jasonsnova

i got a 24x wheel non of my pistons look like that..

.

Loud Mouse

Without seeing the top of the piston, looks like a classic sign of too much fuel. Top ring land still intact (but torched slightly) with second completely melted away along with oil groove. Jus be glad it torched the piston and not the head. If you would of had better pistons might have been the other way around. I go against the norm here and build my engines for FLOW, both in and out, and not create much back pressure which builds heat. If you search there are several(quite a few actually) engines running a lot more timing and living fine. JUS A FYI, I also run another turbo engine that makes 29psi with 29° of timing on pump 93 and makes 3hp per CID.

ElQueFør

I can't see that much difference in the ring lands in this picture provided, look pretty similar to me. I ran around stupid rich while I was trying to scale my IFR in order to determine what my decapped truck injectors liked. AFR was between 9 to 12. Idling it would fume up the shop it was so bad.

99camaroturbo

ddnspider

iTrader: (26)

It is possible your 11.2-11.5 on the wideband wasn't entirely accurate. If you had an injector leak or stick open then that cylinder could be much richer than the rest but still average what the wideband showed. If that cylinder was buried rich it is possible it caused damage.

RICE ETR

iTrader: (3)

I'm definitely not going to compete with the experts in this thread as I am a tuning newb...but I have been running the crap out of my car trying to get rid of the rpm wall at 5500 I was hitting. Once I put it on the dyno, I figured out I was too fat, like way too fat...mid/low 9's AFR and my timing was conservative too at 13-14degrees, 93 octane, meth/water injection (50/50) and only 11psi.
Playing with the tune, I have actually run it even fatter...it woud simply misfire or just cut out completely.
Anyways, as mentioned I am not trying to debate what the more advanced tuners are saying here, just letting you know my expereinces.
Back in the day when I had my camaro, my WB would peg below 10.0 WOT and the more meth I added, the faster it got...so I'm not sure what's true haha.
With my POS stang on the dyno, rw went from 388 to 515 by leaning the AFR from 9's to 10.5-7. I only gained like 5hp going from 10.7-11.0-1. My car may be haunted.

ElQueFør

I think Spiders theory holds some good weight. When you get into these things you really need to flow test your injectors, no matter what they are. Especially for a boosted setup that has made a departure from a stock 5.3 in a soccer moms Suburban and is instead a snarling turbocharged mill.

NicD

iTrader: (7)

I'm not reading through all of this garbage so if you have already mentioned this stuff can you just repeat it for me?

- What is your full engine combo like compression ratio, cam specs, etc?
- What wideband are you using and where is the sensor located in your exhaust?
- What fuel injectors do you have?
- Post up your tune file and a log file since that will also help explain some things...

At a glance running 11-14 degrees of timing at 11 psi on 91 oct with a stock engine sounds like the problem if you were here in AZ, but it looks like you mentioned it had lower compression so that means it was a built motor and that would make a big difference so I just want to see more info to make sure I'm seeing the entire picture here.

99camaroturbo

NicD

iTrader: (7)

OK so an LM7 with flat tops and 241 heads is ~9.6:1 compression or am I doing the math wrong on that?

Where is your wideband O2 sensor in your exhaust? Is it in the downpipe or in the hotside crossover somewhere? What does the rest of your exhaust after the turbo consist of?

IMO running the stock cam on this combo is going to make it VERY timing and heat sensitive, and I don't think the slightly lower compression is enough to get away with running that much boost on crap 91 octane.

99camaroturbo

ddnspider

iTrader: (26)

Just to clarify, I never said the richer the better. It is absolutely possible to be too rich, that's just not the case at 11.2-11.5 on 91 octane LMAO.

NicD

iTrader: (7)

OK so it doesn't look like you would have any back pressure at that point in the exhaust on the sensor so it's more than likely relatively accurate as much as an AEM wideband can be. Your a/f ratio is definitely not the cause as long as the wideband is reading correctly, but I would be double checking it with another wideband just to make sure you don't have a failing sensor/gauge.

Did you get the Deka 80s off of ebay or anything like that or did they come from an authentic reseller? Seen plenty of knock off chinese Dekas over the years that sell for only $250 a set and they are GARBAGE and have seen them take out more than one motor.

99camaroturbo

NicD

iTrader: (7)

Oh yes definitely, detonation/heat is what hurt your piston there is no way around that. But it wasn't your a/f ratio, just too much boost/timing for the combo to handle. It probably would have been fine with less timing but once you get into single digits for timing it's a pretty dirty burn and it's a sign you had better drop some boost out of it instead. E85 is a whole new world but you still don't want to just crank up the timing to 30 with it since it's flame front travels faster than gasoline, compensate with more boost instead and ramp in a little bit more timing.

stevieturbo

At $250 for a set of 8, not a chance in hell is anything flow matched.

When genuine 80lbs are in the region of $60 each.....a full set for $250 ? Also has to raise some alarm bells. That's not just a little discount...that's half price. Or double what Chinese copies sell for when they're not pretending to be genuine.

https://www.siemensdekafuelinjectors...s-short-style/

99camaroturbo

ddnspider

iTrader: (26)

Dealer pricing on those 80s was more than 250 from what I saw lol.

ElQueFør

Decapped truck injectors end up being really close to 80#. And they're cheap and abundant. And a GM part instead of a chinese knockoff. My IFR table is 75# with my decapped injectors.

stevieturbo

There is really no flow match guarantee with de-capped injectors though. Some Subarus whilst they might run great...can see quite a difference in flow when de-capped.

I know the budget thing is cool and I ran cheap although genuine Siemens for years. But it is such an important area using known quality items here is essential