delorean6584 Posted June 5, 2009 Share Posted June 5, 2009 Hi all ! after finishing the megasquirt and acheiving good results with tuning it came the fun part ! broke a piston skirt !! i ran megasquirt, l28et completly stock engine good air/fuel ratio 15psi of boost and intercooled and BOV the thing is i bought this engine used and was sitting for 10 years or so, it was inside a barn and wasnt stuck, but maybe the rings were....so the number 5 piston have the skirt off but the rings intact (they are stuck to the piston though, so i removed another piston wich the cylinder and piston is good, the rings are stuck too.... so i imagine that the broken skirt is due to the stuck rings ??? if not ?? i never heard the engine pinging like popcorn at all, only the number 5 piston is broken all other are in very good shape ?? now what to do ??? i dont want to rebuilt it to break it again...there is now way i pushed 300hp on this motor, the boost is raised to 15psi but very well intercooled, engine coolant temps is always low... i ve put alot of money in this car and i am building my house right now, so money is a problem, but i have 2 sitting engines in my garage (l28e) they both work well, the blocks are the same but not the pistons or heads, my turbo head is good, so the question is, do you think the engine could be reliable if i take the l28e bottom end, put the turbo head on it with all the turbo goodies ? compression will be higher but i could remove some boost ? or i could get a l28et bottom end fairly cheap but i would need atleast new rings/polishing cylinders i really want a reliable engine, this is my daily driver but i want something a little more powerfull than the stock n/a.... comments are welcome ! EDIT : if it can help to find the reason it broke, the skirt is broken on the driver side... the Rh one is okay Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted June 8, 2009 Share Posted June 8, 2009 The block itself will hold as long as it's tuned right and it's not some monster turbo/setup. I have an L28E block that is OK at 21 psi so far. I am using an N42/N47 setup at about 8.5:1. I am overkilling the octane to do it, however. Just playing with it and dialing it in for safety. (A common thing on somewhat knock-sensitive setups) Dial it back on the boost and install an L28E engine for now. Save your pennies for more important things for the time being. Don't get yourself in a hurt over a project car. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 8, 2009 Share Posted June 8, 2009 I've seen N/A engines break the skirts from being revved when cold. I also had a car that had a thermostat stuck open in the winter on the highway and I broke the skirts on all six pistons with no ring damage. Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted June 8, 2009 Author Share Posted June 8, 2009 yes i am pretty sure the skirts breaked because of the stucked rings, number 5 and 6 skirts were broke, these 2 pistons have stuck rings on them, the other pistons are like new, rings are not stuck....i guess when i bought this engine 2 years ago i should have replace the rings...i was hesitating if they were stuck or not, compression was good....live and learn !! as for my new engine, how much boost do you think it could handle to be reliable ? maybe i will run high octane gas just to be sure...i would like 10psi... is it possible without breaking anything ? Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 9, 2009 Share Posted June 9, 2009 If everything else in the fuel system is OK, you should be able to run 12psi with no troubles. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted June 9, 2009 Share Posted June 9, 2009 yes i am pretty sure the skirts breaked because of the stucked rings, number 5 and 6 skirts were broke, these 2 pistons have stuck rings on them, the other pistons are like new, rings are not stuck....i guess when i bought this engine 2 years ago i should have replace the rings...i was hesitating if they were stuck or not, compression was good....live and learn !! as for my new engine, how much boost do you think it could handle to be reliable ? maybe i will run high octane gas just to be sure...i would like 10psi... is it possible without breaking anything ? Well, I've hit 21 psi on my stock L28E with Cam2 and Megasquirt/EDIS/Holset/Cam and 7k rpm. I think the stock engine's detonation tendencies (which are pretty much all solvable, from what I've seen) is what imposes such low limitations on boost/power. Running higher octane can deal with a host of sins in design or tune. Look at my project page (sig link) and you'll see a cooling mod I've done to help as well. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 9, 2009 Share Posted June 9, 2009 The big question is did you pull the pan for an inspection BEFORE you put the engine in the car. It's totally possible the skirts were broken like that when you installed it, and nothing you did contributed to it at all. I have run across several Turbo engines where that was the case... They will run quite well with no skirts. I think Bernard was doing 11's in his car with all six broken off and laying in the pan bottom! But he's off a bit. LOL Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted June 10, 2009 Author Share Posted June 10, 2009 tony, i did replaced the pan gasket when i got the engine...no pieces were found.... the skirts are freshly broken it is obvious, the engine smoked oil and shaked like a v8 when they broke..... the no5 piston was surely damaged before (top section) i think i will run octane boost with each fill of gas to be sure... such a pita to swap all parts !! i also have only one good engine remaining !!! Quote Link to comment Share on other sites More sharing options...
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