Are UK WRX heads strong enough for STi cams?
27 November 2005, 01:32 PM
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Are UK WRX heads strong enough for STi cams?
Can the UK heads take the higher RPM limit of an STI? i.e instead of a 7k limit, are they strong enough to take an 8k limit?
So could you uprate the cams in a WRX, or would it be better to get a set of heads from an STI and uprate those?
So could you uprate the cams in a WRX, or would it be better to get a set of heads from an STI and uprate those?
27 November 2005, 01:43 PM
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I think they use the same casting .no need to buy new heads have yours reworked and same end result.
Originally Posted by Neilo
Can the UK heads take the higher RPM limit of an STI? i.e instead of a 7k limit, are they strong enough to take an 8k limit?
So could you uprate the cams in a WRX, or would it be better to get a set of heads from an STI and uprate those?
So could you uprate the cams in a WRX, or would it be better to get a set of heads from an STI and uprate those?
27 November 2005, 01:50 PM
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The 03 STI are limited to just over 7k as well.
It's not just the cams which enable the higher rpm limit. It is the complete valvetrain.
Buy complete, much easier.
It's not just the cams which enable the higher rpm limit. It is the complete valvetrain.
Buy complete, much easier.
27 November 2005, 02:05 PM
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no arguements there mate it is much easier and probably a lot cheaper if you put on sti heads, I was just suggesting if you are going to go the whole hog, new cams, valvetrain porting, etc then it doesnt matter what heads that you start with as the casting is the same.
Originally Posted by Kael
The 03 STI are limited to just over 7k as well.
It's not just the cams which enable the higher rpm limit. It is the complete valvetrain.
Buy complete, much easier.
It's not just the cams which enable the higher rpm limit. It is the complete valvetrain.
Buy complete, much easier.
Last edited by Dannno; 27 November 2005 at 02:06 PM. Reason: grammer
27 November 2005, 02:19 PM
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well i was going to be using an STI bottom end so didnt know if id be able to use the STI rev limit with them.....if you see what i mean without further mods to the top of the engine. No matter if i have to stick to 7k
27 November 2005, 02:28 PM
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I have a 2.5 bottom end that i run on standard uk turbo heads with no work done to them at 7200 revs and no problems . but it would make perfect sense to use an sti top end with an sti bottom end. if you can get hold of some cheap enough that is.
Originally Posted by Neilo
well i was going to be using an STI bottom end so didnt know if id be able to use the STI rev limit with them.....if you see what i mean without further mods to the top of the engine. No matter if i have to stick to 7k
27 November 2005, 04:04 PM
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If you have '01 > WRX heads, remember that the '01> STi's have "variable cam timimg".
The earlier STi 5/6 cams fit into the WRX heads, but then you'll have to try, and find some.
It's probably easier to fit a set of new aftermarket cams, than a re-profiled set, because a re-profile reduces the cam's base circle by some 2-3mm, and that means a much bigger, heavier shim, unless you convert the followers, etc', and it all starts to get very expensive.
You should be able to run 7500rpm on UK heads, because that's what the rpm limit was on some of the earlier WRX's ('98 as an example).
Mark.
The earlier STi 5/6 cams fit into the WRX heads, but then you'll have to try, and find some.
It's probably easier to fit a set of new aftermarket cams, than a re-profiled set, because a re-profile reduces the cam's base circle by some 2-3mm, and that means a much bigger, heavier shim, unless you convert the followers, etc', and it all starts to get very expensive.
You should be able to run 7500rpm on UK heads, because that's what the rpm limit was on some of the earlier WRX's ('98 as an example).
Mark.