TB42 decompression

[mavtt]

Gday after a bit of help if possible Iam trying to find a thicker than standard head gasket to lower the compression to help pinging issues after I put twin turbos on my Maverick if anybody can help it would be great thanks

[cooki_monsta]

hey mate sorry i cant really help you here, but some one makes a decomp plate for them, or run twin steel head gaskets.

maybe try ontrack they might be able to point you in the right direction.

[mavtt]

hey mate sorry i cant really help you here, but some one makes a decomp plate for them, or run twin steel head gaskets.

maybe try ontrack they might be able to point you in the right direction.

thanks mate I'll look them up

[NutterGQ]

so how much boost are you pushing at factory comp ratio? and how small are these turbos?

[mavtt]

so how much boost are you pushing at factory comp ratio? and how small are these turbos?

at the moment 7 to 8psi, factory boost pressure for the R33GTR turbos that we are using the turbos themselves are T25/28's we are going for more boost, around 12 to 14 but need to sort out the pinging first however we are unsure if the compression ratio is standard the inlet ports are very clean and the motor itself is very healthy so maybe its been apart before

[NutterGQ]

i figured the turbos would be very small, what timing are you running, its not needing a decomp at that boost level.

[PGS 4WD]

Ive run these stock motors sucessfully at 12-14psi with stock compresson, I'd be looking into your advance. On high boost applications I have opened up the combustion chamber in favour of thick or multiple head gaskets.

joel

[drifter** *]

what fuel are you running? those turbo's are probably too small for your application.

[Quadcamshorty]

the motor will only handle single digit timing figures with that smaller exhaust housings i reckon.

What are you using to control the timing?

Are they original gtr turbs, or aftermarket?

Have you had it on a dyno?

Got any pics?

cheers.

[mavtt]

Thanks for your replies we are trying to run it on shell premium 95 0ctane, a Haltek e6k ecu, at the moment any more than 5deg advance timing and it doesnt go much on it, havent had it on a dyno yet but will get there, the turbos are genuine garrett GTR turbos, we are going to clean up the combustion chambers when the head comes off, cc them and see what we are dealing with ridgecrest engineering in VIC can make a 1.6mm or 2mm copper head gasket so we will probably go with one of those unless I can source something a bit thicker its hard to say but all your advice helps I'll post some pics I think theres step by step instructions on here somewhere

[drifter** *]

compression ratio is not your problem. unless the head has been shaved about 10 times.

[Quadcamshorty]

I truely believe the turbo exhaust housings are way too small, especially with 95 octane.
The only fuel that will handle any decent timing with that much restriction would be C16.
Great fuel, But a bit pricey for an offroad machine!

You may be right about the head being modified, but as drifter said, it would need to be heavily altered to produce that much change.

The last thing I want to see you do, is put a wopping great gasket in and still only get 8 degrees of timing, and still no power.

[drifter** *]

E85 is heaps better than C16 and cheap too.

[Quadcamshorty]

I am now out of the tuning game and it wasnt available back then, but my mates in melbourne have been getting real good results with it!

[mavtt]

Thanks for your help seeings its my daily driver as well as the weekend toy I have to try to fix it we werent sure about the exhaust housings being to small probably should've been more scientific about it. I think I can buy E85 locally so I will check that out thanks again