slojoh

0Brian@RPT

I read awhile back the LS2 would have been 395hp under the SAE Cert. The days of the underating are gone if the engine is certified. Kinda like the F-Body LS1 rated at 305hp and some dyno'd that.

Fuego

I've seen the same thing. According to the old rating system, the LS3 would be in excess of 440+hp.

JJC5

The percentage of driveline loss SHOULD change with horsepower. If it didn't, the higher the HP, the more loss there would be. The percentage should DECREASE with more HP. Driveline loss is a relatively consistent number or "baseline". The LS3 SHOULD and does show 30 to 36 more than the LS2.

RRVettes

Badges add weight and drag, so they have an undesirable effect. That is why everyone takes off the GM chicklets, to decrease weight and drag..they just say they don't like the look, while secretly they hope to have a competitive advantage over Vettes with the chicklets.

NyCorvette2017

A couple of weeks ago someone with a manual 08 LS3 with NPP dynod there car and it showed roughly 450HP without any modifications. Who knows, the LS3 is superior to the LS2 in many ways, and is the engine less some mods used in the ZR1. As far as whether the LS3 with NPP has 436 or 450hp, the car is crazy fast. You never use the power, and the margin of difference is just for those who crave HP numbers.

jschindler

HUH? Do you mean that the actual "Corrected" rwhp was 450, or is that what they translated to be the crank HP? No way would a bone stock LS3 actually dyno at the wheels at anywhere even remotely close to 450.

If they were trying to translate it to crank hp, go back and read this whole thread again - they likey used the old rule of thumb that is not valid.

talon90

I'm afraid that this might be one of the type of threads he is referring to.

http://forums.corvetteforum.com/show...ighlight=Horse

In this case it was a matter of the OP using the percentage method to arrive at a back calculated number that I'm afraid was just a bit on the optimistic side.

IRS-Cop

I can tell you that our 436 SAE certified Horsepower is way more than any L71 427 (435 HP) or even the L88 427 (430 HP) ever made.

What I would like to know is what our engines would be rated at in Gross HP.....it would have to be close to 550HP I'm sure....lol.

besz28

you must have an ls2

talon90

As a matter of fact I do. What exactly would that have to do with information I posted? Surely you are not believing that my post would have somehow been different if I had an LS3 are you?

catpat8000

I think one of the reasons this keeps coming up is this apparent contradiction:
The LS2 engine is rated 400hp and many LS2 cars dyno around 340-350 rwhp for a 13% driveline loss.
The LS3 engine is rated 430hp and many cars seem to dyno around 390, for a 9% driveline loss.

Now I used these numbers because I used to own a 2005 LS2 and I currently own a 2008 LS3. I had both cars dynoed when bone stock and these were the numbers I saw.
LS2 - 345 rwhp
LS3 - 390 rwhp

My LS3 appears to dyno approx 45 ponies more than my LS2 at the rear wheels, after the driveline loss. But wait a sec! That's more than the flywheel hp rating difference between the engines! How could that be?

Some say perhaps the LS3 is under-rated but in fact, as you point out, Chevrolet is voluntarily using a new SAE certification for the LS3 engine which requires every engine shipped will deliver within 1% of its advertized rating. So it is unlikely for Chevy to be sandbagging on the engine.

There are two theories floating on the web, both of which probably have some truth:
1. The 2008 vette has a new clutch, new transmission, and significantly altered differential. Perhaps the driveline losses are reduced in 2008.
2. The 2005-2007 LS2 engines were not rated using this new SAE certification. Perhaps Chevy was exaggerating their output.

At any rate, I have seen this contradiction first hand with my cars.

Pat

joytown

Hey - I resemble that remark!

Yeah .. my stock LS3 w/NPP pulled 380HP at the wheels. Based on the 15% drivetrain loss (A6) "rule of thumb", my car would be turning 475 at the crank. As was pointed out in my LS2 vs. LS3 - this is just a tad bit unrealistic.

I bid you to search for that thread - Talon's layout of the calculation was very informative. I love when I learn new stuff.

Bottom line - the 436 is a pretty close number, and while it certainly may be off, it's not off by much.

-jon

not08crmanymore

If it's 90 degrees and MUGGY out you have less HP.
If it's 40 degrees out,you have more...or at least it will feel that way and perception is 90% of the game!!

joytown

Don't forget the optional 1 HP mod as seen here:





-jon

JJC5

You loose 40 to 50 HP through the drive line period. If you had a 1000 HP up front, you'd have about 950 RWHP. If you use the 15% method, you'd loose 150 HP through the same driveline. The LS3 has 30 HP more than the LS2.

'06 Quicksilver Z06

with many of the post above with regard to the Certified horsepower rating of 436hp.

Just a few things to add having been in correspondence with SAE about this very subject, but with regard to the LS7. The same would apply to the LS3 or any SAE Certified horsepower rated engine.

http://forums.corvetteforum.com/show....php?t=1940271



This number is arrived at under specific testing conditions.

Under the controlled repeatable conditions as outlined in SAE J2723, production engines intended for installation into vehicles for sale to the public produce the SAE J1349 Certified Horsepower figure plus or minus 2%.

When the actual testing is done, on the engine dyno, so that the manufacturer can assign a horsepower rating, it is done with an SAE witness present, in part to insure that the testing is done in compliance with SAE document J2723.

The manufacturer is allowed to claim a number which is within 1% up or down of what the SAE witness observes during the testing.

Again, the engines tested have to be intended for use in production vehicles, have to run fuel consistent with that recommended by the manufacturer, and have to run the same calibrations and be emissions compliant, (ie have cats) during the testing.

Underrated. Amazing how many people want that to be true and it simply isn't.

LS3, LS7 and LS9 or any other SAE Certified rated engine, is not "underrated".

I have often wondered, what would be GM's motive for "underrating" any of these engines??

Under the controlled repeatable conditions as outlined in SAE J2723, production engines intended for installation into vehicles for sale to the public produce the SAE J1349 Certified Horsepower figure plus or minus 2%.

Results taken from off a chassis Dyno in the typical tuner shop can vary widely.

Interesting tidbits, the 638 hp SAE Certified LS9 going into the the ZR1 is the 100th engine to receive SAE J1349 certification. The LS7 found in the C6 Z06 was the first GM engine to be Certified under this new standard.

Thus with the SAE J1349 rating system, the manufacturer is saying that under the same controlled conditions, all LS3 engines intended for use into the C6 Corvette, make to within 2% of 436hp plus or minus.

You need not worry that your LS3 is making appreciably less power than your buddy's LS3.

HarleyB

436 HP is fine with me.

GotVett?

Whew!! Ok, the LS3 is the newest out with a few additional hp and slight improvements. No argument there. Some tend to get onto those who think the LS2 is more than it is, so by the same token, don't think the LS3 is more than it is. In real life, on the street, no big difference at all. More "bragging rights" of having the latest year is all. Now, get a Z or equivelent and now your talkin!!

ZPirate

Good points Phil. The LS3 is part of the evolution of the C6 along with the other improvements that began on the 08.