7 replies to this topic

[mattman]

ive got a proton gti as you know 4g93 im in the middle of boosting the car with stock 4g93t parts. i have a rebuilt 4g93t head and mettle decomp gasket which is 2mm now what im asking is a 2mm decomp gasket to big? if so what size should i be using where do i get one from and do i need to use arp head studs

thanks matt :-)

[Evo-00x]

Check out rpw.com.au in West Australia. They might have some decomp hg's for 4G93's?

[3zercrowd]

Check out rpw.com.au in West Australia. They might have some decomp hg's for 4G93's?

^^^Sure do^^^

[mattman]

but what size decomp gasket do i need ? and is the 2mm decomp gasket i have too big ?

[CYBORG-X]

i wouldnt use a decomp plate, no need, as it will run better with the compression it has, also if you use the N/A cams with adj gears that will be better.
if you must run decomp, 2mm will be fine as factory is 1.2mm crushed

[mattman]

i heard 2 mm decomp gasket is too big and will throw the timing out ? and with a decomp gasket do i need to use head studs? people say that 10psi is max you can run on standed 4g93 na with standed head gasket? thanks so far for the replys

[CYBORG-X]

a new, good set of head bolts is required, like ajusa, they are capable of handling the power.
a 4g93p headgasket and gsr head gaskets are the same, its the rods that fail first from boost pressure.
10psi is the safe limit for standard 4g93p compression.

either way you should have adjustable cam gears, and dial them in... esp if your going to the effort of fitting a gsr head...

[leadfoot]

it's not so much the boost pressure it's the torque!