which down pipe

[carsaval]

I have ported my 02 housing side to 2.75 and i was wondering is that what I should go with for my down pipe 2.75 inlet and 3 exhuast. What will I notice, issuses With boost creep ?

 

[absolute_DSM]

With your big 16g, no.

 

[Zmann42087]

What will I notice, issuses With boost creep ?

you might... have you ported your EVO III 16g?

 

[Batman™]

^^exactly. without porting the exhaust housing of the 16g and removing that "hump" in front of the wastegate outlet in the housing, boost creep will probably be noticed. i run a evo 3 2.5 inch o2 housing, apexi n1 downpipe and apexi n1 exhaust. wouldn't want anything else, but on my 16g i boost creep.

 

[Zmann42087]

Yeah, if you want to prevent/eliminate boost creep, its crucial to port the wastegate flapper area. There is a good article on porting turbos here.

As far as what downpipe to go with... I have a Road/Race downpipe between my stock 2g O2 housing and Apexi N1 cat-back, and I'm happy with the results. I'd recommend it.

 

[90 GSX]

You WILL creep with a big downpipe and an unported 16g, even an evo3. My turbine housing, wastegate area, flapper hole, are ported like a sum-ma-bi*** and I'm using an evo3 o2 housing (2.5" all the way through) with an RRE 2.5-->3" after the flex downpipe with full 3" to the back with an open magnaflow. With all that, I can't bring my boost below 14 psi to redline (not that I want to).

I had a buddy with an unported big 16 and 3" from the o2 housing to the tailpipe and it would creep like crazy. It was to the point where to get 18 psi out of the car you would have turn the boost controller to minimum and let the creep bring it up to 18 from like 13 psi. Ridiculous...

Don't go through that, set it up right from the beginning. And the most important part is porting the turbine housing and wastegate area. VFAQ has a good document on porting but once you get into the thick of it you may get creative. It took me about 2 or 3 hours to do it with an extended shaft grinder and a couple cheap grinding stones from home depot that worked great. All in all cost me 25 bucks plus a larger circuit breaker for my air compressor because it kept blowing itself.

 

[90gst_sean]

/\/\ agreed/\/\

I've got a evo 3, with a stock un-ported 1G O2 housing and it creeps to 21psi with the boost source straight to the gate.

This is due to my 3" Megan dn. pipe, no cat/Megan res., and 2.5" exhaust.

16G/no cat = big boost creep; with out major modification.

AVOID BOOST CREEP!!! Its no fun and will have to be fixed.

 

[90gst_sean]

I see you have a 3" dp and testpipe and a 2.5" catback. How did you go about connecting the testpipe to the catback? Did you use an adapter or just bolt the 2.5 to the 3?

I had a friend at a shop build me a cheep 3 to 2.5" changer with the right flange on the resonator side and a slip sleeve on the other. It leaks a little; I still need to get down there and have it all welded.

Watch out for boost creep after making the change to a full exhaust set up. If your removing the stock cat or up grading to a high flow you with most likely have some amount of creep.

Im considering a full 2.5 setup... dp, testpipe and catback. Guess Ill have to throw some porting into that equation.

You may want to consider going with a full 3" if your continuing to upgrade down the road. With the turbo engine, the bigger the better.

Keep in mind, YOU WILL/CAN NEVER HAVE ENOUGH POWER!!!

If your having the exhaust piping run by a good shop with experience then they should be able to run the 3" pipe with out having any room/rattle problems (a good shop will use all the appropriate hangers and such).

If your not planning a cat in the system, and go with a FULL exhaust set up. Make sure and address the boost creep heavily!!! Look to other member profiles and find two that match yours; ask them if they have any creep problems.

If your going to do the install your self (which I did), have a bargain shop, or order a pre-fab set up, then it may be easier to go with the 2.5" piping as it will install easier.

Keep in mind please, that this is all from my experience with a 1G, and we run our piping a little different that you 2G'er do... I think.

Good luck.

 

[90gst_sean]

You WILL creep with a big downpipe and an unported 16g, even an evo3. My turbine housing, wastegate area, flapper hole, are ported like a sum-ma-bi*** and I'm using an evo3 o2 housing (2.5" all the way through) with an RRE 2.5-->3" after the flex downpipe with full 3" to the back with an open magnaflow. With all that, I can't bring my boost below 14 psi to redline (not that I want to).

You can't bring you boost bellow 14psi because 12-14psi is the rating on your waist gate spring; it has nothing to do with boost creep.

Your down pipe and big exhaust is the cause of boost creep; free flowing exhaust past the 02 housing will only make boost creep worse. No cat will really do it!

Opening up the gate bypass and increasing the ability for exhaust gas to divert from the turbo compressor wheel is the answer to boost creep. Opening up the exhaust flow after the plum back of the waist gate will spool the turbo sooner but will also add to boost creep if not properly addressed (16G particular).