[kwiktsi]

Had a little accident last night. I am not sure if it was from just pushing the thing too hard or if it was from a rev limiter "goof" I made earlier in the day (screwed up with HPT) where I missed third prety bad and the motor saw 8300 RPMs a few times. The intake pushrod was bent on that cylinder which leads me to think the valve kissed the piston and fractured it during my little mishap and it came apart later on in the evening when I was beating the snot out of it.

Good new is the car did 648 to the wheels with 7 cylinders :gears: , just my torque was awful since it was misfiring down low. And before anyone asks- no, I did not intentionally dyno it knowing there was a problem, I made my pull and it was breaking up when I first hit it, I assumed my alky was coming on too soon and making it break up a bit since it seemed to clear up with RPM- that wasn't the case, apparently. The plug gap was hammered from the piston chunk. Not bad though, didn't take long at all to get apart- I like working on new cars- they're nice and clean lol..
Joe

 

[Black Devil]

That sucks. How long till it's back together?

 

[kwiktsi]

Depends on how long it takes to get the parts in. I'll call Fred Beans on Monday (stock piston is only $46 )... If I can get the parts here this week, it will hopefully be done that day. I am just a bit nervous since I am unsure if it was damage from the over rev that just let loose like that, or if it is from too much boost, timing, etc. I am running relatively high timing- 25* with 10 psi on the alky with 0 knock and good AFR's, but I am wondering if it isn't knock or a lean condition- just physically too high of a cylinder pressure that caused the failure.

If it was the over rev- I hope there are no other ticking time bombs waiting to go off- the others look good in this bank from the top and I'll pluck the other head to be safe also, but I am really considering pulling them all to be sure there are no other cracks on the ringlands anywhere.

If it wasn't the over rev, it is doomed to happen again at this level. I do not really want to build this motor up, I just want it to hold togeher until I do decide to go nuts with something- at which point, it will be a whole new setup and I'll go turbo, so I am not looking to go that route now. I may have to turn the wick down a bit for safety if it is the cylinder pressures at that advance and boost.
Joe

 

[Jbss71]

umm, have mic'ed out the other pistons/rods 8,300 on a missed shift is pretty on everything

plus being at your hp level i'd be tempted to build or order a short block

 

[kwiktsi]

Yeah, I'll probably pull it apart and check the rest of it out to see if it is still ok. I am tempted to just go with a forged stroker, but the only thing is I am not ready to "build" a motor both financially and mod wise. If I am going to build something, it will be an 8.5-9:1 motor with twin T72's and a bunch of boost and I'll go for big numbers . If I build a low comp. stroker motor now and keep the procharger for a while, it will kill the power of this thing with the P1.

Chances are, it will get a "fix what's broken" repair now and then I'll just order a shortblock over the winter or just run it until I perforate the block .

 

[Black Devil]

I would do a full tear down. thogh, I have never torn apart an LSx engine. Having any damage could just be the biginning of a big problem. You will want to have your rods checked, and your crank miked up. I would go with a set of Mahle pistons, and rings. Do a full rebuild with race bearings. Something that would take the beating you plan on giving this car.

 

[Jbss71]

Chances are, it will get a "fix what's broken" repair now and then I'll just order a shortblock over the winter or just run it until I perforate the block .

think ahead, i'd go get a cheap set of pistons and a rod upgrade. run it till the winter and sell the short block as upgraded rebuild with X amount of miles, that way now you could push alittle harder with your blower and get some of the rebuild price back when you sell it.

 

[kwiktsi]

I would do a full tear down. thogh, I have never torn apart an LSx engine. Having any damage could just be the biginning of a big problem. You will want to have your rods checked, and your crank miked up. I would go with a set of Mahle pistons, and rings. Do a full rebuild with race bearings. Something that would take the beating you plan on giving this car.

The crank is the last of my concerns- there are no issues there, bearings are like new and the crank will handle a lot of stress.

