I want to start by saying I am new to Corvettes so if this is a dumb Q go easy on me. I have been looking for an ls3 for a while and Im not finding what I am looking for. A lot of people around my part don't like ls2's and tell me they don't run any where near as good as an ls3. The biggest Q I have is, does the ls3 only run better because of the difference in the heads? I know the motor is a little bigger but I have always been told that ls2 heads where junk. I was thinking if that is the only difference then that is something that can be easily changed. The price difference between a 2008 and a 2005 is big enough that I could use the left over money for a heads cam swap. I just wanted to get facts and not just opinions of people I know.

 

Those people are not entirely correct, for a VERY long time the LS3 cars appeared to be no quicker than the LS2 cars in the 1/4 mile (though they did seem to trap higher right off the bat). Only years later did a larger sampling of LS3s finally prove to be quicker overall (as they should be) but in some cases it's only by a few tenths (which is certainly still a notable amount in drag racing).





It's likely a combination of the better heads, slightly more aggressive cam and 12 more cubic inches.
And no, the LS2 heads are NOT junk, they have lots of great potential but stock for stock the LS3 heads are generally better in most applications.





Yes, the heads can be easily swapped and yes you might also want to consider a cam change as well to fully compliment the new heads.
There are some other reasons to consider an LS3 car (or at least a later LS2 car) as well such as the stronger rear and some other minor upgrades. If one can swing it I would still suggest getting a used LS3 but I do agree that from a cost point of view the BEST value going right now is the 2005 cars. The money saved there could almost upgrade any/all weak areas of the car to newer/better specs.
If I were buying a used C6 right now with plans to modify it immediately, it would be a 2005 automatic and one of the first areas I would address/upgrade is the rear.

 

If you go with an ls2, I would stay with 06/07 just because of the tranny and rear end. An 05 has an A4 tranny which was upgraded to an A6 in 06 (if you go automatic). I have also heard that the rear end was improved in 06, but I will defer that to the smarter guru's to chime in for the details.

FYI, with my mods, and you can read them in my profile, I beat my buddy's stock 09 coupe pretty handily.

 

There are a number of minor quirks and drawbacks in the 2005 so unless the price difference is large, I'd go 2006 or 2007 too. It seems half the time I see advice that works with the LS3 or 06 - 07 LS2s, there is some minor exception for the 2005.

 

My father's old threory still holds true. He used to tell me never buy the first year of a new model. This holds true for any car. I am not inferring that the 05 is bad, in fact it is an awesome car. However, improvements WERE made in 06 (and again in 08 with the LS3). I am buying a Caddy Escalade EXT for my DD, and I am staying away from the 07 (the first year of the new style) and opting to go with an 08.

 

True, on the 'rear' part at least. The 2006 and up C6 rears are overall much stronger than the 2005's which is especially critical when talking about the manual transmissioned cars. But for the money saved buying an '05 over an '06 or '07 one might be able to upgrade the rear to something far stronger than any of the stock C6 rears.
And yes the A6 is an awesome transmission and performs very well (especially on the highway) but for a moderately to seriously modified automatic C6 I'm not so sure that the 6L80 (A6) is really the better choice over the 4L65 (A4), for now at least. It's far easier to build an A4 to stand up to serious power and racing use/abuse right now than it is to do an A6 in my opinion.

 

That's a good point I forgot to ask about. Does and company make a built auto 6 speed? My buddy has a performabuilt in his ls1 ss and so far it has been a great trans. How strong is the stock A6?

 

What do you mean by "run better?"

 

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To your original question, based on my observations here, including dyno & track, you can pretty much say, on a Dynojet corrected and with a sharp driver on the 1/4 mile track:

LS3 stock = LS2 w/ full bolt ons = (mid-high 11's, 390 rwhp or so)
LS3 w/ full bolt ons = LS2 w/cam & FAST (low 11's, 450 rwhp or so - note, this about stock Z06 power)
LS3 w/ cam, FAST, stock heads = LS2 w/Cam, FAST & trick flow heads (high 10's, 500 rwhp).

This is a little general, but will give you the idea on performance out of a manual car. Some go faster than the figures above, but those are a decent average.

A conclusion you can draw is that if 500 rwhp is your goal N/A, the ls2 can get there with $3000 more money, due to the TF heads/Rocker Arms (not counting labor).

 

lol good to know..... but my 05 will take ur ls3 any day

 

Pbir is closed this weekend but gtodoug and I will be at Tower Shops and Countyline Dragway afterward this Friday if you boys would care to backup these words.....

 

If I was going to really beat on an auto I would rather have the A4. I would upgrade the rear end but IMHO the A4 is a better trans to beat on.

 

No problems out of my 05. The rear diff has to go, but other then that the LS2 is a champ. I think she will fill much better when I get my Kooks headers on, and the 3.90 gears in an upgraded diff.

 

I have an ls2.
And I was referring to the quirks of a new model, and not necessarily the speed of a modified one.
I am sorry if you got insulted, but history does not lie.

 

I don't know if I can come this time Joe. It is a little too close to 04/15.

But I will try. Lots of local boys in this thread!

 

THANKS for this info !! If you did EXACTLY the same mods to both the LS2--&--LS3----how much difference in RWHP ??

 

Probably about the same as there is when stock, roughly 25rwhp/20rwtq, though it depends on which mods one is choosing as well.
One might be able to use a little bigger cam in the LS3 than the LS2 because the LS3's slightly larger displacement and better flowing heads might be able to support it so a cam only LS3 could make even more than that 'already extra 25rwhp' over a cam only LS2. That's assuming that there's enough piston to valve clearance and a few other factors of course.
Cam only LS3s have exceeded 500rwhp yet cam only LS2s might struggle to crack 460rwhp so that gap does tend to widen a little bit more as you mod.
Both motors should respond similarly to forced induction or nitrous.

 

PBIR is closed this weekend?? Damn it, the one time I make time to go with my brother in law-

 

They are.

But Countyline Dragway has a big money race Saturday night, so come out there! I may go Friday too with my friend GTODoug, I'm afraid I got him hooked on drag racing this time...

 

Thanks. I've observed this trend here on the board and at my track where the ls3's are beating up on us ls2's, mod for mod.

As a general statement, I think it's fair to say LS3's start out and stay about 30 rwhp ahead of the ls2 either stock or with equal mods until you put on the top of the line heads on the ls2...and stock heads on the ls3...then they are pretty close with slight edge to ls3.

When Trick Flow comes out with a new head for the ls3, it's likely the ls3 will be ahead again.

It's tough to beat displacement.