[Z06] Strong Ones, Weak Ones, and the SAE.
02-13-2008, 03:09 PM
#1
Team Owner
Thread Starter
Strong Ones, Weak Ones, and the SAE.
My reasons for posting this are to minimize misconceptions about and attack the myth of unusually strong LS7 engines, weak LS7 engines, and to offer some information on SAE J1349 Certification. In other words to add a bit more information on this subject. The LS7 engine is said to make an SAE Certified 505 horsepower.
A while back there was a heated thread on the LS7 engine and whether or not '06s were stronger than others.
It evolved into a discussion on so called "strong" or "freak" LS7 engines out there based upon some of the numbers seen from off of chassis dynos. And variability among production engines and "tolerances".
This concept of "freak" LS7s out there making significantly more power than 505 horsepower is typically fostered by the results of "abnormally high" chassis dyno numbers. There is a lot of emphasis on chassis dyno numbers here, and too often the stock numbers are used, at least in part to determine whether a particular engine is weak or strong.
These engines which are said to lie well outside of the SAE Certified 505HP, either above or below it, seem to be without fail, identified only on chassis dynos, as opposed to engine dynos. When numbers from off of a chassis dyno are used to arrive at crank horsepower, the usual method is to divide the output received from off the chassis dyno by a fixed number, usually .85, representing "driveline losses" of 15%. The so called "15% rule".
It would seem that such a method is not without it's drawbacks however, and results obtained from off of an engine dyno would yield a more accurate measure of actual crank horsepower. Nontheless, the 15% rule is embraced by some as an accurate means of measuring crank horsepower in a manaul transmissioned vehicle.
The 15% rule has "identified" more "underrated" and "overrated" LS7 engines, than DNA tests have identified dead beat dads.
If there are reliable reports of any LS7 engine making significantly above or below 505 horsepower, on an engine dyno, and in accordance with SAE J1349 guidelines for testing, then I ask any forum member here to please post up an image or a link depicting such, because I am unable to find either.
Thank you.
http://forums.corvetteforum.com/show....php?t=1923732
Being fascinated by this subject matter, I had done quite a bit of digging and had already made a few inquiries. But decided to make a few more.
For a background on the SAE J1349 Certification, and This stamp which applies to the LS7 engine, here are a couple of articles.
http://www.motortrend.com/features/e...8_technologue/
The standout points in this article are: "The certified output must be within one percent of the dynamometer output. Of course, ringer engines could easily be slipped through this process, but by certifying an engine the manufacturer guarantees all production engines will produce within two percent of the rated output (Europe allows five-percent deviation)."..
http://www.caranddriver.com/features...olution_column
The standout points here are: "...Since minute differences in the dimensions of engine components that naturally occur during series production—the compression ratio could be a smidge higher in one engine versus another—can result in two identical-looking engines making slightly different horsepower, the SAE allows a one-percent tolerance between the number that the witness observes and the horsepower rating that a manufacturer chooses to publish...."
The people at Katech, a forum sponsor here, had mentioned in more than one thread, that of the hundreds of LS7 engines which they had put on their engine dynos all had produced between 505-508 horsepower. These engines are from a random sampling, and Katech is not in the GM production loop for the LS7 engine.
http://forums.corvetteforum.com/show...post1562787163
http://forums.corvetteforum.com/show...post1562791382 "The truth is if I go pull dyno data from stock LS7s with stock calibration and stock manifolds, they are all going to be around 505-508bhp using SAE J-1349. There may be outliers of single digit horsepower here or there, but I would sooner blame that on air quality or dyno variance than the engine itself. You are implying (at least by the way I read it) that there are factory freaks of excessive amounts of horsepower which isn't the case."
http://forums.corvetteforum.com/show...post1556630620
http://ls1tech.com/forums/showthread.php?t=434419
Their belief, based upon the results which they had seen in their own testing of the LS7, was that all LS7 engines made similar power. And that there were no "factory freaks of excessive amounts of horsepower."
They seemed to be staunch in this belief, and apparently with good reason. Among those reasons seemed to be that an engine dynonometer would have a better chance of more accurately measuring the power output of an engine as opposed to a chassis dynonometer. I believe them and their results.
