does anyone know how this would happen, it looks like the piston got hot and it melted the rings, or could it be that too much fuel wash out the oil on the cylinder walls the car was getting tuned and on that last pass at 17 psi thats when that happend, oil pressure was good
this engine is fully built has darton sleeves, je pistons 9:1 compression the engine is and h23a3 , i would appreciate any input on this thanks

 

look like they over expanded.....p/w might have been alittle tight

 

You sure this motor is sleeved ? Who built it ? If indeed sleeved, then the only thing I can think of is tight clearances of piston to wall, and high revs without addition of piston oil squirters.

 

only 3 of the 4 pistons look scared

 

looks like the cylinder clearance was too tight for that setup. What is the clearance on the non-scuffed piston?

 

yes only 3 pistons are messed up #3 is fine a machine shop in florida that is darton certified installed the sleeves and i gave him the specs on the pistons, i'm gonna get a dial bore gauge and measure all 4 cylinders and see if it was the machin shop's fault

 

here are some more pics

 

i just took it apart last night so i haven't measure anything yet

 

look at my other pics

 

i don't think i need oil squirtirs cuz the tuner was only reving the car to 7,200 rpms i had only put 120miles on the engine when i took it to the tuner, it was making great power after 2 hours of so of tuning thats when that happened

 

p2w too tight.

 

more pics

 

p2w what does that mean?

 

piston to wall

 

Another Chop Shop butcher job.....Time to find a better machine shop.
If I didn't know better I'd say forged slugs in FRM sleeves......but its just shitty work.

 

my block has darton sleeves , and i,m 99% sure the machine shop mess up cuz i measured the bore of the cylinder with my caliper an inch down from the top of the deck and #4 cyl had 3.436 and it should be at 3.445 (87.5 mm) bore but to be sure tomorrow i'll be getting a dial bore gauge.

 

looks painful... Mind me asking why you were tuning for 17 psi on a 150 mile old freshly built motor? why not break it in on a 6psi street tune, then once the engine is properly broken in go after the more aggressive tune... Just a question, not trying to start a e-battle.

Also who assembled the motor, the clearences definately look to be the issue, but if something was loose inside of the rotating mass of the block, well it could have also helped the progress.

 

i feel you bro. fully built my h for all motor and my cam gear wasnt tightened down right and slipped blowing my motor.. my head is trash and my #4 piston detonated. only drove it about 30 miles since i was done with the build. so i feel ya pain

 

live and learn

 

Learn to measure the bore before installing the pistons? I can agree with that somewhat, but if the machine shop is in fact darton certified they should be completely at fault here. They've got to have people coming in who know very little about cars and are having their motor built by someone else, so they rely on the machine shop knowing what they're doing. I don't know how they could have underbored it by 9 thou, that's a huge difference.

 

Even if the piston to wall clearance was fine too much timing and boost will do a good job of expanding the tops of the pistons into the wall.

Might look at the timing map versus boost pressure and consult another tuner to see if it's your tuner's fault. If it's tuned the post up the data logs, dynos, fuel/timing tables and general setup. What power were you making on what fuel and what injectors and fuel pressure?

Consider all aspects of your blown motor. Don't just pin it on the machine shop until you get the measurements off the last cylinder to verify clearances.

-P

 

well my tunner check the bore of the cylinders and they are within specs,which is 3.445 i called JE and they said that thats the bore you should use for an N/A or low boost application( 5psi) that if you go higher boost that it should of been bore out to 3.446- 3.447 so really i can't blame the machine shop cuz i didn't tell him how much boost i was gonna be runnig he tought that i was gonna be running low boost. the car put out 331whp 317wtq @14psi . my tuner said that i didn't needed to brake it in , that you can just brake it in on the dyno thats why i didn't put more miles on it.Timing was 20 degrees BTDC .

 

pics

 

i'm using 780cc pression turbo injectors @55psi running 93 octane.

 

If the piston to wall clearance was set for light boost (~5psi) and you went 3 times that then I'd say that your problem is already identified. Since you're sleeved, get some 88mm pistons and start again with greater piston to wall clearance. When it blows go bigger/stronger.