Popped an MLS gasket and cracked a piston on 100 octane and meth...

[EYE-OPENER]

So the story goes....10.2 a/f, 13.8 volts, RJC FMIC, 63mm turbo, T/A performance headers,TH downpipe, twin in tank lumps with hotwire, and a bunch more goodies. I am running straight 100 octane from Sunoco and 25lbs boost as that's what the tune is for. I have been tweaking the alky down a bit trying to get the a/f higher and to lean it out. I have always been on 7-8 on the dial and ended up at 3-4 when I popped the drivers side front gasket and cracked the piston down the middle. I made a good third gear pull and everything looked great with zero knock....went to roll into it again and about two seconds in she let loose....did the low setting on alky lend ahand in my fate? I thought with 100octane that alky wasn't as needed...this cars killing me...lol

 

[pacecarta]

cracked piston or the cylinder (says piston in title then cylinder in thread )

piston crack ...been there
theres a thread on it ,
couple of us one fall were pushing for nines on stock bottom ends and alky and one by one suffered the same crack stock piston... bison then mine then supersix

nice thing about stock junk ...swap it out with another and move on

and 100 octane wont support 25 psi unless the timing is low

 

[EYE-OPENER]

It was piston. I corrected it. That's what I plan to do..gonna pull her down some more and see how the rest of the bottom end looks. Shoulda left the damn alky alone I guess...damn....

 

[Scott Atk]

Which piston... #1?

 

[EYE-OPENER]

Yep...#1

 

[kidglok]

chip or aftermarket ecm?

 

[EYE-OPENER]

TT 5.6 chip for 50# injectors, alcohol, 23/21 degrees timing, 23-25psi.

 

[TR Custom Parts]

How was your fuel pressure? Are you monitoring it?

 

[Chuck Leeper]

Stock location FPR??

 

[bison]

The factory pistons pin bore wears and combined with the heavy piston starts to crack. This takes a long time to happen in most instances. I ran an engine for 2 years at low 10 sec power or better until I cracked one. I went 10.13 twice two years ago with another and over revved on one pass before that and cracked the piston. It was cracked before the 10.13 passes. You could feel the compression entering the crank case if you put your hand over the vents. I kept ponding it till it cracked all the way. Octane doesn't matter either. I ran 116 octane on the last one and 110 octane on the earlier one. Both engines had high mileage with one at almost 150k. These weren't designed to be pushed like that. A fresh stock shortblock would probably last longer.

 

[Razor]

Shoulda left the damn alky alone I guess...damn....

Yup.. You never lean out a car dropping alcohol.. thats a very bad thing. Its like reducing insurance coverage.
2nd.. once that gain knob starts going down below 4 it makes the pump lazy. If its cold outside even more so as the clearances tighten up on it.
3rd.. Leave the knob on 6 and tune the car is the simplest way. When a cometic goes.. its not pretty. Thats the beauty of the felpro's.

 

[EYE-OPENER]

How was your fuel pressure? Are you monitoring it?

43 psi with hose off at idle and I've been getting a solid 1:1 through the boost levels. I don't have a data logger but am ordering one now. My brother was watching the a/f gauge while I was watching boost level and it was a steady 10.2 at boost and boost gauge was dead on 25 with no fluxuation....I think I fudged up by turning the alky down ...

 

[EYE-OPENER]

Stock location FPR??

Yes stock location billet regulator.

 

[EYE-OPENER]

The factory pistons pin bore wears and combined with the heavy piston starts to crack. This takes a long time to happen in most instances. I ran an engine for 2 years at low 10 sec power or better until I cracked one. I went 10.13 twice two years ago with another and over revved on one pass before that and cracked the piston. It was cracked before the 10.13 passes. You could feel the compression entering the crank case if you put your hand over the vents. I kept ponding it till it cracked all the way. Octane doesn't matter either. I ran 116 octane on the last one and 110 octane on the earlier one. Both engines had high mileage with one at almost 150k. These weren't designed to be pushed like that. A fresh stock shortblock would probably last longer.

The prior owner pushed the limits with this car and that with small issues I've had I think caused it. Who's to say that with everything 100% perfect with the pull and setup that it wouldn't have happened anyways....I just gotta weigh my options with a new short block or replacing the piston if everything looks ok with the bearings....that might be my best choice to at least have the car usable for shows and start hiding parts away for a full on build..

 

[EYE-OPENER]

Yup.. You never lean out a car dropping alcohol.. thats a very bad thing. Its like reducing insurance coverage.
2nd.. once that gain knob starts going down below 4 it makes the pump lazy. If its cold outside even more so as the clearances tighten up on it.
3rd.. Leave the knob on 6 and tune the car is the simplest way. When a cometic goes.. its not pretty. Thats the beauty of the felpro's.

Now you tell me....lol....I might be sending my pump to you to freshen it up next week...thanks for the help everybody...

 

[Razor]

Now you tell me....lol....I might be sending my pump to you to freshen it up next week...thanks for the help everybody...

Got to understand.. You start making tuning decisions you need to be on your toes and not guess. I answer the phone 40x a day.. and here to help.. but cant help if someone doesnt ask.

Yes on pump.. that has to be fresh and up to par.

Note to readers.. if you have a question on the alcohol system.. ask. You take it upon yourself to play with it.. your results may vary. Not saying this is what caused your issue.. but it sure doesnt help to turn it down.

 

[Fast4Ward]

yep watch out for when the pumps start going...and your low on alky ...pita keeping it topped up for sure...once she's an alky she drinks lots ...im always paranoid with the running race chip with pump gas and alky....but tuning abit rich is good...it never ends....my car also drives me nuts...my rebuilt motor only lasted about 75 miles...LOL

 

[TurboBuRick]

#1 again. This is getting old.

I'm gonna send Chuck the rail and injectors from a car sitting here with #1 meltdown. He is going to do some testing and get some real data for us.

There is something going on with #1 on these TB's.

Rick

 

[kidglok]

#1 again. This is getting old.

I'm gonna send Chuck the rail and injectors from a car sitting here with #1 meltdown. He is going to do some testing and get some real data for us.

There is something going on with #1 on these TB's.

Rick

it was #2 for me last time

 

[DR BOOST]

#1 again. This is getting old.

I'm gonna send Chuck the rail and injectors from a car sitting here with #1 meltdown. He is going to do some testing and get some real data for us.

There is something going on with #1 on these TB's.

Rick

i dont think its the rails....we had the same problem on a dual fed billet rail. To be honest, i think it has to do with the alcohol injection. Its not a defect in the kit, but a user misadjustment or misapplication. In the OP's case, he fiddled with the adjustment trying to squeeze out a little extra power and it bit him. I also think the problem is compounded on cars with wideband tracking.