GH Pigma. VR4 Head + Forged Stroker..

redzone · Post by **redzone** » Wed Sep 30, 2009 9:35 pm

well i'd say water is getting in to no 3 to clean the piston like that, but yeah looks like another problem has caused the top of the piston to come off over the top ring. what were your piston to bore clearances?

maybe the clean intake port suggests a leak there? this is weird.. trying to think how water could get there....

Anchor · Post by **Anchor** » Thu Oct 01, 2009 8:47 am

RiceThief wrote:
Anchor wrote:When it killed the old motor, we tried swapping injectors and the wiring between 2&3 at different times to diagnose the problem. Still stuffed up on the one pot. (This was the motor that had a jet valve head, jet valve leaked oil into mixture, leaned it out, pop hole in valve.)
Let me confirm this, with your new setup you swapped injectors 2 and 3 with each other as well as the associated wiring, i assume your autronic is fueling in batch fire mode? Are you still running the pcv into the inlet?

No, we done this with the old setup to try and figure out why it was leaning out on one pot. We put it down to the cracked head and leaking jet valve on cyl 3.

Ok so new setup, everything was plugged in how it was supposed to be. Like, it ran perfect for 1500km, thats the weird part. About 50 dyno pulls as well..

I'm guessing something to do with the ecu.

Anchor · Post by **Anchor** » Thu Oct 01, 2009 8:48 am

redzone wrote:well i'd say water is getting in to no 3 to clean the piston like that, but yeah looks like another problem has caused the top of the piston to come off over the top ring. what were your piston to bore clearances?

maybe the clean intake port suggests a leak there? this is weird.. trying to think how water could get there....

Piston to bore clearances where done to CP's specifications. The bloke who built it has done many twincam 4g63's and a few single cams and was overly happy with how it went together. He's more upset than me cause its his reputation etc.

www.18u · Post by **www.18u** » Thu Oct 01, 2009 9:50 am

Am i correct in saying the following?
You have not bent any valves?
The head is Rads old one with 50cc chambers but o/s exhaust valves from a 64?
Your final compression ratio was 9.0:1?
Your using 64 crank, stroker pistons (with a 9:1 comp?) and 2.0ltr rods?
You are getting water into #3 cylinder?

I would be having your head pressure tested as a precaution. It could be more a hydraulic issue (ie: water can't be compressed)
If not look at the overall compression ratio, (ie what was your deck height?)

dirtygalant · Post by **dirtygalant** » Thu Oct 01, 2009 9:53 am

+1 to the above, coolant is getting into #3 and can't be compressed, therefore increasing the compression ratio on just that cylinder, and causing detonation to happen.

Anchor · Post by **Anchor** » Thu Oct 01, 2009 10:20 am

Rad got the head checked before i bought it, and i trust him.

I'm leaning more towards the block being cracked, but the blokes who done all the machine work didn't pick it up...

Iunno, i'll pull it apart again and start from square one. New block time i think. Or at least get it crack tested.

Luckily there's an xr6 turbo ute in the driveway that pushes 416rwhp on 13psi so i'm not going without my performance car fix :D

Anchor · Post by **Anchor** » Thu Oct 01, 2009 10:21 am

www.18u wrote:Am i correct in saying the following?
You have not bent any valves?
The head is Rads old one with 50cc chambers but o/s exhaust valves from a 64?
Your final compression ratio was 9.0:1?
Your using 64 crank, stroker pistons (with a 9:1 comp?) and 2.0ltr rods?
You are getting water into #3 cylinder?

I would be having your head pressure tested as a precaution. It could be more a hydraulic issue (ie: water can't be compressed)
If not look at the overall compression ratio, (ie what was your deck height?)

Yes to all of this. Still has full comp in all cylinders. Underside of no.3 is just a bit messy on the head, it'll clean up easily though.

www.18u · Post by **www.18u** » Thu Oct 01, 2009 11:54 am

Anchor,
I would trust Rad also, he is a great guy and i did not mean to question his integrity. I am a engine reconditioner by trade, so it is common practice to check for leaks in both the cylinder head and blocks, when something like this was to occur. Keep us informed as to what the problem ended up being.

P.S.
Your engine shop must be a good place, if they are covering the cost. Most would duck for cover when this happens!

Goodluck Mate,
Go the Sigmas

OLD FART · Post by **OLD FART** » Thu Oct 01, 2009 12:53 pm

Thanks for your vote of confidence I sleep easly at night as I will not under any circumstances sell anything that I would not use in my own car/motor
That head was a new unused factory part that was origionally ported etc by Peter Liddle at Sumner Park some years ago and was fully recoed by Peter including resurfacing AND UNUSED before it was sold to Jeri

Anchor · Post by **Anchor** » Thu Oct 01, 2009 1:01 pm

Yeah when i got the head off rad it was wrapped up and super super shiny. Even inside all the ports and stuff, couldn't get it that clean unless it was serviced 100% before i bought it. :)

I'll let you's know how i go. I'm actually hoping the block is cracked, otherwise we're lost..

Post by **TOMSUN** » Thu Oct 01, 2009 1:46 pm

Has the piston got scratches or lots of tiny dents in it?
Or does it jus look like it in the photo?

Anchor · Post by **Anchor** » Thu Oct 01, 2009 1:53 pm

TOMSUN wrote:Has the piston got scratches or lots of tiny dents in it?
Or does it jus look like it in the photo?

Broken skirt (right of the photo) and heaps of tiny dents and scratches. Underside of the head is the same, heaps of tiny dents and scratches. My guess is from the broken piston skirt.

Probably need a new compressor wheel too or something. Meh.

zippo · Post by **zippo** » Thu Oct 01, 2009 4:29 pm

by any chance are you running water/meth injection????

i have seen this caused due to locating the nozzles to high up the inlet .

Anchor · Post by **Anchor** » Thu Oct 01, 2009 5:04 pm

zippo wrote:by any chance are you running water/meth injection????

i have seen this caused due to locating the nozzles to high up the inlet .

Nope.

sucka · Post by **sucka** » Thu Oct 01, 2009 6:50 pm

zippo wrote:by any chance are you running water/meth injection????

i have seen this caused due to locating the nozzles to high up the inlet .

Sorry bit offtopic, but what exactly do you mean by "to(sic) high up the inlet" ?

Austarion

GH Pigma. VR4 Head + Forged Stroker..

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