So all Ferrari's quoted HP is at the crank ?

Porsche tends to understate their power. GM tends to understate as well. Ferrari; the opposite.

 

All companies state crank.

The lastest Benz turbos also vastly understate, quote 495, and run 470-480 at the wheels!

 

OK, i need a little help then. i always thought that just "HP" was to mean at the crank, and "BHP" meant at the rear wheel...hence the "B" for brake?????

can someone clarify?

 

Flywheel

 

The B does mean brake, but not necessarily at the rear wheels. A brake is necessary to measure HP, whether at the rear wheels or at the crank. Without resistance (brake), force (HP) cannot be measured.

Gary

 

All manufacturers quote BHP or crank HP. There has been some speculation recently leading to an adoption of new procedures (SAE HP), b/c many companies were running engines on dyno without any accessories to fluff #'s!

From Wikopedia:

In 2005, the Society of Automotive Engineers introduced a new test procedure (J2723) for engine horsepower and torque. The procedure eliminates some of the areas of flexibility in power measurement, and requires an independent observer present when engines are measured. The test is voluntary, but engines completing it can be advertised as "SAE-certified".

Many manufacturers began switching to the new rating immediately, often with surprising results. The rated output of Cadillac's Northstar V8 jumped from 440 hp (328 kW) to 469 hp (350 kW) under the new tests, while the rating for Toyota's Camry 3.0 L 1MZ-FE V6 fell from 210 hp (157 kW) to 190 hp (142 kW). The first engine certified under the new program was the 7.0 L LS7 used in the 2006 Chevrolet Corvette Z06. Certified power rose slightly from 500 hp (373 kW) to 505 hp (377 kW).

 

So my NSX (which dyno's at 360.0 HP at the wheels) has more horsepower than my Modena? The F car sure "feels" faster. Maybe because it's normally aspirated HP. The throttle response is way quicker!

 

I short, yes. If you back-calculate and assume a 15% drivetrain loss, your NSX is making in the neighborhood of 423HP at the crank. To me, peak HP is much less important than the area under the curve, though.

 

Your NSX has forced induction?

 

This is complete nonsense. It is not up to each manufacturer to decide what it is they want to state. In Europe, anyway, (and I would imagine in the litigous US also), there are norme that are set forth that are to be respected. Those norms require a minimum of X bhp and Y torque. Now if a manufacturer claims more than the actual output that is ok (within reason) but less is not.

I have seen the benches that the factory uses to check bhp output and I doubt very strongly that any third party measurement is going to be more accurate.

In Europe, a number of cars that I know have been checked and the output is always within 5 bhp of the declared amount ( sometimes more). However, have also noted a distinct drop off in power output on 360s that have had their cats removed....... power comes right back when you put the cats back on.

 

Err... no it's not.
Porsche are conservative with their HP quotes. Often when tested they outperform their own manufacturers figures and at the bare minimum MEET the quote.
Ferrari's tend to have a greater spread of HP figures when various cars are tested. Almost NONE exceed the manufacturers quotes while many (that I have seen) are "quoted HP LESS 3 to 7%." You can call this OVERSTATEMENT or "variable build" quality. It's up to you - either way - don't belive that because Ferrari print it, it MUST be accurate. It *may* be, but equally it may not.....

 

The conversion units are as followed

hp to kw -> hp / 1.360
bhp to kw -> hp /1.341

All manufacturers i know quote the hp at the crank. The difference between british brake hp and normal hp depends on the local conversion how much a horse can pull. More details here http://en.wikipedia.org/wiki/Horsepower
So it isn't because an engine dyno with a brake with brake pads give other results then an dyno with an e brake they must give the same result or they are not well programmed and useless for dyno test. Also bhp doesn't mean the the wheel like some people all over the internet think it means. The drivetrainloss is dependend on many things and isn't a fixed factor to put in an fixed conversion also the drivetrainloss is much higher then the difference between bhp to hp.
_______________________
Samy

 

GM most certainly under-rates the HP/Tq numbers on some of their cars. I drive one of them. The LT4 engine was put into some 96 Corvettes as an option, and was rated at 330HP. In 1997, the first year of the C5, the LS1 came with 345HP. What GM had in the LT4 in 96 was in fact a 350chp engine from the factory, but they did not want to overshadow their new block with the previous year's engine, so what did they do? Rated it at 330. Is it actually? No. Numerous dynos of bone-stock cars show much higher than 330chp.

 

>>>Your NSX has forced induction?

Comptech supercharger, 9 PSI boost kit, headers, exhaust.
Horsepower and torque curves (not to mention a video of the dyno run) can be seen at:
http://northwest.nsxca.org/mike.html

 

Schweeet...

 

Very nice, Mike. Great looking car...

 

Didn't the Japanese automakers have a gentleman's agreement of sorts to keep published figures under 300hp? I have wondered about my STI. It claims 300hp along with 300 ft/lbs. Acceleration tests put it dead even with 355's. This is one reason I don't pay a lot of attention to published numbers. As someone mentioned, the power curve can be more important than peak power. Howa car feels on the road does not always correspond to published power or 0-60 times for that matter.

Dave

 

Not for a while now, and it was 280hp, if I recall correctly.

 

I won't answer for him, but my understanding has always been that on STREET cars (for the most part, NA low-output engines), cats provide the necessary backpressure to ensure proper combustion (considering intake/exhuast valve & overlap times). High output, and sometimes forced-induction, race motors do not run cats, true. Keep in mind, the cam profiles of those vehicles wouldn't come within a country mile of passing emmissions if they *did* have cats. That said, the valve timing of those engines likely doesn't require the backpressure of a street engine.

Speaking only from a GM-owner's perspective, the catalytic convertors on my car flow very well from the factory. I have added longtube headers and hi-flow (honeycomb style) aftermarket cats, but I have at most a 5hp loss from the cats...not really worth much in the big scheme of things. Might as well stay "green friendly" as well as keep then engine operating as it was designed.

Just my 2c.

 

red line is with cats

blue line is without cats

very interesting

any comments ?
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yes. don't run cats

 

Is the torque curve available on another pic?