JBACE

There is a lot of talk about the new LS3 but GM hasn't announced any horsepower ratings. I figured I'd take a stab at predicting what it might be.

Looking at the hp ratings of the recent LS motors, we have...

LS1 -- 346 ci -- 350 hp -- 1.01 hp/ci

LS6-I -- 346 ci -- 385 hp -- 1.11 hp/ci
LS2 -- 364 ci -- 400 hp -- 1.10 hp/ci

LS6-II -- 346 ci -- 405 hp -- 1.17 hp/ci
LS7 -- 427 ci -- 505 hp -- 1.18 hp/ci

LS3 -- 378 ci -- ???

The advances in technology are evident when you see that GM was able to take their 346 ci engine from 1.01 hp/ci to 1.11 hp/ci. This level became the norm for a "base" engine as the LS2 came out at 1.10 hp/ci.

Conversely, we have the higher performance offerings of the LS6-II and the LS7 that reached 1.17 and 1.18 hp/ci, respectively.

So, what makes sense for the LS3?

I my opinion, if you consider the general advances in technology plus the few extra ci, then the hp/ci will be higher than 1.10 and 1.11 above. Also, if you consider that it is still a base engine, you would expect it to be less than the 1.17 and 1.18 hp/ci.

An interpolation of the above results in 1.14 hp/ci which means 430 hp for the 378 ci LS3.

430 hp is my prediction

LS1LT1

Makes sense but there is a debate on whether the LS3 (L92) is actually a 378ci or a 376ci motor, that could skew the formulas a tiny bit.

Doughan

I say 425 HP because it's not a new generation Vette and GM will want to keep a substantial difference in HP between the base Vette and Z06. I would imagine that the 2008 Z06 will get a bump to 525HP to keep 100HP difference between the base and Z06.

cmb13

Either way, it's not going to be a seat of the pants difference, I'd bet. Want sotp, go LS7 or aftermarket. It's just a marketing deal. JMHO

glennhl

And if you rate the LS2 using the new SAE standards, it would be at 415 so that's only a 10 hp increase.

'06 Quicksilver Z06

But it will of course be marketed as a 25 hp increase. And the unsuspecting will think that they actually got a 25 hp bump over the current C6.

LS1LT1

Fast Mover

I'm thinking there is no room for a larger Bore so the Stroke might be increased thus very little horsepower gain. More torque should be possible. Any thoughts? I could be way off on this.

LS1LT1

Another good point but the basic block already exists as the L92 in the Escalade and Yukon Denali, I knew it a few months back but I'd have to recheck the actual bore and stroke as compared to the LS2.

OregonC6

I'd feel 25hp...perhaps you need thiner pants?

LS1LT1

I could likely feel it as well, but could you truly feel only 10 crank horsepower as was determined above that a 425hp LS3 would actually be over an LS2 using the new standard?

'06 Quicksilver Z06

And see thats the whole point.

The 400 hp rated LS2 engine actually produces from 406 to 408 hp under the original SAE J1349 standard. It is a known fact that GM rates their engines conservatively. Starting with the LS7, in the 2006 and 2007 Z06, GM now uses the revised SAE J1349 standard for all new engines.

GM has become the first manufacturer to certify its
horsepower and torque rating using the new Society of Automotive
Engineers (SAE) test procedure J2723. The 7.0L LS7 engine for the 2006
Corvette Z06 is the first to be certified under the new test procedure
at 505 horsepower @ 6300 rpm and 470 lb-ft @ 4800 rpm.

The LS2 in our cars was NOT certified under this test procedure, but the LS3 in the new '08 Vette will be.

The position taken by some seems to be that if the current LS2 in Corvettes today had been rated using Society of Automotive Engineers (SAE) test procedure J2723, that it would come in at around 410 to 415 horsepower. So giving us a new 2008 car advertised at 425hp, using this new test procedure J2723, is really only giving us about 10-15 horsepower over what we have now. Hardly enough to trade up for.

So yeah, you can feel an additional 25 horsepower, but its only a 25 hp increase if they are using the same "scale" when they measured one, the LS2, vs the other, the LS3. If the same "scale" is used then you are looking at about a 10 hp gain, assuming that the LS3 comes in at 425hp.

If GM were to recall all of our LS2 equipped cars and certify their horsepower and torque rating using the new Society of Automotive Engineers (SAE) test procedure J2723, I'd have to update my Z51 badges to read 415 hp .

need-for-speed

I think it will be at least 425 because of the hemi.

jschindler

I'm too braindead tonight to try to work out the math, so can someone tell me why they think the LS2 would be rated at 415 under the new standard? It should be somewhat easy to sort it out using RWHP numbers and a correction factor based upon the Z06's losses.

I would think the losses from the Z06's SAE certified horsepower to RWHP would be about the same as the "base" Corvette. Of course, that will start a whole new debate on whether losses on the same car should use a % (such as 15%), or a straight hp loss that would be the same regardless of the difference in crank hp.

JVM225

jschindler

To add a little more fuel to the fire - the Z06 was originally going to be rated at 500 before going to the new SAE standard, so they were only off 1%.

welcome2try

I was always bad in math

welcome2try

Good stuff, Good info..

ben dover

430hp

Jacksonbart

it will be reduced to 350. Its 1974 all over again.