View Full Version : kind of an odd question... t25 / k04 question

05-31-2010, 08:43 PM
k i currently am running an atp high flow exhaust mani, and i am curious how the sizing compares to a t25 flange. i assume that the t25 is bigger, which is why you can get more hp out of a gt2860rs full frame than the elim

05-31-2010, 08:49 PM
The stock flange is a rather rare flange that only exists on Audi and Porsche's, for all I know (could exist on a couple more). The T25 flange is a rectangular flange that is smaller than the T3 (same rectangular shape). The different flange sizes grants different ride and different spool. T25 will grant a quicker spool, but is more restrictive when you want to push more air (exhaust fumes) in the upper RPMs through the flange. The T3 has a slightly later spool, but offers greater top end power.

The reason you can get more hp out of a full frame GT2860RS has a couple reasons behind it. One, is the exhaust housing is non-negotiable (not that I know the difference between a GT28 exhaust housing and the eliminator exhaust housing, but someone else does). Another, is that the compressor inlet for a full frame setup is a full 3". You can not pull in as much air as you would like to with an eliminator setup as you could a full frame GT2860RS (one reason people will swap a full frame compressor housing onto an eliminator turbo and just customise from there for an upgrade). This one makes a huge difference. If someone could actually post the accurate dimensions of cubic square "whatever" of the inner diameter of the t25 flange and the stock flange, then that too would be helpfull information to answer your second inquiry.

05-31-2010, 08:53 PM
so gt2860rs t25 exhaust mani w/ full frame > same turbo but elim w/ atp high flow exhaust mani?

05-31-2010, 09:01 PM
In a nut shell, yes. But they are not neccesarily the same turbo (eliminator is a tweeked GT28 something to fit the stock flange of our vehicle). Talk to a real tuner, and they will be able to tell you the differences (exhaust housing and compressor housings are different. then I don't know about the internals). But the tuner would more than likely tell you the same thing they tell me. They don't consider the eliminator a real turbo. It's really limiting.

For example, look at the k04s for the B5 S4. If you look at the exhaust housings of a PJ K04 and a RS K04. It may be a bad example, but that's all it is. Even though they may "seem" to be the same, they really aren't.

05-31-2010, 09:04 PM
so id be better off with the full frame? I just have two options locally for same price, and am curious which to go with... elim would let me keep my current test pipe and exhaust and apr intake hose and and and and... ya know. and if i go with the full frame i will have to do a lot more work, but im sure itll be worth it XD

Well this then leads into my next question. which of these gaskets will be best for me? does it REALLY matter if i spend $20+ (after shipping) on the gasket, or will the stainless $3.99 one be just as good? I dont really give a shit about the money, because its only about a $10 difference regardless, i am just curious if they will be exactly the same.





05-31-2010, 09:18 PM
Just like the next, I am going to tell you to NOT purchase anything from ATP unless you absolutely have to. They have just about anything you will ever need for customization, but they have a bad rep. And any metal gasket should work, but I would still purchase it from a reputable company (ie Intergrated Engineering, 034, CTS Turbo, etc). STAY AWAY from ebay when it comes to gaskets, uless they are from ebay stores such as Sumitt Racing, Integrated Engineering, etc. If you are wondering if they are the same, they aren't. Don't expect an ebay gasket to fit perfectly like one from say..........034 Motorsports. And as I previously stated, try to stay away from ATP if possible. Quality control is one of the reasons they have bad rep, and don't be surprised if a gasket does not line up exactly like an ebay one won't. Not saying that that will happen. But I am also not saying that it won't.

And really, there isn't much more entailed when going full frame. Just a tad more couple things. You would just now need a custom downpipe (full 3" is better anyways for a dp on this turbo application) and custom intake.

Edit: It's ok to skimp on things. I do it all the time. But there are just some things you just don't skimp on. It ended up costing me more in the long run on some instances, but it's a learning experience. That is one reason I know about the ebay gaskets not matching perfectly. Whether that be the ID of the flange or the bolt holes (simply being off, too small, or too large)

05-31-2010, 09:28 PM
yeah custom intake comes with it.

i know you might say this wont work cause its too quick of a bend, but the car runs really smooth. no hesitation or anything, and pulls reallly hard (for this turbo)


05-31-2010, 09:41 PM
The larger the turbo, the more air it pulls in through the intake. So, you should be able to get away with an intake like that with a GT28RS. Would I personally do it like that if I were to make one? No. But hey, if it works then it works. And be cautious when purchaing kits like that. You just don't know about the issues (driver's know much, and won't disclose that info that won't even be noticed by others) it may have. And what manifold is that?

FWIW, I plan on having a GT2860RS put together by next summer. I was planning on doiung a real BT with built engine when the car gets up there in mileage, but I hardly drive (besides, I'm broke[:(]). And a GT2860RS would be rather perfect for a dd. I will be colecting parts over the next year, but will be buying most parts brand new. Just saying, that kit seems rather finikey.

05-31-2010, 09:52 PM
its from a company called boostfactory. they are now out of business but i have ridden in this car, and it started up perfectly, and the idle didnt bounce or anythign funny and god a good long ride with dd style and also hard driving and it performed a lot like my car does (flawlessly) so i guess i couldnt be happier. plus he is local, and seems like a very straight forward guy (but you are right who knows.)

can i ask how you would do it? i mean i can always start out like this, then tweak things the way i want when i get the time

05-31-2010, 09:53 PM
Just saying, that kit seems rather finikey.

what kit?

05-31-2010, 10:16 PM
^The kit on the car. But Boost Factory is a reputable company, as far as I know. The person whom owns Tyrol Sports is a member on this forum baord, if you ever come across that site.

If you want my real advice, I would suggest you peice together your own kit from scratch (ie don't even consider the ATP kit). Even if it takes you a couple months to do so, this would still be the better route. Just make sure you choose your parts wisely. And install it yourself. It's a learning experience.

06-01-2010, 06:52 AM
this isnt a kit by any means. it was all stuff he pieced together. pm'd