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Old 03-23-2008, 04:27 PM   #1
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Question Turbine housing question

Okay my new manifold is T3 based so my next turbo will have a T3 turbine housing, but in selecting turbine A/R, I had a question, hoping that someone out there has some input based on experience rather than just theoretical numbers as it is next to impossible to find a turbine map for a GT wheel inside a T3 housing. Info to follow:

I will be using a GT2871 turbo for my next setup, BUT I will be getting the T3 turbine housing option. So considering that the T3 turbine inlet is 136% greater than the T2 inlet (38mm x 49.3mm vs. 44.7mm x 57.2mm from Garrett catalog) and considering that the turbine wheel is the same regardless of selected housing, I was wondering if anyone had any comparisons between the different A/Rs T2 vs T3 housings.

For example, I know that on Brad's ~1.7L his T25 0.64A/R turbine housing spools to ~15psi at 4400rpm based on his MS datalogs (with a boost leak no less) so I was wondering will the 0.48 A/R T3 housing be comparable or too small/restrictive or will the 0.63/0.64 T3 housing be about the same.

FWIW, I'm shooting for ~325-350rwhp and would like the broadest powerband possible (aka early spool, relatively speaking) so if the 0.48A/R T3 housing would still make it to 350 and provide earlier spool, I'd opt for that, but if it's going to choke off the top end then I'd go bigger.

Sure, I could just go with the 0.64A/R, but if the 0.48A/R can get me to my goal AND give me an extra 500+/- rpm of spool, then even better. Granted this may be mentally masturbating over a very small detail, but it's all about selecting the "right" turbo for your goals and the devil is in the details.
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Old 03-23-2008, 05:33 PM   #2
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how much are the turbine housings? maybe you can buy one and then later get the other housing.
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Old 03-23-2008, 05:38 PM   #3
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Originally Posted by y8s View Post
how much are the turbine housings? maybe you can buy one and then later get the other housing.
Yeah, I thought about that as well and new housings are ~$150-175 + shipping and then ceramic coating it is another ~$50 or so. Granted that's always an option but it's also an extra expense and effort that I'd prefer not to go thru.

Also forgot to mention, that the 0.48A/R option only comes on the 4-bolt T3 housing whereas the 0.64A/R option comes on both the 4/5 bolt housings. Not a big deal, but the 5-bolt leaves the T3/T4 replacement/upgrade/options open in terms of changing turbos later.
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Old 03-23-2008, 06:05 PM   #4
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From my reading, id go with the .64a/r, espically with a 2871, thats a somewhat small turbo.

Just FYI, my T3 has a .64 a/r houseing, and I get full boost (10 psi) at 3750 rpm in 3rd gear.
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Old 03-27-2008, 04:13 PM   #5
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I got your PM, and I don't have any hard data for you. My gut says to go with the larger housing, unless you are using an external wastegate, in which case a 40mm wastegate and the smaller housing could make it viable to make plenty of power while not constricting flow terribly. This is where a larger external wastegate and bring some balance to the equation.

Mark

PS - the 38 mm external wastegate may flow enough as well.
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Old 03-27-2008, 04:20 PM   #6
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from what i can determine, the .86 a/r t25 housing is comparable to the .63 a/r t3 housing. both have max efficiency at 21 lb/min. that being assumed, the .63 a/r t25 housing and .48 a/r t/3 housings should be comparable as well at 16 lb/min. doing the math with a 1630cc motor and 8500k, that puts you at 14-15 lb/min of exhaust flow.....
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Old 03-27-2008, 04:54 PM   #7
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Quote:
Originally Posted by brgracer View Post
Yeah, I thought about that as well and new housings are ~$150-175 + shipping and then ceramic coating it is another ~$50 or so. Granted that's always an option but it's also an extra expense and effort that I'd prefer not to go thru.

