krambo, I am not too sure how different headers would affect cylinders... unless their could be some drastic differences between cyclinder scavenging as well as amongst manu's(?) Indexing spark plugs? Not sure... great questions

Lots of good discussion in a thread I started over on the Corvette Forum. Peter@APS said he has checked ALL cylinders for EGT and AFR... saying he see's issues with #7 and #5. Also, discussion about firing order... great stuff.

Bill

 

I think its all in the tune.

Just a little info.
I run a stock 5.3 truck with a RADIX 3.0 pulley and Meth. for 25,000 miles.
the rest of the mods are in my sig.

I see 11.5 psi at the top of 1st & 2nd gear and 12.1psi top of 3rd gear on a 75* day at a Baro of 30.09.
My AFR's 11.8 and drop to 11.3 at the shift, I start out at 22* timing and it drops to 17* by the top of 2nd gear, my IAT goes up to 149* at the top of 2nd gear and then drops to 135* by the top of 3rd.

on a cold day 30*F I see 13psi of boost.

Motor still holding together.

 

i agree that allot of this can be found in the calibration, however it is covering up a mechanical issue in the manifold design. OE's do it all the time, calibrating around a design flaw costs less than re tooling.

 

We've had 2 bone stock 06 SSR's with LS2s. (completely diferrent intake again) with broken #7 pistons.

 

i thought everyone knew this one and was old news. number 5 and 7 run lean and you have to tune to the limit of your fuel on those 2 cylinders, they just get more air than the other cylinders. take a look inside the intake and it is easy to see how more air will get pushed into those cylinders. i remember a post awhile back where someone tested the actual intake presure at each intake port and they reported as much as a 2psi higher boost level at 5 and 7 vs the lowest presure at another port.

i talked to kurt at w2w and they tune in a little extra fuel to those cylinders when they have that option with tuning. if you let it knock it will break a piston. i ran 14psi on a stock piston 6.0 for a year with 100's or runs with no problems at all but i ran it on the rich side and ran good fuel when the boost was turned up. any of these gen 3 motors will hold 14psi when properly tuned.

we are at 18-20psi on the pinks car and thats a stock 5.3 other than valve springs. we made 34dyno runs, about 10 track runs and 30+ runs on the street so far. stock truck intake. not real sure how close we are to the edge but that right there gives me a lot of confidence that 15psi will last a very long time. i ran my truck with a 100% stock 4.8 at 18-20psi for a couple of months with no problems either. over 500rwhp on a mustang dyno.

the people that are blowing these things up must not know what detonation sounds like. we log often and are ready to let out in case of a knock. we also go with experience learned along the way, simple and extra safe rules like not going over 9psi on pump gas. not running excessive timing. keeping the air/fuel ratio in the lower 11's. watching the tune when changing from the dyno to the street.

 

What software allows you to tune individual injectors? Something like a stand alone system like Megasquirt? Can HPtuners or LS1 edit do this?

 

AFAIK, non of the tuning software can do it, and MS is batch fire only, so it surly can't do it. Maybe FAST, or BS3???

The only way you can really add more fuel to 5 and 7 is to flow rate the injectors and put higher flow related injectors in those 2 cylinders. I would imagine that's how they are doing it.

 

Well after all this info on top of thought and outside influence....I've decided that I'm going to pull the turbo off, get the motor fixed, and return to normal. If anyone has any interest in the kit send me a PM. After I get everything cleaned up it will be on the classifieds board.

As much as I love the thing, I don't feel like dumping more cash into it when I can build another car. Reliability is playing an important role in my life right now and this is the best choice.

Thanks for all the info and I hope this issue gets worked out!

 

Pulling the hairdryer off will make it feel like a turd... but a reliable turd. I pulled my Magnuson off my daily driver... but I am motivated to install my turbo kit after the feeling of loss of power. You have a good tranny behind the motor... so if/when you revisit power adder or whatever route you choose you will be "halfway" there.
Not sure what you have planned... but if you are going to rebuild existing motor maybe put some forged pistons in it and consider the compression ratio if you will revisit forced induction in the future. If you are going to buy a new motor and not return to forced induction... maybe consider a factory LQ9... drop it in and have a tuner swap in / validate stock LQ9 tune and call it a day. Just some suggestions

Best of Luck
Bill

 

reliable and 10psi of boost does not belong in the same sentence. I would just have the motor rebuilt with forged parts and leave the turbo installed. Its going to be about the same price either way you go.