Is there a formula or rule of thumb to figure the rwhp loss thru trannies?
Trying to figure an approximate ~correct rwhp for my car with the TH400, 12 bolt w/3.73's, 4500 stall.
I know the normal loss through the A4 is ~20%. But what about withg the A3 and 12bolt?

Tim

 

Tim, I might be in the minority, but I think the driveline loss is closer to a fixed number than a percentage of driveline loss. Let's say a stock LS1 with a 4L60E and 3.23 gears puts down 300 rwhp. Research has shown that the stock LS1 motor puts out about 350 hp, so let's call the driveline loss 50 hp or 14.3%. For arguement sake, let's call it a flat 15%. OK, now we add all the bolt-ons plus heads/cam and we now make 400 rwhp. If we divide our rwhp figure by .85, we get 470 hp. Do you really think the driveline loss rose an additional 20 hp because of the additional hp or is using a formula like 15-20% driveline loss misleading?

For your case, here's my best guess. Start with a stock driveline loss of 50 rwhp. 10 bolt with 3,23 gears vs. 12 bolt with 3.73 gears (add 10 hp loss). 4L60E vs TH400 (add 10 hp loss). Stock converter vs. PI 4500 converter (add 25 hp loss). If you do the math, your combination would make 255 rwhp in a stock LS1 (with 350 hp) and 355 rwhp in a modified LS1 (with 450 hp). The driveline loss percentages are 27% and 21% respectively. Now add 50 more hp and we're getting more in line with the power that your motor makes Tim, so I would expect it to be around 405 rwhp with your combination (500 hp- 95 hp driveline loss = 405 rwhp). If you look at the driveline loss as a percentage now, the figure drops to 19%.

So in your case, 20% driveline loss might not be a bad figure to use, but it's way high for a more stock combination.

 

I figure the TH400 is around 25%-30% loss...

I made 370's rwhp and 430's rwtq...through a TH400 with a non-locking converter...

Cars with less HP and TQ than me w/similar setups are going 11.6's...

 

Damn Patrick, I hadda read that one a few times to finally digest it all, but it makes sense now. Thanks

I FINALLY got a dyno on my car after what, 1.5 years.... 388rwhp. I don't remember the tq. Th400, 3.73 gears in a 12 bolt. Seems a bit low to me but the car went 11.87 @114mph 2 weekends ago in Shreveport. Hi humidity, but I don't have any other figures for the air and stuff. I have a few changes to make then I'll run it again to see.

Tim

 

Tim, what is done to your car...(motor work)

 

H/C, long tubes, custom exhaust. The usual crap. LOL
Motor was actually specd/built for N2O, but I have yet to put it on. ARE built it in 2000.

Tim

 

tim did you get to tune that load?if so what did it make before.dont remember the torque??what tha hell,old age getting to ya huh.

 

Yeah, Geoff tuned it but as a shock to me, the old tuning put out as much hp as the new tuning. Idling quality is MUCH better.
When you making the swap to ghetto tranny?

Tim

 

Tim, the TQ was 420. I was suprised it put down those numbers through that drivetrain. Car sounds sweet at WOT on the dyno. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Are you EVER going to do some weight reduction, you are well over stock weight with a 12bolt ( +40lbs ) and TH400 ( +??#s ). <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

Justin

 

Justin,I weighed the car in Shreveport. Weighed 3650 with me and 1/4 tank. Prolly won't do any reductions. Just ain't into it. LOL
Thanks for the tq specs.

Tim

 

tim still not 100% sure on th350,i know ill go faster,but i like bangin gears,but i wont like paying to fix the tranny(m6)hell the clutch and master will pay for my tranny build.prolly pretty soon 2-3 weeks.