Neo Head Mods, Rev Range ?

[Wyn]

Out of interest what are you guys with modded R34 Neo heads getting them to rev to ?

Only ask as read a few posts about them flipping shims out at high rpm ?

What the cause is I don't know but anyone had any experience of this or know why they do this?

Just poor clearance or that's what they do ?

btw do they just run flat if this happens or damage the head/engine ta boot

Alternatively if it is a problem can they be converted to shim under bucket - GTR style n parts ?

Cheers

[GTSBoy]

I don't think I've read any posts where anyone has actually lost a shim, just the usual fearful talk of doing so.

Notwithstanding that, it is a risk with that sort of setup. The usual reason for it is valve float. Therefore the correct fix is to use appropriate valve springs for the cams and revs being used.

[WMDC35]

Have seen one flick a shim out, suspect valve float as above, head was damaged.

[iruvyouskyrine]

SimonS14 had a first hand account of someone spitting a shim. It would do about as much damage as leaving a 20c piece under your cam covers would as that's pretty much what is happening.

[R31Nismoid]

I don't think I've read any posts where anyone has actually lost a shim, just the usual fearful talk of doing so.

Notwithstanding that, it is a risk with that sort of setup. The usual reason for it is valve float. Therefore the correct fix is to use appropriate valve springs for the cams and revs being used.

Same boat, can't say I've read either.

I guess the question is - What RPM are you after OP? Whats the turbo setup etc?

[Dose Pipe Sutututu]

no point revving a motor off it's tits when the turbo stops making power, so more info would be good

[Wyn]

Cheers for the info

It was actually a few posts I read on here a while back that got me thinking but they didn't go into detail as to why

As for the head I am looking at valve springs atm just to see who offers what.

Yes I will be using uprated springs (and cams) so if that's the issue then the problem shouldn't occur

Red line would be set to 8.5k with a GT35 until I decide on a more suitable turbo

[Huzqld]

Yeah I was also worried about the same thing. But couldnt find any hard evidence. Just that it can happen with valve float as others have said.

My motor isn't that old but I'm running performance valve springs and 270 9.2mm cams 7k rev limit