I've asked GCG yesterday so I'll go and check my email now.

Ive seen that page no less than 10 times in my non stop Googleing for this problem as it is whats holding me back from doing further work.

I emailed that guy on his blog and am waiting for a reply about where he got it from.

Looks to me like a custom made part as NO other carbon seal setup looks like that (in terms of machined from solid bar stock and surface finish - seems to me he sent out to an engineering company for it).

The conclusion/plan I've come to now is....

NO turbo exists with a carbon seal that's small enough for a A12 (enlighten me if there is and provide contacts for the rebuild kit/turbo).

Other turbos with carbon seals from factory/kits available with carbon seals are the Garret T2,T22,T25,T28 and T3 - All of which are too big (T2 could work with lots of lag/sub par efficiency).

Options for me are to either go to a bearing/seal supplier and see what carbon seals they have so I can machine up my own setup or adapt a carbon seal from a Garret T2,T22,T25,T28 or T3 to my IHI turbo.

Failing that I will have to bite the bullet and source a T2 with a tiny turbine AR and get a carbon seal.

Looking back on this, whenever "draw through" showed up in a forum the general consensus was "oh yeah slap a carbon seal in it" like it was effortless but it turns out only the Garret T2/T3 models really have them available commonly.

Looks like I'm sticking to my name and will source a carbon seal and make my own thrust collar and plate.

Awesome.

I just gotta sort a carbon seal for my current turbo or get anther turbo then I can make my turbo flanges and I can finally weld up my manifold!

I was after anyone's opinion who has run a draw through turbo setup.

What I was wondering is what did you do with the compressor side seal. In your average draw through setup everyone says "just get a carbon seal" but it seems to me this is quite herd on anything but a T2/T3 turbo!? Which are too big for an A12.

Does anyone know what seal Topgear ran on his A12 turbo (as writen about in the wiki)?

Does any one have a cross sectional diagram of how the carbon seal works? I first thought it was something like a lip seal but it turns out its different.

Ive still got my heart set on a draw through setup, its just that this seal is a problem.

Would anyone know where I can buy a carbon seal for a IHI RHB5 VF1 or how I can convert another one to fit?

Any help would be appreciated.

Either ditch the ugly air filter box and use some angled pods so once on the carb they sit about horizontal OR modify the bonnet

The only other "reasonable" way to get a quicker spooling turbo (while still having a big turbo) is a variable geometry one. In these turbo the exhaust turbine is surrounded by a number of small vanes that are actuated via the "wastegate" diagram canister. They work as such, low rpm, low boost the diaphragm canister is basically off and the vanes are shut which in essence makes the turbine have a small housing (only a few millimeters clearance to the turbine) which will allow the turbo to spool fast as it has at this point a very small A/R number.

Now as boost rises the actuator moves the vanes proportionally and expose more and more of the cast exhaust housing. Allowing the now partially spooled turbo to use a bigger exhaust housing and flow more with its now greater A/R ratio.

With a properly sized variable vane (variable geometry) turbocharger a waste gate would not be needed as when the actuator opens fully the vanes in the fully open position allows extra exhaust gasses out. In saying that, if it isn't apparent already, variable vane turbos don't have waste gates - they rely on the vane control for exhaust gas control.

With all this sounding good and like its the holy grail for big turbo situations with lag, it begs the question "Why isn't it already being used these days?"

Simple fact is that they have used this technology for years but on diesels as diesel have a far lower exhaust gas temperature than petrol engines so turbo manufactures can get away with steel vanes in their turbos. However, if you were to use a steel vaned turbo on a petrol motor you would seize the vanes to the housing because of raise exhaust temperatures.

For this reason I didn't go on an use the Garret GT22U turbo I got for free - despite being the perfect size, in good condition and easy for me to machine up the parts for the carbon seal conversion - I wasn't going to risk it. In my case running water injection to cool the air charge; I may have been able to get away with the steel vaned diesel turbo due to lower exhaust temps but I wasn't going to find out. I'm holding out for a TD04L-13T of a rexxy.

In addition, Porsche has just recently started to use a variable vane turbo on one of their new (petrol) cars but they are using a turbo with ceramic vanes which will withstand the petrol engines higher EGT's.

Oh yeah...so whens the laser cut turbo flanges coming Chris?! Lol

Cant make a turbo manifold without one.

The stainless ones would be the most bent due to stainless being able to absorb so much heat yet not easily dissipate it.

Who ever got stainless flanges, prepare to get them milled after welding as having a 5mm warp in them once done with welding would be expected.

Is there any distortion in them (are they bowed after cutting)?

This is good when it comes to welding the manifold as a straight one will buckle out so using a bowed one to start with will straighten out after welding.

Hey I can see my flange from here! Lol they look great, cant wait.

Before said 5183 is the ideal filler rod for welding 5083.

Honestly, just go with 5083 - its what the laser cutter obviously has used before and are familiar working with it and how it cuts etc. It welds great too.

Its not like your alloy inlet is some super duper scientific instrument that's made light and thin and highly stressed under use - its a slab of plate with pipes welded to it. 5083 is more than sufficient for our inlets.