Now I've seen this "zero-clearance" turbo used on racing fd's. I think apexi makes it, but it's clearance from the turbine to the housing is set when it first spins, it scrapes off whatever amount of the housing needed for it to spin. I'm not sure exactly how that works, but, I read it in scc, so it must be true
Anyone hear of these, got info on them, benifits, applications?

 

I haven't anyone who does retrofit kits to other turbos.

The design is a plastic housing insert is installed on the compressor side.  The first time the turbo spins up, the compressor wheel abrades the plastic to form a very tight tolerance fit.  I've heard efficiency range in the 80%+ range, which was almost impossible with regular machining.  BTW, the stock turbo doesn't even hit 70% efficiency, so you're gaining at least 10% more efficiency.  It would be a nice upgrade if it's economical...


-Ted

 

I never heard of that. That's a pretty cool idea! I wonder why it isn't more popular, it really makes sense!

 

Mazda started using them on the 1999+ FD3S.
I think IHI started doing that to their turbos, and the A'PEXi turbo kits run these turbos.


-Ted

 

godamn just one more thing to make me want a '99 j-spec

 

someone needs to talk to a good turbo shop they should be able to "0" clearance any turbo for you.. you just need a good metal lathe and brain. I wish i had a couple of turbo housings to play with... i 'm sure you could use some sort of tracer or large metal panagraph set up for a lathe. I think i've seen my buddy use one on his bad *** crank grinder.. my ecc. shaft is going on there soon for a good polish.

? idea#3,485

 

Take your turbo to any machine shop and ask for zero clearance and they will laugh at you. I get enough **** for asking the to make parts at .001 tolerance.:

Plus you really need to do some serious calculations to machine something that precise. The blades tend to "expand" outward when they are spinning at xx,xxx rpms. This is the expansion you need to calculate.

 

yes, and this 'expanding' is taken care of when it first spins up. I doubt any machine shop could do zero clearance. that's the whole point of these things!

I wasn't aware that it was used on the 99 spec engines, but it would explain why I saw it on a new j-spec engine. Didn't think it was stock....

 

i can relate. i just learned how to use th lathe at the SAE shop here at UF and the absolute best we can do without a CNC on our best mechanical lathe is about +/-.002 and that is getting lucky half the time. a standard lathe just isnt that accurate even on simple stuff like faicng off and turning down, forget about it on something as complicated as a turbo housing. its definetly beyond the ability of your run of the mill machine shop to accomplish this. besides its not even "machined" per se. the impeler automaticaly matches itself because of the abbresion which allows for the turbo to be initialy set up looser then "zero" tolerance.

 

true 0 teolerance is highly unlikly true but even +/-.005 is close close enough more like milling it out and filling it with some sort of soft metal or high temp plastic???

 

It is possible to retrofit or create an "abradable" compressor housing (near zero clearance) and we have a forum member that is working on it.

Scalliwag bought a "flame spray" set-up for ceramic coating rotary engine housings and one of the 1st powders he bought was a metal/polyester? mix that is used to recondition turbine engine compressor housings for abradable clearancing.

I had asked if anyone did DIY abradable compressor many months ago and was happy to read when he got the flame spray rig and that powder.

I believe Scallywag is setting up a shop as well now, so he may be able to supply us w/ lots on good services.