Conversion From WHP To Flywheel HP? - IW STi Forum

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#1 · Sep 25, 2008 Hey guys, I always wondered.... what is the conversion from what you make at the wheels to what you are making at the flywheel? I have read that you multiply 1.21 by whatever you made on your dyno and that should net you your flywheel hp reading? Thanks, Stifun Sort by Oldest first Oldest first Newest first Most reactions #2 · Sep 25, 2008 whatever the drivetrain loss is. i always thought it was 25%. so 1.25. i am prolly wrong though. #3 · Sep 25, 2008 It depends on what type of dyno. For instance I dynoed at 252whp on a dynojet all stock. If are cars actually make 300hp exactly, my stock car had about a 20% drive train loss. My car however would dyno alot less on a DD or a Mustang dyno. #4 · Sep 25, 2008 I asked about this a while ago. heres my thread with replys- http://www.iwsti.com/forums/general/122655-hp-conversions.html this was the most useful to me and the one I followed:

GilMikalian said: So I went to the Harman Motive website and checked out their dyno plots in the Gallery section. In stock form, they got 240 wtq & 233 whp. Keep in mind the Mustang Dyno is apparently quite stingy so these are conservative numbers, not to mention each vehicle will have a variance to some degree. So taking these numbers and using SOAs numbers of 290 tq and 305 hp, we get about losses of 17% for tq and 24% for hp. So taking the Mustang Dyno ratios, your figures of 325 whp = 427.6 hp at the flywheel (325/76%) and your figure of 340 wtq = 409.6 tq at the flywheel (340/83%). Those are some healthy numbers...assuming I haven't totally botched the numbers! Wow, I must be bored. If anybody wants the excel sheet that will convert your wheel HP/TQ to flywheel HP/TQ (along with the assumptions above), PM me and I'll shoot it to you. You just plug in your dyno numbers and you get the figures. Of course, if you have a baseline chart for your vehicle, nothing beats that. Click to expand...

#5 · Sep 25, 2008 Drivetrain loss is a fixed amount and not a percentage. With that said, every dyno reads differently. #8 · Sep 25, 2008 +1. Realistically, you probably lose about 35 - 70 hp from the flywheel to the wheels. 1 Reply #6 · Sep 25, 2008 it's hard to figure out, because once you put down 450whp, that 20% is a huge number. #7 · Sep 25, 2008 there isnt a truely accurate conversion. #9 · Sep 25, 2008 I've been told our cars standard is 27% drive train loss due to the AWD... #10 · Sep 26, 2008 Depends on the dyno. For example; Dynojet's show much better numbers then mustang dyno's. Stock STi's on our local mustang dyno put down around 215whp, which is a 29% loss in power, on a dyno jet most STi's put down around 250whp, which is only a 17% loss. #11 · Sep 26, 2008 Drivetrain loss is not a flat percentage. There are a lot of variables; RPM, wheel and tire combination, drivetrain temperature. We have the MAHA LPS3000 dyno that measures actual drivetrain loss will calculate flywheel horsepower. If you guys are interested I will post some dyno charts showing the losses and flywheel horsepower. This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread. Insert Quotes Post Reply

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