Long story short took my 97 Corvette with 60K on the clock to have a STS twins installed. Shop called said it put down 300hp to the tire, stock LS1 with just a Corsa catback. They said it was the strongest LS1 stock they had seen. Also found it was number 246 off the line as was used as a promotional car at one time,sticker from GM in glove box. They call me back after turbo install and say head gaskets blew. I gave go ahead to fix them as I figured that would be the weak link in the motor. Couple of days later they call and say something else is wrong and that they are yanking the engine. Owner says we will work it out and he will make sure I am more that satisfied, so I am cool as I believe that he will take care of me on it. As of this moment I have NO issue with shop and I want to be clear on that! I stopped down there today and they said two rings on 2 of the pistons blew off and that two connecting rods are bent. The kicker is it wasn't on the dyno when it happened. It was being rough tuned when it happened. Valvetrain shows no signs of damage,they have no clue what happened? Anyhow now the engine is in pieces,block at the machine shop. I would like to make upgrades without getting too wild dollars wise. I figure forged pistion and rods and maybe a Z06 cam if I can find a used one somewhere. Might as well do a clutch upgrade as well. I really want to keep this build under 600hp as I am not a hard core racer and would rather not start breaking parts. Any suggestions? How about donation of a Z06 cam and springs...lol! Anybody use those Spec Clutches on ebay? Should I keep this a stock crank engine or stroker crank,I have heard keeping it short stroke works better with turbos and longevity. Hs anyone heard of Legend brand forged rods? Thanks for any suggestions or ideas!

 

Eeesh man, that's rough, sorry to hear about that, but now is as good as time as any to build that thing up! If you want to stick stock displacement, just a set of forged pistons/rods will do the trick. A good custom turbo cam will do better than a Z06 cam, but even the late Z06 cam does surprisingly well, and still has awesome drivability. Spec 3+ or 4 clutches are good, any of the other ones, I'd never personally use with a turbo setup, even in a vette. Stock crank is awesome, many people have run them past 900hp, and they generally aren't what breaks. Never heard of Legend rods, are they chinese made? Get a good set of H-beams, a set of diamond pistons, and call it a day! I'd get a set of pistons with a dish, or swap to a set of #317 heads with larger chambers to lower that compression to run more boost and timing. You could get that thing on the road and making 600rwhp before you know it!

 

If 2 rods are 'bent' and two rings are gone, the chances that the damage has some damage is also good. The block might be able to be cleaned up and it might not. If the block is junk, you can find a good used LS6 block pretty cheap. As a bear minimum, you will have to replace the rods and pistons. I am going to guess that you will want to keep your current heads( valve covers and coil packs ), so I would suggest a good set of Diamond forged pistons with -12cc dishes. That will drop your static compression level to about 9.3:1 which will allow to run a good amount of boost if you desire. For the rods, a set of forged ones that are 6.125" in length will be good. Make sure to use ARP rod and head bolts.

 

I wrote two responces, and erased them both. If you dont have anything good to say, dont say anything at all right?

Good luck.

 

Any clues as to what would make the conn rods bend like that. I wonder if fuel may have been way to rich and hydrolocked it? Anyway 1320 please chime in with suggestion. I have built a few 400 SBC and a couple of 468 BBC but am new to both the LS and forced induction!

 

Also have a guy ready to donate a 2001 Z06 cam for free would that work better with turbo than stock. I have read that 2002 on up is better but free is free. Like I said we are about $3000 over budget now!

 

I bet $20 that the rods bent from being hydrolocked from the head gasket letting go....

 

The 01 Z06 cam will work better than a stock cam, but not as good as the later Z06 cam. Just pray the block can be cleaned up, and get a good set of H-beams and some diamond pistons (-12cc like mentioned above will work awesome).

 

it would take a top fuel dragster dose of fuel to hydrolock lol it was probally your head gasket that went and let coolant in the chamber.and i agree with everybodys recomendations on a h beam rods and forged dished pistons. best of luck to ya

 

It's the shops fault. Your head gaskets should not blow and you shouldn't blow rings off unless they were running way to much boost.

 

Or entirely too much advance under boost. =)

 

Either motor was ready to blow when they installed the system or something went terribly wrong.

It sounds like they over boosted the motor and the rods and rings could not take the pressure (boost). Sounds like the wastegate was not set-up right. I've heard of boost creep on the single STS wastegate systems, not sure if you're running single or dual wastegates.

At this point I would go with forged rods and pistons. ML head gasket for a good seal and some better valve springs or heads.

BTW, what size spring are you running in the wastegates and are you using a boost controller ?

 

if rods are bent I am sure there is ALOT more wrong inside the engine and it will require some seriously thorough examining and measuring to ensure you don't build up new good parts on damaged goods.

if the rings let go it happened most likely from detonation.. sounds like an overboost.. maybe a reference line to the gate came off or was forgotten to be put on or tightened... it happens. If the shop is taking care of you then that is great says alot for them!!

may as well put some forged goodies in and drop the compression so you can actually get more for your money out of that STS kit!

Good luck with it.

Chris

 

IMO Cut the BS out of the problem. Just get a new short block and dont worry about all the other possiblities of what went wrong and what can go wrong. I think you may only be eating 500-600 and saving bigtime headache....

 

Block is good...Looks like we are going with 347ci.,stock crank, Scat forged rods and Speed-Pro forged pistions. A member at Corvette forum is donating a 01 Z06 cam and matching valvetrain with only 5K miles on them. Figure its apart so Spec 3-4 clutch also. Anyone see 550-600 RWHP being a problem on conservative tune? I would like to avoid meth injection if at all possible as this is more of a weekend toy than anything else. Again we are using a STS twin setup that has a large intercooler, stock exhaust manifolds and no cats! It is going into a 97 Vette Z-51 6 speed ...I believe 3:42 gears. Any guesses on actual RWHP and what it should run in the 1/4?

 

go with a spec 3+ clutch,its a very good clutch for turbo cars

 

If you haven't purchased the pistons yet, Diamond makes a special piston especially made for boosted applications. It is a different material, and has a thick top land so it won't break like your stockers did.
Just a suggestion, best of luck.

 

Don't need a spec 4 then? Should stock flywheel be ok?

 

Stick with the 3+ spec. It is rated for something like 850 ft lbs of torque and is very driveable. Just be sure to break it in correctly before you start making some hard dyno pulls. Break in seems to be the most important thing with the Spec clutches. Put about 500 miles on it first and you should be fine. I've got a 3+ in my '01 and love it!

Good luck with the build.

 

Looks as if all said and done I am looking at STS system installed and now that stock bottom end blew: 346, stock crank,scat forged rods, speed pro forged stock ( flat tops) replacements (I will explain at end),balanced,stock heads w/afr bolts, with (donated) 01 Z06 springs and retainers, 01 Z06 cam (donated),timming chain and gears and oil pump (also donated for 01 Z06 with 8K miles),New Spec 3+ clutch,Stock manifolds ,No cats...$10,300...installed. Going with stock compression to keep more power under the curve. Anyone care to comment on what power one could expect with conservite tune. Had also considered E85 tune but would need bigger injectors! Mind you I didn't have to turn a bolt to get to this point. Does it seems like a fair resolution to the first post as far as how the shop is handeling things? I really don't see where they are making much if anything on labor to do the work. Thanks for your opinions! I figure at 500+RWHP and safe tune I sould be near bullet proof engine wise and traction issues are next thing to address before turning boost up. Remember we are talking about a 99.5% street car.