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Old 20-05-2010, 06:14 PM   #1
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compression

what compression would i get from fitting 200hp xr2 heads on a 2.5 200?
is it worth it or shall i just skim the heads?
cheers
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Old 20-05-2010, 07:28 PM   #2
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Think you end up with 170psi compression or something, bit too much if you want it to be relliable
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Old 20-05-2010, 09:22 PM   #3
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bit too much!!!!!!!!!!! alot too much!!!!!!!!! 145psi max on petrol station unleaded
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Old 20-05-2010, 11:03 PM   #4
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are the relative chamber sizes know?

I.e its all very well saying "have the heads skimmed", but by how much?
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Old 21-05-2010, 12:30 AM   #5
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Cutting hundreds of set of heads a year I find that 34 CC's with a 1 MM head gasket at seal level will yield 138-145 psi cranking compression IF motor is healthy, the highest I suggest on pump gas premium..

High performance heads that stock come in at 38 CC's ( 260 HP ) I find can be cut successfully by this formula :

For each .010" of metal removed you reduce the CC's by .7

Example if you cut .030" off you have reduced the CC by 2.1

Hope that helps...

Jay @ JSRE
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Old 21-05-2010, 12:36 AM   #6
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so a safe/sensible route for Sean to take with his newly aquired 2.5 200 powerhead would be to buy some std 260 heads ............ or do you think that will not make sufficient difference?

I have no idea what his exisiting heads should be in cc
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Old 21-05-2010, 07:25 AM   #7
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I have some std 260 heads.. One plug needs helicoiling though
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Old 21-05-2010, 07:29 AM   #8
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Cheers, i didnt think the xr2 heads would be to good an idea, heads are coming off anyway to replace headgaskets so il get the heads cut by 40- 50 thou, dont want to go too far,
chhers
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