Engine Hp Rating

[SSTibet]

Folks (including you too Ken ),

I read somewhere on the internet that sometime ago in the 80's Chevrolette started stating power rating of the Corvette cars as the Hp measured at the rear wheels . Would it be correct to say that my LT-1 produces net 300Hp at the wheels then??? Or is it still at the flywheel? :J

 

[Ken]

Although the standard for rating horsepower has been available for over 200 years, clever car manufacturers have found ways to change the ratings of their engines to suit their needs. During the famous horsepower wars of the 1960s, manufacturers could get higher figures by testing without auxiliary items such as alternators or even water pumps. High ratings backfired when insurance companies noticed them and started to charge more for what they saw as a higher risk. Manufacturers sometimes responded by listing lower horsepower figures, forcing enthusiasts to look at the magazine test reports to determine what was going on. In the early seventies the SAE (Society of Automotive Engineers) stepped in with standardized test procedures and the fiqures were more consistent.

In short, yes, your horsepower figures are supposed to reflect the horsepower at the rear wheels, with all accessories attached.

 

[Edmond]

Doesn't GM have a tendency to underrate the Corvette's slightly just in case? I'm sure they don't want one of those Mustang Cobra HP fiasco's that happened a few years ago.

 

[JEFNLSA]

"I'm sure they don't want one of those Mustang Cobra HP fiasco's that happened a few years ago.[/QUOTE] "


Would you expand on that? Just curious....thx
Jeff

 

[Edmond]

Would you expand on that? Just curious....thx
Jeff

Sure. They advertised the 99' Cobra at 320hp but dyno tests revealed that most models were putting out less than 300.

Cite: http://www.fast-autos.net/ford/fordmustang.html

 

[JEFNLSA]

Well it looks like Ford got it right w/ the 2005 Mustang cuz, as much as I hate to admit it, that is a great retro design job. I imagine the Cobra version will be a beast but then again so will the ZO6 version of the C6! Guess I gotta keep moddin' to keep up.

 

[Gorgon]

In short, yes, your horsepower figures are supposed to reflect the horsepower at the rear wheels, with all accessories attached.

I thought SAE net was flywheel HP with all accessories attached. I don't know any stock LT1's dynoing at 300 at the wheels.

Leon

 

[DRTH VTR]

I thought SAE net was flywheel HP with all accessories attached. I don't know any stock LT1's dynoing at 300 at the wheels.

Leon

That is what I thought, too. The RWHP will be about 15% lower than at the flywheel.

 

[Ken]

I give up.

If you want a copy of the SAE's standard for that test, it's available for only $59.00:

SAE Standards

Document Number: J3046/1

Date Published: November 1994

Title: Reciprocating Internal Combustion Engines--Performance--Part 1: Standard Reference Conditions, Declarations of Power, Fuel and Lubricating Oil Consumptions, and Test Methods

 

[Tim Scales]

F.O.R.D. As the advertisment states...."The best never rest"...My moto for F.O.R.D. is this (FROM EXPERIENCE!) Found On Road Dead!

YOU can'r REST if you OWN one...working on it!

Sure. They advertised the 99' Cobra at 320hp but dyno tests revealed that most models were putting out less than 300.

Cite: http://www.fast-autos.net/ford/fordmustang.html

 

[MoeJr]

The 99 Cobra problem was related to flashing not being removed properly from the intake ports. Ford did go back and fix them all.

The hp of engines from 1972 and up is SAE Net hp with all accessories hooked up thru the exhuast but taken at the flywheel.

 

[SSTibet]

I give up.

If you want a copy of the SAE's standard for that test, it's available for only $59.00:

Folks, I will take Ken's advice on this matter since he refers to a document (SAE spec) rather than stating his opinion. I am an engineer who respects documented evidence...

Thanks Ken

 

[Gorgon]

I had a copy of the J1394 spec when I worked at a previous job but several sites I found last night on a google search all said the same thing, flywheel. Do your own research and you should find similar results.

Leon

 

[SSTibet]

Hmmm, the matter has started becoming a confusion... Well, I am happy with my Corvette and I really do not care if Hp is at the flywheel or rear wheel... It is at a wheel at the end of the day..

 

[Black Bart]

You can find all the skinny here. Also talks about the GM F body being under rated.
http:\neptune.spacebears.com/opine/horsepwr.html

 

[FX GS]

I imagine the Cobra version will be a beast but then again so will the ZO6 version of the C6! .

Yeah, at probably TWICE the cost of the Mustang!!

 

[FX GS]

... It is at a wheel at the end of the day..

Yes, SS, I agree, you are correct

 

[SSTibet]

Yes, SS, I agree, you are correct

Thx for the agreement FX GS