jschindler

In about a 60 second scan of this thread, I noticed this...

There is one fallacy there. The 36.8 hp difference your refer to is rwhp, not crank. If you apply a consistent "loss" factor to both engines, it would be about 36.8 divided by .89 to get the difference in crank hp. That means the LS3 would be putting out about 41 more crank hp, which takes the LS2 down to 395 at the crank.

395 is a familiar number, isn't it? It is the number that confused some folks that was on the powerpoint presentation shown at the 08 introduction in BG. I'm sure Talon can post a shot of that chart.

I'll go through the rest in the morning, but either way - it's a great write-up and I commend you for the information.

Marina Blue

Good try, but that mistake was debunked a long time ago in this thread: http://forums.corvetteforum.com/show....php?t=1796312

Apparently you have that old paddle out again and are trying to stir the pot. It's time to accept the facts that you helped write.

When you read my collection of posts and reference threads tomorrow morning I believe you will see that your calculation is incorrect. There is no fallacy here. Back calculations of chassis dyno numbers, especially using a single number, with percentages pulled out of a hat do not make for a reliable way to determine crank horsepower. In my manuscript "LS2 - 400+ Horsepower" I do refer to a range of chassis dyno numbers for both LS2 and LS3, which I feel gives a more accurate, even though still unreliable, representation than using a single number.

My ducks are in order and they all point in one direction. I am hoping you recognize this. If you don't, I'm sure there is nothing else I could say to convince you.

lkelliott

I would take the LS2 has 407hp at the crank with no problem. Vette Magazine put a brand new 08 LS3 with an MN6 and Z51 package on the dyno and it pulled 396 RWHP. With a 16.8% correction a stock LS3 has 462hp at the crank!

talon90

Where on earth does the 16.8% number come from?

Well then with a 30% correction a stock LS3 has 514.8hp at the crank. That correction factor is as factual as the 16.8 is, not at all. It is impossible to determine crank horse power from rear wheel horse power using a "correction factor" there simply is no such thing. There is and only ever was an amount of horse power lost over driveline loss.

The LS3 with the T6060 transmission has less loss due to friction and tolerance. If you insist on applying a correction factor, the LS3 and T6060 are approximately 10% with a resulting 435.6 horse power at the crank for the tested 396 RWHP.

harddrivin1le

Amen, brother.

http://www.sportcompactcarweb.com/pr...t_4/index.html

"Horsepower Hype--Separating Fact from Fiction

Converting rear-wheel power figures to crank numbers is anything but straight-forward. When translating wheel figures to engine claims, some experts use fixed conversion factors. That is, if a stock 218 rear-wheel hp RX-7 is rated from the factory at 255 crank hp, it must have 17-percent driveline losses. A 284 rear-wheel hp RX-7, then, must be blessed with 332 crank hp. This popular, if somewhat optimistic, correction technique assumes driveline loss is proportionate with engine output. That is, as wheel horsepower increases, driveline loss must also increase commensurably. Some would even disregard stock quotes and apply a standard 20-percent drivetrain loss figure. Using this popular correction factor, we already have a 340-hp monster! Some would vehemently disagree. These folks would tend to use a fixed number to represent driveline loss. In this case, they would believe that all RX-7s are faced with a driveline loss of 37 hp. (255 minus 218). Using this correction method, Project RX-7 produces a more conservative 321 ponies at the crank. All three techniques, (as well as other far more [Ahem.] optimistic methods) have been used at one time or another...

Paulsen also believes that drivetrain losses are neither an absolute percentage nor a fixed number. Instead, he feels the crank-to-wheel relationship is far more beguiling. From his considerable experience, Paulsen suggests that low horsepower (100-200 hp) cars may suffer from as much as 15 to 20 percent of drivetrain loss at the rear wheels. For more powerful cars (200-400 hp), the figure is around 12 to 15 percent. And for mega-powered cars (above 400 hp), the drivetrain losses can reduce to 10 percent or less. What's going on? Getting into the physics behind this complex relationship is worthy of a project in itself. (Engineering editor, Dave Coleman says he's working on it.)

"

jschindler

I don't believe everything I read. I don't buy that - why would they post power figures for a Trailblazer SS in a Corvette presentation? I've been around big business for a long, long time. I've seen plenty of people in big business try to cover up one mistake with a line of B.S.

There is simply too much evidence - including your own comparison of dyno figures to support that the LS2 would have put out 395 if rated at the new system.

But you are still my friend!

TTUbaker

Very interesting read! Sounds like you definitely did some research!!

JJC5

I agree that using a "percentage" to calculate drive train loss across the board for different engines is wrong. The same drive train from the clutch back will have the same horsepower loss for any engine provided the RPMs are the same at the time peak horsepower is measured. Since different engines produce peak horsepower at different RPMs, it's tough to do an accurate comparison because the drive train will loose different percentages of horsepower at different RPMs. Why won't somebody just put a LS2 and a LS3 on the same ENGINE DYNO and we can finally see the real truth?

