How can Mazda rate the RX8 6 MT at 238 hp, but in all actuality it's only around 200? I thought that 238 would be wheel horsepower....am I wrong?

p.s., sorry if the answer to this was already given....too much crap comes up when I do a search

 

your wrong

 

I am? then why do all the dyno tests that I've seen included in the sticky above show around 180 - 200 hp?

 

flywheel horsepower is around 210-215 hp . wheel hp is around 175-180 .

How can Mazda claim 238 ? We would all like to know the answer to that one !

 

http://www.edmunds.com/ownership/tec...5/article.html

 

thanks a lot guys! Good to know that the car only produces 180 - 190 at the wheel. Even if it's only 180, it feels like a lot more at high RPMS.

 

The whole number game is a little silly.

Take the car out for a test drive and floor it. That's how much HP it has.

 

im abreast of the HP number game that manufacturers play... i know of drive train loss etc etc, the quesiton thats floating around in my mind righ tnow is how much drivetrain loss does a G35C get or a 350Z get. They feel all high and mightly with the 300HP mark, but I'd love to know the whp of each. I'll probably search later.

I'm sitting a little under 200whp (yes I dyno'd at Rotary Performance in Garland, TX) right now. Lightweight RP supercat, RB exhaust, and a few odds and ends. Next step is either lightweight flywhee and clutch or whatever FI solution that comes out next and doenst suck.

 

^I'd like to know whps of those cars too. I'm too lazy to search though =/

 

^Ask IKE lol

 

Its too late to think about why the hp is low if you have bought the car, what matters is what you are gonna do with what you have

 

^Yup. I mean if thats the case just trade in and get something with more hp.

 

Yes, you're wrong. Why would you think it would be wheel horsepower? NO manufacturer has EVER advertised the horsepower rating in wheel hp - by law, they are required to report hp as determined by SAE testing in bhp - brake horsepower.

BHP is determined with the engine itself mounted to a brake dynamometer, which is why it's called brake horsepower. It's measuring power at the flywheel, so that's why it's also referred to as flywheel hp.

Every horsepower rating you see given by any manufacturer is bhp, measured at the flywheel.

 

IMO a clean 1/4 mile run w/ trap speed is a better measurement of how fast a car *really* is than some arbitrary 'horsepower' number.

 

Ehh..

A stock, base (read: no traction control) RX8 has dynoed at 190rwhp.

From 238bhp, With 15% drivetrain loss, that puts the flywheel horsepower at roughly 200rwhp.


10rwhp isn't anything to fuss about, really..especially with how Mazda is ALWAYS overrating their vehicles (or underrating, as far as the Mazdaspeed 6+3 are concerned )

 

Dynos are far more useful for tuning than they are for factual numbers unless you are into bench racing, but you can get some rough comparisons. The VQ35DE in the Z dynos in the 230-240rwhp range.

 

and then you have to keep in mind they weigh ~6-800lbs more.

 

more like ~300-400lbs more.

base RX-8 is around 2900, base 06 350Z is around 3300lbs.

 

gotta love that nissan vq engine, such a beast

 

Advertised horsepower is always questionable. My old Mustang Cobra was rated at 240 horsepower, yet I hard a hard time keeping up with a friend's Mustang LX that was rated at 225 horsepower. Yea, I know he had a weight advantage, but sometimes manufacturers play with the numbers.

Occasionally, some cars are underrated. I think the Buick Grand National Turbos are the best example. If I recall they were rated at 235 but in reality they were well over 300! Much faster than even the Corvette at the time!

 

turbo induced torque is another beast in and of itself to compare to an N/A motor.