1G Evo 3 O2 housing

[AWD-Tony]

I have about an inch of clearance between downpipe and tcase. The downpipe flange is also slotted to accommodate a bigger housing. Will there be a fitment issue?

Also, I currently have what I think is a stock O2 housing with open dump welded. Is there a big difference in performance for exhaust flow?

Thanks, Tony

Hard to tell from the pic but it’s more or less an inch

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Big 16g

 

[2gmitsueclipse]

The angle of the flange for Evo 3 o2 housing is at a different angle than the DSM o2 housing. The easiest fix is to cut and re-weld the flange on the downpipe to account for the angle change.

 

[AWD-Tony]

Thanks, Nate! I've read the previous post and saw the side by side pic showing the difference in angle. Wasn't sure if it can be done without changing the angle of the flange. Thanks!

 

[2gmitsueclipse]

Depending on the downpipe, it may be able to adjust for the angle, but often creates another fitment issue. If your downpipe has a flex section, trying to move it enough to fit the will cause premature failure on the flex section. Aftermarket Downpipes don't usually have an issue with the Evo 3 flange surface. At most, you may have to extent a slot. When RRE still made parts for the DSM platform, they featured a downpipe made to accommodate the Evo 3 o2 housing.

 

[AWD-Tony]

The bolt hole on my downpipe flange are slotted. You’re probably right about the flex eventually breaking if there’s too much tension from it being twisted. I can try it and worst comes to worst, I’ll have it cut and welded to fit properly.

I’ll have to research which is better for spool. Not a big fan of how my current setup sounds when O2 dumps to atmosphere.

Thanks!!