Turbo flange question - for aftermarket turbos

[Hindsight]

Before I spend all the time fabricating a new collector and ensuring the alignment is 100% right, I'm curious to know if the aftermarket stock-location turbos (like the dominator 1.5 or the 18g 20g etc) have their flanges in EXACTLY the same place and at the same angle as stock. I know that, being stock location, they obviously have to be close enough not to cause any fitment issues in a WRX, but what I need to know is if they are exact. IE if you built a jig that had the input flange and the output flange, would a stock turbo and a stock-location aftermarket turbo line up perfectly to that jig?

Not sure if anyone is going to know this but I need to ask.

Thanks in advance!

[redfogo]

Every turbo is going to be different it will not sit up in the same spot an example is lets say you have a t3/t4 turbo the oil return is going to be about an inch lower then a GT30 turbo.

Larger turbo normally has a larger inlet depending on the size it may be to large so you will have to angle the turbo so the intake goes around the manifold versus through the manifold.

Water lines are a hit and miss sometimes they line up but a lot of times those change spots as well. It just depends on how you end up rotating the turbo to position all your other lines. Also not all turbos are water cooled some are oil only.

Most aftermarket turbos do not have the same exhaust inlet and outlet flange, flange style and position is going to change for every turbo.

Lastly the waistgate internal vs external brand A vs brand B they all have different style flanges. Some may fit in one spot others may not.

You can build a jig for sure to get the overall length and everything, but you will have to adjust it from time to time, just depends on how wild you want to go on a turbo.

If you stick to Blouch Turbos specifically you should be fine from what I have seen. I know the flange style does change from single to twin port depending on the turbo.

[Hindsight]

Thanks for the info redfogo. In the case of the bolt-on turbos, they should all have the same bolt-pattern on the inlet and outlet flange, so I know that has to be the same (otherwise they wouldn't be considered a bolt-on turbo) so they can bolt on to the factory up-pipe and down-pipe, but what I don't know is if the flanges themselves are in the EXACT same location. I know they will work with the factory up/down pipes but obviously there is a half inch to an inch or so of room for things to move around before it causes an issue in the WRX, but even 1/4" may cause me an issue on the 818.

[STiPWRD]

I'm running the 18G and the exhaust flange locations seem to be exactly the same as the stock TD04. There's plenty of clearance for the wastegate actuator arm and the brackets that bolt from the up-pipe flange to the cylinder head for stability fit where they should. However, the two water fittings and the oil fill line were different than stock. The oil drain line was same as stock.
49489

[redfogo]

Thanks for the info redfogo. In the case of the bolt-on turbos, they should all have the same bolt-pattern on the inlet and outlet flange, so I know that has to be the same (otherwise they wouldn't be considered a bolt-on turbo) so they can bolt on to the factory up-pipe and down-pipe, but what I don't know is if the flanges themselves are in the EXACT same location. I know they will work with the factory up/down pipes but obviously there is a half inch to an inch or so of room for things to move around before it causes an issue in the WRX, but even 1/4" may cause me an issue on the 818.

Its really going to depend on the turbo for sure then. Some are going to have larger compressors on either side so the housings are going to be taller how much depends on the turbo. As another example on a different set up I used a ford style 5bolt flange on a t3/t4 50trim turbo with T4 flange on the bottom. I got the same set up on a Gt30 and everything moved up about 1/4 of an inch. This made everything moved up a bit so I had to buy a longer oil feed line. The oil return line was hell: it moved up and back further because the turbo sat farther back then forward, exhaust housing was just a bit larger.

Blouch I'm sure could answer your question though a lot better. I am just talking about my experience with it and a few other cars i have worked on with turbo upgrades and such.

[Aero STI]

Thanks for the info redfogo. In the case of the bolt-on turbos, they should all have the same bolt-pattern on the inlet and outlet flange, so I know that has to be the same (otherwise they wouldn't be considered a bolt-on turbo) so they can bolt on to the factory up-pipe and down-pipe, but what I don't know is if the flanges themselves are in the EXACT same location. I know they will work with the factory up/down pipes but obviously there is a half inch to an inch or so of room for things to move around before it causes an issue in the WRX, but even 1/4" may cause me an issue on the 818.

The factory replacement Subaru turbos are pretty close when it comes to exhaust side locating. The downpipe is rigidly mounted to the turbo and the trans in the car, so there isn't much wiggle room. I think it would be 1/4" or less.

[Hindsight]

Ok thanks guys.

[DMC7492]

I am using the Blouche td05-18xt. The inlet is bigger than stock and the intake manifold needed to be modified for clearance of the clamp