hi people iv bought a 2.5 block for my impreza 98 uk turbo. any one fitted one of these there self, or got a guide what i could go by? thanks

 

Re-post in General Technical forum below, and also check out the Projects section.

I don't know the detailed spec of your car but I can tell you that fitting a 2.5 to my MY2000 Classic was not a simple bolt-on job. Nor was it cheap. Every conversion is different, so get expert advice. I use API and Zen, but there are other specialists that may be more local to you. Frankly KJ, if you have to ask, this perhaps isn't a DIY job for you mate.

You have to consider every aspect of the car - obviously the engine from induction, fuel pump, injectors, turbo, headers and exhaust, plus a custom-mapped ECU. 2.5s are also very torquey and can eat gearboxes/clutch. Then don't forget brakes and suspension to match.

Good luck,

Richard.

 

IV A FMIC, WALBRO FUEL PUMP, APEXI INDUCTION AND A 3" DECATTED EXHAUST. THE OTHER MODS I WAS GUNNA GET 4 IT IS A APEXI PFC, 550 INJECTORS, TD05 20G TURBO, GT SPEC HEADERS.

 

Okay, you're obviously going for it but I would still urge expert advice.

For starters, I can tell you that a TD05 20G will rip your gearbox to bits (my 16G has already done so) and the 2-pot brakes I think you've got will not stop a 160mph car safely. You should also be around 400bhp which will need up-rated internals.

 

WOULD IT BE CHEAPER 2 GET UPRATED INTERNALS 4 THE 2.0L BLOCK INSTEAD, AS I HAVENT YET RECIEVED THE 2.5L BLOCK YET

 

Again, I would say post in General Technical but I'd guess an up-rated 2l would be cheaper. However, for a reliable 400bhp I think you'd need a closed-deck block, so it may be six of one and half-dozen of the other. You'll also need the stronger 6-speed box.

It also depends on how you want your power delivered. I wanted a relatively lazy easy driver, hence the 2.5 route. My car is getting going at 2,500rpm and really on it by 3,000, but runs out of puff at 6,500. 2l cars often don't give much below 4,000, then go like the clappers until maybe 8,000 with the right bits. Fun, but hard work on a daily driver.

A mate on here told me the best mod he ever made to his car was to detune it from 450bhp to 350. Much easier to drive and in reality therefore actually faster 90% of the time.

Also, 350bhp is just about achievable using mostly standard parts. Eg, check out Floyd's car in Projects.

Richard.

 

ok thanks 4 the advice richard

 

I was interested in the same sort of question. It seems US market 2.5 STi short blocks can be had for £1300 roughly which is a lot less than it would cost to do a forged build on a 2.0 AFAIK. What sort of power are the US 2.5 blocks good for, assuming all supporting mods are in place - fuelling, intercooling, mapping, inlet/exhaust, turbo, drivetrain etc.

 

hi mate my 97 car iv fitted the 2.5 block all me self and ported the exhaust and inlet took me 1 month to port and pollish awsome job iv done i do all my motocross bikes at british championship level have done the last 11 year so no what im doing took all the valve seat out all together so more vol of gasses flow took loads out were ya spark plug fits its mostly shaped like a slice of bread took that all the way round in a circle shape smaller than the piston to 2mm to lower the piston compression,ya then will need a 6spd box cause im on my 4th gearbox its just far to torquey it at round about 444bhp iv also got the 20g turbo fitted fmic list goes on mate but u must upgrade bigger injectors to 440cc min im going for 565 and im all sorted iv got the 440cc for now but need bigger gud luck mate

but the 2.5 is an awsome block if u drive the car sensible u got to get them gears warmed up first thats half the problem but its mainly down to the pure torque

 

Mmmm next item on the list would be a 6 speed box...

 

These are the same blocks as the UK STi's and are good for up to 400 bhp in std form. If you are buying one though - get some drop in forged pistons and it will then be good for 450

 

Nice, I'll add that little nugget of info into long term memory!