Flywheel hp vs Rearwheel hp?

[Duner]

Does anybody have any engine/chassis dyno comparisons for our combination of 46RE trans and 9.25" rearend to tell how much of a driveline loss we actually have?

Obviously the online calculators are all over the map when it comes to giving us numbers based upon performance. I have timeslips vs chassis dyno info to compare things with, but still don't know what the actual numbers are at the flywheel. Anybody have that answer?

[slvr03dakrt]

from what i have been told it is around 18%

[BTLFED R/T]

Based off what most are stock. 250 at the flywheels was 200 at the wheels, 20% loss.

[bad360rt]

I'll let you know here in the next month or so :) Ryan will be dynoing my engine and then of course I'll be dynoing it when it gets tuned. 46RE (built, but not rollerized) and 9.25" rear. Altho I might have 4.10s in by the time I dyno, not sure if that makes a difference or not, but then again, I might still be on the stock gears, I'm gonna be short on time and tuning is more important than getting the gears/locker put in.

[mtlcafan79]

I'm gonna be short on time

Hmm, when have we seen that before?

[Duner]

Thanks guys.

After reading thru a thread about proven dyno combos over on CarJunkie, it got me wondering. A bunch of these guys numbers don't make any sense to me. But without any real numbers for comparison, I'm sure not going to question anybody about them.

http://www.carjunkieforums.com/index.php?topic=2057.45

For instance: "Dyno: Superflow 902 engine dyno at Dougan's
Peak power numbers: 820 hp @ 6,400 rpm, 745 lb-ft @ 4,300 rpm
On the Spectre Mustang dyno we got 504 hp at the tires with a t56 trans"

It's obvious the engine dyno is generous, and the chassis dyno in this case is stingy.... but that sure is a huge spread between the numbers. I mean 38% loss is huge. I only hope that our real losses are only in the 16-18% range.

[mtlcafan79]

Dan Arcand claims the 408 in mine did 485/485 on an engine dyno. We'll see what it does at the wheels here shortly. Marty at KRC has been doing engine dyno time on their builds recently. He should have some numbers for comparison.

[Danno]

Here is my .02..

727 and 8 3/4 combos typically are 18-20% loss.

OD 727 ( 46RE ) and a 9 1/4 are going to be higher, because the OD takes more to turn, and the 9 1/4 isnt as efficient either. So Ive always figured 22% as my losses with that combo.

Now, with that said, percentage is the wrong way to look at it. The tranny and rear are going to take about the same amount of HP to turn no matter what you have in front of it. Yeah there will be slightly higher losses at higher HP levels, but not in a linear way. IE a 100hp car would need at least 50 HP to turn the trans/ rear at a given speed, where a 1000 HP with the same tranny and rear might only need 75HP to turn the same trans/rear at the same speed.

At least thats how I understand it.

Danno

[bad360rt]

Hmm, when have we seen that before?

Story of my life LOL

Not gonna half ass anything, but I need to get as much done in April as I can, so I can have time to work out any bugs before the Nats.

[rattler360]

hey i need your email to send you the pics you wanted of that fitting