Stock Valve Train Rev Limit

[BezerkR32]

Have dynod a few RB25s with similar modifications. Standard pring limit seemed to be around 7000rpm running 20psi boost. Tune started to get ugly over & above this. the fittment of Tomei springs solved issue, can know rev the engine to 7800rpm at 25psi. Cars are tuned at UNIGROUP in Sydney. Can contact them for any further advise. 02 9631 2470

Does anyone know for sure or has had experience when valve float has started to occur in the 25's with whatever modifications they have had done?

Im curious to know if it happens often or not at all, i have yet to see anyone complain about 25det and valve float. Ive heard its a problem in neo25's cause their springs are weaker then the previous models, is that true as well if anyone knows?

[R31Nismoid]

seems to be majorly dependant on the state of the head

be it in great condition or a bit tired as to where the limit is, being that i had no one problem with mine.

[bigcarl]

cheers thanks for the replies. to change valve springs over do i need to remove the head??

[rb26s13]

you dont need to remove the head to do so

how ever it is much easier in a way if you do

[BezerkR32]

looking at making some tooling to do this incar a bit easier, ill let you know how we go.

cheers thanks for the replies. to change valve springs over do i need to remove the head??

[bigcarl]

be very interested in this, definately keep me posted cheers

[Guilt-Toy]

I know this thread is years old but Better to bring it back from the dead then to create another thread.

Anyone have any more experience with the stock valve springs on rb25det with bigger cams? I am using the Kelford 264's with 9.5mm lift.

I run RB30DET and keep the revs below 7100rpm and have not had any dramas with 2 bar and over 374kw at wheels but i do realise the bigger cams will be much harsher on the springs and could cause some issues.

Should i just replace the springs at the same time or just give the cams a go with stock springs?

[R31Nismoid]

You could give it a go - but how long it will last is more a guess than anything especially when people other than ourselves had/have issues at a lot less than we have.