Hi guys,

I'd like to do a 2.5l turbo conversion to my Impreza (2l turbo) and I have a few questions.

Can I simply put in a 2.5l RS crank with forged rods and pistons to do that?

Are the pistons the same diameter in both models?

I'll obviously need a bigger head gasket and bolts, etc.

Would it be diffcult for the guy who'll be honing my bloc to close it?

I think someone on here was doing this type of thing? Any threads?

Thanks for your thoughts and URLs

 

I would highly recommend PerFOURmance Motorsport in Australia, www.pms.net.au

You can purchase a short block from them already kitted out.

You will need to upgrade everything else accordingly Fuel Pump, Injectors, engine mounts, etc..

 

Hi Chris,

thanks for the link. Just looked. They do the type of thing I'd like to do. The thing is, I can get a big stock of parts for relatively little money (blocs, a head, driveshafts, transmission shafts, interiour, dampers, etc etc.) so I thought I'd make the engine myself, or say with the help of people here, just get a set of rods and pistons and a US RS model crankshaft. Would you say that's feasible or am I dreaming here?

 

In addition to having to buy and assemble it, the bloc will need honing, which is no problem, but how much do you think I'm looking at to get it closed?

Would it be better to just buy a closed deck bloc from an STI 5 or so or the whole damn engine from Australia or to get it all done here? What do you guys reckon?

 

It sounds like you think the regular impreza block can be used for a 2.5. It cannot, the 2.5 is a completely different block.
EJ25 = 79mm bore x 99.5mm
EJ20 = 75mm bore x 92.0mm

In the UK, and id guess europe too, the only place you will find a 2.5 block, is in a legacy, non turbo. It is also found in some imprezas in the US, again non turbo.

 

Thanks for that. Yeah, I thought it might be feasible, with honing. Looks like it isnt.

Anybody know how much these OZ guys sell those engines for? Are there better alternatives?

Oh, and does the EJ25 fit straight into a classic shape Impreza (MY 97)?

 

Yup. Blocks are the same dimensions externally. Just transfer over your 2 litre bits. Heads, inlet manifold etc, though as Christian said, you'll need to upgrade certain components.

Alan

 

Email and ask Robin @ PerFOURmance Motorsport

http://www.pms.net.au/contact.htm

 

Claudius,

I might be able to help you

Whats your e-mail?

 

Claudius, I wanted a 2.5 litre for 450 BHP and 400 lbft as this was the safe limit for available streetable gearboxes and clutches.

However, the 2.5 does not come as a closed deck block from factory. There are 2.2 and 2.0 closed deck blocks with the latter far more available.

If you fit a 2.5 Phase I crank to a 2.0 Phase I CDB without boring and relinering you would only get 2.12 litres.

Pavlo was working on closing the deck on a 2.5, then it just needs rods and pistons.

In the end I am having built:

Phase I CDB 2.0 linered to 2.2
Phase I 2.5 crank, brings it to 2.35 litres.

So I end up with a toughie that will take boost.

Going for some Phase II STi heads with some flow work on them.

Have a search back this year - I and others have posted a load of US suppliers - there are a few options.

Note the Phase I 2.5 crank has 48mm big end size, unlike the 52mm of the Phase II 2.5 and all the 2.0s.

A lot of the US rods seem to be for Phase II 2.5 which is a pain since the 2.5 cranks and block available easily here seem to be Phase I.

2.5 with closed deck block would be better than mine ultimately - with no longer stroke, but price and availability put me off, as well as the needs of my project.

I was wondering about leaving the 2.5 open deck and running lower boost since my power aims are quite conservative for the sake of the transmission, but I thought it was best to spend more and have a tougher engine in case I go mad at some point and want 550 BHP

 

I did as soon as I looked at their website! No reply yet, but hey, I guess it's Sunday even in OZ!

 

Sorry I deactivated it in my profile. It's cbkramer@hotmail.com.

 

Good point there! Are you sure that box can take that much? Evo boxes are supposed to be quite strong (stronger than the scooby box and with quite big gears). Clutch is no problem I guess since they are available up to ridiculously high torque capacities with 2 or 3 plates...

Ok; what do you mean by phase 1 and 2? How is the closing of the 2.5l going on? Ideally, that's what I'd like. Maybe with bigger pistons to make it 2.55 or 2.6? Would that be possible?

Couldnt you just get a closed deck 2.5l honed etc with pistons and rods from a US engine builder, ready to get a nice ported and flowed head on it?

What is the price to get a closed 2.5l bloc from a US pro?

