legacycentral bbs

I'm not looking to do anything fancy on my Leggy. It has a JDM WAIC, fuel pump, 3in catback, and an Apexi intake. There's not smoke from anything so there's no hurry to replace or upgrade stuff. I want to play with this and learn from it.

I'll be swapping a 3in downpipe on soon. It currently makes 6psi on wastegate. Will that intake pressure go up or down with a catless downpipe replacing the catted one? I would think boost pressure would drop, but then I read about spiking and boost creep with downpipes.

I was thinking too big with a 20g turbo. The TD04 and TD05 caught my attention and you guys appear to really like them. Which one is better? I figure it will be a cheap enough turbo to pick up used. 180-200hp is a modest enough goal on wastegate.

Third, I want to port match the exhaust manifold just for shits and giggles. I've never done it to a turbo car, but it looks like the stock stuff needs some love like the n/a stuff. WRX guys rave about port matched stock headers. How do T-legs do?

Boost pressure shouldn't change much with the turbos you're looking at. The boost creep problem tends to happen with turbos whose wastegates are mismatched to the compressor, and even then it's usually because of the switch from a flat(-ish) plate to a bellmouth.

I personally like the TD05. The bigger exhaust housing really seems to let the engine breathe better and I like the driveability off boost. I don't think anybody could say for sure which turbo is better, though -- it's just what you like. Either one ought to be able to get you to your goal.

I have a tdo4 and like it.My goals are for more than that but for now it is nice.The spool is fast and it works beyond what the stocker will do.I would really like to try a tdo5 but i think if i get another turbo i will just save for a vf series unit....anyways get a td04 and be happy!


BTW: i dont think port matching is going to net you anything noticeable until your power levels are much higher,besides its not like subaru does a bad job of making their openings match up to begin with.

180-200 WHP (not crank/flywheel) @ WG pressure sounds unlikely w/a TD04. I'm close to 180 w/my 17psi and Revtronix Stage 2 TD04 chip.

Everything I've read so far states the TD05 spools later than a TD04 (but it IS worth it), so depending on how you drive and what tranny you have it may be a consideration....the TD05 is a LOT more $$, as well. I paid $140 for a <10K TD04; $250-ish for a TD05 w/about 60K (hope to install in the next week!).


The 3" bellmouth downpipe can cause boost creep. My TD04's 10psi wastegate increased to 12-ish, which has occurred w/others I've read about it too.

How well do the TD04/05s mate up to a JDM WAIC? I'd get the TD05. Another $100 for the extra performance isn't a bad deal.

I've been eyeballing a bellmouth downpipe. A used Invidia looks fairly common. Skyhigh dyno numbers aren't my goal at all. After doing more reading here, 14sec 1/4s aren't unreasonable from just basic upgrades which it has most of.

I'm trying to match everything else that's already on it. A new factory turbo, better downpipe and a little bit of labor looks to be damn good bang for the buck. Porting the wastegate on the new turbo is doable. I lay this stuff out with good plans to save on labor. I pay just as much attention to the order of things as much as the parts that go on.

This car has a couple of tankfuls of high ethanol blends already, BTW. I can watch the IDC on the AVCR and it hasn't gone above 70%. 440s are all it needs, really. It doesn't need 550+ like a newer turbo car. A little bit of creep on the gauge doesn't really worry me with a better fuel on board. Does porting the wastegate stop that creeping or give any better response? Spikes worry me more than a little creep on the gauge.

ImprezaRSC wrote:How well do they mate up to a JDM WAIC?

No experience, but the TD04/TD05 have a straight outlet and the the VF11's is clocked.

I'm trying to match everything else that's already on it. A new factory turbo, better downpipe and a little bit of labor looks to be damn good bang for the buck.

A new VF11 is $1,000+ online @ 1st Subaru Parts...is that what you have now?

It has the stock turbo on right now and it does okay. No smoke, no spikes, no creep.

"New/used" turbo is what I meant. It doesn't look like anything is a perfect replacement for the stock vf11. I was sticking to the right size/price moreso than a specific turbo type. Newer stock turbo stuff looks like the best options for price. Is there a direct fit upgrade? Searching didn't turn up anything that was a perfect match.

If you are looking to get into something larger than what the Revtronix chips cover, you are talking a lot more money. Some sort of piggy back or standalone plus tuning if you can't handle it yourself. That adds $1-3k to your plan. A 20G is nice, but there are lots of other odds and ends that need to be covered. Clutch, injectors, and a host of other things.




Do not hog out your exhaust ports to match the manifold. That step in size is there for a reason, as it prevents reversion. It may help up top, but your low can really suffer. People make 500whp+ with the factory manifold and other heads, so work on other restrictions like your turbo and exhaust before things like that.

If you get a TD04 or TD05 from an EJ20G model (i.e. one that has an elbow on the compressor inlet), it fits perfectly with the air/water intercooler. Right now I'm using a TD05 from a 93-96 Impreza STi with a stock air/water intercooler (with its stock plumbing).

I don't even know where to find those older turbos in good condition. Aren't they all imported? I can get a cast 90 degree elbow if needed. It's the outlet not mating up with the intercooler that worries me as far as a turbo upgrade.

I DO NOT WANT a "large" turbo on this car---Just something a bit better than the stocker that's on it.

Yes, they're all imported. None were sold here in North America originally.

If you're willing to do some work to make the inlet fit, then it sounds like a TD04 from a recent WRX would fit the bill nicely. It's still a small turbo, but a little bit better than your stock turbo, and its outlet will mate right up to the air/water intercooler's stock pipe.

I don't mind getting an elbow for the inlet. It was the clocking issue that worried me.

What IS good and torquey for about 1 bar? Should I get the TD04? I'm looking for a wider torque curve and decent spool.

Before getting to the turbo upgrade, some bigger issues needed to be addressed. I ordered the pressure sensor needed for the AVCR. It should be here midweek. Wastegate boost is getting old...

It's as comfy and spunky as a stock RS, IMO. Preserving that while upping the performance a bit is what I'd like from the car. If I'm lucky enough to get it quicker than a stock WRX, then that's fine. This car definitely has its own learning curve. The turbo upgrade will come a bit later.

For now, I'll keep all my misadventures, crazy ideas, and progress contained in one thread :p. I didn't want to get too crazy with the car without learning more about it first. The mods it has are mild enough to keep me out of trouble and still have some fun. It likes mild ethanol blends so far, but I haven't been able to up the boost into the sweet spot. 5th gear pulling uphill leaves a bit to be desired.