legend4life

The .63ar T3 flange is equivalent in flow to the larger .86ar T25 flange. The .64ar T25 flange's T3 equivalent would be a .48ar T3 housing. The .82ar T3 is significantly larger and will be much laggier than the one you drove.

The equivalent T3 version would spool and flow similar, but have better boost control and improved turbine efficiency from an external wastegate that doesn't interfere with turbine flow.

What are the details of the motor/build and what are your goals for the setup? Define power level, rpm powerband, spool/response required, fuel available, primary usage, etc.

Markp

^--- Pretty much what I would have said. I am using the .82 on my T3 next, I will let you know how laggy that is compared to the previous .63 housing. I have a huge freaking turbine on the miata now, and if it won't spool naturally, then the NOS will fix that problem. I pick it up on the 21st of Dec from Corky's place.

Mark

Bochinam

Thanks Legend for putting the T25 & T3 flanges into perspective. The complete details of my motor / build really belong in another thread, I've already done enough hi-jacking here. In a nutshell, I'm twincharging using an M45 on the coldside and a small T3/T4 (.48 turbine) on the other. The block is a Racing Mazda 1.9L. The existing turbo is too small. It spools violently during the compound phase, then it's all over by 5K. In a nutshell, I need to target the turbo for the top half of the RPM band. 300~350whp goal. I have no experience with the "new" GT series turbos and jumped on this thread when Maz said he drove a GT3071.

Thanks Mark, let us know how that .82 spools...or doesn't.

J

Markp

I didn't realize you were still twincharging... in that case, just grab one of these Ebay specials and try it on for size. I think you will be blown away by how badass it is in a twincharged setup.

http://cgi.ebay.com/ebaymotors/T04E-...QQcmdZViewItem

For $200 delivered to your door, it's sick and it will make 300+ RWHP with ease.


My current turbo has the turbine below with the compressor from above. Don't believe that ebay site when it says the below turbo is a 600 HP turbo, it's not it has a smaller compressor that the T3/T4 above, it does however have a huge *** turbine.

http://cgi.ebay.com/ebaymotors/T-70-...QQcmdZViewItem

Amazing that you can play swaptronics with cheap chinachargers.

Mark

MazDilla

iTrader: (7)

Bochinam, no need to apologize for adding momentum to the thread with relevant questions/info.

I am beginning to shift from lurking mode to active Q & A. It will be at least 6 mos. before I begin my install. I have a 97 Miata, stock 99 engine, ACT XT clutch, 6-Speed, 3.9 Torsen, and FM/PWR Twincooler. I have a spare short block ready to build up with a set of CAT forged rods and SuperTech 8.6:1 forged pistons. I plan to run 10psi on the stock motor for a while and take my time on the other block, maybe pickup a spare head as well.

My end goal is 300 RWHP daily driver on 91 octane. I take the car to the track (road course) 3-4 times a year, that's where I plan to enjoy this turbo. My commute is slow and mundane so I don't mind if the turbo never crawls out of bed on the way to work. And yes, I have a back-up car just in case, but its a POS and I won't drive it unless I have to.

I want to be fully spooled by 5k. I intend to spin the built motor to 8k. Will the T3 .63ar/60mm wheel combo get me to 15 -17 psi by 5k rpm?

Markp

The first turbo I referenced for $200 did everything you just asked for. It's a T3/T4 50 trim compressor with a .63 A/R turbine. Fully spooled at 5000 RPM and made 300 RWHP at 17 PSI on 93 octane gas with a rough street tune. Redline was set for 8500 RPM. At 10 PSI it made over 250 RWHP, oh, and peak HP on the stock cams... 7200 RPM. If you go for this turbo, make sure you get the one that is pictured exactly as pictured below. There are other T3/T4 50 trims which are actually not the same turbo sold by others that use a smaller less desirable compressor.

Mark

http://cgi.ebay.com/ebaymotors/T04E-...QQcmdZViewItem

MazDilla

iTrader: (7)

Mark, that is so tempting... but can I expect it to hold up to track abuse? Even though they're so cheap I don't want to replace one every 20k. Are there any cons you care to share, or are you just trying to lord it over me and my spendy ways?

Auction lists T4 flange, is that correct? I'd be more willing to try one if I knew I could go back to my original plan without scrapping the manifold.

TurboTim

iTrader: (9)

I'll lord over you the brand new GT2871R 56 trim I have for sale for $1025. Will last longer than an ebay turbo.

