I was bored and stumbled upon a dyno vid of an IS350 with PPE headers. It showed a final HP reading of 281hp @ the wheels with the PPE headers, F sport intake and custom magnaflow exhaust. Also it showed that the headers gained 16hp meaning with the Fsport intake and custom exhaust hp would of been 265. Damn this is getting too long, let me cut to the chase.

Im trying to figure out how much HP the IS350 makes stock at wheels and more importantly i REALLY want to know the drivetrain loss%.

My guess is anywhere from 18%-20%, the reason i brought the video up was if i used a drivertrain loss of 18-19% it doesnt add up right unless the fsport intake and custom exhaust make monster HP(about much as the headers if not more) using 19% loss that equals about 248hp stock, add 16hp at the wheels from the headers and that means 17hp from the intake/exh...i dont think So!!??!
My cuz's mustang gt lost about 16.5%, thats a rwd with a manual trans, so since our IS' are auto we should lose a lot more. We dynoed the mustang 3 times and it was rock solid reliable and steady, but i think the dyno was a sweetheart, going off the 320BHP.

Ive seen rwd + auto trans cars lose 22%, does the IS350 really only lose under 20% and if so anyone know why? Great tranny, light drive shaft, anyone????

There's a reason I call manuals antiques. There's little to no measurable benefit to them anymore.


The most common stock dyno # I've seen for an IS350 is 265 hp. With 306 at the engine this puts drivetrain loss at 13.4%

Does it really matter what the true horsepower number is? Are you in a contest of some sort? The car is not overly fast but has more than adequate power for most people.

13.4% is incredible. Im just wondering how. I guess manuals are antiques Kurtz if now these autos are losing less.

I was just wondering, does it matter why i want to know...no it doesnt so no need for your little hoe *** comments, you understand me miss whiny? Not overly fast but adequate power for most people, wow thanks for that brilliant assumptive discovery, are you in the Lexus census bureau?

I think drivetrain loss is more than 13%, but I also think the Lexus claims of 306hp is underrated.

that's certainly possible, but the only way to be sure (unless you want to go with trap speed math) is to yank an engine out of the car and run it on an engine dyno

Everything I've seen say's @ 18% loss.

I truely think the IS350 puts out close to 316-320HP stock.

= 262WHP + 14whp PPE Headers

+ 5 hp for the Intake and Exhaust

= 281 WHP......


This also works out about right for displacement vs compression being @ 53HP per cyclinder

^^Sounds about right to me. 13% just sounded too good to be true.

I wonder if the IS350 motor was truly put on an engine dyno, or if the 306hp figure was from an estimation.

Pretty sure a "guess" would be illegal.

Remember the whole thing back in 2005 where SAE came up with the new "certified hp" measure for HP? (and many cars magically lost hp without any changes-including some Toyota and Lexus vehicles because they switched to the new system right away).

Now, what I do wonder is perhaps the 18-20% drivetrain loss that "everyone knows" is from the older ways of measuring hp (which going way back tested the engine with no accessories on it even)... such that if the "old" test would've indicated the IS350 engine makes 320 hp, an 18% loss would put you at 262.4... pretty close to the 265 we've often seen on a dyno.... but under the "new" system the engine measure is only 306... it still puts the same 265 down to the wheels though, making it appear like it's only a 13% loss.

Just a theory, but it makes more sense than "We're lying about our hp to make ourselves look worse compared to the #s BMW and Infiniti offer"

you can't take the difference between engine hp and wheel hp to assume a drivetrain loss percentage

UNLESS you only use that percentage for stock cars

When headers/exhaust/intake are added to the car, that PERCENTAGE of loss no longer applies. The things that suck power between crank and wheels haven't changed, they are not taking away any more power than they were before

so your "loss percentage" when modded will then be significantly lower

Unless you're talking a supercharger nothing will add enough power to really change the numbers that much though.

(and a supercharger has its own drivetrain loss from how it's driven, so perhaps not even then)


Just to toss out some math:

Stock:
306 at the crank
265 at the wheels

drivetrain loss= ~13.4%

With an intake we assume a 5 hp gain so-
311 at the crank
270 at the wheels

drivetrain loss= 13.2%

That's pretty f'ing minor. But lets go nuts... I/H/and E. So about 25 hp.

331 at the crank
290 at the wheels

drivetrain loss=~12.4%

Still not what I'd really call significant. A 1% difference from stock.

^^ True that..!!

All the R&D Dynos I have accumulated over the years (on a DynoJet), put us in a 13%-14% drive train power loss on an IS350..

~ Joe Z

I guess I've never asked or heard this question answered but is adding mods (intake, exhaust, etc...) adding to the crank hp or just reducing the drive train loss %? For example, by adding an intake, does the crank hp go up to 311 from 306 or does the drive train loss % go from 13.4% (265 vs 306) to 11.8% (270 vs 306)? I was always under the impression that items such as intake and exhaust were a component of the drive train loss so by adding aftermarket parts you were actually making the car more efficient hence reducing drive train loss but not actually affecting the crank hp. Only mechanical additions (turbos, superchargers, nitrous, etc..) would actually increase the crank hp. Please feel free to correct my understanding.