Let's Talk Uppipes
 

I received my downpipe today and before I installed it followed up on information I heard regarding uppipe install and needing to pull the downpipe to install the uppipe. (Thus I decided it would be a better thing to do them at the same time). :)

I am seeking your experiences and opinions on uppipes.

Flex or no flex?


Install a beyotch? (I love a good challenge and most times can do this stuff provided I have clear instructions).



Thanks

Okay. I went with flex only after hearing Scott's horror stories. With the MRT flex, Evan and I got it in within 4 and a half hours. This was with downpipe.

Install is a royal pain in the ass, but we didn't run into any snags. We used the idea of jack the engine up out of the engine bay.

Re: Let's Talk Uppipes
 

What year is your car again? '04+ have no cat in the uppipe which was the biggest reason IMO for doing the swap on the '02 and '03s. You might not want to bother since the OEM pipe fits really well, and has the heat shielding. Remember, the more heat you keep in the exhaust before the turbo, the more thermal expansion there is to spin the turbo!

That said, uppipe installs aren't too bad if you've got good instructions. The biggest thing to do is plan ahead, and know exactly what you're going to need to do so you'll have the proper tools. A O2 sensor socket would really help (I was never able to find one...) and a 14mm angle joint socket and 14mm crow's foot socket are clutch. Patience and Liquid Wrench are your new best friends. Make sure eveything's nice and cooled off, then soak all the bolts you'll need to remove in LW and wait. Take your time so you don't strip any nuts or shear any studs.

The STIs are the only 04s with no cat in the uppipe. The 04 WRXes definitely still do (at least mine did). For a 4eat driver, it's by far the best mod you can do.

Yeah, AFAIK only STis and Foresters are lacking the pre-cats, and I'm not positive about the Forester.

Re: Let's Talk Uppipes
 

All USDM WRX's have a cat in the uppipe. The STi does not. Mine definately had one.

Okie. I just remember all the hoopla about one of the changes for '04 was the inclusion of a better O2 sensor so the up-pipe cat was unecessary. I guess that was a load of bunk?

I would vote for that new cast tapered up-pipe I think Tyson found, but now I can't find his post about it...

I wouldn't. It's cast, which means non-flex, which means thermal expansion and contraction will cause leaks, and it's tapered, which, although I admit I've seen no data, doesn't sound productive in the least to me.

nope only part of it is cast.

the other part is flex, OMG.

link ownz j00!

http://www.airpowersystems.com/wrx/m...pe/up_pipe.htm

Damn that thing looks cool. And, with the flex it *probably* won't cause leaks, although I wouldn't be happy about having a second 2-bolt flange in the system. Also, the tapered part is snake oil- the end "...matches the standard WRX and STI turbocharger entry port and stud pattern and is therefore suitable for use with the stock TD04 Mitsubishi turbocharger..." That's nice, but it just means that the upstream end is larger, which doesn't help you at all really, since the OEM and most replacement uppipes are the proper diameter at the turbine end as well. But hey, it's APS, so at least it's really expensive. ;)

OK, I do no know what diameter the end of the headers are vs. the turbo inlet, but assuming the inlet is smaller, a smooth taper is going to create less turbulence than just about any other shape, especialy a butt joint reduction. I also really like the design of the flex section with the internal solid section. As long as the alignment at the far end is pretty close, it will probably create less turbulance than a standard unlined flex section.

Good flow is not snake oil. What bothers me is that even though they claim 2 years of testing, where is the data from that testing... But at least they claim to have done testing. I'm not sure any of the other up-pipes have undergone much of any testing...

come on you set yourself up there.

I thought both ends of the uppipe are the same diameter?

The idea behind a taper is that you increase the velocity of the exhaust gasses as they approach the turbo for faster spool. However, if the headers already have the same size pipe, then I don't see where they're tapering from.