IzzY_IS350

I know this has probably come up before If it has, just please point me in the right direction. I will appreciate it.

Lexus claims the IS350 generates 306 HP. Is this correct? According to the dynos posted in this forum, it sems that the actual horsepower is around 268-270 HP. WTF!!

Could this be considered false advertisement?

javyLSU

iTrader: (21)

No, because all auto companies quote HP at the crank, not at the wheel. What you're seeing here are dynographs which measure rear wheel horsepower, not engine horsepower. There's usually a ~15% loss through the drivetrain to the rear wheels.

Javier

DaveGS4

iTrader: (2)

Actually with Lexus trannys it's more like 20%. Those smooth shifts come with a price.

IzzY_IS350

I see....Thanks for the quick replies!!

Ramon

It is actually almost exactly 15% drive line loss.

Say the average IS is putting down 258RWHP, that's just over 84% of 306HP so we're looking at a driveline loss of under 16%

Hip_hop77

i heard bmw advertises whp is dat true?

Ramon

I highly doubt an M5 is putting down 500RWHP

Realfresh

agreed, that would be DISGUSTING

ff_

Why doubt that? If their 3.2 inline 6 can put out as much as 360 HP from the factory, why wouldn't they be able to pump 500 HP out of a 5.0 V10?

DaveGS4

iTrader: (2)

Interesting, so either the 2IS tranny is more efficient than others or the average dyno number is a bit high (I haven't paid a lot of attention to baseline dynos posted so will take your word for it). 15% is not unusual to see with stick cars

Just for background for the OP, the formula to calculate hp = rwhp / (1 - dtl)
where hp = crank horsepower
rwhp = the rear wheel horsepower from the dyno
and dtl = the drivetrain loss

Tony1

Of course the IS350'S Tranny is a great performer, how many other 300 hp, (automatic) cars that weigh in at almost 3,600lbs do you know of that can
do the 0-60 in about 5.3 seconds!

javyLSU

iTrader: (21)

You heard wrong. BMW, like every other car manufacturer (and more importantly, it's marketing department) advertises engine horsepower measured at the crank. The BMW M5 IS NOT putting down 500 HP to the rear wheels, it's engine horsepower. RWHP for a stock E60 M5 is ~420HP.

Javier

Ramon

I didn't say it can't put out 500HP, I said 500 RWHP (REAR WHEEL HORSE POWER) Thier 3.2 Inline 6 is not putting out 360 RWPH, that is crank/flywheel HP, there is a difference.

Ramon

Either it is very efficient or the engine may be slightly underrated. When I got my car dyno'd my basline numbers varied from 258-260 rwhp.

lobuxracer

iTrader: (2)

I'd bet on the engine being slightly underrated. My Supra put 330 hp to the wheels on Silver State Motorsport's Dynojet in Las Vegas with nothing but a 6 psi boost increase (internally bleeding wastegate VSV) and a lightweight flywheel. It was rated at 320 crank and was stock right down to the air cleaner and cats in every other respect. The plugs were OEM NGKs and they even had 40k miles on them. Oh, yeah, a small shot of 100 octane fuel helped just a little too. Actual tank octane was about 95.

Almost forgot to mention, the odometer had 110,000 miles on it at the time, and it had never been opened. Still on factory build. Maybe that's part of why I like Toyota so much...