Fitted on STi version 4 with 2.5 conversion.

Here are the details:

My 2.5 conversion was done over 12 months ago & the old turbo was holding boost fine. This weekend I fitted an MD321T and headers (which I skimped on via ebay).

Here's the problem:

It can boost up to 1.6 bar but this quicky falls to 0.3 bar It is in the hands of a bloody good mapper so leak test & other standard tests have been done.

I'll be changing to a decent set of headers to see if these are causing the problem.

Has anyone else experienced a similar problem after fitting a new turbo or headers? Any suggestions?

 

If it's in the hands of a good mapper then I'm sure they'll find the problem soon enough.

As a suggestion though faulty dump valve?

 

Did you also add a silicon inlet pipe to the turbo? Collapsing with high air flow?

 

would put money on it

 

Yes, it's samco hosing that was already fitted. It was troublesome to put on the turbo too. Could well be a possibility, cheers.

I was thinking along the lines that the new headers & up-pipe weren't creating enough back pressure, whats your views on this?

 

Not really possible, you would hear it blowing quite bad for not to be spinning the turbo properly so fault is definately on the compressor side.

 

Cheers mate, no the pipes aren't blowing at all. They are cheap stainless ones though.

I'll get your suggestion checked first

 

What air filter /size are you using on the induction? Maybe that is too small and causing suction as soon as it starts to flow significant masses of air.

What ecu?

 

Interesting point, I was looking at the K+N filter covers that effectively make a cold air box with a feed (think they're called vortex or typhoon, something like that ) then the small print said good for 350hp. I've seen some of these filters on the CAK and some are tiny.

 

Piper air filter- not the biggest. Looks like some of the chaps may have hit the nail on the head with the silicon hose theory, I will let you know soon hopefully.

& It's a Simtek

 

Fairly easy to diagnose if you have a boost gauge. Plumb the gauge into the inlet silicone hose. If it draws some serious vac on boost then you can bet is collapsing.

Mike

 

Yep, it was definately the silicon inlet hose. Anyone else had this problem when fitting the MD321T?

Solutions on a postcard please...............

 

no problems with mine

 

on a samco inlet pipe yes on a few turbo's

depends how bad it is (yours sound bad btw) - jubilee clips on the pipe as it has to expand oval when collapses and the jubilee on the outside re-enforces it.

a different inlet pipe

 

APS hard inlet pipe is the solution

 

In actual fact, you're all correct, but for slightly different reasons!
We were mapping the car as a fait accompli, meaning we were doing a "tune what you brung"! We quickly realised that the turbo needed to be moved over to the centre from its arrival position, which was crushing the intake pipe big style. These always look a bit like that as it's very busy in there, and I've never been comfortable with the way it looks when they are in with some of these hybrids.
We moved the turbo another half inch over, and tried it again. We gained 50 bhp! but it still dropped boost over 5000 rpm, even at actuator pressure.
We have a number of other 2.5's in with our GT30 core turbo, and we don't get that issue. My feeling is it's down to the inlet port shape when the intake silicon hose is on. Our GT30 uses a larger inlet, and the slight kink to the intake hose doesn't cause an issue. We eventually removed the intake hose altogether, and the boost was then pukka all the way up.
We'd like to replace the ebay headers, and if anybody wants them you'll probably find them on ebay! The fitting of the MD321 with the small intake looks critical, and it makes me wonder how many others out there have the same issue. Dazza's uses the small intake as well, so I'm guessing he has Lateral headers, and a more centrally fitted turbo, proving they work just fine if these problems are sorted out!

 

Hi Alan, thanks for that.

mmmm, I'd love the lateral headers & I have stacks of room on the paintwork for sponsor's details

I think the hard inlet pipe would cure the asthma, any thoughts about APS hard inlet pipes & how much are they?

 

What version is Dazza's car? the samco inlet pipe's routing on the version 4 even with a smaller turbo looks traumatic.

 

Worth pointing out the MD321 is available with a near standard size or larger 3" inlet. The poor inlet pipe is not the fault of the turbo!

 

The APS hard inlet pipe works out at about £170 and includes hose adapters for both the 2.4 inch and 3 inch turbo inlets. Handy if you are possibly wanting to change or experiment on inlet sizing without having to change the whole inlet pipe again.

 

Where did you buy yours?

 

I got mine from Scoobymania

 

Like I said Paul, these are fine if sorted out! It isn't the intake hose that's at fault, or the turbo, so much as the tight bend just as it goes into the turbo. Even a little bit of a fitting issue has a dramatic effect on the boost. We think the headers on the car are contributing to the slightly offside bias to the turbo mounting, and we're going to fix it.
The interesting part is the fact that all these units have some degree of compromise, and the point at which it becomes a problem is marginal. Just that last little bit of restriction, and it appears to be game over. I'd say it isn't the size that's the problem, it's the shape, and the proximity.
Sponsorship? as we had thirty six cars at the last drag meet with my logos on, I think you know the answer to that one!

 

Alan,


I suspect that if the up pipe positions the turbo 1/2" over from it's standard position, any turbo will be a struggle to fit, but I think the smaller intake would have given more room in this instance, with a 76mm intake being even more difficult to fit.


Mark.

 

i thought i had the larger intake ?

correct me if i'm wrong Mark

 

larger inlet on my own md321t fits under a phase 1 inlet manifold with no spacers without issue..

the samco inlet pipe is notorious for sucking shut..

The position of the turbo will be effected by the bell housing bolt which needs removing as with any large turbo 20g size and up.

Simon

 

Which inlet pipe do you use? I don't think you can get APS hard inlet for this MY.

& I'm pretty sure that the bolt has been removed.

 

I'll report back on this one when we get the Lateral headers on, and sort out any other issues.

 

I use a silicone one I think it came from scoobyclinic... it is a lot thicker5 than the samco one but don't know if the do it in standard size.. it has no takeoffs though, so wouldn't suit everyone..

Simon

 

I put jubilee clips around my Samco.