For the 350Z, is there a rough rule of the ratio of engine HP to rear wheel HP? In other words, if your engine creates 287 HP, how much rear wheel HP would there likely be?

 

yep... you are talking about "drivetrain loss" and in our cars it's roughly 15%. So, if you have 287 hp at the crank, you are about 243 hp at the rear wheels.

Likewise, when you makes mods and go dyno the car, the same 15% applies... so if you make 255 rwhp, that is about 293 crank hp.

Cheers,

PeteH

 

Everyone has been using around 17% drive train loss. So 287HP minus 17% equals 238 rwhp. This has been the average of what most people are getting on the dyno stock. Some have dynoed as low as the 220's and a few have dynoed 240's so 17% is IMO a more inclusive percentage.

Jeff

 

Thanks Audito350Z and jak! Very clear.

 

I concur with 17% loss

 

I too would use 17%. Assuming the 17% drivetrain loss, you do NOT multiply the RWHP * 1.17 to get back to crank HP!

You would divide RWHP by 0.83.

 

I don't think 17% is likely, given the persistent effort by manufacturers to improve efficiency, and because the rule-of-thumb for a 'front-engine-rear-drive' layout is 15% drivetrain loss. I suspect 15% is more accurate, and our cars actually have about 280hp.

 

The fact of the matter is you have no idea how much HP we have at the motor because you have never put a VQ35DE on an engine dyno. You can't calculate drivetrain loss as a percentage over a span of more than one vehicle. Sorry. You just have what you have. None of us have the same thing and none of us have the same drivetrain loss either.