BC Bob

Hi Guys,
First post from a newbee.
I am in a quandry. I have an '07 Corvette LS2 and added long tube headers, ported throttle body, cold air intake, and Magnaflow catbak. I've dynoed and tuned the CPU twice and the numbers came up at 362 RWHP and 365 RWTQ. According to both tuners, the numbers are about 20-25 HP low.
The last tuner I dynoed with noticed that the head casting numbers were 799 when he thought all LS2's came with 243's.
Neither one of us is sure what the correct number is although he is pretty comfortable with 243.
Will any of you experts please verify that both the 799 heads and the 243 heads are used on the LS2, or are the 243 heads used exclusively.
If I have the wrong heads on the car, I also may have the wrong engine and I'll need to have a conversation with Chevrolet.
Thanks much. Great forum.
Bob

HEMIETR

iTrader: (2)

Not sure on the castings. HP and TQ are about right. May be a touch low for a M6(?) What make dyno?

LS1IMPULSE

iTrader: (42)

found this:

01redws6ta

243 is the LS6 head. The 5.3 in the M.C. and Impala ss/G.P. GXP also have 243 heads. I don't believe the LS2 uses these.

LS1IMPULSE

iTrader: (42)

LS2 uses 243 casting heads, they just dont have the lighter sodium filled valves

BC Bob

DynoJets. One was a new light-weight with a smaller drum. The other was an older model and well maintained. Large drum was in the floor of the shop.
Both dyno numbers within 7HP of each other.
Found two other '07 Corvette owners with build dates 10-06-06 to 10-18-06. Both have 799 heads as well.
Opinions from two well-respected tuners and several owners are that my numbers are low for an MN6 LS2.
I am trying to verify how many LS2's were built with the 799 heads, why they were used, and what the differences are between the 799's and the 243 heads. Not sure where to start looking.
Thanks.

brad8266

iTrader: (23)

Those HP/TQ numbers are fine. 243 is the usual head cast# for the LS2.

HEMIETR

iTrader: (2)

I can't understand why you would have 799's. Every LS2 I know of has 243's. Your #'s could be a touch low for a DJ. If it were a Mustang I could understand. Keep us posted on your finds.

PREDATOR-Z

Looks like maybe the General took a shortcut somewhere. It has been known to happen.

Project GatTagO

iTrader: (7)

799 castings were also used on pre-production LS6 engines.






Andrew

BC Bob

Preproduction means what date? Why were the 799's used on an '07 Corvette with a build date of 10/6/06 when 99% of other LS2's were built with 243's?
I am really confused and can't seem to get an answer from the experts at GM. I sent Bowling Green an email and have not heard back. No surprises there.
I want to know if I have a case against GM. My car has low dyno numbers and I'm beginning to think that the heads are the culprit.
When you spend a lot of money for a car and it doesn't match up with others with comparable modifications, I think I deserve to know why.
Sorry for the rant and thanks for the help.

Project GatTagO

iTrader: (7)

LS6s...as in back in 1999-2000. They haven't produced LS6s since 2004.

Dyno numbers are somewhat relative. Run the car at the track. MPH is a much more accurate measure of the engine output.

Andrew

12secSS

iTrader: (30)

I agree with PredatorZ. Just because this LS2 doesn't have the typical 243 casting heads, doesn't mean GM screwed up. Just look at the casting numbers found on LS1: 853, 806, 241. GM is possibly using the 799 casting on new LS2s, possibly due to a 243 shorting or some other reason. Do not sweat the casting numbers too much as a GM fault. Obviously GM is using those castings on other Gen4 engines.

brad8266

iTrader: (23)

When you buy a car there is no agreement on what set of heads it comes with, you have no real claim again GM. They can choose whatever heads they want to put on it.

Sucks but thats how it is.