'06 Quicksilver Z06

and Marina Blue is a friend of mine as well.

But I brought this out in the thread he linked to in his prior response to you.

I have a strong suspicion that they were hiding the LS2 from the most recent SAE ratings procedures, because they knew that under the new ratings rules, that they would never have been able to call it 400 HP.

The LS7 underwent the new ratings testing in 2005 for the 2006 Z06. So GM had the ability to have the LS2 submit to the same testing back then for the 2006, and even the 2007 C6.

So why didn't they?

The new guidelines will only allow a manufacturer to claim a HP rating which is within 1% of what is observed by an SAE witness.

If GM knew that it was going to make 407 or thereabouts, they could have advertised the 2006 Vette at as much as 410hp or therabouts.

401 they could have called as much as 405.

Why not jump at that chance to get a free boost in it's HP rating just by having it undergo the testing?

I believe that the reason why is likely because they knew it wasn't going to make more than 395 if it were tested. Making the max they could advertise it as an SAE Certified 398 HP. .

Which would have been a marketing disaster after they had already claimed 400 in the 2005 model.

They knew that it was liable to end up being rated lower than previously advertised using the new SAE guidelines. A few other engines from other manufacturers had already suffered this fate.

Their own information, their own graph presented at that birthday bash, in that slide presentation when the LS3 was released in the '08, shows that the LS2 was making 395hp.

So they kept on with the old ratings system for the LS2, which gave them a lot more leeway to call it 400hp, even though it would run another two model years, 2006 and 2007, and they had plenty of time to submit it for testing under the new guidelines.

They knew had they submitted it for testing under the new SAE guidelines that it was only going to make 395. They already had a graph indicating as such.

Think about it. Had they put the LS2 on an engine dyno, with a stock calibration and under the other most recent SAE rules as they do the LS3 and the LS7, and it had made 407 or 408HP in front of an SAE witness, this would have immediately given Chevy the right to say that the 2006 and 2007 C6 Corvette makes an SAE Certified 411 or 412HP. Why wouldn't they jump at that opportunity, if it was a sure or close to sure thing?

They would not have had to alter a thing in the engine, just submit it for testing under SAE J1329, and the testing would have given them a "free" hp bump, as it did with the LS7.

The LS7 was at 500hp. when tested under the new guidelines, it got a "free" 5hp bump. Which is why it is referred to as 505 to this day. Look at the initial reference to the LS7 and you will see 500hp.
http://corvetteactioncenter.com/spec...6/z06/ls7.html

Why wouldn't GM jump at a chance like that for the LS2. I believe that it was because they were hiding it. They were ducking that test because they knew it was making 395. AND their own graph showed that it was making 395. And if it was, they could not stretch that to 400 under the SAE rules.

mcwire

That helps to explain the disproportionate difference in rwhp, between the LS2 and the LS3.

-- --

Marina Blue

Well Jim, all I can tell you is that Tony ******** did not lie to me. He had no reason to and was in a high enough position in Corvette production to know the answer to the question I asked. Do you really think that when confronted with someone looking for solid numbers on which to base a magazine article, that a man in his position would intentionally give bad information. Also, Crush1 was obviously an honest poster. He hasn’t posted here in a long time, but I have always had a sense that he knew of that which he spoke. Over a couple of years now solid evidence has come forth, which all supports LS2 making over 400 horsepower. However, there are some that refuse to believe this, are not capable of understanding it, or just like to argue. I am not sure where you stand here, but at this time I think it is pointless to enter into an endless loop of argument. I have made my case and will let it stand on its merits. I don’t have to worry about the evidence that I presented because it all began with a statement by someone very well placed at the Bowling Green Plant telling me what the actual engine dyno numbers were for LS2. This wasn’t just any engine dyno, it was the one Chevy uses to come up with their advertised horsepower ratings… yes, even those Certified ratings.

After postings of chassis dyno numbers for the LS3 arrived on this forum, there were a lot of doubters concerning the power of LS2. For a while I became one of them, even though I had previously championed the LS2 numbers I used in that magazine article. Some on this forum even questioned the honesty of Tony ********** because of the information he gave me. I felt obligated to make sense out of the chassis dyno numbers we were seeing. Now, after evaluating much information and taking into account the changes made to the C6 drivetrain in 2008, I conclude that I always had reliable information about actual LS2 power. If you don’t agree with what I presented, that is fine. We will leave it at that.

By-the-way, as I explained in that post I referenced--mistakes are made. In making up that slide presentation, it is obvious someone well down the chain was using numbers from the only LS2 vehicle still in production, the "Trailblazer SS LS2". Another mistake was made in that Birthday Bash slide show presentation. LS3 did not do the as presented 7:56 at the ring. That number was established by the 2004 C5-Z06 and mistakenly carried into the LS3 presentation. Mistakes happen and that is just what that 395 number was. I am sure the culprit heard about it after the slide show.

