black newage

ok please tell me why uk go bang more often than jdm? you are dreaming

black newage

as the uk ones will be anyway, jdm , uk both will go bang as apart from cast pistons in the jdm, all the rest is the same

black newage

just to add this nitrated crank type thing in spec c is different to uk but uk dont break either

banny sti

iTrader: (68)

The newage uk or jdm engines are very robust and big step up in reliability compared to any classic, so you should be happy with either

Banny

black newage

that was what, basically i was told, they are more or less the same though spec c car is better than uk car, buts thats a different issue, i will post tomorrow what matt from rcm took the time to explain to me about both engines,

banny sti

iTrader: (68)

The JDM engine has a cross drilled nitrided crank, larger ports on the head for better flow, higher rev limit due to better valvetrain and more aggressive cams iirc. So overall it is a better base to start modifying from but then you are limited by the twin scroll setup, if chasing over 400bhp.

Banny

black newage

you forgot the crap cast pistons in a jdm//spec c though, forged in a uk

sticks

iTrader: (1)

come on guys we are all scooby lovers on here.this disscussion is like scooby vrs evo.all in all uk and jdm are top motors.each to there own.
rear wipers(LOL).

black newage

sorry mate but somebody is saying that jdm are stronger than uk engines but the people/tuner that i use beg to differ,

black newage

forgot to add rcm are correct

TonyBurns

iTrader: (3)

The JDM's are a stronger engine the even worse crap cast pistons in the 2.5ltr engines are totally useless for tuning, the "forged" pistons in the 2ltrs are well, ok forged but not the highest quality by far, the engine base is stronger in the JDM, the pistons can take much more than people understand, the downside to the hyperheutic is they need a very good map and det reduction, something they have but dont think that the 2ltr uk is a stronger engine, its internals are not as good as those of the JDM, and yes the JDM's are a better tuning point, but push silly bhp and both engines will need decent forged items in there (though still note how the nitrated/grooved crank is added to the uk cars ) but the 2.5ltr sucks in comparison and more of those forged 2ltr uk/jdm cars blow up than you think

Tony

MrRA

Newage UK cars have hypereutectic cast pistons also. I think they were introduced into UK models from MY04 onwards.

As for them being crap, I think not. They are as strong as forged item and expand very little due to a high silicon content. They don't use as much oil or make as much noise as forged pistons. The only draw back with them is that they cannot handle det as well as a forged piston. And if really made that much of a difference then JDM spec cars would come with them also.

As for the debate over which is better, then it is a JDM car, plain and simple.

- Equal length steel headers (unequal length cast on UK)
- 13:1 quick rack (15:1 on UK cars)
- Twin scroll turbo [roller bearing unit on Spec C] (single scroll on UK)
- Cross-drilled nitrided crank
- Stronger valvetrain
- Larger valved heads
- More aggressive inlet cams
- Better spec ECU

No one here is saying a UK Impreza is a bad car, well I'm not anyway, but the truth is that a JDM is the better car.

So back to the question in hand, there are no real cons to owning a JDM over a UK spec variant. If ever there was one factor that used to stop people going JDM in years gone by then insurance could be counted as the main cause. But nowadays with the likes of A-Plan and Kieth Michaels around, prices are more or less the same. Hell, Direct Line insured my RA-R without so much as a fuss, and that was after clearly explaining what the car was and how it differed.

MrRA

Sounds like a post I have made many a time when this question has been posed.

I know of a Spec C Type-RA that melted a piston under extreme track conditions in New Zealand. After that the owner fitted a Tomei 2.2 stroker kit. It's still my favourtire modded Impreza ever and had inspired me with some of the mods I'm having fitted to my RA-R.

Here's the thread: MY06 STI Spec C Type RA - Type-RA.co.uk - Forum for Subaru Impreza WRX Type RA, WRX STi, Spec-C, S202, Type RA-R

black newage

bit of info for you technically minded out there

uk2000 turbo has cast pistons
p12000 turbo has forged pistons
22b has forged pistons
jdmsti has cast pistons
uksti 2.0 newage has forged pistons, 2.5 has cast

forged pistons are much stronger than cast but a standard subaru bottom end runs a very tightbore clearance to reduce piston slap when cold this can cause engine problems when engine performance is increased in a uk or jdm spec, its the piston bore clearance that causes the problems especially sustained speed in 5th and 6th.

