# Wheel HP vs Engine HP



## Guest (Jun 13, 2003)

Why do some companies state the engine horsepower, while others state the wheel horsepower? For example, I've read in a lot of places that a Sunfire gt has 150 hp, 155 torque. A nissan sentra se has like 145 hp, 135 toqrue. But the dynos I've found tell a different tale (130 hp, 126 torque, and that's with exhaust, cai, and timing). So I pose two questions.... Does the sunfire gt really have 150 hp, 155 torque to the wheels? And how the hell could a sentra se ever beat a sunfire gt in a race? (I asked who would win a long time ago, and some said it'd be a driver's race....but there's such a huge difference)


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## olsaltybastard (May 11, 2003)

Stating the engine hp allows companies to brag about higher numbers. This has been standard for many years.


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## chimmike (Oct 17, 2002)

no car company EVER says what whp their cars make.


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## James (Apr 29, 2002)

chimmike said:


> *no car company EVER says what whp their cars make. *


because it can vary with every car... even in the same model.

I think they show crank power because it an easier way to know what the average output of the car will be.


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## tekmode (Feb 22, 2003)

and also because insurance will be higher with higher hp numbers


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## FletchSpecV (Nov 26, 2002)

tekmode said:


> *and also because insurance will be higher with higher hp numbers  *


Good point, .


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## tekmode (Feb 22, 2003)

FletchSpecV said:


> *Good point, . *


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## Guest (Jun 18, 2003)

Isnt wheell HP the one thats important anyway?


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## tekmode (Feb 22, 2003)

SENTRAGROOVIN said:


> *Isnt wheell HP the one thats important anyway? *


yes it is


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## Scissors (Mar 24, 2003)

Engine HP has always been used by companies to make themselves look better. They used to use Gross HP before they changed over to SAE Net HP (and torque) 30 years ago. Gross HP ratings were generally about 20% higher than SAE Net ratings.

Deduct another 13%-20% for the drivetrain and you have your WHP and WTQ.

These days, cars with higher HP numbers actually advertise a lower number than what they truly have in order to avoid attracting the wrath of the Feds and avoid higher insurance ratings.


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## UpChuck (Jul 20, 2002)

Scissors said:


> *These days, cars with higher HP numbers actually advertise a lower number than what they truly have in order to avoid attracting the wrath of the Feds and avoid higher insurance ratings. *


The SRT-4 is a good example.


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## Adam (Apr 30, 2002)

Think about it from the company's perspective, is it easier to build and entire car, strap it down to the dyno and make enough runs to be consistant, or just take that engine you've got sitting in the corner and hook it up to an engine dyno? The same engine in different cars will be making different numbers, this way they test it once and be done. Lets not forget that they would also have to dyno ever car with a different type of transmission to get individual numbers for each of them because of the driveline losses inherent in each design.


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## Adam (Apr 30, 2002)

> And how the hell could a sentra se ever beat a sunfire gt in a race?


 Weight.
1000th post


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## FletchSpecV (Nov 26, 2002)

Adam said:


> *Weight.
> 1000th post  *


Haha, no kidding weight, oh and congrats on the 1000th post, . Later,
Fletch


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## tekmode (Feb 22, 2003)

Adam said:


> *Weight.
> 1000th post  *


wow you are way behind me


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## Adam (Apr 30, 2002)

tekmode said:


> *wow you are way behind me  *


Yeah, and look at the registration dates *cough*whore*cough*
Not much time for posting when you're a super mod


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## nitestridar (Jun 29, 2002)

Registered: Feb 2003
Location: Arlington, TX
Car: 2003 spec-V
Posts: 1545


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## Ninety-Nine SE-L (May 5, 2002)

or 2341 posts


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## Ninety-Nine SE-L (May 5, 2002)

back in the old days, they would strap the are engine down on the engine dyno but all of the accessories and such (power, water pump, sensors, and so on) would be provided by an external source. This would make the numbers higher b/c the engine had no stress on it. 

Newer cars are tested with all the necessary accessories being run off the engine's own power. Alternator, pumps, injectors, sensors, and so on are running off the engine's pulley, just like in a normal car. The number is lower than the first method, but it gives a more realistic HP number of what the engine is putting out before the drivetrain.


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## StreEtdraggR (Jul 4, 2003)

The horsepower a manufacturer uses is an engine dyno is out of the car and measured at the flywheel. The actual horsepower bein' put to the ground is measured by a chassis dynometer. The reason a Sentra will spank Sunfire is because the Sunfires weigh a lot more. If it were an older Sentra or maybe a 200sx I could say we also has LSDs but if you refering to a 1998 Sentra SE 2.0 they came without them. Understain??? Oh yeah, it also has to do with the driver as well, I mean the Sunfire could've jus' been out driven??? The Sentra beat the Sunfire because it has more:balls:J/k


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## nitestridar (Jun 29, 2002)

selrider99 said:


> *Registered: Feb 2003
> Location: Arlington, TX
> Car: 2003 spec-V
> Posts: 1545
> ...



WOW    


Registered: Feb 2003
Location: Arlington, TX
Car: 2003 spec-V
Posts: 2698


1100 posts in less than a month


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## himilefrontier (Jan 21, 2003)

Remember also that the Hp an engine makes stays the same, but the amount it actually gets to the ground varies by the type of transmission the car has.An automatic is less efficient than a manual, and some designs are more efficient than others.Thsu,if you had 4 transmission options(I.E B13 with GA16DE), each one may put significantly different amounts of power to the ground


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## Ninety-Nine SE-L (May 5, 2002)

selrider99 said:


> *WOW
> 
> 
> Registered: Feb 2003
> ...


 holy crap man, where did u come from? that post above is the only post I've seen of tekmode's, and yet, he blew way by me in the post count.


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## FletchSpecV (Nov 26, 2002)

1997 GA16DE said:


> *holy crap man, where did u come from? that post above is the only post I've seen of tekmode's, and yet, he blew way by me in the post count. *


Haha, he's everywhere, .


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