Valve Spring Upgrade

[Alf]

I have a R33 RB25DET VVT head on a rb30 with a GT35R.

At the moment it has stock cams and valve springs running @ 12 psi.

At what point will the standard valve springs need to be upgraded? I intend to go +20psi

What springs would you guys recommend?

Edited April 7, 2010 by Alf

[Sheriff Wan]

It really depends on the rest of the motor...

If you just have a standard RB30 bottom end - then uprated springs wouldn't do much good.

If you had a fully balanced bottom end and a wanted to spin the thing to 8,000 then springs are a must.

[Alf]

It has a forged bottom end with all rotating parts balanced, Rpm is limited to 7500.

[R31Nismoid]

I made 370rwkw @ 24psi (GT30), 8000rpm (RB25/sunoco104)

I know Guilt-Toy has also made 350rwkw/GT35 RB25/30 @ around 20psi...

Both were stock heads.

However that being said, there have been people who have had valve float below 300rwkw and 16-18psi.

So it largely comes down to the condition of the head before you begin proceedings.

I would say give it a shot, see what happens.

If you need them you do, if you don't - you don't

[Alf]

Thanks for the fast replies.

What seat pressure does an Rb25 valve suppose to make? I'll check mine first.

Edited April 7, 2010 by Alf

[MercuryMotorsport]

We have a standard neo head (just head studs and nitto head gasket) on a standard bottom end making 587hp on 25-26psi and the valve train is fine. As it has been said before, just crank the boost and power into it until there is a problem. If you do have the head apart for cams etc, then obviously maximise the opportunity and put some springs in there too.

[MBS206]

Mine valve floats at 14PSi from 6600RPM onwards using a modified TD07S...

[Guilt-Toy]

actually i was up at around 374rwkw with stock head and stock cams. i ran up to 2 bar around 31psi on power cruise weekend and normally use 20psi low boost and 26psi high boost

i have some kelford 272 cams to install but i was told i NEED the valve springs to be able to use them.

so if you have stock cams you should not need valve springs unless yours are lazy etc etc.. also my head has done over 300,000km.s... 330k actually

i never rev the engine past 7200rpm at the drag strip and 7000rpm limit on the street.

[R31Nismoid]

meh, i was near enough lol