Do you think a 6 speed gearbox with heat treated gears could take around 500/500? I could do with a dog box in the Evo, with a roll cage, no isolation etc, but I want to keep this one nice and discreet. A "sleeper" look I believe they say LOL (already took the rear spoiler off!) Is it more the torque opr the power that break gears? I guess the torque?


You just did my head in with all the phases and heads and STI etc.

[Edited by Claudius - 4/28/2003 12:16:12 AM]

 

Lateral Performance supply a gearset, that I use in my car. It is just like driving a normal everyday car - but can handle the power

 

I heard of lateral performance. I think it was David telling me about them about a month ago, but the website wasnt ready then...
How much money does that gearset cost?

 

I went for 2.5 phase one ODB - mine's also a 'sleeper' (Swiss based - it has to be ) and will be running a tmic

I reckon it'll be fine for the the 400 hp & lb/ft mark...but only time will tell. Certainly, John's approach is the desireable one...but someone offered me an ej25 free of charge, which kind of settled it

John - where you at with yours? Mine's gone off to get the rebore to fit the 100mm pistons. All parts now waiting

Richard

 

Hold on!! 100mm pistons! Now we're talkin! Tell me about your engine! Did you get the bloc closed or not?

 

The Lateral/PAR gearset is guaranteed for 450 BHP and 400 lbft.

My gearbox is awaiting, engine coming along nicely.

Phase I changed to Phase II in late 1998.

 

Gearkit is in the scooby shop, and it isnt guaranteed if you build it in your back garden apparently..

David

 

Oh yeah? I'll remove the std bonnet and put a fiber thing without the scoop, only two little heat extractors. That will make it look like a 1.6 litre

 

Thanks David, £2000 is ok if it holds up. Any experiences with it already?

 

Do lateral performance also supply complete EJ25 blocs, closed with forged internals? They seem to have quite a few parts. Anybody know if their website is up already?

 

No the website hasnt / hadnt changed..

Mark can supply pre built engines from 2.0 - 2.5+

Best bet is to give him a call or drop him an email.. dont think he is about today though..

mark@lateralperformance.co.uk

David

 

OK, I'll do that. thanks for the email address.

Just got a response from Robin at perFOURmance:

Thanks for the enquiry.
I have attached some prices for you.
You can fit the US 2.5 litre crank into your 1997 EJ20 block but there are two types of EJ25 cranks. and you will need to modify the pistons and/or rods also.
Is your model car the GT turbo??
I can supply 2nd hand heads for $1400 (or you can send me yours to modify)
port and polish $900
billet cams and heavy duty valve springs $1725

EJ25 assembled short block fully modified $8950
EJ22 assembled short block closed deck $7100
The above two assembled short blocks come with the crankcase as part of the package (no core exchange)
The above costs are for heads and short block. IF you need me to supply a complete engine Eg. cam gears,plastic covers, water pump, oil pump, sump, etc,etc, please advise so i can do up a estimate.


What does that mean, "no core exchange"? My English sucks

As you pointed out, everything is a straight fit, so I can do with just the bloc, right? Oil pump, sump etc all fit straight on?

 

oil pump.. water pump all fit..

would go for a modified oil pump from roger clark.

David

 

claudius,

do you have an email address, failing that email me on adam@22b.com.

I have done exactly what you are talking about to the extremes of strength and power, and if you need help, can point you in the right direction.

john has hit the nail on the head already, and mark will certainly be able to help you, but if you have any specific question, I dont doubt I would have found out the answers already.

 

Hey, over in the US the 2.5 comes in both imprezza and legacy models. You can get a new short block from the dealer for $1500. I also have my old 2.5 short block sitting around the garage, it has piston slap and a spun big end bearing. I may be able to do some trading for some fiat x1/9 parts from over there if you have a need for spme us spec parts.
Ryan
Eugene, OR USA

 

Hi Adam,

I do have an email address. It hasnt changed since I posted it on page one of this thread this morning LOL it's cbkramer@hotmail.com

I'd appreciate to hear about your experience. Thanks for "helping out a bro" as they say in the US

 

Update: I am now being told I could get a EJ25 bloc from the US or Japan and put a JUN stroker kit in there for even more capacity. My tuner recommends I use a NA head from the EJ25 with cams for the turbo, as the NA head is better shaped than the turbo head and that would avoid the need for head porting / flowing the head. A TD06 20G running about 1.4 bars would be a good reliable road setup he says. Any comments on this from the engine gurus here?

 

The NA heads are completely different design, they only have one camshaft per side. I think it´s not a good idea to use these!

Mark.