However, wanting more information from others who have access to the results of engine dynographs from examples of this engine, in it's production/consumer form, I decided to contact a couple of other people who should know.
I sent inquiries to the Society of Automotive Engineers, http://www.sae.org/about/contact/
and to the National Corvette Museum's Gary Cockrell.
Interestingly, it turned out that the person I contacted at the SAE is also named Gary and is a Corvette owner.
Below follows my email correspondence with both Garys. The one at the SAE and the one at the National Corvette Museum. At one point, I got confused as to which one I was talking to.
The following is a response from the SAE with regard to general questions I had about the certification process, and the LS7 in particular. I placed my questions at the SAE site and they were kind enough to reply.
Subject: horsepower question
Date: Wed, 6 Feb 2008 14:12:29 -0500
From: "Gary Pollak" <gary@sae.org> Add Mobile Alert
To: *********
Hello,
Thanks for your interest in SAE’s Certified Power Program.
You are correct that the test results of the particular engine tested must be within 1% of the certified value. In addition, normal production variation of engines produced must result in horsepower output that is at least 98% of the certified claim.
Remember the horsepower values used for certification are at the flywheel. SAE does not certify power to the driving wheels.
A bit of trivia that might be of interest to you as a fellow Corvette owner (although I am not fortunate enough to own an LS7 powered Corvette) is that the LS7 engine as used in the Z06 was the first engine to be certified under SAE’s program. This took place on Apr 5, 2005.
Gary Pollak - SAE
At this point, I had not looked closely and thought this was from the Museum. It is actually from the SAE.
I wrote back, thinking that I was talking to Gary at the museum. :
Date: Thu, 7 Feb 2008 16:12:55 -0800 (PST)
From: *******
Subject: Re: horsepower question
To: "Gary Pollak" <gary@sae.org>
Thank you very much for your reply Gary.
Excellent information.
As I understand you, the bare minimum for any LS7 will be 98% of the rated horsepower, thats good to know.
I guess what I am trying to find out though is, is there a possibility of a factory LS7 engine making significantly more than the rated horsepower?
The reason I ask this is because I believe that the new SAE Certification pretty much prohibits underrating engines.
But what is the possibility or probability that an LS7 engine has actually left out of there making 520 horsepower or more? I think there may be some stronger than others. Much stronger than that 505 you guys say.
Likely or no???? Am I off base here or not?
Gary from the SAE wrote back.
Subject: RE: horsepower question
Date: Fri, 8 Feb 2008 10:17:37 -0500
From: "Gary Pollak" <gary@sae.org> Add Mobile Alert
To: *********
Since certification claims are for minimum output I guess it is possible that some engines might produce higher outputs but it is highly unlikely. For the certification tests we did run a few engines but none produced more than 507 or 508 hp.
Gary
Now that came from the SAE.
Date: Tue, 12 Feb 2008 14:21:19 -0800 (PST)
From: *******
Subject: RE: horsepower question
To: "Gary Pollak" <gary@sae.org>
Gary, I appreciate your answers and I am trying to become as knowlegable about this as I can. I hope that I am not being a gadfly but a couple of more questions, if you don't mind and can answer..
You mention that: "For the certification process, we did run a few engines but none produced more than 507 or 508 horsepower."
Were these run in independent tests with engines procured by the Society of Automotive engineers, or were these few engines provided by the manufacturer?
With regard to the SAE J1349 Certified Horsepower program, how are a manufacturer's prospective engines selected to be tested?
Are they randomly selected from dealer inventory under the auspices of the Society of Automotive Engineers.
Or does the manufacturer select/hand pick engines to be submitted for the testing process?
Thanks.
Subject: RE: horsepower question
Date: Wed, 13 Feb 2008 09:34:45 -0500
From: "Gary Pollak" <gary@sae.org> Add Mobile Alert
To: ********
All engines for the certification process are provided by the manufacturers. SAE makes no random selections. The engines are inspected by the witnesses to ensure that they are configured in a manner that is consistent with typical production engines available to the consumer.
