When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Factory spec 282 hp is at the crank. On a dyno, you have to account for driveline loss of about 15%. Also different dynos yield slightly different values.
What did it dyno to the wheels? What brand? Temp at test time? Many many factors play in when a car is dyno'd. I personally never focus on the baseline numbers as I use chassis dynos for tuning and to track engine modifications.
That being said, a corrected 236hp IS low compared to where it should be. What does your "butt dyno" tell you? Certainly warrants a look over.
ok, few things. 1. Is this corrected as engine horsepower? 2. Why do the graphs not cross at 5252 rpm?
Hi QC - typically hp = torque if hp is measured in hp and torque is measure in ft-lbs. Here, torque is measured in Nm (you can see this at the top right of the graph --- it says "Nm") which is why the values do not cross at 5252 rpm. That said if HP here at 238 is measured at the rear wheels, the seems reasonable after accounting for conversion back to crankshaft figures.
Last edited by Jlaa; 08-07-2015 at 12:18 PM.
Reason: pointed out that you can see "Nm" at the top right of the graph
What makes me wonder is an engine torque of 292 - is that ft.lb or Nm? Low for Nm but high for ft.lb. When mine was on the dyno last year after an engine rebuild my torque curve read a max. of 233.1 at the wheel. Factory spec is around 250 at the engine. Please correct me if I'm wrong. My engine was tweaked a bit that's why my max. Pw is up a bit...
Maybe you should consider redoing your test on a different dyno. Just looks odd.
Hi QC - typically hp = torque if hp is measured in hp and torque is measure in ft-lbs. Here, torque is measured it Nm which is why the values do not cross at 5252 rpm.
Hi QC - typically hp = torque if hp is measured in hp and torque is measure in ft-lbs. Here, torque is measured in Nm (you can see this at the top right of the graph --- it says "Nm") which is why the values do not cross at 5252 rpm. That said if HP here at 238 is measured at the rear wheels, the seems reasonable after accounting for conversion back to crankshaft figures.
08-07-2015, 05:25 AM
Heeeelp - Just dyno-ed the 4S
