Late 5S block is the one to go for if you want to give it some serious stick, the whole block is far meatier when put side by side with any 3S block, and the increase in bore size is nice as well- even if you use a 3S crank and keep it at
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~2l.
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There are supposed to be later 3S blocks, rev5 and possibly some rev4, that have more material around the bores.
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.
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.I've not seen one in the flesh, so can't comment.
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The early rev3 blocks are probably the worst, having dissected a couple of them- the cylinder wall thicknesses vary all over the place, and potentially get a bit too thin in places- which increases the potential for cylinder wall cracking when you get localised super heating of the coolant
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(through over retarded timing, too much boost, hot intake temps, etc).
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The rev 1/2 block cylinder walls are more consistent, and thicker than the rev3/4/5 blocks I've seen, but there seems to be an inherent weakness around the water pump area- and this can lead to cracking on the outside of the block.
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My pet theory is this is exacerbated by deleting the aircon, and not using the bolt hole through the outside edge of the water pump that would have supported the pump bracket anymore.
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So.
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.
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.all blocks have their own potential areas that can go wrong, it's just a case of how much abuse you give them, and what lets go first.
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The best bet is to concentrate on rock solid cooling and fueling
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(oil, coolant and charge temps), and a safe tune.
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.
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.don't go crazy with timing retardation as this will stress the block as peak combustion temperatures occur further and further down the cylinders instead of in the head
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(which causes localised pockets of steam in the coolant system on the outside of the bores, and potential cracking).
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As for cylinder heads.
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.
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.supposedly rev 1/2 heads actually flow more gas in their stock form than the rev3/4/5 heads.
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.
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.but the rev3+ MAP sensor system is superior.
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The ultimate would be the 3S beams heads, where the port angle into the intake valves is superior.
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That said, the rev3+ is a good head for most power levels in these cars, and can be improved with proper porting and larger valves.
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.
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.just make sure this is done by someone who has actually bench tested these heads, they are easy to f**k up if just done
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"by eye".
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The main area of improvement to look for is on the exhaust side, and trying to get gas out of the head.
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All in my opinion of course
![blackeye :eye:](./images/smilies/icon_blackeye.gif)