hks gt-rs setup need information

[jonask]

Hi,

I wondering how many boost the hks gt-rs can take ?
I have an rb20det, with poncam and stock internals.

plus, I wonder if I should keep the stock manifold (I don't have the stock exhaust anymore).

thank you

[Skym]

More like how much boost engine can take, stay below 20psi with stock pistons, mild turbo upgrade (applies to all stock RB engines). With stock headgasket, keep below 1bar.

Stock intake manifold gasket's can blow with higher boost levels and Cometic make stronger intake gaskets.

Short intake runners = more mid to topend hp, torque. Longer exhaust runners = more mid to topend hp, torque.

If replacing intake manifold, use this intake manifold (that type of design flows near to perfect into each runner) -

http://www.ebay.com/itm/NISSAN-SKYLINE-R32-RB20DET-INTAKE-MANIFOLD-RB20-plenum-/170850298284?pt=Motors_Car_Truck_Parts_Accessories&hash=item27c778a9ac&vxp=mtr

You'll need a longer throttle cable (I think most use S14, S14 / 240sx).

[jonask]

Thank you for the information,

I plan to change the intake / manifold, however I would like to keep the stock one a bit longer and then change it next year.

so in order to exploit the turbo, you tell me to change :

1- intake gasket (http://www.ebay.ca/itm/Cometic-IR658...-/180873017577)
2- head gasket (http://www.ebay.com/itm/COMETIC-GASK...738bfd&vxp=mtr)

should I change the manifold gasket as well ? (http://www.ebay.com/itm/Cometic-Exha...55353d&vxp=mtr)


Is it worth it to change the headgasket for more boost with stock internals ?

some tell that the headgasket can hold about 400-450whp is it true ?

[Skym]

Stock intake gaskets are the weak point and there's 3x of them, throttlebody gasket, gasket inbetween 2x halfs of intake plenum, gasket on head to intake manifold flange (I think is a weaker paper style gasket). Cometic sell a intake kit (gaskets are made partly of metal, so stronger than stock intake gaskets) or can buy them individually. Most use stock exhaust gaskets on exhaust side (not sure if there is a stronger option).

Unless you are going over 500hp or so (as done on 500hp Group-A RB20DET engines), not worth changing out stock intake manifold. But in doing so (with tune) you can gain more mid to topend hp, torque (racetrack use, where at 4000rpm+ most of the time). It's not much of a torque, hp gain, but still a gain in torque, hp.

Group-A RB20DET engine with stock intake manifold produces up to 500hp at engine at around 1.7bar, but compression runs into high 7's to run those higher boost levels with reliability. Into 7's with compression requires forged pistons (with stock conrods that are shot penned, crack tested, new stock conrod bolts or H beam conrods with stronger ARP conrod bolts, ACL bearings, etc), thicker headgasket and slight porting of dome area in head (helps to prevent knock).

Gasket thickness vs compression ratio with stock pistons can be seen here (I would use Tomei 1.2mm, 80.5mm metal headgasket, as gets close to stock compression, thicker if want some reliability, but lose off boost performance) -

http://www.tomei-p.co.jp/_2003web-catalogue/e105_RB20_gasket.html

Stock headgasket on Group-A RB20DET in Australia has been used up to 24psi, 380whp on "dyno" (more hp with refresh, metal headgasket, etc), but when engines is old, not as good as it was (usually when done high km, have lower compression).

If using car with full weight of car on engine (more stress on engine), best to change headgasket to metal headgasket (minimum mod) with stronger head studs. Ideally refresh engine and fit new stronger gaskets, fix short oilpump drive on front of crank, etc (these engines can be up to 23 years old). If engine has done over 100,000km (recommended rebuild km) without a rebuild, it's time to do one (basic refresh or upgrade with forged pistons, ACL bearings, new stock conrod bolts and have stock forged I beam conrods shotpenned, cracked tested, etc, which is good to 550hp at engine on E85 fuel).

[jonask]

thank you very much for that information, very useful and informative !

I checked for the arp headstuds, I think it's a good and inexpensive way to ensure that the engine won't "break" on high pressure.
The cams have to be removed and replaced, so an easy way to make the engine "stronger" would be to change the headstud without removing the headgasket while the cams are removed.

I'll probably change the 3 gaskets of the intake knowing that they are bottle the neck.

what about the permatex gasket maker, are they good ? some say yes (depending on the application)

I found some nice cometic kit : http://www.rawbrokerage.com/cometic-...mm-x-051-rb20/
thinking about buying it ... but more if I rebuild the engine i.e. not this year...