, but you said it not me.

 

There are so many factors contributing to drivetrain loss, it's mind blowing. And the fact that it will be different for each car, you can't have a blanket formula. The best way to know for sure is to use either one of two methods.
#1) Stop quessing, yank the engine and put it on a real dyno.
#2) Stop quessing and run it at the track.
Track times tell no tales. If your 500 rwhp Camaro runs 13.20 @ 110, then you got taken by another crooked chassis dyno shop trying to sell you numbers you want to hear, instead of telling you the hard facts about the real power output of your engine.

 

torque arm flex, rear squat, etc contribute too.

 

Really? How much?

 

I was referring to the guy who asked the question - his car has an LS1 and that is about 15-17% on those cars stock. I wrote that at 11pm and may have not been very clear.

 

Na, I was being a dick too. I am simply fealing argumentative.

 

well the stock stamped steel arm takes about 2-4% when accellerating. depending on how old it is, how well the bushings are, how tight the bolts on the rear end are. aftermarket chrome-moly or 4140 tubular steel arms dont flex, and is why you feel the rear is tight. and the polyurethane bushings help out alot too.

rear squat absorbs the energy through the weight transfer. thats why when youre up at 500+hp or if your ***** out with alot of money you get drag shocks that are adjustable with springs. when you take your front sway bar off you get more weight sent to the rear from the front and that will hinder performance, so they balance it out with the shocks. but you also use the shocks with the sway bar on.

transmission mount too will cause drivetrain loss. the trans will sink when load is placed on it so thats another 1-2% loss if its worn. when i replaced mine it was noticeable.

 

18% Just use that as a figure.