1G Some questions on 14b/ exhaust manifolds / o2 housings

[badbird]

Hey guys, I have been researching for a while and have some questions to possibly find some clarification or anything I may be missing.

I would first like to state the goals of my car would be to have a pretty fun/simple autocross/rallycross car yet daily drive it as well. I so far have been successful in that endeavor and am needing some final opinions/advice.

I have a 90 Talon Tsi awd, 5 speed manual. I currently am facing an exhaust leak at the manifold pre-turbo, mainly on one stud closest to the upper coolant hose. I received an Evo3 manifold as a gift and would like to upgrade to that.

I am still on the stock 14b and have around 123k miles, turbo is in good shape. I would like to upgrade to a 7cm evo3 housing - Probably this one (http://www.ebay.com/itm/7cm-EVO3-16...HI-/111519430640?_trksid=p2141725.m3641.l6368) from Turbo Lab.

It would either be that or port my existing housing to match the 7cm collector on the evo3 manifold. I know that 7cm housing above is a direct bolt on and would work fine, however I am wondering about what to do about an o2 housing. I am running stock exhaust with test pipe currently, and mostly just have free mods. I did invest in DSMlink v3 full from the beginning so I can gain from mods in the future and be able to monitor everything. I even have A/C!

I also needed to make sure I am getting everything and replacing what I need to while in there doing this. I know I will need:

Exhaust manifold studs/nuts
Exhaust manifold gasket
Manifold to turbo gasket (7cm to fit evo3 manifold)

Will a 1g heat shield work on an Evo3 manifold?
Should I replace the turbo stud with a bolt? How hard is this?
Will I need new turbo bolts?
If yes to any of this can you suggest best place to get them, or part numbers. I have looked at vfaq and know many of the sites, just sometimes helps to have a more direct answer from people with experience.

Can I easily replace the 1g turbine housing to the 7cm Evo3 without taking the whole turbo assembly out?

Thanks so much for any time/help/advice.

-Badbird

 

[Reverendlimeter]

Can't answer too much about the Evo3 stuff, but I can tell if the hotside of the 14b is cracked internally any hotside replacement is going to help. My 14b was cracked at the wastegate flapper and a 16g actually spools way earlier and harder than my 14b.

Getting your hands on all of the bolts and gaskets ahead of time is a good idea with this job. Bolts breaking and threads stripping can happen with this job. I would go to a fastenal for the hardware, but I do not know the thread pitch and size.

Removing the turbo completely is probably worth it on this job. You will need a couple crush washers for the coolant and the oil lines.

Just some general advice for a job like this, crack open the potential tough bolts first. This would be the down pipe to o2, o2 to hotside, and manifold to turbo. This will give you an idea if any bolts break, or you mutilate threads and need to go get a tap or a bolt.

 

[JusMX141]

If you're on the stock downpipe/exhaust, just port your existing 6cm2 turbine housing *assuming it's not cracked beyond use around the wastegate hole*. Open the "funnel" at the inlet to match the outlet of the Evo III manifold, and maybe port it to direct some of the exhaust flow toward the wastegate hole and that's about all you can do as no amount of porting can physically make the housing flow more than the nozzle area of the housing itself around the radius of the turbine wheel will allow.

The only people who stand to gain performance from going to a 7cm2 housing on a 14B are those going for max performance for drag racing, etc, or someone replacing a badly-cracked 6cm2 housing which is preventing the turbo from spooling as it should. Otherwise, directly-replacing a working 6cm2 housing with a 7cm2 housing on a 14B will cost around 300rpms of spool that you'll never gain back in performance unless you're trying to run 20+psi which is definitely not recommended on a 14B.

Using an Evo III turbine housing will also pose a problem where you could never really connect it to the stock downpipe properly. There are no cast o2 housings that match the Evo III turbine housing outlet and still fit a stock downpipe's bolt spread on the flange...there are aftermarket tubular ones that do, but they will crack eventually and I've never seen a cracked cast stock o2 housing to this day. So your only durable option should you decide to run the Evo III turbine housing is to port your stock o2 housing, which is a major pain in the ass and could never be a full 60mm throughout due to the design of the casting...meaning no matter how much you port a 1G or 2G o2 housing it will never flow as much as an off-the-shelf Evo III o2 housing.

 

[badbird]

I know you can bolt on a 1g, 2g and evo3 o2 housing to stock turbos. My question pertains to o2 housing heat shields, will my 1g o2 housing heat shield bolt onto a 2g o2 housing if I upgrade my stock 1g o2 housing to a 2g?

 

[boostdawd]

I don't believe so. The O2 sensor is positioned differently. It may work with a little cutting and modding. Not a bolt on.