I am going to pop the rest of the pistons out, might as well since I am right there, and check them out. I'm really not too concerned- I don't think there is any further damage, other than perhaps another matching piston or one with a stress crack from a valve contact. None of the valves are bent, so I really don't think it was too hard of a shot.

Thing that makes it tough is I don't know if it was piston to valve contact that caused this or if it was detonation/pressure. We had 0 knock on the logs, but I also just got done taking someone for a ride and doing a "john force style burnout" with the thing bouncing off the limiter (tried to throttle through it, but it is a losing battle with 650 whp on the stock 18's ) right before I pulled it onto the dyno, so I wonder if that may have hammered it with a bit of knock. Once I get it back together, we'll spend more time logging it under all conditions and see what happens. If I knew- ok, the piston smacked the valve, and this caused it- or- ok, we detonated/leaned the crap out of it and it broke- I'd be fine. It's not knowing what exactly caused it that makes me wonder. It is the #5 piston though, so it very well could have just been the "fuse" before something else went. If that's the case, when I get it back together, we could tone the tune down a bit.

Either way, I am not overly concerned- I've done far worse damage to motors in the past :drink: .
Joe

 

[kwiktsi]

think ahead, i'd go get a cheap set of pistons and a rod upgrade. run it till the winter and sell the short block as upgraded rebuild with X amount of miles, that way now you could push alittle harder with your blower and get some of the rebuild price back when you sell it.

I didn't think of that- not a bad idea either. I wasn't planning on selling the stock motor though just in case I ever parted the car out and put it back to stock to sell it. It is something else to consider though. Any info on who has the better prices for some of this stuff? I am not going to spend $2k on rods and pistons for a motor that I don't really want to build though, so if there are options, please let me know. Thanks!
Joe

 

[Nmbr1GMfan]

With that RWHP why don't you just go rods pistons and have the heads checked. If you put it together stock pistons and lunch it again you will have paid for the piston rod combo.

 

[kwiktsi]

I am tempted- but like I said, this isn't the setup I want to build around- 1)- this isn't the car I want to "build" as a serious car, it is more of a cruiser/play toy for me and 2) if I do decide to build it- it will be a low compression turbo motor with boost in the 20's- and I don't have the $$$ to go that route now.

I'm in a tough place with what to do right now, I need to sleep on it a bit lol. The piston is only $40, plus $20 for the rings for one cyl (the car has 8k miles, I don't need to go through the whole thing with rings, bearings, etc.) and gaskets are cheap, I can be done for less than $200 with new push rods. The only thing I will probably upgrade now is rod bolts. I'll probably inspect everything, reassemble with replacing what needs to be and pull back a bit on the tune for safety sake. I'm not too concerned with it happening again, it lasted 3k miles with no issues at all as it was, until the retune and rev limiter "hiccup" yesterday, so whichever of the two caused it will be resolved. I'll be pondering my options over the weekend and pull the other 7 slugs out to see how they look and decide from there.
Joe

 

[Jbss71]

I didn't think of that- not a bad idea either. I wasn't planning on selling the stock motor though just in case I ever parted the car out and put it back to stock to sell it. It is something else to consider though. Any info on who has the better prices for some of this stuff? I am not going to spend $2k on rods and pistons for a motor that I don't really want to build though, so if there are options, please let me know. Thanks!
Joe

a very quick check, rods 600 - 700 pistons 600+ 130 for rings bearing 70


this being the cheap way i'd go if i had more RPM left in the blower, if your blower is maxed i'd be more on the side of changin the one piston...

 

[kwiktsi]

a very quick check, rods 600 - 700 pistons 600+ 130 for rings bearing 70

Cool thanks- who had this?
Joe

 

[Jbss71]

Cool thanks- who had this?
Joe

speed-inc and thunder list it but every shop should beable to get these parts. call jegs and summit tech lines i know they carry lsx engine parts but dont list to many

 

[kwiktsi]

Yeah, I didn't see much on Summits site. I'll call them tomorrow to get an idea. If anything, maybe forged pistons with stock rods and upgraded bolts, but I really like the $40 stock piston idea and run it until winter fix .

Thanks again!
Joe