turbo/engine Q

[shmoov69]

Ok I got a Q for those smarter than I on this stuff....and that ain't saying much!
I took the car to the strip last night and ran 1/8 mile in a true street class (ran 7.44@100 BTW spinning) and I hurt the motor. I think I popped a piston cause one hole don't have compression. I don't have the head off tho yet.
Anyway, I have my old n/a engine sitting in the floor from 9 years ago going to waste and was thinking about sticking it in the place of this one. The info on it is mini dome slugs, vortec heads, 11:1 I think and a 507/235@50 cam with 108 LSA and 104 centerline.
I know most will say it's a horrible idea and I prolly would too, but it is sitting there rotting..... Everyone said this wouldn't work 10 years ago too!

Gimmie some info and ideas

[MonzaRacer]

Freshen it up with new seals/gaskets, maybe some good moly rings and open the gaps, relube lifters with breaking lube, big cam should dump enough cylinder pressure, if not keeps car rolling till get engine fixed!

Oh and triple check fueling as it may have leaned out enough to burn hole in piston and keep timing conservative till you get it scienced out as that can hurt'em too.

[shmoov69]

I am just concerned about the CR. Has anyone here or that y'all know ran high CR with boost on the street?

[WS6]

How much boost are you running Jimmy? LSx engines get boosted in stock form all the time. The boost is minimal though 5-7 PSI.

[DeltaT]

Is this a carb setup? If so, I wouldn't do it. The CR is too high for a non-electronically-controlled engine. Take the time to change your pistons and you will appreciate it later. Right now your max boost will be so low as to not be satisfying, IMO. No turbo rush at all...

Jim

[shmoov69]

That is what I was thinking, but didn't know if things had changed in the last few years since I built it. It is carb'd and on the street I have it about 10psi and bump it up on good gas. I do however have a new programmable MSD 6AL 2 box that is awesome! Has theories changed on thumpy Cam's and turbos changed?

[turbo69bird]

I am new here but I moderate the forced induction board at Pontiac zone.com
Your compression is way too high for boost.

A little trick I have seen done is to pop the heads off. Us a carbide cutter and cut the domes off the piston with the negine together. Keep a shop vac there and make sure you suck up all the shavings as they come off. Obviously cover the engine with plastic of something other then the hole you working on.

As long as they arent hollow domes you should be oK.
Then get a set of thicker cometics and go racing.

Either that or change the pistons.

If you burned a piston then you detonated the engine. Did you have an AFR gauge in the car?

If not I would highly suggest one.

Boost in itslef doesnt really urt engines its the detonation that hurts them. If you keep your tune safe the engimne should last.

MY car runs 9.70 at 145 with a T88 on traditional 2 bolt main pontiac with a performer intake and holley 850 I do burn pistons from time to time but The engine is usually very relaible if I am not uching to the next level and detonate it.

Hope that helps.

[shmoov69]

Well, it turned out that the head gasket was fine, the piston was fine, the cyl wall was fine AND the rings were fine. What wasn't was 4 lifters. 1 had come completely apart, 1 was half apart and 2 others had the retaining rings out or broken. Kind of strange to say the least! They were Comp pro magnums (similar to a Rhodes). My machinist told me that he had some like that come apart after being readjusted after being run at one setting for a long time. Sooooo, I am going to call my buddy at Comp tomorrow.

[turbo69bird]

That sucks but at least you didnt wreck the whole engine.

My brother had some comp roller lifters in his boat bothe negines had the tie bars let go within a week of eachother, that same week Liefert racing engines had a few GT1 race engines lose tie bars too.
Ended up eing a bad run on roller lifters. for a while you couldnt even get a set. this wa probably 5 or 6 years ago.


Maybe they have had other bad batches like yours.

[shmoov69]

well, I called my buddy there at comp And he looked up when I got them and it was in April of 04! He ended up talking me out of just putting lifters in it for fear of eating the cam. Well now I got a solid roller being made! Dooohh!!! LOL. So I guess it will be a few more weeks before it gets back together!

[turbo69bird]

I suggest cam motion for turbo cams.
Comp SUCKS IMHO