The manufacturers then take on the responsibility of certifying that the engine tested is representative of all engines produced and all production engines will produce a minimum of 98% of the certified claim. SAE certifies via our witnesses that the tests were conducted accurately in accordance to the SAE standards.
Hope this clears up your questions.
Gary
Meantime, I had heard back from Gary at the National Corvette Museum in response to a similar question I had asked the SAE.
Subject: RE: Question regarding LS7 Z06
Date: Mon, 11 Feb 2008 11:17:08 -0600
From: "Gary Cockriel" <gary@corvettemuseum.com>
To: *******
Hi,
Sorry to take so long in getting back to you I have been out for over a week. I am afraid I can’t answer all of your questions about the LS7. I will check into the questions you have and get back to you as soon as I can. Please forgive the lateness of this email and give me a little more time to get the answers for you if I can. I will be in touch.
Thanks,
Gary Cockriel
Guest Services / Delivery Manager
National Corvette Museum
gary@corvettemuseum.com
Telephone-******
Facsimile - ******
The key to life is what you add to it - add something!
I am still waiting to hear from the Museum. But the bottom line appears to be this:
1. "The certified output must be within one percent of the dynomometer output. This has been mentioned several times. The manufacturer has to state a horsepower number which is within 1% of what the SAE observer sees.
2. Of the hundreds of LS7 engines tested by Katech, and of the LS7 engines tested by the Society of Automotive Engineers, all made at least 505 horsepower and none was above 508 horsepower.
All engines tested by these two seperate entities, have made at least 505. Even though the guidelines allow for as low as 495, neither Katech, nor the SAE has seen one coming in at that low in the engines they have tested.
3. It is "highly unlikely" that there are LS7 engines producing significantly more than the Certified output. This statement is from the SAE. "For the certification tests we did run a few engines but none produced more than 507 or 508 hp"
4. The engines submitted for the testing are "inspected by the witnesses to ensure that they are configured in a manner that is consistent with typical production engines available to the consumer."
5. The manufacturer certifies that the engine tested is representative of all engines produced.
6. SAE certifies via their witnesses that the tests were conducted accurately in accordance to the SAE standards.
7. All outliers reported on this forum have been identified thus far from off of chassis dynos. There is no report here of an LS7 engine which produced significantly more than 505 hp on an engine dyno while in accordance with SAE J1349 guidelines for testing. And those guidelines include the use of an engine which is "configured in a manner that is consistent with typical production engines available to the consumer."
8. The 15% rule, coupled with chassis dyno numbers has been used to arrive at a scattershot plot of crank horsepower figures indicating outliers to both extremes. Some approaching the 560+ crank horsepower range.
However no reliable test of a production LS7 engine on an engine dyno and in accordance with the SAE guidelines, indicates a range wider than a few horsepower above 505. If anyone has access to one, or knows of one, then please come forward.
Indeed there is nothing which I have found reliable, out there, in terms of an engine dynograph indicating even 550, 540, or 530 crank horsepower for a production configured LS7 engine.
Two seperate reliable entities, Katech, and the Society of Automotive Engineers state that they have seen ranges of from 505-508 horsepower on an engine dyno
A while back there was a heated thread on the LS7 engine and whether or not '06s were stronger than others.
It evolved into a discussion on so called "strong" or "freak" LS7 engines out there based upon some of the numbers seen from off of chassis dynos. And variability among production engines and "tolerances".
This concept of "freak" LS7s out there making significantly more power than 505 horsepower is typically fostered by the results of "abnormally high" chassis dyno numbers. There is a lot of emphasis on chassis dyno numbers here, and too often the stock numbers are used, at least in part to determine whether a particular engine is weak or strong.
These engines which are said to lie well outside of the SAE Certified 505HP, either above or below it, seem to be without fail, identified only on chassis dynos, as opposed to engine dynos. When numbers from off of a chassis dyno are used to arrive at crank horsepower, the usual method is to divide the output received from off the chassis dyno by a fixed number, usually .85, representing "driveline losses" of 15%. The so called "15% rule".
It would seem that such a method is not without it's drawbacks however, and results obtained from off of an engine dyno would yield a more accurate measure of actual crank horsepower. Nontheless, the 15% rule is embraced by some as an accurate means of measuring crank horsepower in a manaul transmissioned vehicle.
