How do you do the whp to crank hp conversion?

 

whp is roughly 15-20% less than crank hp depending on the car, type of clutch you have, auto or manual transmission, how heavy your wheels are, and how heavy other misc engine parts are.

 

Yeah, I know all that. I meant the actually equation. Do I just do 255x.18? Earlier Nano stated that 255 from 300 = 15% drivetrain loss. But when I do 255x.18 I get 300. I am doing something wrong?

 

300 x .85 = 255

 

Ah, Im so retarded. I knew that.

 

[(300 - 255) / 300 ]*100 = drivetrainloss %

 

That means the 287hp model has 20.9% drivetrain loss...you sure that's right? Nevermind...you edited it.

 

hey thawk...this is off topic. When you broke-in the car, did the car get more quiet? I just hit 900miles on my 05 and my car got little more quiet. I use to hear it starting to growl when i get to 3100rpms. Now i have to push it to 3500rpms for it to start growling.

 

I am not sure on the growl, but it did get a lot smoother. After I change my oil it made it even more smoother.

 

Why does everybody express drivetrain loss as a percentage? The flywheel, tranny,driveshaft, rear end, and wheel and tire combos are what create parasitic drivetrain loss and these don't change as engine power is increased. A miniscule amount of increased friction as power goes up true, but that would barely be measurable on a 300hp engine. Doesn't it just cost about 45hp from the engine to the wheels whether your Z has 280 or 400hp? I have never seen a broken in motor dynoed on an engine dyno and then on a chassis dyno to support the "percentage loss" arguement. Does anyone have a link to one?

 

255hp for an 03 is incredible! If these are posted somewhere please put up a link. It will feed the bench racing for months

 

just wanted to make sure you dyno'd in 5th gear???

 

Thats insane, nice numbers. Thats bone stock?

 

I played with some numbers a few months back more for amusement than anything else, since it wasnt really scientific. I read some online articles on drivetrain loss and looked at some dyno results from stock Zs, and I did this post on another forum, so here it is for what its worth. 17% is as good a number as any, but when you consider the variances in dyno machines, temperature, manufacturing of Zs, etc., it is impossible to come at ONE number that is accurate for ALL Zs. This is just a "guesstimate". Your mileage may vary.

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I have been reading a lot about drivetrain loss to see how to estimate how much hp my car has from the rwhp number. I have read in most places MT cars average 15-20% I took all the stock MT dyno results from the dyno thread and averaged them - it came out to 236hp and 230tq. In order to get to the advertised 287hp and and 274tq, you would have to apply a 17.75% loss (divide by .8225) to hp and 16% loss (divide by .84) to torque to get the published numbers. 17% across the board sounds like a nice round number, and it is consistent with the 15-20% estimates I have been reading everywhere.

Soooo, if you take your rwhp number and divide by .83, voila! you get an hp estimate.

Never mind that dyno results vary from machine to machine as much as 30hp.

Never mind the results I used has no info on SAE correction, ambient temperatures, machine type, etc. etc. (they are all stock).

I just needed a number I could impress my friends with when they asked me "so, how much hp you got", and I didn't feel like explaining the difference between hp and rwhp and drivetrain loss and stuff. I just give them a big "332hp" and they go "wwwwwoooooowwww". Its when one asks me "is that at the wheels?" that the conversation gets interesting.....

Year hp torque
???? 230 219
???? 230 220
2003 230 230
2004 231 224
???? 233 227
2003 235 230
???? 236 228
2003 238 228
2003 242 240
???? 242 238
???? 243 240
2003 244 236

Average 236 230

287.11 273.89

Published 287 274

 

Sure is.

 

I highly doubt someone hit 255 whp in the original engine variant, otherwise it was freak of the year.

Remember, not all dyno's are the same, nor are they done the same. People dyno in 4th and not in 5th for the MT's (5th is the correct gear), which will give you a higher number. Dynopacks give higher numbers than Dynojets which give higher number than Mustang Dyno's. Some people use SAE corrections, others leave them at STD numbers. There is way to many variables in play to try and get fixated on one number that represents all models.

 

Actually it is not a freak engine at all, it is the new factory 300hp engine for the 05 Track and the 05 35th Aniv. 6spd. It was a dynojet and I dynoed in 5th gear. The smoothing on the dyno sheet is set to 3 and these are SAE corrected numbers. Hopefully I will be going to the dyno tomm with a crawford plenum. I will post the numbers and video after I get back.

 

Ran my car in 4th AND 5th last time I was at the dyno...difference was half of one hp.

 

255whp on the new 300hp engines actually sounds about right. If you use the 17% drivetrain loss and multiply 300 * .83, you get 249. With SAE correction, differences in dyno machines, etc., this is very likely. 287hp (crank rating of the 03-04Z) * .83 = 238hp. So, 11whp more? Sure! And 255whp? Of course! These numbers are +/- 10hp at best.

 

First of all 4th is the gear you should dyno in, but Briguy said 4th and 5th was nonexistant in terms of power differences. Second, from what I understand SAE corrected numbers are always lower than standard #'s.

And his are great numbers for being stock.