toyney83

iTrader: (3)

What is it that makes a twinscroll setup produce so much more torque than a single scroll? I've a 2005 uk sti with a built 2.1 and I'm looking at converting it to twinscroll. Is it the equal length headers or the twinscroll turbo that give the jdm's that bit more? Thanks in advance

dnc

Think the main point with the JDM set up is that it produces much more torque in the lower rev range, rather than much more peak torque. I believe it is mainly the twin-scroll set unit (it reduces interference of the exhaust pulses in the manifold by having twin feeds to the turbine) rather than the headers that gives this effect, though the EL headers are more efficient also.

TonyBurns

iTrader: (3)

The equal length headers help with the increased torque and you get a better torque range lower down which is where you need it, they do produce more than a similar single scroll but that is all to do with the complete setup.

ronjeramy

iTrader: (1)

Don't the jdm's have different cams and poss heads or is that just the spec c?

toyney83

iTrader: (3)

The jdm and uk heads are the same but cams are a different profile (don't know which). The spec c has big port heads I believe

craigyp

iTrader: (5)

u still not happy with the torque then mate??

Tidgy

should have gone 2.5 if torque was what was after.

LegacySTi

iTrader: (13)

Incorrect.

all jdm newage sti heads are big port.

jura11

iTrader: (7)

+1


JDM WRX are too big port,cams are different on JDM WRX,both are AVCS

Jura

toyney83

iTrader: (3)

Torques not bad mate but always looking for ways to improve

Normally I'd agree, if it was just for road use. Seen some pretty decent results from the jdms lately so just looking into what makes them different

Tidgy

2.35 if for track as well, 2,1 is just the latest fad.

the phrase no replacement for displacemet def rings true mate.

MartynJ

The other one that still rings true is "Horses for courses"
Toyney had a 2.5 and it didn't suit him.
In my experience, the 2.1 still offers the best balance when it comes to fast road/track day use. It's far from just a fad and as we've probably built more than anyone (Including Toyney's) I'm quite well placed to say that.

What turbo do you currently have again Mike ?
As we didn't set yours up I can't remember !

toyney83

iTrader: (3)

Hi Martyn. I'm running an md321t at present. My 1st choice was to have this converted to billet. Then the more I looked, the better a twinscroll conversion looked (seen as I already have the sump etc) but would want to go the whole hog which would mean jdm heads by the looks of it. So figure it means I'll be after some equal length headers and up pipe. A new turbo (twinscroll sc46) downpipe and some jdm heads. I'd sell my current headers and turbo which would fund a good part of the conversion. Thanks Martyn