good day

im facing a low numbers of HP & TQ with my combo & dont know the reason
car details as shown below

corvette 2007 Z51 LS2 (forged)

Piston -2 (wisko )
Rods 6.125 (compostar)
heads gasket 0.040 (cometec )
Bore 4.005
AFR heads 225 62 cc
G6X3 CAM
Fast 102

dyno'd at 460 RWHP 400 TQ
on my search's car should achieve around 480 - 510 hp anyone know the reason of low numbers ? my tuner said that car timing is at 21 & air fuel is between 12.7 - 13

 

You've provided good details but there are some we still need.

What kind of dyno? Dynojet? Mustang? Dyno Dynamics?
I'm assuming your car is a manual?

Just from waht you provided you timing is on the low side for N/A. Thats the kind of timing guys spray on and you A/F is a little lean but its not bad. I personally wouldn't run it that high, 12.5-12.8 would be a little more inline.

 

Timing is low for sure.

What about exhaust?

SCR, DCR?

 

It was in a dyno jet
I have c6 npp exhaust
Regarding timing how much it should be for n/a ??
What is SCR / DCR ?
And yes my car is manual z51

 

my ls3 g6x3 c5 trapped 128mph with 28 in it and with 22 my nitrous tune it was 122-123mph never dynoed it

 

I would say that mid-high 400s is definitely the norm for stock cubed LS2s. You're in the lower of that range due to the seemingly poor tune...21* of timing? That's stock timing and is most definitely not what a close to max effort LS2 should be at.

I would say in the mid-high 20s is what it should have for timing. That alone could get you another 15rwhp which I would say is a good point for the car.

 

I have a g6x3 also and I was told by lg it was more of a stock-ish motor cam. I.e. not suited as well for upgraded heads and intakes manifolds. Also it is designed for ls3 heads which have very different flow characteristics than yours or stock ls2 heads... Maybe you should look into a different cam.

I mean I love mine, but it's in the motor it was designed for. They have te g5 series for ls2 and ls1 motors...

 

Is head/cam selection not working as effeciently as they should either?

Isnt the G6x3 cam ment for rectangular port L92/LS3 headed engines and G5X3 for cathedral port

 

Thanks for replaying guys

I am tge guy who tuned the vette

I rised the timing up to 25
I had some .9 kr
There was no gain in the Hp
This is the reson that i lowered it to 21
Because at 21
23
25
I had the same hp
This is the weird thing

 

Do you guys have a dyno graph?
What headers?

with the same cam and botlons on M6 Z51 stock 243 heads a friend of mine dyno 465rwhp 418rwtq I beleive it was on 24 degrees of timing..
12.7 A/F ratio.

 

Dyno grahp
The owner of the car have one
He should attach it
But on the dyno
After few pulls
The x-pipe has been opened
So the u might see a lean run
Its almost the same file for the 1st run

 

that cam is designed for ls3 heads which have very different flow characteristics than for your heads... Maybe you should look into a different cam. +1

 

Something is causing the knock then. Bad fuel? carbon on the pistons? Cam too big causing PTV?

The SCR is only 11.3:1 if the deck is 0 and the chamber is actually 62 cc.

 

The timing may be just fine. My modded LS2 timing works best at 20 degrees and makes 473 rwhp / 425 rwtq. More timing does not always give more power. All stock LS2 can take up to 26 degrees before knocking but if it makes max power at less, why add more? Listen to the tuner. With my mods, m car made no more power with more advance.

 

I understand that more timing doesn't always make more power but he was getting Knock at 23*. If a stock LS2 can take up 26* then an aftermarket headed motor should be able to get there with the same or less timing.

Your engine is a different animal. You are running stock heads and he is running AFR's which are a more efficient head. Plus listening to the tuner isn't always helpful some guys know what they're doing but alot do not.

 

fyi the ls2's do NOT like timing.......higher compression will like even less timing......a more efficent chamber will also add to it liking less timing due to faster burn rates...im in the same boat and made good power for what i have.......i run a mild 22x/23x street cam.....tuned the car my self and found that 21* was all the car wanted....i could get 23* into it but it made 0 more hp and 0 more torque so for RA load i dropped it back to 21.....this is not uncommon.......also that AFR is a bit leaner than usual....usually these motors like running down around 12.4-12.6.....at 13.0 i made 410 at 12.4 afr which is where mine is i made 422 cam only with supporting exhaust mods....

 

What does the MAP show during the WOT run start to finish?

Is it possible the WB is not calibrated properly, by chance did you try richening the AFR?

I always think if the cam was degreed when low power issue's come up.

I've two sets of AFR cylinder heads 205's & 230's, two different engine combinations, they always seem happy with high 20*'s & even 30*. That is 11.5 SCR on a Mustang that may load harder than the DJ. So I would agree the timing is low for those heads & a clue.

 

I think the numbers are fine for a LS2. If it was a LS3 then I would be scratching my head. I'd be more concerned with the timing issue.

 

i also think the numbers are spot on, my 418 ls3 dynos 508 on a dynojet and it has a g6x3 cam and ported milled ls3 heads running the same compression are,
for you to be at 460hp thats pretty good for a stock cube ls2. i cant see you getting much more out of it without getting a cam specificly matched to the heads and intake setup. a g6x3 is going to perform best on a ls3 head and not saying you are losing power but its not going to be potimal for your heads. its still ging to make good numbers and good power and like i siad 460 isnt bad numbers.

 

im still wondering about the kr. i dont tune, but have a very basic understanding for it. what were IAT's, coolant temp, and someone also mentioned bad fuel, but what about fuel pressure?