Yesterday, I broke my 3rd SRP piston (3 separate occasions). It seems as soon as the engine gets into any detonation, the ring lands let go. No melting or other damage, just broken ring lands. Anyone else have problems with these? I know that detonation kills pistons, but these seem to be awfully fragile and will tolerate basically zero detonation. Also, I would expect them to melt some before they break. . . They failed the same way that hypereutectics fail.

 

WHy are you setting the car up so close that it can have the chance to detonate?

 

Wow, three different pistons. Thats no easy chore to fix. I am sorry that happened to you. I looked at those pistons when I did my build. They are very nice and lightweight pistons. I went with the TRW's because they are built like a tank. Heavy but built like a tank.

How much boost are you running!

 

I'm not doing this on purpose, Alvin!!!

The first time was at 13 psi from a Vortech using 8 - 42lb injectors and a superfueler with 3 - 55lb injectors. It broke #1 at 12.5/1 A/F ratio. I figured that the superfueler didn't have good distribution and #1 may have gone lean, though there was no signs of melting.

The 2nd time was 2 weeks at 19 psi with 8 - 84lb injectors and Methanol injection. It broke #1 again at 11/1 A/F ratio. I figured this time that maybe I didn't purge the Methanol after repairing the Opti.

The 3rd one was yesterday at 19 psi and same fuel system as before. It broke #8 this time at 11/1 A/F ratio. I have some more checking to do, but I think the Methanol is not working at all (though the A/F ratio was good).

This is all beside the point, though. The point is that they're breaking during very brief spurts of detonation (this last time I was at full boost for less than 1 second) with no signs of melting.

Mike

 

Some quick research on JE/SRP's site discloses the following about your pistons...

"Ring land and crown thickness specifically engineered for MILD turbo, supercharged, and nitrous applications.

I think a lightweight piston like that one in particular is not cut out for the work load you are putting it through...it's not like you bolted on a 6 psi S-trim!!! And the detonation is just putting it out of it's misery....especially if you think you have fuel distribution problems and/or a malfunctioning methonal kit.

Just my 2 cents, of course.

 

Not sure what your problem is. Those are very strong pistons & should survive moderate detonation. I have seen head gaskets blow on studded heads due to heavy detonation & those pistons survived.... repeatedly making in excess of 800hp.

What part of the piston is breaking, the top or between the 2 top rings?
Give some more info as I'm not sure this should be happening.

 

You know fuel is only half the equation here.. What timing are you running with the alky. I have to run gobs of timing to make my alky kit worth keeping on the car.. if it pukes out or runs out of meth it will ping no matter how fat it continues to stay.

 

Both, actually.

1st: Broken lip above the top ring. Also, cracked between the top and 2nd ring.

2nd: Cracked ring land between the top and 2nd ring.

3rd: Cracked ring land between the top and 2nd ring. Also, top lip starting to break off.

Ring gap is .026 - .028 top and .018 - .020 2nd.

 

I'm using the Crane HI-6 TR. The **** is highly inaccurate, so I really have no idea how much timing I'm running. I did tune the timing on the dyno and setting it conservative based on KR.

 

Look.. my point is while spraying alky I have to run about 5 degrees more timing to "break even" with HP spraying vs. not spraying. Spraying alky on a car without running more timing or less fuel than it normally likes has always proven to me on the dyno to lose power.

I've got to push even more timing at the same afr to actually make power on it.

If your running advance that makes the car run good under alky its likely way too much for when your not running alky. That coupled with some transistional burst knock and you have major problems.

 

Yikes! I got the same setup for my turbo buildup...

 

I've had the 24cc dish SRPs for about 3 years now with no problems until now. MOst of the time I had a 10 psi Procharger on them until the turbo this year where I've run 12psi on them with no problem. I turned up the boost a little the last time I was at the track (about 20 psi) and didn't have enough fuel and probably a little too much timing. I did 2 runs like that and broke a chunk off the top of one ringland and the other piston looks like it just melted around the ringland. I was in the 13.5 AFR range though is probably the reason mine didn't last. The studs and cometic gaskets never leaked a drop. Was still able to drive home although it smoked like a freight train.

 

Any pics of your turbo setup?

 

Never got any final pics but, just mounted the turbo on the front driver's side of the engine. Just used some Patriot super block hugger 1-5/8" headers with a 2-1/4" crossover going into a 3" flowmaster collector and a 3" downpipe. First time at welding so it didn't look too pretty.

 

Any performance #'s? What bout the integrity of the headers? Did they leak or crack?