Impreza 2.1 Stroker Billet GT30 or Twinscroll Stock location Turbo.
 

Relisted due to thread being put in the general discussions.




Hi,I have an 04 Impreza Sti Jdm model which had an engine failure and at the moment it's being built as a 2.1 Stroker.Besides the 2.1 stroker the engine will still run stock jdm heads and the only mods i had done to date were the Twinscroll 3inch Milltek decat exhaust,3port boost selenoid,walbro pump,uprated actuator,pfr7b plugs and cosworth air filter and a remap.As i will be running a 2.1 stroker i am in need of a larger turbo than the vf37.I am looking to use the car for ocassionally track,a little more drag and mostly road use.My options are: to keep the stock location twinscroll setup and go with an MD321T Or V(or litchfield's equivalents) or go the rotated route and fit a Billet GT30 .63 turbo(GT35 is out of the question as i was told that its a 'little' laggy on a 2.1 even with avcs).As far as costs the rotated setup will cost almost the same as buying a twinscroll turbo big as an md321V(i will utilise my milltek downpipe just modify/weld the housing part).But im not worried about costs etc,im interested in having the best spool and possibly top end from such setup.Reason for this is because i've heard that besides having a better top end,the billet Gt30 still spools faster than example an md321T or V(litchfield's included) in a stock twinscroll setup still on a 2.1.I dont know about this,that why i need your opinions.What do you guys think?.Thanks.

As I said over on the other thread, Billet GT30 all the way m8.

Ok martyn i will take your advice and just go and buy the billet gt30.Do you think the stroker kit which consists of the mahle pistons,manley rods and stock ej25 crank will be sufficient for the billet gt30 turbo running at max power?also i will be running a new stage 1 exedy organic clutch as its about 4 times cheaper than the twin plate and i dont do any standing start racing so i think it will be sufficient what do you think?many thanks.

The torque from a gt30 will kill a exedy organic eventually standing starts or not,if you can afford it future proof with the best clutch you can fit twin plates are good but you have to get use to the way they engage I.e work.as they are a bit more on and off,the exedy organic clutch drives nice like a o.e clutch but when you are aiming at higher power and torque figures a tuff clutch is the price you have to pay,but it's worth it in the long run to hold down the improved torque.

Hi there

Personally i would go with MDX321T or MD321V which are both great turbo's and T will make on V-power around 450bhp(with better heads like you have i would expect 470bhp),V should make 500bhp on Vpower easily.

T will work amazingly on yours,we are running on our 2.1 T and spool great with AVCS nd with Methanol is just amazing to drive,we are running 490bhp

Your engine should be OK for about the 500-550bhp,what head studs you will be running?
If you are planning run GT30 Billet i would say 12mm ARP Head studs is minimum,but still think 14mm will be better choice


Jura

Agreed about the clutch,Exedy Twin plate will be better choice.Not the best clutch for daily driving,but will hold any power or torque


Jura

I wouldn't fit Manley rods on any engine m8, it's a matter of preference.
We fit K1 rods on most applications and Cosworth rods on those with a bit more in their budget.

The clutch is inadequate as others have pointed out, better sort a better one !
Helix paddle clutch isn't bad to drive and hacked 2 years of my heavy foot and 560bhp on my own car.

Hi all,thanks for your replies.That's why i didnt want to step to a twin plate because i find the exedy organic stage 1 kit very good around town,but a paddle/twin plate clutch will be a little 'trickier'.I will be running the cosworth ultra 11mm head studs(260,000) as i think they would be better than the arp what do you think?.I see,i thought that the manleys are like the K1 rods as they look very much alike.Martyn So you think that the k1 rods and mahle 2618 pistons would be more than sufficient to hold the max power produced from the billet gt30?im looking to run on stock ecu if its possible or its not recommended?.thanks

The paddle is a little trickier, but the twin plate is fine to drive but the noise is annoying in traffic.
The Mahle piston and K1 rods are an excellent choice and well mapped won't struggle with the power the GT30 will produce at all.
I personally don't map the stock ecu at those levels, but plenty out there will.
I prefer the resolution and fine control you get from live mapping on cars of that kind of specification. With the new Alcatek ecu being a bargain for it's spec, it's a no brainer for me.

How much does the Alcatek ecu costs Martyn and is it a plug and play fit?I see that's better than i will get that combo,still considering the cosworth though but they are about £685 more.Martyn,wanted to ask you about the injectors...I've got hold on a set of Deatcshwerks 1000cc injectors for a very good price.They are for an evo X type.I fitted then in my stock jdm rails and they fitted perfectly(even the connector) just by removing the loose spacer they have on top.They are a little taller but still fits the rails with ease.I measured the impedance of them with my digital meter and founded them to be about 15ohms each while my stock pink injectors are 14ohms.Do you think they will work perfectly?thanks

Will pm you in 5

Ok thanks alot