New SAE horsepower measuring standards/techniques, who knows what was changed?

[Guest bastaad525]

Been seeing this mentioned a lot lately, I guess the SAE has changed the method for testing/figuring out an engines HP rating, which has caused a lot of cars' HP ratings to change one way or the other.

 

I'm really curious what they changed or what they're doing differently.

 

One odd thing I am noticing, is that this change is for some reason benefitting some motors, particularly larger displacement motors, yet smaller motors like your typical 2.0 cylinder four banger, actually ended up with LOWER numbers. I've seen this trend again and again in car magazines over the last few months.

 

So who here knows the tech details on what was changed and WHY it would seem 4 cylinders are losing out and V6-8's ended up with higher ratings?

[Guest 73TPIZ]

I remember hearing about it recently. Seems the SAE changed (or rather standardized) their testing requirements for Manufacturers. I found this interesting blurb about it.

 

http://waw.wardsauto.com/ar/auto_enginerating_ripup

 

I typed in the "J1349 Standard" they mention in Yahoo and got a lot more info.

 

Gonna be a little harder for the Manufacturers to fudge their numbers from now on.

 

Take Care.

[johnc]

You can buy your own personal copy of SAE J1349 as revised August 2004 right here:

 

http://www.sae.org/servlets/productDetail?PROD_TYP=STD&PROD_CD=J1349_200408

 

The revision basically tightenes up the testing process itself and adjusts the correction factors, reference points, and measurement processes. The last revision of J1349 was in 1995 (which you can buy here: http://www.sae.org/servlets/productDetail?PROD_TYP=STD&PROD_CD=J1995_199506).

 

I have no idea why the car magazines are making a big deal out of this revision, its a normal, periodic review and update that SAE does to all of its standards. Actually, I do have an idea - they are trying to fabricate a story out of nothing.

[johnc]

One odd thing I am noticing, is that this change is for some reason benefitting some motors, particularly larger displacement motors, yet smaller motors like your typical 2.0 cylinder four banger, actually ended up with LOWER numbers. I've seen this trend again and again in car magazines over the last few months.

 

So who here knows the tech details on what was changed and WHY it would seem 4 cylinders are losing out and V6-8's ended up with higher ratings?

 

Ah yes, another conspiracy!

 

In reality, US auto manufacturers have been using the revised J1349 since the beginning of model year 2004 because they knew it was coming, so you need to look back a couple years to see the changes in US vehicle power ratings. The German DIN 70020 standard for engine power rating is very accurate and the 2004 revisions of SAE J1349 bring it more in line with what the Germans have been doing. You will see slight changes in the power ratings for German vehicles but nothing really worth noticing. The Japanese JIN engine power standard was a little futher off from where SAE J1349 is now. The biggest horsepower rating adjustments will be on Japanese vehicles.