Ok guys.. I just picked up an 05 Evolution MR (all 05 share this part) Compressor cover, this was intended to use in conjunction with the 10.5 housing..

So far, externally the stock 03 turbo and the 05 compressor housing looks similar, internally there are what appears to be some slight differences, the discharge looks to be a little larger, but I will be taking some measurements over the weekend when I get a large snap-ring pliers to seperate the compressor from the cartridge.

Originally it seemed like the only revision to the new turbo was the new 10.5 housing (It has a different flapper than the older 10.5 housing) When I was reviewing the part #'s, I noticed the compressor cover and the turbine housing were different.

When I began examining the compressor cover, the casting number is different, and there appears to be some slight external differences.

I will post more information later, however this may contribute slightly to the gains seen on the 05's compared to the 03's with a 10.5 housing...

Not sure how useful this mod is, but I'll have some idea of its value when I get some more data.

Initially this cover is to be used with my Titanium HRA cartridge and 10.5 housing to produce a hybrid with better spool and less boost taper at high RPM, possibly a slight gain in air volume overall..


We'll see what value this has...

 

Deffinitly Keep Us Updated

 

Not sure what value it will have, but at the least I can see what can be done with porting if its not worth any real gains..

 

It spools a lot quicker......and boost comes harder with more power....... my 2c

 

Thanks for doing the research. Some pics would be great if you have time. Let me know if you need help editing, hosting, etc.

Joe
www.joe250.com

 

Good find Jack

 

Let us know what you find Jack. I ported the compressor housing outlet of my stock 14b on my 1g and it made a pretty noticeable difference. Boost hit harder.

 

Oh BTW, I use a angled tip needle nose plier with grinded down tips to take the compressor snap ring off turbos. It works better since I have a cheap snap ring plier that's real flimsy.

 

Yeah, the hard part is finding the right size snap-ring plier.. Turns out its the kind of snap-ring used to retain the bearings in a helecopter turbine engine, which Is a tool I can get my hands on..

I'll lay my calipers all over it tomorrow, I'll also be CC'ing the internal volume of both to get a definitive answer..

Honestly, if I took photos of the two side by side, you'd be hard pressed to even tell the difference.. Its even hard to see if the discharge outlet is any different in size if it is at all.

If I do decide to port this thing (if I find that there's really no notable difference) any thoughts on how I can hone the inside of the scroll to give it more internal volume? The inlet is matched to the cartridge so you can't do anything to that without adding clearance between the impeller and cover..

I plan on using this part regardless of if its noticibly different in size, if its not, I'm going to spend some time porting and smoothing..

What I should do is see if there are different part numbers for the discharge pipes between the 03 and 05.. if there is, that could mean that their a different size.

So far, it just looks like their different castings dimensionally their not visibly different (however we all know visual assessments are fairly difficult to gauge since there would have to be a few millimeters difference before we can tell)

But since my car isn't running (waiting for one of the shops I work with to send back a modified intercooler pipe for me) at the moment, I figured I'd take on a nice little project..

 

They are the same part.

 

Ok thanks.. So its just a matter of measuring the compressor housings..

 

Due you think this "revised" compressor housing may fit bigger compressor wheels?

 

Well, it shares the same basic "Cartridge section" which means that out of the box, the compressor wheel is the same size as all the other 16G6 Evo twin scroll turbos, Is there room for a bigger wheel? Well, dimensionally the inlet and face appear to have the same amount of material as the older 03, What appears to be different is the scroll portion and the "Slot" the air escapes into to get into the scroll when its compressed.. But I'm going by visuals and not measurement at the moment, so that may not be any different.. I plan on putting calipers to measure the thickness of the walls, and interior volume and see if its any different... But as far as I can tell, I don't think there's enough material to machine for a larger compressor wheel.. at least enough to make a difference..

Where I can see some potential improvement is the slot and scroll with a bit more volume, a larger slot, and larger discharge (this has not been confirmed yet) you can increase the volume of air that can be compressed.. at least reduce boost taper.. Give me a few days to get more conclusive data..

 

Any luck CC'ing the compressor housings for comparo?

 

Not a hell of alot of luck, everything I tried kept leaking liquid.. However its a few CC's larger just not sure exactly how much.. I assembled the turbo and plan on testing it shortly, I was originally going to try to build another complete turbo with this cover and compare it side-by-side to the TME style turbo I have, instead I put the cover on that turbo.