The 15% rule has "identified" more "underrated" and "overrated" LS7 engines, than DNA tests have identified dead beat dads.
If there are reliable reports of any LS7 engine making significantly above or below 505 horsepower, on an engine dyno, and in accordance with SAE J1349 guidelines for testing, then I ask any forum member here to please post up an image or a link depicting such, because I am unable to find either.
Thank you.
http://forums.corvetteforum.com/show....php?t=1923732
Being fascinated by this subject matter, I had done quite a bit of digging and had already made a few inquiries. But decided to make a few more.
For a background on the SAE J1349 Certification, and This stamp which applies to the LS7 engine, here are a couple of articles.
http://www.motortrend.com/features/e...8_technologue/
The standout points in this article are: "The certified output must be within one percent of the dynamometer output. Of course, ringer engines could easily be slipped through this process, but by certifying an engine the manufacturer guarantees all production engines will produce within two percent of the rated output (Europe allows five-percent deviation)."..
http://www.caranddriver.com/features...olution_column
The standout points here are: "...Since minute differences in the dimensions of engine components that naturally occur during series production—the compression ratio could be a smidge higher in one engine versus another—can result in two identical-looking engines making slightly different horsepower, the SAE allows a one-percent tolerance between the number that the witness observes and the horsepower rating that a manufacturer chooses to publish...."
The people at Katech, a forum sponsor here, had mentioned in more than one thread, that of the hundreds of LS7 engines which they had put on their engine dynos all had produced between 505-508 horsepower. These engines are from a random sampling, and Katech is not in the GM production loop for the LS7 engine.
http://forums.corvetteforum.com/show...post1562787163
http://forums.corvetteforum.com/show...post1562791382 "The truth is if I go pull dyno data from stock LS7s with stock calibration and stock manifolds, they are all going to be around 505-508bhp using SAE J-1349. There may be outliers of single digit horsepower here or there, but I would sooner blame that on air quality or dyno variance than the engine itself. You are implying (at least by the way I read it) that there are factory freaks of excessive amounts of horsepower which isn't the case."
http://forums.corvetteforum.com/show...post1556630620
http://ls1tech.com/forums/showthread.php?t=434419
Their belief, based upon the results which they had seen in their own testing of the LS7, was that all LS7 engines made similar power. And that there were no "factory freaks of excessive amounts of horsepower."
They seemed to be staunch in this belief, and apparently with good reason. Among those reasons seemed to be that an engine dynonometer would have a better chance of more accurately measuring the power output of an engine as opposed to a chassis dynonometer. I believe them and their results.
However, wanting more information from others who have access to the results of engine dynographs from examples of this engine, in it's production/consumer form, I decided to contact a couple of other people who should know.
I sent inquiries to the Society of Automotive Engineers, http://www.sae.org/about/contact/
and to the National Corvette Museum's Gary Cockrell.
Interestingly, it turned out that the person I contacted at the SAE is also named Gary and is a Corvette owner.
Below follows my email correspondence with both Garys. The one at the SAE and the one at the National Corvette Museum. At one point, I got confused as to which one I was talking to.
The following is a response from the SAE with regard to general questions I had about the certification process, and the LS7 in particular. I placed my questions at the SAE site and they were kind enough to reply.
Subject: horsepower question
Date: Wed, 6 Feb 2008 14:12:29 -0500
From: "Gary Pollak" <gary@sae.org> Add Mobile Alert
To: *********
Hello,
Thanks for your interest in SAE’s Certified Power Program.
You are correct that the test results of the particular engine tested must be within 1% of the certified value. In addition, normal production variation of engines produced must result in horsepower output that is at least 98% of the certified claim.
Remember the horsepower values used for certification are at the flywheel. SAE does not certify power to the driving wheels.
A bit of trivia that might be of interest to you as a fellow Corvette owner (although I am not fortunate enough to own an LS7 powered Corvette) is that the LS7 engine as used in the Z06 was the first engine to be certified under SAE’s program. This took place on Apr 5, 2005.
Gary Pollak - SAE
At this point, I had not looked closely and thought this was from the Museum. It is actually from the SAE.
