KILLER-LS1

iTrader: (18)

on a side note- youre "thanksgiving day drive" video on youtube convinced me to buy my turbo set-up!

and to the OP: I agree with everyone else, especially considering you said youve had many other problems with the car. something went out of spec which caused it to go lean / detonate....

darkhorizon

x2 on not the pistons fault.

lmt0705

iTrader: (7)

a higher quality piston may have given him a chance at not breaking the ringland

hissin'98

iTrader: (1)

After fixing the problem here, I talked to the engine tuner who suggested right off that the #7 can go from improper cooling since the coolant passageways are blocked off. When I put it back together, I made a crossover tube so that it ensures flow across the rear of the heads. No problems thus far and the car better be happy since its getting new sway bars in a couple days.

stock48

iTrader: (17)

Man you guys are starting to worry me. Im running custom dished flat tops mahle's in my truck. Been low 10's at 5000lbs and 14~16 psi with them, and getting ready to turn it up to 20

hissin'98

iTrader: (1)

I was told they should handle 18-20psi. Been said a hundred times, depends on the tune. In my case, the tune went out the pipe when the maf shut down.

maceydog

iTrader: (2)

Ive seen Mahle pistons take 20+ psi in 4cy 944 turbo engine making 500rwhp. Cant tell me there wasnt something wrong with the tune. More expensive pistons may (underline may) be better but at that boost, someone didnt do their homework.

That being said, because I going to use Mahle, lets hear some boost stories. How much? How long? Intercooler? Fuel?

later, maceydog

hissin'98

iTrader: (1)

Gettin ready for round number two guys. This time it let go at 12psi but #5. I'm seriously about ready to call this thing quits, for good.

I'm sick and tired of spending the money on tuning. This is just rediculous. As this previous story went, I ended up doing the work myself; total R&R. Yet it still cost me 3k for the piston, rings, machining and re-tuning. I'm half tempted to either sell this thing or put it away for a long while. I just don't have the resources or space to do this again having just moved. I'm frustrated to say the least. There was no code, no lean/rich condition or warning. 3rd gear, 4000 rpm and dropped the cylinder. It's been monitored with an LM2 system. Just don't know...

NicD

iTrader: (7)

Who is doing the tuning and is it still MAF based running 12 psi? What happened exactly when you say dropped a cylinder? Did it break under a pull or just mildly accelerating?

Monte4ever

iTrader: (2)

Damn, that's messed up.

red90cobra

iTrader: (36)

that sucks.

Novaray64

If the MAF sensor caused a lean condition why is the #7 cyl the only one that got hurt?

stevieturbo

No offence. But why not just get a competent tuner to do the job ?

If you're breaking pistons, it is a tuning issue. Plain and simple.

stevieturbo

There is likely damage elsewhere. But one has to go first. They all wont fail at exactly the same time.

But 7 seems to run hottest due to cooling system design

hissin'98

iTrader: (1)

Hey Nic, sorry we could get a time together to have you look at the tune. I'm the one that has been emailing back and forth trying to set up a time to look this thing over for the past month or two. I jumped on the 60 last night headed to the company x-mas party and passed a slow rv after the on-ramp (under accelleration). It immediately dropped the cylinder and I could clearly heard the sound of a piece of piston bouncing around which beat and broke the spark plug. Got off the next off ramp and drove it home. Thought it was 7 again but turned out to be #5. Only thing I can think of is not enough timing pulled near the torque peak, 3500-4500 which lead to det.

At the beginning, it was a maf problem. #7 gets hot because it's last in line. I added a coolant passover to the rear to help this issue.

The shop that did the dyno tuning is a very reputable shop that specializes in LS tuning. It has been run a few times on their dyno. Nothing has changed since the last tune back in March. If I decide to push forward and rebuild, I'll be investing in software...

Grr

iTrader: (2)

well there you go, keep going there your gonna keep breaking pistons, end of story. Theres alot of shops that "specialize in LS tuning", and overall MOST of them are hacks with no idea what they are doing

hissin'98

iTrader: (1)

Trust me buddy, I'm not going back but they are by no means hacks.

1fast bird

iTrader: (22)

What kind of pistons did you use this past time? May be a tuning issue or could just be getting a bad tank of fuel. If you decide to go on with this, run meth as a safety precaution if you don't already. It will help and is good cheap insurance for a crappy tune or bad fuel.

hissin'98

iTrader: (1)

Same pistons. I'm thinking it was an aggresive tune. I've gotta get over the depression slump I'm in and get my head into a new build. Obviously the combo I have now isn't happy. Not sure how the head will look but I'll probably do some major research and set up my own combo. Also need to find some resources in the Phoenix area and see what's available, possibly get some recommendations. It's all open at this point as far as I'm concerned. Really too bad this happened because I was going to switch over to E85.

71 chevy

iTrader: (18)

Sorry man.

Here is what I will suggest, why not throw a cheap 5.3 in it for the time being ? They run 250 to 400 and if you break it...well you're only out hundreds, not thousands.