Melted a piston - unsure why.
Staging Lane
Joined: Jul 2016
Posts: 61
Likes: 0
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.
TECH Enthusiast
Joined: Dec 2011
Posts: 531
Likes: 5
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.
Thread Starter
Teching In
Joined: Jun 2018
Posts: 21
Likes: 0
Something tells me if i add 5* of timing and lean it up to 11.9, I wont make it past the first pull...... this is very frustrating, I just dont understand how a few people are suggestion I was too rich and not enough timing.
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.
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.
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.
TECH Enthusiast
Joined: Dec 2011
Posts: 531
Likes: 5
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.
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.
- 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.
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Verdad Gallardo Thread Starter
Teching In
Joined: Jun 2018
Posts: 21
Likes: 0
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.
- 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.
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.
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.
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.
Thread Starter
Teching In
Joined: Jun 2018
Posts: 21
Likes: 0
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.
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.
I just feel like 11.5 afr with 150* temps and maybe a little to much timing is my killer. Im going to switch to e85 to help that, but now Im starting fresh. Been reading a lot of e85 tuning and see you talking quite frequently, so I appreciate your input, all g with everyone else whose been helpful here
OK that's good but not sure that they flow match anything, I think they just resell what they get in boxes so with an injector of that size I would buy something that has been flow matched.
I just feel like 11.5 afr with 150* temps and maybe a little to much timing is my killer. Im going to switch to e85 to help that, but now Im starting fresh. Been reading a lot of e85 tuning and see you talking quite frequently, so I appreciate your input, all g with everyone else whose been helpful here
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
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/
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/
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
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
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