I wrote back, thinking that I was talking to Gary at the museum. :Date: Thu, 7 Feb 2008 16:12:55 -0800 (PST)
From: *******
Subject: Re: horsepower question
To: "Gary Pollak" <gary@sae.org>
Thank you very much for your reply Gary.
Excellent information.
As I understand you, the bare minimum for any LS7 will be 98% of the rated horsepower, thats good to know.
I guess what I am trying to find out though is, is there a possibility of a factory LS7 engine making significantly more than the rated horsepower?
The reason I ask this is because I believe that the new SAE Certification pretty much prohibits underrating engines.
But what is the possibility or probability that an LS7 engine has actually left out of there making 520 horsepower or more? I think there may be some stronger than others. Much stronger than that 505 you guys say.
Likely or no???? Am I off base here or not?
Gary from the SAE wrote back.
Subject: RE: horsepower question
Date: Fri, 8 Feb 2008 10:17:37 -0500
From: "Gary Pollak" <gary@sae.org> Add Mobile Alert
To: *********
Since certification claims are for minimum output I guess it is possible that some engines might produce higher outputs but it is highly unlikely. For the certification tests we did run a few engines but none produced more than 507 or 508 hp.
Gary
Now that came from the SAE.
Date: Tue, 12 Feb 2008 14:21:19 -0800 (PST)
From: *******
Subject: RE: horsepower question
To: "Gary Pollak" <gary@sae.org>
Gary, I appreciate your answers and I am trying to become as knowlegable about this as I can. I hope that I am not being a gadfly but a couple of more questions, if you don't mind and can answer..
You mention that: "For the certification process, we did run a few engines but none produced more than 507 or 508 horsepower."
Were these run in independent tests with engines procured by the Society of Automotive engineers, or were these few engines provided by the manufacturer?
With regard to the SAE J1349 Certified Horsepower program, how are a manufacturer's prospective engines selected to be tested?
Are they randomly selected from dealer inventory under the auspices of the Society of Automotive Engineers.
Or does the manufacturer select/hand pick engines to be submitted for the testing process?
Thanks.
Subject: RE: horsepower question
Date: Wed, 13 Feb 2008 09:34:45 -0500
From: "Gary Pollak" <gary@sae.org> Add Mobile Alert
To: ********
All engines for the certification process are provided by the manufacturers. SAE makes no random selections. The engines are inspected by the witnesses to ensure that they are configured in a manner that is consistent with typical production engines available to the consumer.
The manufacturers then take on the responsibility of certifying that the engine tested is representative of all engines produced and all production engines will produce a minimum of 98% of the certified claim. SAE certifies via our witnesses that the tests were conducted accurately in accordance to the SAE standards.
Hope this clears up your questions.
Gary
Meantime, I had heard back from Gary at the National Corvette Museum in response to a similar question I had asked the SAE.
Subject: RE: Question regarding LS7 Z06
Date: Mon, 11 Feb 2008 11:17:08 -0600
From: "Gary Cockriel" <gary@corvettemuseum.com>
To: *******
Hi,
Sorry to take so long in getting back to you I have been out for over a week. I am afraid I can’t answer all of your questions about the LS7. I will check into the questions you have and get back to you as soon as I can. Please forgive the lateness of this email and give me a little more time to get the answers for you if I can. I will be in touch.
Thanks,
Gary Cockriel
Guest Services / Delivery Manager
National Corvette Museum
gary@corvettemuseum.com
Telephone-******
Facsimile - ******
The key to life is what you add to it - add something!
I am still waiting to hear from the Museum. But the bottom line appears to be this:
1. "The certified output must be within one percent of the dynomometer output. This has been mentioned several times. The manufacturer has to state a horsepower number which is within 1% of what the SAE observer sees.
2. Of the hundreds of LS7 engines tested by Katech, and of the LS7 engines tested by the Society of Automotive Engineers, all made at least 505 horsepower and none was above 508 horsepower.
All engines tested by these two seperate entities, have made at least 505. Even though the guidelines allow for as low as 495, neither Katech, nor the SAE has seen one coming in at that low in the engines they have tested.
