Hawk STI 2.5L Forged or 2.0L JDM?
 

Will be in the market soon for a Hawk STI, just undecided on whether its worth going for an already forged 2.5L UK Type or a JDM 2.0L??

Is one more reliable than the other considering a 2.5L is fully forged yet the JDM is claimed to have better stock internals?

Any massive pros/cons to either one??

Or just scrap it and go for a regular Hawk UK Type STI??

Personally, I'd get a forged 2.5 UK car.
A forged 2.5 if built well, does make for a great road car with bags of torque available. Piston slap when cold, but that's normal with forged pistons....slightly more clearance in the bores to allow for piston expansion when hot.


Some people will avoid a 2.5 full stop - forged or not.


A con for me on a 2.0 JDM is that (I think) they are all twin scroll turbo (no biggie) but run equal length exhaust manifolds....losing the Subaru burble which, lets face it, is why most of us are here.


My forged 2.5 STi Spec D is 450 bhp capable, but runs a mere 342bhp / 410lb ft torque with standard turbo, injectors etc, and was mapped for V-Power fuel by Bob Rawle 2 1/2 years ago (when I had the engine forged)
I do have a couple of Prodrive exhaust sections, but it's a nice subtle quiet(ish) car.


A JDM may well be better out of the box, but a forged 2.5 can be just as good.
Or, like I did, buy a non forged 2.5 and factor in a decent build of approx. £4-5k


Of course, be sure to see proper build invoices, and maybe contact the builder to see if they remember the car. Lots of people are "told" that engines are forged but with no back-up paperwork, and that the paperwork "got lost a few owners ago" etc.

has to be a forged 2.5 for me every time

A convincing argument :) And one I agree with :)

With all the 'advantages' JDM brings, some of the Scooby character is certainly lost with the equal headers (for one thing). Many don't mind that and when they hear the un-equal lub-dub think inefficiency and compromise (which it is). Thinking you're missing a little power when let's face it we're talking Subaru which is big power anyway is lame.

JDM's are revvy - and love to do it relentlessly up to 8K rpm. Is that your style of driving? You drive a 2.5 on the torque, with the accompanying soundtrack

There are more differences too

Both are great. If you're new to Subaru, you need to test drive both as they are quite a different experience

It’s been said many times that a jdm car is better equipped, I don’t doubt this but once you start modding and upping the power there’s not a lot in it.

My background was motorbikes and my 2 wheel love affair ended on a fireblade and a few broken bones. I spent almost 5 years riding a Ducati 916 that got me hooked to the burble of a v twin.

I feel the same about Subaru, without the soundtrack it’s just not ‘subaru’

Siv :thumb:

2.0 jdm everyday for me, love the twinscroll sound when you push the car and never any issues re dbs when doing track days also never miss the burble but guess it's all down to personal choice and what you use the car for :-)

You really need to drive both as they are completely different expiriences. I much prefer the twinscroll 2.0. yes you lose the burble but it sounds epic up the rev range with an aftermarket exhaust! :thumb:

Twinscroll all the way for me

Another for Twinscroll 2.0 here, I prefer the sound on full chat

JDM with unequal headers and single scroll turbo?

Twin scroll can't be the only benefit of the JDM as you can fit a TS to a 2.5 also.

But why take something off your performance car and replace with something inferior?

2.5 forged with a twin scroll setup? Best of both worlds!

Twin scroll's overated :)

Mines 2.1 Twinscroll

I would see what comes up at the price you are looking at and take it for there, I’ve owned 2.0’s 2.1’s 2.35’s and 2.5’s and all have been totally different to drive at different power levels

Appreciate all the comments and thoughts, seems to be fairly mixed so will definitely have a test with both.

Just about waiting for the right one to come up I suppose, leaning towards the forged 2.5 slightly though as a few of you have stated, who doesn't love the scooby burble;)

As a road car the 2.5 is perfect with the torque

+1 for the 2.5 once forged and mapped the torque is amazing even off boost and the sound :notworthy

I like the linearity a 2.0 twinscroll gives, the low down torque, the sound it makes between 4-8k and the willingness to rev.

Seems to be just down to personal preference really and what you want out of the car, as for me it would a daily driver.

The idea of doing it myself for that kind of money is tempting to be be fair, anyone you'd recommend that around that price range or a little bit more if needed?

2.5 has lovely torque for the road....but if I was in the market for one it would have to be fully forged already or a JDM twin scroll 2.0 litre would be the way to go.SJ.

Never drove the 2.5 but it would have to b freakin great to compare with the Jdm ts

^
Well mine will spank yours ass for sure lol :)

Nah it's all about that 8k redline Rob!

Bugeye JDM cars are not Twinscroll (including the STi) and neither are the JDM WRX.
But the overall better equipment spec should be taken into consideration.

The Legacy 2.5 JDM cars are twinscroll.

I currently have a forged 2.5 running 447 with the older MD321H - what would I gain (and lose) going twinscroll, using an equivalent turbo?

I've ran two of each and still it's a treasure chest discovery

We are moving away from topic
A jdm 2.0 twinscroll just needs exhaust, fuel pump, air filter and remap and is awesome, no need for a 10k min spend and resale value is good 😊

^^^^^^

A Renault kangoo is quicker than mine at the moment mate

Ive owned a fair few Imprezas now, both twin and single scroll. It’s a tough one. However, for me personally, it’s the single scroll setup that wins. I prefer the sound and the power delivery. Yes, the twinscroll setup is more linear and spools earlier, but for normal driving on UK roads, especially motorways, the single scroll / UK ratios is a better setup. Especially with the 2.5, you can sit on the motorway off boost and chilled....you can’t do that in a JDM, it’s always pulling at the leash. That’s fine for a Sunday blast / on the track etc, but for a normal journey, I found it irritating.