would i be better to uprate my ej20 with forged pistons etc for more bhp? or stick in a 2.5 sti block? ive heard that the 2.5 is not as quick as the old ej20?

 

Its not that the 2.5 isnt as quick, its lazier rather than revvy.
Personally id stick with a 2ltr, but it depends on what sort of power your after, a 2.5 will mean more torque so thats strain on the gearbox and clutch over the 2ltr, but the 2ltr will be more rev happy, both will have different characteristics when driving though, the 2.5 being more torquey means less gearchanges and better in gear accelleration.

Tony

 

I would personally stick with the 2ltr as well

 

2.33/2.35 ... way to go but not cheap

bob

 

What sort of money are you looking at for the 2.2 block?

 

take a look here some info that might be of use to you towards costing

P1 Web Owners Club :: Warning, may contain nuts! go to projects and '2.33 build and a ppg gear box'

matt

 

how much bhp would a standard 2.5l sti block handle? a new complete block would cost £1500 but to rebuild my ej20 would cost £3000 plus and budget wise i was swaying to the 2.5

 

You would need to uprate everything on the 2.5 also, so the initial 1500 quid works out more than your 2ltr as you would need the pistons/crank etc plus the 2.5 would need liners in as the standard block is not as strong as the 2ltr.
Have a word with an engine builder like API, see what they say, in 99.9% of the cases, advice is free Oh and you still havent said what sort of power your looking at?

Tony

 

For a 400/450 road car, you simply cannot beat the grunt and driveability of a 2.5.

Full stop.

Case closed.

 

likely some where between 380-400 bhp? will the 2.5 sti block not have forged pistons as standard?

 

The standard EJ257 Pistons are a bit crap, Swap them out for some forged ones. Dont have to split the block to do it either, then 400 / 400 all day.

Renno

 

I don't seem to see any mention of what other upgrades you are doing to get to 400bhp. You'll need a bigger turbo like and AndyF 18/20g for that sort of power, then add on a sti tmic, fuel pump, injectors......

Rebuilding an engine wont give you anything like 400bp on it's own. It'll make it stronger and more happier to take higher power but you'll need a few other things too, unless you already have all of this ???

James.

 

yeah i know what other parts will be needed but im just looking for engine advice as i have most of the other parts already

 

I've been running 370bhp on standard newage wrx internals for 12 months now with no worries. Cars done 30k now.

Would definitley move on to a 2.5 block if it went **** up though.

James.

 

Good example of a 2.5 upgrade...

If James' engine went pop (not wishing this on you James ), and he needed a new bottom end, then the cost of putting a brand new 2.5 in, would be identical to putting a new 2.0 in.

The upside would be that with a tweak of the map, he would see a touch more power, but loads more torque, and the result would be a much nicer car to drive, and would be reliable at that level.

If drop-in pistons were installed at the same time, he would then have an engine capable of 400bhp/torque along with a turbo upgrade at a later date, when funds allow..

 

so go for the 2.5 sti block instead of rebulding my 2.0 with fordged pistons and uprated crank, shells etc?

 

That's what I would do as the 2.0 head, cams etc fit the 2.5 block without any need for further mods.

I'm running an AndyF 18g which is capable of 380bhp. A 2.5 block would achieve this easily and I would see torque figures of over 400ftlbs....which is searious torque !! If I upgraded to a 20g then I would have slightly more than 400bhp and probably 450ft lbs of torque.

I would need to consider upgrading my standard wrx gear box though as I doubt it would last long with that sort of power, probably a PPG gear kit. Wouldn't go for an sti 6 speed as the ratios are too short for me.

James.

 

I wouldent have thought your 100% to get 400bhp even on a 2.5 Litre ??

Also I think the bores have to matched to the heads or you have to use a certain head gasket instead ?

 

In my opinion the TD05 18 and 20 going to be working right at the top end of their capabilities on this 2.5 idea above.

The turbo to consider is the MD321H for low 400's and 312T for high 400's Both of which will be well within their range and have some headroom.

I'd be very surprised to see 380 hp on an 18G even on a 2.5.

The 2.5 's that we have built this year using the 321 range have all been fast spooling, very driveable turbos and we have upped our rev limiter setting to 7,600 in most cases, as it seems to still be going on, up there in the 7's.

A year or so ago the 2.5 was decidedly lazy and didn't want to rev well. BUt the 321 range has fixed that and nowadays I have little hesitation in recommending a 2.5 conversion.

David API

 

Ditto what David has said..

I had an 18G on a 2.5, standard internals, and produced 371 bhp/392 lb/ft torque.

I later put an MD321T on it, along with new rods/pistons, and the transformation was awesome. 453bhp/450lb/ft torque.

 

hi david thanks for ur advice, would u recommend i get a 2.5 sti block and use my 2.0 heads? im looking for bout 400bhp how would the internals cope would i need to upgrade? say pistons rods and shell? would the standard crank be ok or something like a crossdrilled one?

 

was this with 2.0l heads?

 

Sorry for the delay just catching up here.

Yep, I'd go with the 2.0 heads - STi cams would be a great help to get a bit more response and mid range torque. Fit standard bore forged pistons [ supplied by APi of course ] use original rings.

We would also usually go with the original crank bearings. The reason being that they are selectively sized by Subaru when they build the engine and with the best will in the world none of us can measure as finely as they do.

Selectively sized bearings are factory fit only at first build and cannot be bought. That is what all those letters stamped on the number one crank web are all about.

Thus whilst we might fit competiton grade tri-metal bearings, the clearance will not be as finely set as Subaru can achieve.

My advice would be to fit steel rods too, as you never know what upgrade you might wish for in the future and doing it now will save another full engine build in the future. The latest style rods in the 2.5 and late 2.0 are very good, but they do bend when worked hard.

Standard crasnk is fine and I am not certain that there is a cross drilled option yet from Subaru.

Call if you want to talk it through, good luck David

 

AndyF has seen 380 on an 18g with the same mods as mine but I accept that it wont put out any more. I wouldn't say it would be working it's **** off though. Putting out 1.5BAR on an 18g is what Andy designed them for.

James.