piston clearance on standard subaru is 0.010-0.30 (0.0004"-0.0012") a sheet of paper is 0.10 (0.004")
piston clearance limit on subaru is 0.050 (0.0020")
piston clearance for motorsport use is 0.10 (0.004")
thanks to matt from rogerclark motorsport for taking the time and effort for the above.
matt is stating that the jdm sti is not stronger than the uk engine, they have the same rods, different cranks (the uk crank is very strong) as for the pistons thats already been mentioned, people will always say jdm are stronger for whatever the reason but i know who i believe.
just to add its the engine thats being referred NOT the cars

TonyBurns

iTrader: (3)

Ok i want to point this out.
Yes the JDM pistons in the twin scroll cars are cast but you cannot compare those pistons to that of a uk turbo or wrx because they are made from different materials.
Also note how the JDM engines are 80% different to that of the UK car in 2ltr form, the "cast" JDM pistons are as good as those in the 2ltr "forged" engine, now its a shame that the cranks are different because those grooved and nitrated ones in the JDM cars are in there because one of the main issues was oil starvation to the bearings, note how they are now grooved to give oil to the bearing
If you want to know which engine is "stronger" it is still the JDM STi engine, mainly because they have uprated more parts to deal with issues in older engines (like the UK 2ltr engine) because just having one part that is stronger and the rest weaker does not make for a better engine.
JDM engines if you will, are "better" than their 2ltr counterparts, if they were not, do you think they would have replaced the "forged" 2ltr engines they use to use?
The technology in casting has come along way, yes its cheaper and yes they are not as "good" in some situations as a "forged" piston, but if you were going for a rebuild, i seriously doubt you would want to use STi forged pistons in your build

Tony

Terminator X

iTrader: (7)

Tony.

There is an expression about arguing with idiots ...

Suggest you just leave it.

TX.

rickya

iTrader: (18)

Its not worth arguing, I think most of us know the answer anyway.

black newage

but if you were going for a rebuild, i seriously doubt you would want to use STi forged pistons in your build

Tony[/QUOTE] too right

bluenose172

iTrader: (2)

If the UK engine was a strong as the JDM why doesn't it have the 8250rpm limit? Change the limit on the UK car and see how long it lasts.

When I was getting my car mapped, my mapper told me of two customers that were running around 500bhp on standard Spec C internals, one for 2 years.

bluenose172

iTrader: (2)

Hope you don't follow his lead, if I remember correctly he fitted some stupid mods to that car. Some useless FMIC of some sorts if I think. I remember reading that thread and saying that things going to blow, low and behold.......

MrRA

He had originally fitted a Power Enterprise V-Mount I/C kit, but then went with an APS 525 which is what I'm having fitted to my car along with some bits and bobs. What I really liked was the Tomei Stroker Kit, which is temptng me. Tomei do some quality stuff for Imprezas, both classic and Newage. They've recently developed an ITB system for the Impreza with a complete new inlet manifold and four throttle bodies. I've ordered a set of their headers and will be having them ceramic coated by Zircotec.

bluenose172

iTrader: (2)

It would be interesting to see what power you make with a remap, exhaust and filter on that before you start doing anything else. Have you done that already?

MrRA

I would imagine an RA-R would make around 375bhp with those mods.

My car was remapped when Litcho imported it. It's now at Powerstation having an APS FMIC, APS CAI, Sard 650 injectors and few other bits.

I want to keep the car looking as standard as possible which is why I chose an APS FMIC as you can have the IC core in black. As for the exhaust I want to keep the STI back box that came on the car, again maintaining the standard look so I'll have to it modded in order to be used with an aftermarket system.

The car was plenty quick enough in standard trim. I'll wait and see what results I get and whether or not I feel it will need more power.

bluenose172

iTrader: (2)

I was just wondering what the limit of the turbo was, i.e. does it flow past 360bhp, this seems to be around the limit of the VF36.

MrRA

RA-R has the larger VF42 unit fitted, along with a larger GrpN spec STI turbo inlet hose and a blueprinted, handbuilt engine, so they will make more power than a standard Spec C. They were quoted as 320bhp straight from the factory.

bluenose172

iTrader: (2)

No, I know that, lol. What I was getting at is, if a VF42 came up for sale would it be worth it over the VF36. i.e. does it make more power when maxed out.

MrRA

Ah right. Yes it would make more power. Not yet seen a VF42 up for sale anywhere though, in fact they are pretty hard to get hold of I've been told. I remember reading a thread on NASIOC where someone was asking for one. There was a guy from AVO who said he could probably get them and you would be looking at approx. $2500 USD for one.

jimser

iTrader: (1)

yip 1 of them would be mine running around 500bhp and still on a top mount.
mines is a bugeye though so not twin scroll but i am using equal length headers through choice,no trademark burble as such but still sounds good
to me