Confusion regarding T25, T3 and T4 turbine flanges
Confusion regarding T25, T3 and T4 turbine flanges
People are putting way too much emphasis on the size of the turbine flange (i.e., T25, T3, T4, etc.) without putting any consideration into the structures before and after the flange... The flange is only a connection point... that's it.
The flange sits a couple of inches from the turbine inlet, and the exhaust gases being passed through the flange need to be channeled into the turbine inlet.
If the flange is 3X the area if the turbine inlet, what happens to the exhaust gasses when they get to the inlet. Well, for the most part, they hit a heavy restriction. Now, if the flange is 1.5X the area of the turbine inlet, over the distance of a couple of inches, there is a better opportunity to direct the exhaust flow. Fluid flows respond better to gradual transitions than they do to sharp transitions.
Now, with a header style manifold, you will need a T3 or T4 flange because you are pulling 3 large pipes into one at the collector, and you do not want that transition to be too sharp.
Finally, good luck trying to get a turbo that mates to a T3 or T4 flange on a log style manifold to fit inside the engine bays of our cars.
EDIT: I edited this to make it more brief and directly to the point.
The flange sits a couple of inches from the turbine inlet, and the exhaust gases being passed through the flange need to be channeled into the turbine inlet.
If the flange is 3X the area if the turbine inlet, what happens to the exhaust gasses when they get to the inlet. Well, for the most part, they hit a heavy restriction. Now, if the flange is 1.5X the area of the turbine inlet, over the distance of a couple of inches, there is a better opportunity to direct the exhaust flow. Fluid flows respond better to gradual transitions than they do to sharp transitions.
Now, with a header style manifold, you will need a T3 or T4 flange because you are pulling 3 large pipes into one at the collector, and you do not want that transition to be too sharp.
Finally, good luck trying to get a turbo that mates to a T3 or T4 flange on a log style manifold to fit inside the engine bays of our cars.
EDIT: I edited this to make it more brief and directly to the point.
Last edited by ttg35fort; Oct 11, 2009 at 08:54 AM.
I am open to discussions relating to this subject, but PLEASE do not respond with an "I think..." comment that has absolutley no data or scientific analysis to back it up...
I have fully analysed this subject. I always appreciate contradictary opinions when they are based on fact and/or a true scientific analysis. Unless you have facts or a strong scientific analysis to present, then please refrain from posting. If, however, you are well experienced in thiis area and you see something that I either am overlooking or in which I am incorrect in my interpretation, please post and open it up for discussion.
I have fully analysed this subject. I always appreciate contradictary opinions when they are based on fact and/or a true scientific analysis. Unless you have facts or a strong scientific analysis to present, then please refrain from posting. If, however, you are well experienced in thiis area and you see something that I either am overlooking or in which I am incorrect in my interpretation, please post and open it up for discussion.
Last edited by ttg35fort; Oct 9, 2009 at 07:51 PM.
What is this threads purpose? Different strokes for different folks. If your track oriented then a t25 would be the best option, but when going for serious power you will not find anyone that recommends it over a t3 or t4.
Last edited by thawk408; Oct 11, 2009 at 01:43 PM.
Me likey - there is a lot of win going on in that pic Tom.
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Last edited by GT-ER; Oct 11, 2009 at 06:21 PM.
Depends what your definition of big power is. I don't see a T25 flange/housing being too restrictive up to about 700-800whp...after that I would agree that T3 is the way to go up to maybe 1200-1400whp or so. Heck, I got almost 400whp ( 378whp to be exact ) out of a GT2871R with a T25 housing ( small .64 A/R to boot ) on an otherwise stock 1.8L 4 cyl. Getting twice that out of TWO GT3071R's with .86 T25 housings should be no problem. Then again....I'd shoot at those numbers with T3 housings simply because their is no doubt that they can flow more and there are more options as far as housings go ( gotta love those smooth GT housing ).
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