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Piston Selection (need Compression Help)

Careless

By Careless,
in Engines & Forced Induction

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Careless Contributor

Careless

Posted
Posted

Hi everyone.

I have a fellow board member who wants to sell me some custom wiseco forgies, with wrist pins and rings and locks.

87mm

1.260 compression height

.165 dome rise

16cc dome volume

what i've been told is that I can get 11:1 compression by decking the block to get the piston out of the bore by 0.01 inches, get a 1.2 mm (0.47) headgasket, and shave the head to achieve 60cc's or whatever is required to get 11:1. they are for RB25/30 combo, but I'm using an RB26 head.

is this a good idea. by that, i mean, is using the headgasket area an ideal way of building up the quench, or should it ideally be built up using the block and piston at 0 over or under the deck?

does anyone know if the valve clearances will be an issue with 8.7mm cams? Also, what if i want to go higher at one point? will i be able to, if increase the lift (after making the head compatible with the longer/higher cams), and still not hit the pistons?

they are originally to obtain a 9.3:1 CR, so I think they will be pretty close to what I need. But then again, wiseco measured up their RB26 head at 66cc. So It's possible that by putting this into a head with lets say.... 64cc, i'd have closer to 9.8 or something to start with.

I've posted a picture.

The reason I ask is that I'm getting this set (brand new) for half the price of a custom set from a distributor, and it's also free shipping too.

my machinist wants to know if they will be compatible with this setup before i buy it, but I think it is, and i have a feeling he's gonna say no.

(im also posting this in both the n/a and engine forums, because there is no "general engine" forum ,and i'd like both turbo and n/a enthusiasts to be able to view this and help me out. Thanks :P )

post-29116-1184375789_thumb.jpg

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