Still friends.

'06 Quicksilver Z06

I am still having a hard time understanding why they would not have the LS2 Certified under SAE J1349 if it was known to have been making 407 hp.

It doesn't make any sense that Chevy would have other engines certified under this and not the LS2. That would have given them a "free" 11-12 hp for 2006 with no effort at all on their part.

Just submitting to the test and having the engine come in at 407 in the presence of an SAE witness would have allowed them to claim an SAE Certified 411 or 412HP for the LS2. Why on earth would they pass on an opportunity like that???

Unless they already knew that it wasn't going to come in at 407hp.

The '06 was already coming with the paddle shifters. An SAE Certified 412 hp rating would have been a real coup for them.

The caddy engine got a boost in it's HP rating under the new SAE guideline when it was submitted for the testing. The LS7 did too. Why not test the LS2 under those same guidelines if they knew that it would allow them to make a higher HP claim than they were already?

The reason why the LS2 was not submitted for testing under SAE J1349 was because they knew that they would no longer be able to claim it as making 400hp under that set of guidelines.

Marina Blue

LS2 was a discontinued engine at that point except for remnants in the TrailBlazer.

Marketing is the reason it wasn't initially rated higher as I mentioned in my original posts. Z06 wasn't to be outdone. Also rating LS2 higher in the middle of its production run would not have allowed the LS3 to look as good. Why re-rate a cancelled engine?

'06 Quicksilver Z06

Marketing. Plus it would not have cost them a thing, or very little to simply have the engine tested and witnessed. How much trouble would that have been?

You say "cancelled" but the first Corvette that the LS2 showed up in was the 2005 model.

You say "cancelled", but the LS2 would show up in the 2006 and the 2007. If it was already cancelled, then why did it show up in 2007 C6s? Why didn't we stop seeing the LS2 after the '06 model if it was cancelled in the year 2005?

In early 2005, April, I believe, the LS7 was rated under the new SAE guidelines.

LS2 would show up in MY 2006 C6s (along with the Z06), and in 2007 C6s. Better than 60,000 more coupes and verts than they had already built.

http://corvetteactioncenter.com/spec.../2007prod.html
http://corvetteactioncenter.com/spec.../2006prod.html

All 2006 AND 2007 C6 Corvettes would have had an SAE Certified 412hp rating, had they simply had the LS2 tested at or around the same time as the LS7 was. Thats if it was in fact making 407 hp.

No way they would have passed that up if they could have swung it. They would have jumped all over that.

They had already re rated the engine in that Caddy, simply by submitting it for the testing, and gotten a very decent hp bump under the new SAE guidelines. I'll have to look up the model.

So if they did this for the Caddy, then why not the Vette?

Fuego

LS3's aren't underrated and now LS2's are. Crazy. Anyone who spent this much time to basically prove nothing is boiling this whole "LS2 is almost as good as LS3" thing to one thing-jealousy. Just enjoy your car and quit with the pissing contest.

Fuego

Why won't somebody just put a LS2 and a LS3 on the same ENGINE DYNO and we can finally see the real truth?[/QUOTE]

Someone who can do so, please do.

harddrivin1le

LS3s produce roughly 30 - 36 more SAE Net HP than LS2s - depending on whether or not the LS3 is equipped with NPP and assuming all engines are 100% bone stock.

That's the "real truth."

If anything, real world chassis dyno results suggest that the LS3s advantage is actually slightly greater than those figures.

The LS3's heads are substantially superior to the LS2's and the LS3s intake manifold is also more efficient. Furthermore, the LS3 has an advantage in displacement and also uses a stronger block/main bearings:

http://corvetteactioncenter.com/spec...ls3_page1.html

The LS2 is a nice engine, but it will never be an LS3.

Fuego

I know this. I have one. LS2 was not SAE rated for fear they could not match the original 400hp rating. 395hpsae is what gm is saying.(according to the material Talon has). So, more like 41 hp sae.

Petesflht

I think you LS3 guys better hide from us ; Pull up to us LS2's and your gonna get spanked.. Its very clear to me. Thanks Marina..

'06 Quicksilver Z06

Thats exactly the way it seems to me.

If LS2 was a lead pipe cinch to make 407hp on the engine dyno, in the presence of an SAE witness, under SAE J1349, they would have done that in a heartbeat.

And they would have been shouting from the rooftops that while they had initially stated that the LS2 was only making 400hp, that under the auspices and new stringent testing procedures of the SAE, using the same methods of testing as used for the 505hp Z06, that the LS2 was actually making an SAE Certified, 412 hp. And they would have plastered "412hp" on every LS2 based Vette they made in 2006 and 2007.

No way they would have turned their backs on an opportunity, no, a marketing coup, like that. Absolutely no way. Especially when they had two years worth of LS2 based C6s left to make. 2006 and 2007.

The only reason why they didn't is because they knew the LS2 couldn't make 407hp under SAE J1349. If it could have, they'd have done it.