Question on exhaust manifold and exhaust...

[tsi1991awd]

Would it be a bad idea to get an aftermarket exhaust manifold, downpipe, and full exhaust if I'm not wanting to heavily mod the car? And will it affect the backpressure negatively?

I bought my 91 TSI AWD from a mechanic and he said he wouldn't put an exhaust on the car because it will mess with the backpressure. I am wanting just a bit more power and my exhaust manifold has a couple of small cracks in it. That's why I ask about the aftermarket manifolds.

What type of manifold would be good?

 

[MrBoxx]

It depends on if it's a cat-delete downpipe or not. If it is, then the downpipe will extend to the cat-back flange. If it's not, then it should bolt up to the cat. If you're getting it from Punishment Racing, just contact him and let him know what you need. He's pretty good at fulfilling his customers' specific needs.

 

[tsi1991awd]

If I didn't port the turbine housing and just ran the ported EVO3 manifold and the O2 housing with 3 inch DP and 3 inch catback, would it make a difference? Because I am not upgrading the turbo or wastegate or anything else. So would it be necessary? Does just adding the manifold and DP really make it have boost creep and spike that bad? Because its all stock right now and I don't notice anything....

 

[ricktb]

I've upgraded to a tubular manifold, evo 16g turbo, and full 3" turbo back exhaust and hot damn my car is faster than stock for sure, just waiting on my FP evo o2 housing, and the exhaust is wide open. (only engine mods I've done so far)

 

[tsi1991awd]

So you didn't do any of the porting or anything? How is that going for you?

 

[Boosted98gsx]

There is an aftermarket cast manifold made by FP. A little late to bring it to your attention, since no one else did. You wont find a cast manifold that flows better, and it doesn't need to be ported. For 02 housings, I would recommend a stainless mandrel bent replacement, that way, no porting needed.

Forced Performance Turbochargers: FP DSM Race Manifold

 

[tsi1991awd]

That is a nice manifold, but a bit pricey. I ordered an EVO 3 ported manifold, as I said. I should be OK with that, I hope. Thanks for clarifying on the O2 housing...I'm probably picking up the PR one. also can anybody tell me if porting the turbine housing would really be necessary since I'm not upgrading the turbo or anything....

 

[pboglio]

I don't agree FP's manifold flows better. There is something about the midrange torque that I didn't care for with the FP manifold. It reminds me very much of a ported 1g exhaust manifold with the flow divider cut down, except without the spool loss.

Its possible the intense heat loss from my FP manifold was superheating my intake, which it was, as well as causing a power loss from the lack of retained heat in the turbine.

There is something in the collector of the FP manifold I don't like, very little to any flow divider between runners. It might work if the runners were bending into the collector BEFORE they intersect each other. Instead there is a tiny little semi-hemispherical divider that creates the 90* turn into the collector for each runner. I'd have liked to have seen a full division of the 1,4 & 2,3 runners all the way up to the collector/turbine housing mating flange. This is the only place I could see which is causing the problem. Runner lengths are close to the same as stock, port dia and runner diameters seem normal and even better designed than stock. Collector design is the only radical difference and its the one place you don't want to deviate from stock.

Its also likely the reason why the exhaust note sounds "radically" different above 6000 rpm's. I wish they would have copied Mitsubishi.

My FP manifold sits in a box, if it made even equal power to a 2g ported manifold it would be on my car right now.

 

[MrBoxx]

You don't NEED to port the turbine housing. But it's recommended that you do. If you don't want to do it when the turbo is off the car for your mani/O2 swap, then you'll need to take it off again if you experience creep or spike. It's just easier to port it at the same time. But it's just a recommendation. Go ahead and not port it; maybe you won't spike or creep.

 

[BrokenTsi]

So that manifold is basically all I would need? Since it's already ported and all....and I bolt my turbo and everything up to it and that's it?

And on the O2 housing, what would be bad about dumping it?

Also, would this be the recirculated one? eBay Motors: DSM PORTED INTERNAL O2 DUMP HOUSING Talon Eclipse 1g 2g (item 250303448222 end time Oct-09-08 21:23:07 PDT)


Does the lower part of the manifold need to be ported too? The part that the turbo bolts up to....or only the upper portion of the manifold and the O2 housing?

Personally I prefer to dump it. It works better, I love the sound, and its not THAT loud. Just dont floor it near cops.

 

[tsi1991awd]

MrBoxx, just changing the manifold and O2 housing really makes that much of a difference as to make a stock car creep/spike? I guess I will port the turbine housing then......


BrokenTsi, thanks for the input, you have a sound clip?

**Does this turbine housing look like it's ported or is it the same as stock? eBay Motors: DSM ECLIPSE 16G TD05H 7MC2 TURBINE HOUSING TURBO (item 230298804566 end time Oct-16-08 18:56:23 PDT)

I'd rather buy the turbine housing ported if possible because I don't have the tools required to do the job and I can't take the part to the shop because I need my car for work.