3. It is "highly unlikely" that there are LS7 engines producing significantly more than the Certified output. This statement is from the SAE. "For the certification tests we did run a few engines but none produced more than 507 or 508 hp"
4. The engines submitted for the testing are "inspected by the witnesses to ensure that they are configured in a manner that is consistent with typical production engines available to the consumer."
5. The manufacturer certifies that the engine tested is representative of all engines produced.
6. SAE certifies via their witnesses that the tests were conducted accurately in accordance to the SAE standards.
7. All outliers reported on this forum have been identified thus far from off of chassis dynos. There is no report here of an LS7 engine which produced significantly more than 505 hp on an engine dyno while in accordance with SAE J1349 guidelines for testing. And those guidelines include the use of an engine which is "configured in a manner that is consistent with typical production engines available to the consumer."
8. The 15% rule, coupled with chassis dyno numbers has been used to arrive at a scattershot plot of crank horsepower figures indicating outliers to both extremes. Some approaching the 560+ crank horsepower range.
However no reliable test of a production LS7 engine on an engine dyno and in accordance with the SAE guidelines, indicates a range wider than a few horsepower above 505. If anyone has access to one, or knows of one, then please come forward.
Indeed there is nothing which I have found reliable, out there, in terms of an engine dynograph indicating even 550, 540, or 530 crank horsepower for a production configured LS7 engine.
Two seperate reliable entities, Katech, and the Society of Automotive Engineers state that they have seen ranges of from 505-508 horsepower on an engine dyno
Last edited by '06 Quicksilver Z06; 02-15-2008 at 08:52 PM. Reason: spelling
02-13-2008, 04:29 PM
#8
Heel & Toe
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Location: Greenville South Carolina
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02-13-2008, 04:39 PM
#9
Team Owner
Thread Starter
02-13-2008, 06:02 PM
#10
Pro
Look at the air temps and d/a for these cars that run freakish trap speeds. I challenge anyone of those 128 129 130 mph trappers to come tp Florida in August and run they're car. They'll think they lost a cylinder. Thats why they run in the winter in the sunshine.
Let me know i'll give directions and meet you for a test and tune.
C5FRANK and I ran at Moroso side by side both stock, same tires, and watched each other as we went down the track (it was so close we could have shaken hands) my 07 his 06, same miles on the odo. We were within a half mph of each other or closer. Look at the fast list picture....thats us.
As for dynos, they vary between brands and the operator can manipulate the output #'s
Let me know i'll give directions and meet you for a test and tune.
C5FRANK and I ran at Moroso side by side both stock, same tires, and watched each other as we went down the track (it was so close we could have shaken hands) my 07 his 06, same miles on the odo. We were within a half mph of each other or closer. Look at the fast list picture....thats us.
As for dynos, they vary between brands and the operator can manipulate the output #'s
02-14-2008, 10:12 AM
#16
Le Mans Master
Member Since: Jan 2003
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Also one must also assume that all their test engines that were run by SAE and witnessed by SAE were all run on the same engine controller with the same engine calibration.
So that means that all the engines were dressed with emissions controls intact, and the engine calibration is probably what is running the production engines in delivered cars. I think that with the current high accuracy manufacturing methods that we have today, it is very possible that the engines being produced are within the SAE tolerances. And we all know that we can squeak a little more power out of them with bolt ons and PCM tweaks.
The GM standards for testing a engine for a passenger car vs a marine engine is totally different. The same LS7 tested under a marine standard will yield several Hp more. The reason is that the intake and exhaust restrictions are considerably less than the passenger car test standard.
So that means that all the engines were dressed with emissions controls intact, and the engine calibration is probably what is running the production engines in delivered cars. I think that with the current high accuracy manufacturing methods that we have today, it is very possible that the engines being produced are within the SAE tolerances. And we all know that we can squeak a little more power out of them with bolt ons and PCM tweaks.
The GM standards for testing a engine for a passenger car vs a marine engine is totally different. The same LS7 tested under a marine standard will yield several Hp more. The reason is that the intake and exhaust restrictions are considerably less than the passenger car test standard.
02-14-2008, 02:36 PM
#17
Drifting
