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**Raven855** · 03-13-2008, 04:44 PM

Do you have any pics of the pistons?* How was the coloration of the tops? What was the static comp ratio? How much boost were you running? We have a set of those pistons in a car and was just curious as to what to expect.

**Horsewidower** · 03-13-2008, 07:25 PM

I'll post pics. Nice burn pattern across the top. 9:1 CR. No evidence of detonation. Peak boost pressure was 16. We started to think the rings had been short gapped, but it looks like they were set at .20 and there were no shiny ends, so probably not a ring butting problem.

We were reflecting on the fact that the "safe tune" had only 19 degrees of advance and wondering if this had created a "retard" timing situation that might heat up the pistons causing them to deform the way they did. But the fact remains that the piston is very thin at that intake valve relief and that's where the problem occured.

We have a lot of reversion. Not sure we can cure that given the turbo caused back pressure, and the desire to reduce lag by using a t3 turbine. Its going to take some more thinking.

So far we have picked up:

750cc injectors
Mounted the BOV to the throttle body
Picked up an intercooler
Welded a new oil filler cap assembly to the valve cover in order to stop that leaking
Ordered a Bob's 120* rotated upper
Sent the block, crank, rods and head to the machinist for a once over check.

We'll see if we can this thing buttoned back up by next weekend.

Bob

**Henson** · 03-13-2008, 07:31 PM

Originally posted by MikeFleming

Henson never really said that - he just saw it written somewhere and snatched it up as his tagline cause it rhymes with his middle name.

“Everybody wants to be like Henson.”

Oh, I did say that one either. Mmm let me think, who did? Is that a correct quote?

Hey Great Minds Think a Like. There are a few here I can relate too. Scarry.

**Horsewidower** · 03-13-2008, 07:38 PM

I need to amend an earlier statement about the rod length. They are 5.2s not 5.7s.

**Pat_in_L.A.** · 03-14-2008, 04:00 AM

Originally posted by Horsewidower View Post

They are 5.2s not 5.7s.

Oh? I thought you had the chevy length rods. Now I'm very curious to see the piston pics. I had better go back and read how thin the domes were.

**Horsewidower** · 03-14-2008, 10:33 PM

When I get the pistons back I'll post some detailed pictures.

I was talking to my turbo guy about the problem, he use to build engines for Comptech and Hendrick. He described the problem before I even finished. His contention is that the valve relief was cut too deep. With the 9:1 and 16 psi, the ring actually pushes up against the ring land and blows through the crown. That's exactly what happened. On the piston that had not broke, the top of the piston was pushed up. On another one the piston rind was actually though the break and bent up. Hmmm.

Anyhow, got a bunch of the parts. We should have some fabrication and assembly pics to add over the next week.

Bob

**Horsewidower** · 03-16-2008, 12:44 AM

In block blown piston photos:

Attached Files

**Horsewidower** · 03-16-2008, 12:54 AM

New Parts:

New IC and BOV mounted to the throttle body
Fixed the oil leaking from the filler cap, once and for all!!
Testing the IC for leaks. Passed no problem
Mounting mock up.

Bob

Attached Files

**8T6 SVO** · 03-16-2008, 12:44 PM

Originally posted by Horsewidower View Post

In block blown piston photos:

When I saw the car at Shad's - It sure sounded nice, but the computer problems didn't helped the pistons IMO. As long as you've got them sorted out now, you should be alright - the learning curve of a new system is a b*tch forsure.

Oh - does your system have a knock sensor?

**Horsewidower** · 03-24-2008, 02:11 PM

No knock sensor. We are rewiring it again and will be teaching ourselves how to tune. Not gonna put in an engine that is too expensive for that process!! We'll see how it goes..

**Horsewidower** · 03-28-2008, 10:48 PM

Looks like we are going to throw in the old tc mule motor and one of the extra t3s either this weekend or next. Scott should have the wiring back together by then. We all, finally, agreed that it wasn't prudent to put the newly rebuilt t3/t4 on with a new engine and then learn how to tune on it. The good head is going back to Bo for a once over and a cam change.

Got a couple of pieces back from the machinist. The standard bore block was boiled, so I'll start prepping it. The crank was fillet radiused and ground a 10th. Looks really good. We clearly are not going to make April, but hopefully we'll be close by May.

Bob