r32-joel

Hey ppls,

I've just had a motor built up for my R32 GTST.

I've used the R32 RB25DE NA head and a RB30E bottom end.

I've had a few people tell me that they have had issues with running over 1bar of boost.

Apparently they are experience a type of valve bounce or flutter that causes the lifters to pump up and cause the car to miss until the lifters bleed back down again.. The higher the boost the earlier the rpm the valve bounce/flutter occurs.

I've also been told this is a problem with the CA18DET's when you a high boost.

Is this true with regards to the CA18DET as they have the same setup as the RB heads.

Thanx ppls.

93blackSER

it's not so much to do with boost as it is RPM. at high RPM the valves start to float, as it's called. i dont know about the RB, but the CA doesnt get valve float until around 8700rpm.

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1989 S13 240sx

Nizmodore

I've never heard of this happening with RB30/25 hybrid motors, then again, 99% of the hybrid motors use the R33 2.5 litre head, rather than the R32 one....anyway most people with engines like this have hugely laggy turbochargers etc.......yes I have been playing around with roots style superchargers on Single Cam RB engines (That come on boost at 900ish RPM....oh playing with RB30E's) And havent had these problems!

No I havent had any problems with CA18DE heads doing this, but also I've never run more than 12psi through one.....

I'd imagine new/stronger valve spings would cure this problem....I hope your engine builder did this when the engine was built.....

Sorry I can't help!

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Holden VL Commodore Calais......a domestic Aussie car thats RB Nissan powered (From the factory) and hated by Australian domestic people and Japanese import people alike, due to its mixed heritage.....*sigh* I can't win can I?