Bugeye WRX 2.5 conversion ......which heads ?
30 July 2010, 09:48 PM
#32
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http://bbs.22b.com/cgi-bin/ultimateb...=001030#000011
Lots of discussions on 22B about this type of thing (one example above). Mostly from a few years ago so apologies if the SoTA has changed in the mean time.
It was argued that 2.0L heads without relieving the squish leads to HG problems on a 2.5 at or above certain power/torque levels. Either reworking the heads to match the bore or relieving the extra squish at say 10deg into the bowl were mooted as possible answers.
J.
Lots of discussions on 22B about this type of thing (one example above). Mostly from a few years ago so apologies if the SoTA has changed in the mean time.
It was argued that 2.0L heads without relieving the squish leads to HG problems on a 2.5 at or above certain power/torque levels. Either reworking the heads to match the bore or relieving the extra squish at say 10deg into the bowl were mooted as possible answers.
J.
31 July 2010, 12:07 AM
#34
Vindaloo......Just tried to look at 22B and it's not letting me in at the moment LOL
MIke... It looks like ABI took over Beverly Caravans in the 70's ..
http://www.dunedin.com/casestudies/abi_uk_holdings.html
Having said that I've been on a few sites in the last few years and seen a couple of Beverly Caravans knocking about the place
SportyMark.... Blimey it's a small world !! I thought long and hard about working in the USA. North Carolina was brilliant and I spent a while further south in the Outer banks...... went there for holidays later as well
I just couldn't cope with your healthcare system compared to the UK....sorry
Shaun
MIke... It looks like ABI took over Beverly Caravans in the 70's ..
http://www.dunedin.com/casestudies/abi_uk_holdings.html
Having said that I've been on a few sites in the last few years and seen a couple of Beverly Caravans knocking about the place
SportyMark.... Blimey it's a small world !! I thought long and hard about working in the USA. North Carolina was brilliant and I spent a while further south in the Outer banks...... went there for holidays later as well
I just couldn't cope with your healthcare system compared to the UK....sorry
Shaun
31 July 2010, 12:57 AM
#35
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Yeah, I have lived in a couple of states and North carolina has a bunch going for it both work and weatherwise, I could live without the heat (102 degrees last week) but other than that good. healthcare is not bad if you have insurance though an employer.
We do alot of hybrid EJ20 heads on EJ25 blocks, as it is super cheap over here, the STI 2.5 shortblock is only like $1795 US from subaru. Alot of times we will do a drop in replacement piston from wiseco if they want a high quality forging. alot of the issue is the slight raise in compression, and the large squish area (if we do nto do the bore matching). it does make it a tad more detonation prone, but a good tuner and safe boost levels can make a huge difference there, as routinly make over 300hp at the wheels with them, and rarely tune over 19lbs of boost on street cars. But we can and have goine all out on the EJ20 heads and ported the hell out of them and bore matched them these are my wife's heads
All depends on what you are going to do with the car. On the average street car with a good tune and good gas, with the 2 litre heads on a EJ25, you shoudl be good with the right subaru head gasket. if you are going bollocks out and trying for super high boost... port the hell out of them!
We do alot of hybrid EJ20 heads on EJ25 blocks, as it is super cheap over here, the STI 2.5 shortblock is only like $1795 US from subaru. Alot of times we will do a drop in replacement piston from wiseco if they want a high quality forging. alot of the issue is the slight raise in compression, and the large squish area (if we do nto do the bore matching). it does make it a tad more detonation prone, but a good tuner and safe boost levels can make a huge difference there, as routinly make over 300hp at the wheels with them, and rarely tune over 19lbs of boost on street cars. But we can and have goine all out on the EJ20 heads and ported the hell out of them and bore matched them these are my wife's heads
All depends on what you are going to do with the car. On the average street car with a good tune and good gas, with the 2 litre heads on a EJ25, you shoudl be good with the right subaru head gasket. if you are going bollocks out and trying for super high boost... port the hell out of them!
31 July 2010, 01:33 PM
#36
Hmmmm several comments come to mind here.
The original heads will work but are small port with nothing special for cams. They cannot flow enough air in standard form to cope with big turbo.
The better heads - without going down the Avecs route, would be STi 5 or 6, they bolt straight on and work well. I think as a comparison, we gained some 40 hp on a car that originally made 419 on the WRX heads with nothing else changed. You would need STi 5 cam wheels to match the heads as the trigger points on the Avecs pulleys are in the wrong place.
Avecs cams are designed to do their job as Avecs and no matter how you statically time them, the result will be compromised.
Wiring in the Avecs is time consuming and not for the faint hearted.
Fitting Version 4 backwards manifolds and heads to a Vers 5 on type engine is also a fraught-with-pitfalls job, as all of the senders and electronics are wired differently with differing connectors. It can be done - but is best avoided.
David APi
The original heads will work but are small port with nothing special for cams. They cannot flow enough air in standard form to cope with big turbo.
The better heads - without going down the Avecs route, would be STi 5 or 6, they bolt straight on and work well. I think as a comparison, we gained some 40 hp on a car that originally made 419 on the WRX heads with nothing else changed. You would need STi 5 cam wheels to match the heads as the trigger points on the Avecs pulleys are in the wrong place.
Avecs cams are designed to do their job as Avecs and no matter how you statically time them, the result will be compromised.
Wiring in the Avecs is time consuming and not for the faint hearted.
Fitting Version 4 backwards manifolds and heads to a Vers 5 on type engine is also a fraught-with-pitfalls job, as all of the senders and electronics are wired differently with differing connectors. It can be done - but is best avoided.
David APi
a good bit of this thread has been on the issue of taking meat off the 2lt head bowl so the combustion chamber marries better with the larger size of the 2.5 piston chamber. Would you give us your thoughts on this please?
Clearly the Newage WRX heads would become a limiting factor but not for the OP as it appears he would be happy with hp in the lower 400's, as I remember you telling me the WRX heads with a decent MD turbo would be good for 430hp/450lbsft.
regards
Trevor
31 July 2010, 11:54 PM
#37
Hi Trevor
As the OP I've decided to stay with my Bugeye WRX heads
I'm running a Deadbolt monster ported 18G and water / meth injection so I don't think that the increased CR will be a problem
I looked at some STi 5/6 heads but at £450 a pop not a good cost / benefit as my managers would say LOL
Cheers
Shaun
Cheers
As the OP I've decided to stay with my Bugeye WRX heads
I'm running a Deadbolt monster ported 18G and water / meth injection so I don't think that the increased CR will be a problem
I looked at some STi 5/6 heads but at £450 a pop not a good cost / benefit as my managers would say LOL
Cheers
Shaun
Cheers
01 August 2010, 10:28 AM
#42
Hi Trevor
As the OP I've decided to stay with my Bugeye WRX heads
I'm running a Deadbolt monster ported 18G and water / meth injection so I don't think that the increased CR will be a problem
I looked at some STi 5/6 heads but at £450 a pop not a good cost / benefit as my managers would say LOL
Cheers
Shaun
Cheers
As the OP I've decided to stay with my Bugeye WRX heads
I'm running a Deadbolt monster ported 18G and water / meth injection so I don't think that the increased CR will be a problem
I looked at some STi 5/6 heads but at £450 a pop not a good cost / benefit as my managers would say LOL
Cheers
Shaun
Cheers
Trev
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