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Shaving The Rb25 Head

aphid

By aphid,
in Engines & Forced Induction

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aphid Proficient

aphid

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Hey guys,

I've got my head off my rb25/30 at the moment (rb30e block with the standard r33 rb25 head) and am curious to know if it is possible to shave enough off the head to get a comp close to 9:1?

I've had pretty decent search around the place for how much people have shaved off there heads but can't actually find a figure, only that it is recommended to get extra compression..

I've tried calculating it out myself with a calculater but I seriously can't get the numbers to match :O

I've also tried two online engine compression calculators and according to them I've currently got a 6.4:1 and a 4. something :1 compression ratio respectivly, using exactly the same data, when I'm thinking I should be after a figure closer to 8.2:1 :rofl:

Any help would be very much appreciated :D

Thanks guys

Marcus

:)

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R338OY Veteran

R338OY

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Posted

8.2:1 sounds pretty convincing for a 25/30. Have you asked anyone in the Hybrid build section? I disagree with the above comment, i reckon it's worth it. The head's off anyway, and if you can bump comp from 8.2 to 9:1 that's more response for the taking :ermm:

Will be interested to hear more opinions on this.

aphid Proficient

aphid

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yeah see that's the thing, i can recall reading in a few places of people shaving the head to increase compression but now that i'm actually interested in it I can't find the posts :happy:

to get an increase from 8.2:1 to 9.0:1 it seems to me that you'd have to take off atleast 3mm, which to me seems an aweful lot :ermm:

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