FLYWHEEL HP Question
02-24-2008, 05:08 PM
#1
Drifting
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FLYWHEEL HP Question
I have a 2005 with A4 transmission. I am dynoing at 419 rwhp. Is there a formula to figure out FLYWHEEL HP? I know the general rule of thumb is 20% loss for auto. Is there a more precise calculation?
02-24-2008, 05:26 PM
#2
Drifting
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St. Jude Donor '07-'08-'09
No calculations that would meet the definition of precise for this conversion. An engine dyno can give you an accurate engine hp. A rear wheel dyno can give you an accurate rear wheel hp (although whether it will give you one in an absolute sense is highly questionable). There is also the question of conditions - SAE, STD, actual, etc ad nauseam...
Or you can use rules of thumb - Auto 18-20%, Manual 12-15%.
At the end of the day though, who really cares what the absolute number is? It either converts to real world acceleration and velocity or it doesn't. If the purpose of the number is to get a feel for what different mods have given you, use the same dyno (well maintained of course) at similar atmospheric conditions corrected to the same standard and you should be close.
Or you can use rules of thumb - Auto 18-20%, Manual 12-15%.
At the end of the day though, who really cares what the absolute number is? It either converts to real world acceleration and velocity or it doesn't. If the purpose of the number is to get a feel for what different mods have given you, use the same dyno (well maintained of course) at similar atmospheric conditions corrected to the same standard and you should be close.
02-24-2008, 06:19 PM
#4
The original poster has an LS2 based '05.
The first GM engine to be certified via SAE J2723 to the standard test conditions of SAE J1349 was the LS7 found in the 2006 and up Z06.
Document SAE J2723 specifies the procedure to be used for a manufacturer to certify the net power and torque rating of a production engine according to SAE J1349.
The LS7 and LS3 engines are rated at SAE J1349 Certified 505HP and 430 or 436HP. They carry this badge
Here are a few other engines rated to the SAE J1349 Certified standard.
The LS2 was not included in this program.
I agree with Dvlray6.
Last edited by '06 Quicksilver Z06; 02-24-2008 at 06:40 PM.
02-24-2008, 06:22 PM
#5
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St. Jude Donor '08
This is in regard to an LS2 based '05.
The first GM engine to be certified via SAE J2723 to the standard test conditions of SAE J1349 was the LS7 found in the 2006 and up Z06.
Document SAE J2723 specifies the procedure to be used for a manufacturer to certify the net power and torque rating of a production engine according to SAE J1349
For the LS7 and LS3 engines are rated at SAE Certified 505HP and 430 or 436HP. The LS2 was not included in this program.
The first GM engine to be certified via SAE J2723 to the standard test conditions of SAE J1349 was the LS7 found in the 2006 and up Z06.
Document SAE J2723 specifies the procedure to be used for a manufacturer to certify the net power and torque rating of a production engine according to SAE J1349
For the LS7 and LS3 engines are rated at SAE Certified 505HP and 430 or 436HP. The LS2 was not included in this program.
02-24-2008, 11:13 PM
#6
The original poster has an LS2 based '05.
The first GM engine to be certified via SAE J2723 to the standard test conditions of SAE J1349 was the LS7 found in the 2006 and up Z06.
Document SAE J2723 specifies the procedure to be used for a manufacturer to certify the net power and torque rating of a production engine according to SAE J1349.
The LS7 and LS3 engines are rated at SAE J1349 Certified 505HP and 430 or 436HP. They carry this badge
Here are a few other engines rated to the SAE J1349 Certified standard.
The LS2 was not included in this program.
I agree with Dvlray6.
The first GM engine to be certified via SAE J2723 to the standard test conditions of SAE J1349 was the LS7 found in the 2006 and up Z06.
Document SAE J2723 specifies the procedure to be used for a manufacturer to certify the net power and torque rating of a production engine according to SAE J1349.
The LS7 and LS3 engines are rated at SAE J1349 Certified 505HP and 430 or 436HP. They carry this badge
Here are a few other engines rated to the SAE J1349 Certified standard.
The LS2 was not included in this program.
I agree with Dvlray6.
Just to add a few more tidbits of info, the LS7 was the first engine period to be certified under SAE J2723. Before going through the certification process (and preproduction), GM rated the LS7 at 500 HP under SAE J1349 (in fact you'll still see references to 500 HP some places and that's where it comes from). A lot of the GM engines certified under J2723 had been rated under J1349 and only gained 2-5 HP indicating GM rates their engines pretty close but slightly under. I'd say the LS2 is 400 HP -0/+5 HP.
On the other hand, most Japanese engines rated under J1349 lost as much as 10% of their HP when certified under J2723.
02-24-2008, 11:25 PM
#7
Just to add a few more tidbits of info, the LS7 was the first engine period to be certified under SAE J2723. Before going through the certification process (and preproduction), GM rated the LS7 at 500 HP under SAE J1349 (in fact you'll still see references to 500 HP some places and that's where it comes from). A lot of the GM engines certified under J2723 had been rated under J1349 and only gained 2-5 HP indicating GM rates their engines pretty close but slightly under. I'd say the LS2 is 400 HP -0/+5 HP.
On the other hand, most Japanese engines rated under J1349 lost as much as 10% of their HP when certified under J2723.
Thanks for the additional info.
Last edited by '06 Quicksilver Z06; 02-24-2008 at 11:27 PM.
02-25-2008, 03:55 AM
#8
http://www.detnews.com/2005/autosins...A01-283759.htm
Toyotas are at the top of the article and you'll see the LS7 listed for the 2005 model which we know doesn't exist. They were just trying to show the preproduction rating GM was using before certifying it.
02-25-2008, 08:40 AM
#9
You'll enjoy this link:
http://www.detnews.com/2005/autosins...A01-283759.htm
Toyotas are at the top of the article and you'll see the LS7 listed for the 2005 model which we know doesn't exist. They were just trying to show the preproduction rating GM was using before certifying it.
http://www.detnews.com/2005/autosins...A01-283759.htm
Toyotas are at the top of the article and you'll see the LS7 listed for the 2005 model which we know doesn't exist. They were just trying to show the preproduction rating GM was using before certifying it.
There were several interesting parts in the article, but do you know the ones I found most interesting?
"The news is better for General Motors Corp. and Ford Motor Co. Some models such as the Chevrolet Corvette and the Ford Fusion sedan are faring better under the new testing procedures, which could give them a much-needed edge in the marketplace.
The Cadillac STSV luxury sedan roadster with a Northstar engine saw its horsepower rating go from 440 to 469"
The Cadillac STSV luxury sedan roadster with a Northstar engine saw its horsepower rating go from 440 to 469"
That way owners and some of these tuners could have gone around talking about how that model of Cadillac was "underrated".
Why didn't they "underrate" it like they did the Z06?
"DaimlerChrysler is using the new SAE procedures on any model with changes in its powertrain, said spokesman Cole Quinnell. He said the company expects new ratings to be within 3 percent of the old ratings, with some going up and some going down. DaimlerChrysler is making a special effort to test high-performance models, like the Dodge Viper V-10. The Viper now tests at 510 horsepower, up from 500 in 2005."
Man, I can sure see why Chevy decided to "underrate" the LS7 based Z06, and only called it 505hp when it , by some accounts, based on chassis dyno reports and dividing by that trusty constant of 0.85, is actually making 545-560 horsepower.
But what I don't see is why didn't they just keep calling it 500HP. That way it would be even more "underrated" than it is now.
Last edited by '06 Quicksilver Z06; 02-25-2008 at 07:51 PM.
02-25-2008, 02:09 PM
#10
