You can measure drivetrain loss with a "negative run" on the dyno... Simply start recording the run AFTER the car has accelerated and starts to drop speed. After you are tired, you will see that the drivetrain accounts for very little. Granted the trans is pretty much disengaged, but you could do a trans in gear/Clutch depressed type of thing to try it out.

I've seen a corvette only loose 9rwhp like this... so go figure.

 

Im not an engineer, so if Im wrong Im sure someone will correct me.

People post about drivetrain losses as a fixed percentage a lot. I hear about it most on the 5.0 boards it seems.

From the factory a certain chassis, engine, and drivetrain combo results in a rated flywheel HP number; and then when put on a dyno a RWHP number. Its easy math to figure out the difference as a % of loss.

What a LOT of people forget is that with no more mods to the vehicle other than increasing HP, IE same clutch, driveshaft, rearend, and wheels; the drivetrain still takes the SAME amount of work to turn it. In other words, there will be a bit more loss due to the greater work the motor is putting on it; but not a fixed percentage of the total hp. It will be more of a percentage loss of the original amount that the chassis loses. For example, if a 400hp car makes 350 at the tires. The drivetrain loses 50hp. increasing the hp will increase the % of the 50 thats lost, not the original 400.

OR to put it another way, a 400hp car dynoes 350 to the tire looses 12.5% through the drivetrain. Put in a 1200 hp motor, and the same drivetrain and the loses ARENT going to be the same fixed 12.5% (would now 150 hp lost). More like the same 50 hp + a % of that 50. Even if the drivetrain loss grew by 100% because the same amount of work is being done faster, you would only have 100hp lost to the rear wheels.

And Im willing to bet that the increase wont be 100%, probably more like 10-25% more hp robbed. of the 50hp that the drivetrain consumes.

GRANTED, Im talking about stick shift cars where there aren't slippage issue's with a tq converter.

 

The WS6 website has a coastdown dyno test. The losses are calcualted at 16.3HP with a 1LE aluminum DS, and 14.5HP with an ACPT CF DS. That represents the "inertial" portion of drivetrain loss. That is a "fixed" value, as long as the mass is accelerated at the same rate.

http://www.ws6.com/mod-10.htm

In simplified terms, the balance of the losses in a manual trans drivetrain are primarily frictional losses, which are proportional to the power being transmitted.

The total loss is inertial + frictional, and since one element of the equation if a fixed value, the percent of flywheel power lost will drop as the power transmitted goes up.

 

But is that the case? More HP => higher rate of acceleration.

 

The faster you accelerate the the rotating mass, the more energy is absorbs = more HP consumed. As I noted earlier, "brake" style engine dynos, and Mustang dynos are capable of controlling the rate of engine acceleration, and can eliminate the effects inertia energy absorbtion CHANGES due to HP level. The DynoJet is not a brake style dyno, and can not eliminate these changes in loss due to a more powerful engine accelerating the rotating mass of the drivetrain more rapidly.

If I could have eliminated the effects of using the DynoJet for my rear wheel numbers, I could have solved for the "fixed" and variable components of loss, using simultaneous equations.

 

corvette owners won't get upset....as long as the camaro stays at 3900++pounds it's no threat.

 

Then I guess at 3880 they should be worried...

GM doesnt spend money to detune it. Thigns like exhaust work, muffler tuning, and even the PCM calibration for the car can cause the power to drop off compared to other cars.

 

Corvette owners also have the 505Hp and 638HP options as well, so if 430HP/436HP is not enough, then there is always more.

 

I was told on Saturday when I placed my order it should be around 430horse same as the corvette. I will know soon my order was excepted Today by GM. they start production next week

 

The LS3 for the SS has been SAE certified at 426HP.

 

You placed an order this past week and are going to production already.....?

 

426hp is awesome for a stock vehicle at this price. I plan on eventually adding an STS Turbo system to it (I'm sure they will produce one) to bump it closer to 600hp and a small gain in gas mileage.

 

Wow great info to know.....

 

He said "they start production" next week (and he said that on 3/10) -- not that his car was up for production.

 

OK...I see now, misunderstood.