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2.5 short block question?

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Old Nov 19, 2007 | 09:22 AM
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Default 2.5 short block question?

on a classic scooby, if I just change the block around from my standard wrx engine to the 2.5 adding the standard heads etc. Will it need a remap? what sort of map?
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Old Nov 19, 2007 | 09:37 AM
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yes it will need a full tek 3 remap
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Old Nov 19, 2007 | 09:42 AM
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Apart from a remap I think the best thing you can do is with a bit of wet and dry sandpaper take the sharp edge off the cyl head combustion chamber - the 2.0 bore is significantly smaller than the 2.5 - if you leave the "edge" present it makes the engine more prone to DET / Pre ign as you have this sharp edge glowing, smooth it off to prevent "hot spots" etc - not enough to change volumes etc - if you put a 2.5 head gasket on a 2.0 head you will see what I mean
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Old Nov 19, 2007 | 10:45 AM
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Originally Posted by Tidgy
yes it will need a full tek 3 remap
even though everything else is standard?
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Old Nov 19, 2007 | 10:48 AM
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you gonna need to remap
as each cylinder is a different size !

the amount of air created by the combustion is more - means turbo spools sooner - means peak torque is achieved sooner in rev range - means you need more fuel and probably less spark ! and thats just for starters !
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Old Nov 19, 2007 | 10:50 AM
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what he said lol
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Old Nov 19, 2007 | 11:13 AM
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Dont fire me for saying this, I am no mechanic, so I'm asking. Wouldn't the above be resolved by apexi safc & adjusting fuel pressure?
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Old Nov 19, 2007 | 11:32 AM
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Originally Posted by harry007
Dont fire me for saying this, I am no mechanic, so I'm asking. Wouldn't the above be resolved by apexi safc & adjusting fuel pressure?
Nope, not really. Making it work without blowing up and making it work to its potential are 2 different things. If you want to run anywhere near a respectable amout of boost through it, do it properly, or it's more than likely it WILL blow up....

Depending on year/phase, you'd either need a Power FC or similar (MY93-MY98).... Or a TEK3 remap(MY99-00).


J.
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Old Nov 19, 2007 | 11:42 AM
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harry007Dont fire me for saying this, I am no mechanic, so I'm asking. Wouldn't the above be resolved by apexi safc & adjusting fuel pressure?
only if you enjoying swopping short blocks often
it may work for a while but at probably 75% of its ability
in general a 2.5 runs less timing than a 2.0 and but then again there are loads that bolt it in, cane it all day long without any issues ! run the best fuel possible ! but your experience may be different
do it right and enj0y the meatier torque of the 2.5
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Old Nov 19, 2007 | 05:52 PM
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iirc Bob Rawle is mapping it for you isn't he ?
he'll do a running in map for 1000 - 1500 miles running actuator boost only (approx 0.8 bar) then he'll give it the full beans

this is the way i went when i had my ej257 built at AP Motors

Daz
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