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Rb25 Neo Quench Pad Removal

Guishnu

By Guishnu,
in Engines & Forced Induction

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Guishnu Enthusiast

Guishnu

Posted
Posted

Hi All,

In July 2010 i built an RB30/26 with the quench pads removed from the head mated to Endyn softhead pistons (for a friend) It seems to have ran well so far and the folks mapping it say she's strong etc. As it turns out i have done the head gasket on my 25 neo I’m going to pull the engine and do a rebuild on the bench while it's out. I think i have managed to find a 26 crank, rods and 87mm wiseco pistons for a good price which I’ll throw in for good measure.

By banging a neo head on top of that little lot, the CR backs out at about just under 10.3:1. I was planning on pulling the quench pads out of the head which should let me drop about 9cc's from the combustion chamber and with a 1.2mm gasket leave me with 9.2:1 compression ratio.

I think most are pretty argued out on the whole "remove/don't remove" the quench pads debate. But does anybody have any experience with removing the quench pads on a neo head? If so, how many cc's are gained in the combustion chamber by doing it?

Cheers

Chris

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https://www.sau.com.au/forums/topic/394541-rb25-neo-quench-pad-removal/
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RRob Community Regular

RRob

Posted
Posted

Just been through this exact saga myself.

26 Crank, rods and pistons. CP pistons at 86.5 bore have 15.5~cc dome. My NEO head was 54cc, And I had originally bought a 1.2mm gasket. (nearly 11:1CR from memory)

Long story short I had the head taken out to 57cc and added a 1.8mm gasket which landed me at 9.3:1CR.

Guishnu Enthusiast

Guishnu

Posted
  • Author
Posted

Ahh!

You know what, skyline Australia forum is genuinely the best skyline form in the world. The UK forums are okay, but for technical knowledge this place is the poodles privates.

What did you take out of the head to get your 57cc?

Thanks Again

Chris

r33_racer Grand Master

r33_racer

Posted
Posted

You could look at just deshrouding the valves by scalloping into the quench pads each side rather then removing them completely. Then see what that gets you in chamber volume and use headgasket thickness to achieve the rest.

WIth fuels and tuning as good as they are these days, you can run in the mid to high 9's without any worry. It's only going to help off-boost drivability and reduce lag.

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