Head gasket and cams

[SLY33]

Im just after peoples experiences after changing head gasket to drop comp ratio so more boost can be run safely.

I will be looking at a drop down from 9:1 to 8.6:1 on my rb25, worried about it becoming sluggish off boost, im really happy with how responsive it is now. Can anyone whos dropped to 8.6 tell me how noticeable it is?

Also after some results of cam changes, did a search but couldnt find anything. Sydneykid has posted some about the poncams, but id like to hear from someone whos done the HKS256in 8.8mm lift/264ex 9.0mm lift, and the resultant gains there.

thanks

[Sydneykid]

How much boost do you want to run? What is the power target?

[SLY33]

hi SK, well i was told "with cams and more boost you'll see 300rwkw"

so i dont know exactly how much boost, but was thinking around 1.5bar. This is with a 2835proS thats currently making ~265rwkw on i believe 1.1bar with stock cams and compression.

So basically id love to see the 300rwkw mark if possible!

[SLY33]

anyone else?

[Bl4cK32]

Steve ran the same setup you're looking at running and it worked well for him didnt it? 321 rwkw with the 3037s??

I think Joel and myself ended up with 8.2 "ish" compression and it aint that doughy off boost....besides the extra cc's of course

[SLY33]

yeah i wouldnt think off boost driveability would be affected nearly as much with a 3litre, let alone in an even lighter 32!

[cameron]

If you go for a ride in a skyline with all the usual modification's - R33 GTS-T

Stock turbo, Dumpipe, exhaust, cooler, 12 psi etc etc... and one has lower comp with 1.2mm HeadGasket other has stock, i've noticed that the one with the lower compression takes about 300rpm longer before the turbo starts spooling and comes on full boost.

Eg:

Stock comp ratio might start at 2200rpm and on full boost by 35000rpm

Lower comp engine starts spooling at 2500rpm hits full at 3800rpm

Its nothing too noticable but drivability is fine

I hope that give's you some sort of idea !

Jun