I just ran my car today on the Dyno (results in Sig) and I was just curious if anyone knew how to convert that to crank horsepower and torque. Thanks

 

assuming an 18 perecent drive train loss ud have about.....

372.76 HP and 404.74 TQ at the motor..


you could be losing more or less than 18% but it should be in thar region.....nice numbers.

 

Thanks!

 

Assuming a 18% loss, the crank rwhp would be 385.24 ...

 

315.9 x 1.18 = 372.762 hp according to my calculator??????

 

No, it's 315.9 / 0.82 = 385.24. Remember, drivetrain loss is a percentage of flywheel HP. Multiplying by 1.18 is adding 18% of rear-wheel horsepower.

So the numbers are 385 HP and 418 TQ (*theoretically*, based on 18%).

 

now u see if i was less tired, i wouldn't have made a dumb mistake like that......i'm looking at it again and i cant believe i did that that way....lol sorry bout that

 

Man those are some good numbers i think for the mods you have. I wonder if i am around the same numbers you are, i have about the same mods as you. Where did you get it dynoed at?

 

Got it dynoed at Terrapin Motorsports dyno day at UMD. I'm happy with the numbers but I wish the horsepower was a little high. I only let it go to 6000rpms when I dynoed it because i was afraid of detonation. I was hoping for around 330HP but 315 is still good, 343TQ was the number I was really happy about.

 

18% loss seems high.

I'd put it more around 15%.

 

If that were the case, then the crank numbers would be:

371.65 HP
403.53 TQ

Truthfully, that's probably a little more realistic, but regardless, the engine is making "somewhere" in the neighbourhood of 370 - 380 HP, and 400 - 415 TQ.............that ain't bad!

 

I remember reading a post on another board some time ago where someone did an engine dyno and a rw dyno with a Mustang ... suprisingly the loss was in excess of 20% ...

 

At a certain point in the curve that doesn't surprise me. There was an article written somewhere that said some Buick lost up to 38% at a point.

But at the peak? I won't buy 20% on a stock Mustang or 18% on a stock F-body. On our cars, I usually place manuals at 11-14%, and autos at 15-17%. It's hard to nail it down to a certain place, but anywhere in those percentages usually makes sense.

 

Why would a power train be any more efficient at peak than it would any place else in the power band???

 

Remember guys, it's not really a "percentage" of engine power that you can accurately calculate. That "loss" happens in the transmission (mostly), through the gears in the back, and even between the tires and the road (or dyno).

Unless someone disagrees with me, I think it's safe to say that the drivetrain loss is actually a given amount of HP, which doesn't change regardless of what engine is in front of it. I mean, if we want to say that it's always 15% (arbitrary number for an example) then do you honestly think that you're losing only ~50HP when the car is bone stock (based on 350 crank HP) but that you're losing 90HP if you have a 600 HP engine?! I think not.

So based on that theory, let's say it truly takes "50 HP" to turn the tranny, gears, etc. (again, just for argument's sake). If a Mustang engine makes 260 HP (I think that's what a GT makes? ) then the drivetrain loss would be about ~19%. However, the LS1 makes 350 HP, so a 50 HP loss is actually about ~14%.

Does that make a little more sense?