Markp

It's a T3 flange. All I can say is that I was not having a problem with mine and even if you did replace one every 20k miles, that would be what, a new turbo every 2 years. Seriously I put a few thousand miles on mine and it didn't have any shaft play despite damaging the turbine blades from debris (stainless steel weld beads went into the turbine causing damage.)

Given the relatively low cost it's hard to argue with, and Tim while there is no doubt that the GT2871 will likely last longer, will it last 5 times longer??? Dunno if I would make that bet. And I will bet you the T3/T4 50 trim ebay turbo makes more power per PSI of boost.

Mark

Bochinam

That is almost too cheap not to try. I'll probably go this route and spend the savings on better engine management.

Thanks Mark

Markp

You know, I was really skeptical about these until I saw one on a car in Corky's shop that a customer had brought in. I looked it over really carefully and realized it might not be such a bad turbo. So I took the risk and picked one up for myself. It made some mad power for a $200 turbo. I can't speak about how they all fair, but mine did pretty damn well.

Mark

legend4life

Nice setup....but is it worth twincharging with only a 300-350whp goal out of a 1.9L? You could go with only a small turbo ie 2860RS and reach your goal with huge low end and instant response, without the complexities of a twincharger setup. Or if you are already twincharged and wish to keep it, you could go with a larger turbo and higher hp goal, since you already have big low end torque and no problem spooling up.

Normally for only 300whp I'd go for a 2860RS, and for 350whp, I'd do a 2871R. You should probably plot out your motor's airflow with the SC also taken into consideration and see if it still fits those compressor maps.

legend4life

If you definitely want the 3071R, I'd stay away from the T2 housing and get it in .63ar T3 with the proper 4 bolt GT housing with the 3" conical discharge it was originally designed with from Garrett. This housing has higher turbine efficiency and flow compared to the restrictive T2 flanged internal wastegate housing, which is a compromise produced mainly for packaging purposes and bolt on upgrades for stock T25 turbos. With the 3071 there are also other options if you want to go for a fancy manifold, including the new twin scroll housings and Tial Vband housings; housing design does play a significant role in turbo performance.

But for your goals the 3071 (450whp turbo) isn't needed and you would sacrifice some spool and response, though it may still hit full boost by 5000rpm. The 2871 will easily make 300whp on pump gas around 15-17psi and hit full boost by 4500rpm.

Markp

Not to argue the point too much but the 2871 is much better suited to making 300 RWHP than the 2860RS. Given the choice I would spec the 51mm inducer over the RS's 47mm inducer. Granted it can be done 2860RS, but it's smack dab in the middle of the 2871's map (71mm/52 trim/0.60 A/R)

Mark

PS - Bad enough that people in the miata world are afraid of big turbos to begin with.

Markp

You see that's funny because the GT2871 is what a $1200 turbo?

My crappy ebay $200 turbo hit full boost by 5000 RPM (on the dyno, on the street in 4th gear it will make full boost at 4500.) and makes 300 WHP on pump gas at 15-17 PSI of boost.

I really don't see what all the fuss about these GT series turbos is about give the price point and the performance. Even if the 2871 did spool 500 RPM faster, it wouldn't make a difference, since I never drop out of boost shifting at 7000 RPM.

Mark

PS - I know it's a better turbo, I just don't think it's $1000 better.

TurboTim

iTrader: (9)

Just like chinese intercoolers. Is a fancy BEGI or garrett intercooler better than the chinese, sure, but probably not 5x better.

But my chinese intercooler doesn't spin at 100xxx+ rpm

I'd go with the $200 turbo that markp suggested; he has experience with it lasting.

fmowry

iTrader: (8)

Mark,
How many miles on your chinacharger?

Frank

Markp

There was only about 5,000 miles on it. I know that's not much of a datapoint, but everything was really in perfect shape, so it's hard to see how it would start becoming a problem. Either the bearings are right or they are not. So it's hardly enough to make a definitive analysis but it looked to good to argue with. After hearing that these things blew themselves up out of the box, I can safely say that's not the case.

Mark

Bochinam

Probably not, but it's not really a question of worth. For me it's more about the car's personality. The delivery of a twincharged setup during the compound phase is absolutely cat like. I've got an old video of some throttle blips with the blower on page 3 of my cardomain site. Bolting up a turbo just adds to the drama. Very fun. My 300~350 goal is not set in stone. Are you trying to talk me into a GT3076R?

You are right, I should plot the flow of the blower on some compressor maps. Anyone know how to do this? I'm still trying to figured out that squirrel calculator.

Here's the inlet flow of an M45:



I'll be spinning it at about a 2 to 1 ratio.

Markp

It would look something like this I suppose. Squirrel doesn't let me put everything where it needs to be though.




Mark