Also forgot to mention, that the 0.48A/R option only comes on the 4-bolt T3 housing whereas the 0.64A/R option comes on both the 4/5 bolt housings. Not a big deal, but the 5-bolt leaves the T3/T4 replacement/upgrade/options open in terms of changing turbos later.
All 3 of my .48 housings on the shelf are 5-bolt, so where did you get your info from?
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Old 03-27-2008, 04:56 PM   #8
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is for t25 turbine (54mm vs 59mm). i assume ATP gets them machined specifically for such.
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Old 03-27-2008, 04:56 PM   #9
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I have an extra .48 housing with a big ol f'n crack in it, if you want to get the .63 and then want to try the .48 it is in good enough shape to run a while to see if you like it or not. It's standard 5 bolt.
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Old 03-27-2008, 05:05 PM   #10
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Are you going to track this car? If you are, go with the larger turbine because it should help reduce underhood temps a bit.

I intended to buy a t3s60 with the .63 turbine but the company I bought from was out of the .63 turbines so I had to go with the .48. I plan to "upgrade" to the .63 some day.
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Old 03-27-2008, 05:08 PM   #11
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If Tom can run his turbine at max efficiency without choking out, more power to him (figuratively speaking).


I run a .48 myself. My engine produced 13 lb/min of airflow volume out my exhaust at 7000RPM. no reason to rock turbine designed for max 21 lb/min when the .48 is maxed at 16 lb/min.....


it's one of those compromises, while the .63 will probably produce more power per psi, it will spool slower coupled with his tubular manifold and produce a torque curve he doesn't want. If the .48 can satisfy his power goals and reduce the spool 500rpm, then again more power to him.
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Old 03-27-2008, 06:56 PM   #12
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Thanks for the offers and info. As for the 0.48 A/R only being offered in the 4 bolt T3 housing, that's the only way ATP offers that A/R for the 2871.

If I had a 1.8L, then without hesitation, I'd rock the 0.63/0.64 but considering the 200cc less displacement + longer runner tubular manifold + turbine flow estimates based on other T3 turbos, I think that the 0.48 will be better matched for my goals. From further research, I'm pretty sure a 0.48 A/R T3 turbine housing should flow very similar to the 0.64 A/R T28 turbine housing. So if Brad got 15psi at 4400rpm with the 0.64A/R T28 housing then I should be in a similar ballpark. Sure max power can be fun but so is spool/max boost before 5k rpm, regardless of redline. Granted if I was shooting for 375-400, then I would go larger, but my power goals are more modest.
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Old 03-28-2008, 09:40 AM   #13
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If you are getting a mani made from scratch, to me it seems easier to get a standard T2 turbine, that way you know what the flow rates are or at least it would be less of a guess. Why go to a T3? If a .48 T3 flows like a .64 T2, they why not use the T2 and simplify things?
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Old 03-28-2008, 09:53 AM   #14
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Quote:
Originally Posted by TurboTim View Post
If you are getting a mani made from scratch, to me it seems easier to get a standard T2 turbine, that way you know what the flow rates are or at least it would be less of a guess. Why go to a T3? If a .48 T3 flows like a .64 T2, they why not use the T2 and simplify things?
Agreed that T2 footprint would have been easier, but either the manifold was already partially made/assembled or he already had all the materials, but it was being sold as a T3 manifold with extra cost to adapt to T2, and it didn't make sense to do that to me since ATP had T3 housing options available. Not 100% sure, but what's done is done.
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Old 03-28-2008, 10:26 AM   #15
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t3's are bomb....now its easier for him to upgrade to a 3076 or a t3/t4.
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Old 03-28-2008, 10:46 AM   #16
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Quote:
Originally Posted by Braineack View Post
t3's are bomb....now its easier for him to upgrade to a 3076 or a t3/t4.
Yeah that's true. Seems to me to be a lot of serious coinage to be dropping on a kinda unknown combo (2871 + .48T3). If tom picks it right, it'll be sick though!
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Old 03-28-2008, 10:56 AM   #17
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says mr two gt15s.
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Old 03-28-2008, 04:45 PM   #18
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why not just use a 60 trim or even a super 60?
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Old 03-28-2008, 04:50 PM   #19
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he's looking to make OVER 300rwhp...s60 would be reaching limits at 270-300rwhp.
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Old 03-28-2008, 04:55 PM   #20
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a 60-1 or sc61 would get him over 300rwhp wouldn't it? whatever term you want to call it anyway.
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