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Rb25det Neo Valve Spring Limits?

Pr0x1mity

By Pr0x1mity,
in Engines & Forced Induction

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Pr0x1mity Proficient

Pr0x1mity

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Recently we put together a 25/30 with a neo de head inc valve springs (bad idea) and wanted to see what the general limitations of standard turbo ones are. This engine was a budget build (though it was done pretty well) but im still a Uni student and on a budget with higher ambitions.

This is generally just me asking for experience with 25's not 30's. Trying to just use it as a rough outline from unopened DET neo's :)

EDIT: Here's a pic of where it starts valve floating. We backed off the boost and touched up the tune a little bit more and managed to make 280 and 550nm but this photo best represents where it dies off.

YspmeMO.jpg

Big thanks to Rob at Weltmeister Eastside for Dyno tuning (And can definitely recommend him!)

Thanks!

Edited by Pr0x1mity
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GTSBoy Grand Master

GTSBoy

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Is there/was there definitely valve float? The reason I ask is that that graph show no signs of it directly. Just a sudden stop to proceedings. Granted the sudden stop does appear to be early, and at a lowish power level for a 30.

How much boost was that? What revs is the stop at?

Power expectation should probably be a bit lower given the smaller ports (they are smaller, aren't they?) and the valve springs are certainly going to flop about with some boost behind them.

If it is/was valve float, then you know what you have to do.

Pr0x1mity Proficient

Pr0x1mity

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There was another dyno sheet where it looped around with definitely valve float characteristics! Ill try find it.

Running 20psi on a DE head. It's been ported out to DET intake specs and exhaust has been ported out to take full advantage of the manifold.

The turbo still has a bit more boost left in it too!

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