T-4 divided flange.
Why would you want to remove it? Cutting it back slightly and knife edging (dull knife edge anyway) it is what I've seen the "pros" do to help with laminar flow. I don't see how porting the inlet does anything? The exit volute diameter remains the same. It would be similar to running a larger hotside than necessary pre-turbo. It isn't going to change back pressure, just slow down the air. Thats the last thing you want to improve "spool-up".
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From: Lombard .IL
I can't see how it helps for max performance. Always looking for a edge. I have to run the t 4 to be legal in my class with a weight break. The inside of the housing is rough, thought it would help to smooth it and remove that divider?
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I've ported and about completely removed the divider in my 1.25 Divided T4 housing. Not sure how much it was worth but single T4 76mm @3420 lbs went 171.xx mph. Still has some power left in tune I think.
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Everywhere Ive read, says the twin scroll comes from them being based of the diesel world where each scroll is fed by a different bank. I see no need for a twin scroll in a twin turbo application. Inst that why Tial made v band inlets?
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From: Norn Iron
This is much easier to do on a 4cyl motor than it ever will be on an 8cyl motor, but some say isolating each cylinder bank on a V is helpful too....I dont really see it other than perhaps if it helps maintain gas velocity using smaller tubing for each bank.
Tial made V band inlets so people could install their turbos with V-bands for easy fitting/removal.
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i don't know why on earth you would cut the divider out of a divided flange... just buy a undivided flange? Why did you buy a divided flange if you have a single scroll turbo to begin with? Maybe i'm missing something?
As I understand it:
A T4 divided flange should flow the same as a T4 undivided flange. The exhaust volume the motor produces under WOT is a relatively consistent scale. The restriction is the turbo, not the flange. So increasing the size of the flange or pre turbo piping will just slow the velocity of the exhaust down resulting in slower spool.
As stevieturbo (sort of) said, the whole point of a divided flange is to run a twin scroll turbo. The whole point of a twin scroll turbo is to group cyl's together by valve event so back pressure from one cyl isn't breathing into another cyl as the exhaust valve opens thus reducing back pressure, allowing the motor to rev faster thus spool a turbo faster...etc. Same basic principal as long tube headers on a non turbo motor, keep the cyls isolated
As I understand it:
A T4 divided flange should flow the same as a T4 undivided flange. The exhaust volume the motor produces under WOT is a relatively consistent scale. The restriction is the turbo, not the flange. So increasing the size of the flange or pre turbo piping will just slow the velocity of the exhaust down resulting in slower spool.
As stevieturbo (sort of) said, the whole point of a divided flange is to run a twin scroll turbo. The whole point of a twin scroll turbo is to group cyl's together by valve event so back pressure from one cyl isn't breathing into another cyl as the exhaust valve opens thus reducing back pressure, allowing the motor to rev faster thus spool a turbo faster...etc. Same basic principal as long tube headers on a non turbo motor, keep the cyls isolated
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From: Norn Iron
For your first questions...I've no idea why people buy housings they dont need.
A T4 divided flange with a larger number will flow the same as an undivided with a smaller number. From what I understand the divider simply takes up space in that respect making it flow less.
Whether the restriction is the "turbo" or not....bad wording. The restriction is either the turbine wheel, or the turbine housing.
Sometimes there just seem to be more divided housing options so I guess if you want much larger you'd need to opt for the divided housing, and larger again, machine that divider away altogether.
A T4 divided flange with a larger number will flow the same as an undivided with a smaller number. From what I understand the divider simply takes up space in that respect making it flow less.
Whether the restriction is the "turbo" or not....bad wording. The restriction is either the turbine wheel, or the turbine housing.
Sometimes there just seem to be more divided housing options so I guess if you want much larger you'd need to opt for the divided housing, and larger again, machine that divider away altogether.
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From: Lombard .IL
Twin scroll is largely about isolating valve events in the pipework to reduce effects of backpressure re-entering the cylinder.
This is much easier to do on a 4cyl motor than it ever will be on an 8cyl motor, but some say isolating each cylinder bank on a V is helpful too....I dont really see it other than perhaps if it helps maintain gas velocity using smaller tubing for each bank.
Tial made V band inlets so people could install their turbos with V-bands for easy fitting/removal.
This is much easier to do on a 4cyl motor than it ever will be on an 8cyl motor, but some say isolating each cylinder bank on a V is helpful too....I dont really see it other than perhaps if it helps maintain gas velocity using smaller tubing for each bank.
Tial made V band inlets so people could install their turbos with V-bands for easy fitting/removal.
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From: Norn Iron
TBH I considered it on mine....but if anything it would probably have made things more awkward.
I can just unbolt turbo/manifold as one piece very quickly. It'd be far harder and pointless to unbolt the turbo.
But V-Bands definitely are great and does put the whole divided scroll aspect in the bin for those wanting to use them
I can just unbolt turbo/manifold as one piece very quickly. It'd be far harder and pointless to unbolt the turbo.
But V-Bands definitely are great and does put the whole divided scroll aspect in the bin for those wanting to use them
Last edited by stevieturbo; Jan 8, 2016 at 05:10 AM.
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I'm not sure how picky your sanctioning body is on "grey area" rules but why not take your current t4 housing, chop off the flange, and weld your vband of choice on. It's still "technically" a t4 housing just with a different flange. I doubt it would be allowed but it doesn't hurt to check.
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From: Lombard .IL
I'm not sure how picky your sanctioning body is on "grey area" rules but why not take your current t4 housing, chop off the flange, and weld your vband of choice on. It's still "technically" a t4 housing just with a different flange. I doubt it would be allowed but it doesn't hurt to check.