Well, I finished putting the new O2 housing on the car. I had looked around at a lot of boards and sites trying to find a good review of the install before but cant find any that has enough tech. details. So for those of you thinking about the EVO3 O2 housing, here's a sweet review.

The EVO unit is physically larger and beefier than the 1G counterpart that I have in there before. The exhaust passage in the EVO housing is bigger, and the outlet is also bigger. It is a true 2.5" from in and out. The wastegate passage is also bigger and the section where it joins back to the main exhaust passage has a bigger cross section opening area. The one thing that sucks about the EVO housing is the wastegate passage hole.

When you overlay the old and the new O2 housing gasket, You immediately notice 2 things. One is that the new EVO gasket has a larger main exhaust hole and two is that the wastegate hole on the new EVO housing is smaller than the old one. I had previously ported the 1G O2 housing that I have to match the 1G gasket opening so installing the EVO housing without porting it will be a step backward. I had also match ported my 7cm turbine housing to the old O2 gasket so again here installing the EVO housing without porting it will probably give me a bad boost creep.

So on with the porting! Using a Sears’s heavy-duty industrial grinder and a carbide bit I went to work.

First I take the EVO housing and overlay the 1G O2 gasket on top of it. I mark the cut area with a marker, basically enlarging the EVO housing wastegate passage opening to the 1G housing opening spec. I ported a heck lot of the lower part of the chamber opening to match it. This reduces the area between the wastegate passage hole to the main exhaust passage to a mere 3-4 mm. Very thin compared to what it was before. I ported maybe about 1 inch to the inside of the chamber to make a smooth floor transition and ended up with a slight bell shape on the floor of the chamber just because I didn’t want to ended up with a too thin of a wall there. As it is right now, the wall between the wastegate passage and the exhaust passage is only about 4mm. Clean up all the porting mark with various regular grinding bits and finished it all till I get a smooth wall all around.

Then I took the old 7cm turbine housing, overlay the new EVO O2 gasket on it and mark the turbine outlet hole with a marker, enlarging it to match the exhaust passage opening of the EVO O2 housing. Took the grinder to it and open up the outer hole of the turbine to the new bigger diameter. I also grind in about an inch and a half deep to get a very nice bell shape so that the entire chamber transition smoothly from inside (original diameter) to outside (new much bigger diameter). Same here, I ended up with about 4mm wall between the wastegate hole and the turbine outlet hole.

After everything is ported, you can see a real big difference. Now the wastegate exhaust flow is smooth between the turbine housing to the EVO O2 housing, and the main turbine flow is also smooth from the enlarged turbine outlet to the bigger EVO O2 turbine inlet.

I also have to do some shaving to the new EVO O2 gasket itself to match the wastegate hole area to the now bigger opening. Not hard at all to shave the gasket, just use the carbide bit and then some touch up with the grinding bit and a flat file to take out the sharp edge.

Afterwards, the turbine housing is bolted back to the EVO O2 housing and installed back on the car. The original 1G lower heat shield fits fine over the new housing. I have to knead and hand bend some parts of it to fit around the bigger housing but it works just fine. The O2 sensor is positioned at the same spot as where the factory put the 1G O2 sensor at so the original O2 hole on the shield works great. There is no issue with the oil filter fitment. There is still a good distance between the housing and the oil filter. The 2.5” pressbent BR DP that I have right now matched up okay with the new EVO housing. The studs on the EVO housing is distanced farther apart so that it clears the bigger DP pipe better too. The DP flange has a slotted stud hole so it is okay. I used to have issues with the socket hitting the pipe or the nut hitting the weld on the DP now no more problems.

Okay, enough on of this install stuff, how does it drives?

So this time, nothing else is changed before and after the install except for the port work. This test is done with a 2.5” BR pressbent DP, test pipe, pressbent catback piping and a Dynomax super turbo muffler.  I also have a bigger 34mm wastegate valve installed on the 7cm-turbine housing so keep that in mind. The ported wastegate hole on the turbine housing is bigger than what Shawn has on his.  This is a pic. of Shawn’s wastegate opening (only used as a reference, cause I forgot to take picture of mine), my opening is a little bit bigger than that, with the seat around the opening only about 3mm all around. (As big as the wall on the 2 o’clock position on this picture below)  BTW, Shawn, I have the same crack at the same position there too!

http://www.pics.dsm.org/files/16g%2034mm%20valve1.jpg

The car was set at 12psi before and boost controller isn’t touched.  The car spool up a little quicker noticeably.  I can only give you a seat of the pants feel so take it with a grain of salt but my butt said it spooled up better than before.  Not that on off switch feel but there is a definite improvement on how it spools up.  On highway, jamming the throttle WOT and riding the rpm all the way up there, there is no boost creep evident. The boost is still good and pegged at 12psi. So that’s good. I was a little bit worried that installing the new housing will give me creep but its all good now.

This coming Thursday I am going to have the 3” mandrel turbo back installed with test pipe and a straight flow Magnaflow muffler and we’ll see if the bigger exhaust will cause it to creep or not. I have a feeling that the 2.5" pressbent and Dynomax muffler (not a straight true shot muffler) I have on there does give a bit more backpressure to help with non creeping. I hope the 3" piping and stright thru muffler wont give me way too high of a creep.

UPDATE: I got the 3" turbo back mandrel bend exhaust put on there. The bigger DP upper flange that I got from RRE helps a lot. It is much easier to weld the biggger 3" pipe close to the flange and I have no issue with the nuts hitting the welds or the socket getting pinched by the pipe like on the old system anymore. The bigger distance between the EVO3 O2 housing studs really do help a lot.