Not sure if this made it in a post anywhere. Stumbled on it in "Google News"
http://www.automobilemag.com/featur...ord-shelby-gt350-run-to-170-mph-and-hit-dyno/
http://www.automobilemag.com/featur...ord-shelby-gt350-run-to-170-mph-and-hit-dyno/
I'm really not trying to be a jerk, I just want to tell you that that's not how you find 15% drive train loss. You actually want to multiply 526 by 0.85, which equals 447.1hp.
never heard the .85 way of doing it. but either way its just an estimation equation, obviously all manual cars don't have 15% drivetrain loss and of course there are other variables. but still 482 seams real high for a car rated at 526 at the crank. and that wasn't even an R, these numbers would make more sense on the R cuz of the carbon wheels.
Even as an estimation, 15% is too much to take away from a manual car. Nowadays, it could probably be as little as 8%, which I'd believe for the GT350 considering the lightened transmission internals.
That 15% rule of thumb is so out of date.
That 15% rule of thumb is so out of date.
It's not out of date, just the variances have changed a great deal.
Front engine mid engine rear engine
Front tranny gears or rear tranny gears
Fwd awd rwd
Manual auto
The vette is closer to 10/12 where the AMG Merced are still around 18. The only way to know for sure is run it on a chassis and engine dyno back to back. Really who ever pulls a motor these days?
I don't think the 15% "rule of thumb" is very accurate much after 300hp for all manual rwd cars.
A transmission doesn't magically sap 15% of an engine's power production. The heat transfer, heat loses, etc vary widely from one rwd drivetrain application to another, and are largely because of necessary torque requirements to move the given components, or drive them. Just as an alternator, a.c. pump, et al will "sap" power, a few lbs/ft of torque, so will transmissions, differentials, etc. That said, requisite thermal loss will occure when the components being driven are hotter than optimal. This loss will rise as temperature rises, and is indeed more so a function than a static amount, but it is a function of loss related to temperature which is linear/exponential.
Anyways, here's a great example of why a static 15% loss doesn't work.
Example,
Manufacturer A builds a 3500lbs rwd manual car making 526hp with the following combo.
-lightweight t3160 6spd
-stage 3 dual plate clutch
-drilled aluminum flywheel
-carbon fiber driveshaft
-3.55's in a torsen differential
-transmission cooler
-differential cooler
-16lbs light weight 18x8 wheels -225/40/18 tires
Manufacturer B builds a 3500lbs 526hp rwd manual car with the following combo
-t6060 heavy duty 6spd
-heavy duty stage 2 single plate
-reinforced steel flywheel
-2pc steel driveshaft
-4.10's in an eaton posi
-28lb 18x10 wheels
-285/35/18's
Manufacturer C builds a 3500lbs rwd manual car making 225hp with the following combo.
-lightweight t3160 6spd
-stage 3 dual plate clutch
-drilled aluminum flywheel
-carbon fiber driveshaft
-3.55's in a torsen differential
-transmission cooler
-differential cooler
-16lbs light weight 18x8 wheels -225/40/18 tires
Manufacturer D builds a 3500lbs 225hp rwd manual car with the following combo
-t6060 heavy duty 6spd
-heavy duty stage 2 single plate
-reinforced steel flywheel
-2pc steel driveshaft
-4.10's in an eaton posi
-28lb 18x10 wheels
-285/35/18's
There is no possible way A and B both require 78hp/tq to be spun at 5252rpms in a 1:1 gear (5th or 4th) if we are to believe that cars C and D also require 15%, which would be 33.75hp/tq at 5252rpms in 1:1 (4th and 5th)
There is no possible way car A and C, nor B and D, can require different drivetrain requirements to spin at 5252rpms if they have the exact same drive train, and simply differ in their engines. (I copied and pasted a and b for c and d, but changed c and d to 225hp.)
Again, this is all assuming a consistent operating temperature for all for hypothetical vehicles. As heat rises, the heavier components may be less prone to lose power to thermal losses, the lighter components may be more likely to fail,etc.
End rant.
I think the gt350's drivetrain eats up about 50hp/tq at 5252rpm.
If anybody is an engineer, and knows the actual reality of all this, please correct me, this is just my grasp of it.
Reducing driveline mass has nothing to do with increasing the overall output of the engine. All it does is allow the engine to accelerate faster. Once both engine reach peak rpm's the output will be the same. The heavier driveline just stores more energy which is why it accelerates slower and who want's that.
The rear diff is what saps the most power which I think is about 13% total on most cars. AWD can be as high at 18%