Why are so many cars underrated?

[3000ways]

Ok, WTF is going on, why are so many freaking cars being underrated these days? I mean seriously I believe there is freakin' problem, and I don't think it's necessarily a new problem, but since now it is much easier, simpler, and cheaper for people to dyno their vehicles the HP rating from factories and actual customers are becoming more and more apparent. Take for example the Neon SRT-4, rated at 230HP, absolute BS. The actual SRT-4 really makes around 270-280 engine HP. How and why does Dodge miss this, insurance is not the reason, because it really doesn't matter how much power you make, but what you have on your car, that is what insurance people care about.

Also another example, the Mitsubishi EVO, 271HP, absolute BS, the car dyno numbers have been around 230-250HP depending on the dyno application (some read lower than others) and if you factor in the suppose 20-25% drivetrain loss for an AWD car, that would put the EVO at around 300-310 engine HP, is this correct. Compare the EVO to the 350Z, both post similiar dyno numbers, yet the EVO suffers more drivetrain loss and is only rated at 271HP to 287HP for the Z. In reality shouldn't the EVO actually be rated at 300-310HP compared to 287HP for the Z. There are plenty of other examples. Why is this happending, can factory HP ratings ever really be trusted?

My main belief on these differences, is that some manufactuers rate their cars on the actual engine. Meaning the HP measurements are taken on the engine outside of the car, so in reality the actual engine is making a "X" amount of HP, but when placed in the car and the car is actually put competely together with exhaust and other important power making components, the engine's HP numbers actually rises, in some cases drastically. I believe some manufactuers account for these differences and some do not? Sorry this is so long, but are my assumptions correct? If so can manufactuer ratings ever really be trusted and shouldn't there be a uniform system of testing a vehicles true engine output?

[BeEfCaKe]

I think you need to calm down about this matter. Is it really that big of a deal? These are just all numbers in the end.

If you read a few threads below, you will learn that there is already such a standard measurement system in place, and most car manufacturers are compliant with it:

http://www.automotiveforums.com/vbul...d.php?t=263914

Posted by Alastor187:
SAE Net Horspower

In 1972, American manufacturers phased in SAE net horsepower. This is the standard on which current American ratings are based. This rating is measured at the flywheel, on an engine dyno, but the engine is tested with all accessories installed, including a full exhaust system, all pumps, the alternator, the starter, and emissions controls. Both SAE net and SAE gross horsepower test procedures are documented in Society of Automotive Engineers standard J1349. Because SAE net is so common, this is the standard we will use to compare all others.

[MagicRat]

Factory HP ratings are pretty much worthless anyways. You don't just drive the engine around on its own. The weight and gearing of a car are just as important as hp.
Therefore, how the car actually performs is the most important thing. The hp on its own is just a number, no more.

[Alastor187]

I forget the source, but I once heard/read that many of Japanese manufactures had a kind of “gentlemen’s agreement” to limit horsepower on their highest performing cars. The limit was around 300 hp so most of the cars were usually rated (by the mfg.) around 280hp, but more often than not they dynoed (sp?) and/or performed better.

Anyone else ever heard this rumor or can confirm whether it is true or false?

[01rollaS&accordv6]

Most Manufactures Base Their System On Bhp Which Usually Is The Main Reading And Can Vary On Horsepower Output Weight, Regular Or Premium Fuel And Other Factors. It Really Is Not That Big Of A Deal And No I've Never Heard The Japanese Doing That. Plus Why Would They They Are Some Of The Easiest Systems To Work With Look At Honda For Example And Chevy And Ford.

[Hudson]

3000Ways:

A dyno won't give you a more accurate ratings since, as is pointed out above, that's wheel-horsepower and engines are rated at the crank. I think your claim that the SRT-4 engine puts out 270-280 is a bit high, though. Insurance is STILL a major source of any claim that engines are "under-reported" in terms of horsepower. Another reason is that if, for some reason, engines are OVER rated (even by a hp or two), the manufacturer can be sued by owners; nobody's going to complain (except for you) that they're getting TOO MUCH power for their money.

Alastor:

It's not a rumor. The "gentleman's agreement" holds that all manufacturers limited the ADVERTISED horsepower rating of their engines to 276hp.

[Alastor187]

Originally Posted by Hudson

It's not a rumor. The "gentleman's agreement" holds that all manufacturers limited the ADVERTISED horsepower rating of their engines to 276hp.

That is pretty interesting, thanks for the feedback.

[kman10587]

Yeah, they actually have to advertise the Skyline GT-R and Supra RZ at 276 horsepower...c'mon, that's total BS

[SaabJohan]

The car manufacturers measure the engine power directly on the crankshaft, this is done with airfilter, exhaust system and all that we can found on the engine in the car so the power output should be correct.

Car manufacturers do their reading according to certain standards and with dynos that are very accurate. They also correct their values with for example air temperature and pressure so they don't get any advantage of low temps and high pressures. Since the reading is done on the crank there is no guessing of powerloss to calculate engine power either.

Then car manufacturers must calculate with that the power might differ a bit between the different engines in the serial production.

So with the aftermarket tests it is usually easier to get a higher value than the manufacturers have listed.

In Japan there is a 280 hp limit.