I've been wondering for a very long time...what's the technical term for the 2 and 3 bolt flanges that are on the inlet and outlet of some compressor housings?

I've seen identical turbos with those flanges and with the machined tube fittings, yet I don't think I've ever seen any options to choose between the two when purchasing a turbo.

 

I haven't ever seen them called anything other than a 2-bolt inlet or a 3-bolt outlet. If you see a turbo advertised as a direct drop-in upgrade for a Nissan OEM turbo, that usually means it will have those flanges. Garrett sells a bunch of different 2871 turbos and you can get them with either that pattern or the bare slip-on style (and different wheel combinations) depending on part number. You can also buy adapters for the 2 & 3-bolt flanges, so there are options to deal with either.

 

Thanks for clearing that up. It sounds like Nissan used those flanges to bolt right onto the intake piping...it's probably a better connection than a worm clamp, especially when used at an OEM level.

I've seen the adapters, but I'd imagine it could create some spacing issues just from the bulk of the flanges.

 

dsm's and generally older cars also have them.

Most newer cars don't though, so I don't really see it being "better" imo.

And there's always tbolt clamps. You don't have to suffer with worms

 

Do newer turbo cars use t-bolt clamps on their piping? If not, then what? I haven't taken apart anything turbocharged made in the last decade.

It also brings up another question: It seems like most everyone has issues with turbo-to-downpipe nuts loosing up after track use or whatever on their aftermarket setups, yet I've never heard of this being an issue for the OEMs. I mean, look at those fancy Stage 8 locking fasteners FM recommends...I can't see manufacturers using something like that.

 

The turbo to downpipe connection/bolts aren't usually the problem; the turbo to exhaust manifold flange connection & bolts can be problematic on cars running boost for extended periods of time (e.g., track cars running boost). Oversized studs made of more durable alloys (iconel) combined with oversize SS safety wire (to prevent loosening which creates more stress) seem to help with this. Not really an issue if you are running moderate boost on a street car.

 

The GT2560R's from FM have the flanges machined off, I think BEGI just welds a piece of pipe to the flange area. At some point (maybe still) FM/BEGI sourced these turbos from Limit Engineering who did the machine work. Many years ago I got my 2560 directly from limit with these flanges machined into 2.5" inlet and 2" outlet. It does make it a little easier to fit things, but I had to pay extra for it. At the time I didn't know where to get the pieces that bolt to the flanges. Now you can get them from ebay or ATP in all sorts of sizes.