ROSSCNEW

My Car is a japanese import sti version 8 GL . Is there a code or name on the turbo unit ?

Cheers

ROSSCNEW

It has an IHI something on it

Nathan L

Twin Scrolls are IHI VF36 and VF37.

The first twin scroll cars were the current 'blob eye' Imprezas.

Nathan..

Bob Rawle

It should be a VF37 on the GL which is the sleeve bearing version.

Close inspection of the compressor cover should find the part number engraved on it.

bob

AJbaseBloke

Here we go with "numbering" again - anyone seen greasemonkey about?

If your car is a JDM GDBC or later (we are up to E in Japan now), you'll have a twinscroll set up.

Enjoy the car m8 - don't let Bob near it, it'll get waaaay too fast

Seriously though, and you prolly already know from reading Snet so feel free to ignore the following, unless you are going to keep a steady stock of booster going through to keep the juice at or near the 100 octane the ECU will be looking for, a tune by a pro like Bob is a good investment IMHO. Having it tuned for 98 should keep it happier and more reliable, AND release a few more ponies and torque beasties Naturally the tuner is the key...

HTH

Nathan L

AJbaseBloke

You have a PM.

Nathan..

AJbaseBloke

Back atcha, Nathan

ROSSCNEW

Thanks guys,

The car is booked in for a remap on the 14th of august at wallace performance in Aberdeen.
Ever since i put on my hks hiper exhaust the is a slight boost then i dies then its ok again, im hopeing the remap will sort this out also the power delivery isn't very smooth .

Any idea's / solutions

Gary C

A quick question,
I read somewhere that the twin scroll turbo was developed for the subaru engine because the unequal length headers mess up the flow into the turbine.

If this is so, why does the Spec C with equal length headers use a twin scroll ?

I must not have something right.

Nathan L

All the new twin scroll cars use equal length manifolds. AFAIK

Borrowed from another thread.

The twin scroll turbo/equal length 4:2 header setup increases turbo efficiency over the single scroll/ unequal length 4:1 header used by most Subarus in a number of different ways.

The hotside of the turbo has two separate gas inlets. The exhaust manifolds, instead of being combined into a single up-pipe, are combined into two, with the twin up-pipes keeping the gas from adjacent (in firing order) cylinders separate all the way up into the turbo, where the twin scroll exhaust housing separates them all the way onto the turbine blades.

The first advantage is that the equal length design of the headers evens out the time intervals with which the exhaust gas pulses hit the turbine blades. This imparts more energy into the turbo, which helps promote quicker spool.

The second advantage is that the separation of adjacent gas pulses in the headers and turbo prevents something called reversal, which is where part of the gas pulse takes a "wrong turn" in the normal manifold, and starts travelling back towards the other cylinders instead of to the turbo, where it can collide with the next gas pulse, reducing the energy available to drive the turbine round in the process. By virtually eliminating this, you're again getting more energy into the turbine blades rather than wasting it.

The increases in turbine efficiency mean a smaller one can be used for any given size of compressor and desired flow rate, and the reduction in size leads to a reduction in rotating mass, which again helps spool and response.

Another happy advantage of the lack of reversal is that the knock-on effects can improve fuel efficiency, so it's an improvement all round.

Nathan..

marklemac

So as all the new models seem to have switched to equal length, in your opinions, do you think that getting equal length headers fitted to my MY02 STI is a good thing to do. (obviously remap too)

Nathan L

Apart from the fact you lose the majority of the flat four throb, equal length headers are the way to go IMHO

Nathan..

Johnny50

Yep, considering the small mods i have on my car, chainging to equal lenth headers (HKS) has definately played a big part in the way it goes now.

Costly, but very worthwhile IMO

WallacePerformance

[QUOTE=Ever since i put on my hks hiper exhaust the is a slight boost then i dies then its ok again, im hopeing the remap will sort this out also the power delivery isn't very smooth .
QUOTE]


This is due to the car overboosting past it's target boost. The ECU will cut the wastegate duty cycle until it drops below this target boost level and then it will increase the DC until it goes up to it's target boost level. This gives a surging effect and does it quite a few times through the rev range.

The re-map will definitely sort this out

Gavin

CustomScoobyIOM

How gives a flying ****! Call it what you want! People know what you mean........

Sick of being told off for me calling my STI8....an STI8!

/On Topic
Agreed, yes the equal length headers are spot on.

marklemac

Anyone have any experience or comments about the headers that Powerstation are recommending.

Also, can any 'competent' garage fit my headers, or should I go to a 'subaru' recommended specialist ?

Nathan L

I've got no experience of the Powerstation stuff but someone on here might. I've seen the HKS stuff and the quality was excellent.

Any competent garage should be okay with the fitting.

Nathan..

Gary C

Ah, so the twin scroll is a bit like My GT4's twin entry turbo.
Shame equals get rid of the throb, don't think I will get them for my STi

TonyBurns

iTrader: (3)

Only the JDM cars (and only STi's) have changed to this method, the euro/rotw market still use uneven length.

Tony