05 rwhp...anyone know?

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bat24 said:
probably a stupid question but why does ford claim 300hp ?
Just curious. But is it an American thing to think manufactures claimed BHP figures are at the wheels??

It's not adig, but I see it all the time on US forums, but never non-American forums.

Manufactures have ALWAYS claimed the output at the engine, at least since before the First World War, so it always suprises me why so many think it's at the wheels, lol.

As for the 05, well 300bhp SAE Net is probably bang on for the engine. Howver you will probably see claims from 250-280rwhp.

This is because some dyno's achieve readings in different ways, also there are correction factors for temp/humidity/altitude/and others, plus spike smoothing on the graph. And the addition of different stands such as STD or SAE.

All in all I would expect 250-260rwhp to be a REALISTIC value, anything higher is most probably due to a variation in HOW the numbers where acheived, however it won't actually mean it's anymore powerful or faster.

So take ALL rwhp numbers with a pinch of salt, as they are anything but accurate.
 
tom281 said:
My '06 manual with 2000 miles on it dyno'd yesterday at 266 h / 294 tq. On a Dynojet dyno.

ts


I can see the 266 rwhp but not 294 rwtrq. I just dynoed an 05 with 25000 miles on it and it put down 261 hp and 271 torque. This is on a Dynojet and the is stock. Hey if your car is making more power then sweet. :nice:
 
JTGrant said:
I can see the 266 rwhp but not 294 rwtrq. I just dynoed an 05 with 25000 miles on it and it put down 261 hp and 271 torque. This is on a Dynojet and the is stock. Hey if your car is making more power then sweet. :nice:


I was surprised too. We were on the dyno that day for several hours, actually trying to find out why my car with a JLT II cai, X2 tuner, and Bassani axle-back kit only made 279/301; we were expecting more hp. So, we removed the cai and reinstalled the factory airbox and filter. Then we installed the stock tune (I saw this myself) and dyno'ed the car just with the Bassani kit on it. The dyno did read 266/294. I does seem odd, but none the less that's what it said. I was more upset that the mods I've purchased didn't produce more power, which we're still working on now.

Thanks,

tom281
 
Dyno numbers are all over the place, like said above, they rely on a measurement, and then several correction factors that can heavily influence the measurement. It's like we're all trying to measure the same thing with different rulers. Just because you're ruler say's it's longer, that doesn't mean it really is. The Dyno's are really only good for comparing two cars or the same car before and after mods on the same dyno. Everything is apples and oranges, and absolute numbers are doubtfull.
 
"Just curious. But is it an American thing to think manufactures claimed BHP figures are at the wheels??

It's not adig, but I see it all the time on US forums, but never non-American forums."

I'll get flamed for this, but you shouldn't be surprised. Half of adult Americans think the sun revolves around the earth. We're not real strong on science and engineering.
 
HP #'s are a joke, my 03 maxima (which is getting traded in very soon) claims 255 at the crank, after hundreds of dynos its 240 at the crank. A lawsuit was being filed not sure where it is now.
Manufacturers know HP sells cars so they will go as far as lying to make a sale. At least nissan did.
 
How did you measure HP at the crank? A new SAE procedure went into effect this year and several Asian manufacturers have had to dial back their advertised HP. Toyota's 3 liter engine went from 220 to 190 hp.
 
Hp measured at the crank is done on an engine dyno. Rear wheel horsepower is measured on a wheel dyno, like a dynojet or mustang Dyno. Engine (or crank) Hp is higher than RWHP since friction and other factors eat up some power. Typically people like to measure things in RWHP since it gives a better idea of what the car can actually do and it is easily measured on a wheel dyno. Two cars can have exactly the same crank hp, but completely different RWHP numbers based on how much parasitic loss the drivetrain has.

As to why americans think it is RWHP. I think the switch from gross to net hp confused a lot of people. I know a lot of older guys who think the HP claimed by the manufacture is gross HP (measured at the crank with no accessories on the engine) and that RWHP numbers or wheel dyno numbers are net hp (what the engine actually puts out with all the accessories). I think many after the switch never took the time to learn what it all meant, so instead of trying to figure it out they just stayed confused. So my guess is a lot of guys on american forums dont trust manufacture's ratings and look for what they think are NET ratings.