GT28 Ball Bearing Turbo on a 2G???

[Hideki]

I originally planned on installing a FP big T28 on my 2G, but was jealous of the ball bearing GT28 turbo on my buddies S13. Does anyone make a GT28 with a mitsubishi turbo flange that'll bolt onto a 2G???

 

[wret]

Gt2871r

 

[eclipsegsx1736]

I had a GT2871 on mine. It was a kickas turbo on the 2.0. Full boost (25psi) by about 3400ish and made almost 50 trim power. Lots of fun on the street. It was a custom job. it had a PTE turbine housing, and the compressor wheel was quite big. looked like a 30r wheel.

PS I noticed you're in Woodland Hills. You're only a few minutes from me and about 10+ other DSMers that regularly meet up in the valley.

 

[We're on Boost]

Been thinking about the GT2871 myself. Took a look at the Garrett catalog, here's what I see:

Turbine wheel is smaller than the GT3071 wheel,,
53.8mm - 76 trim for the gt2871
56.5mm or 60mm - 84 trim for the gt3071
Turbine gas flow ratings are consistant: 21 lbs/min for 3071, 18 lbs/min for the 2871.
So, the gt2871 should definitely spool faster than a gt3071. Should spool like a 16g.

COMPRESSOR - The 52 trim wheel looks like a good one:
45 lbs/minute max, 3.1 pressure ratio max, but the likely max operating point would be at a PR~3.0 which would give you ~ 24psi boost. At that PR you have 40+ lbs/minute compressor flow, at an efficiency of about 75% - Pump gas anybody? This compares almost dead on the same as a TD06 20G - if you use the 145,000 RPM line that Robert at FP has refered to as a "valid" speed. You get ~ 40 lbs/minute at about 3.0 PR, anybody's guess what the efficiency is because that point is off the 20G map but it looks like it would be about 73%.
Be aware there is also a 48 trim compressor wheel available for the gt2871 which is not as impressive, does about 38 lbs/min max and 2.8 PR max - would not want that one for the money. There is also a 56 trim wheel which unfortunately doesn't have quite as much PR as the 52 trim, so less boost.

GT2871 is a little expensive, but TD06 20G's aren't cheap either.
Don't forget you need an R at the end: GT2871R
R is for rolling element bearings (ball bearings).

 

[We're on Boost]

The more I look into the GT2871R the more I like it.
I found out there are some guys on the SRTforums.com who are going ga ga over a particular version of the GT2871R. They are using the 56 trim compressor wheel, not the 52 trim. This is the same wheel used in the GT3071R. They are also using the same compressor cover used by the GT3071R, with a 4" diameter inlet. Looks like there is only one turbine wheel available, but several turbine housings.
These guys are saying they like them better than any 50 trim they have had. Not more hp, but quicker spool, wider power band, faster boost recovery after shifts.

I would say, anybody who wants to bolt one up to a DSM, read over how the SRT guys configure theirs (they buy em from AGP) then get one like theirs only with a DSM turbine housing from PTE.

As for me, I want to convert to pure T3 anyway. So I like what I see on the ATP web site where they have some killer looking T3 turbine housings and a big anti-surge ported compressor cover for the little bugger.

Gary

 

[We're on Boost]

Oh yeah, here are links to couple of the interesting threads on SRTforums.com:

http://www.srtforums.com/forums/showthread.php?t=395405&highlight=GT2871


http://www.srtforums.com/forums/showthread.php?t=277742&page=11&highlight=GT2871

 

[tkelly27]

SRT guys are also running 2.4's, so it would make sense that they'd need less of a pressure ratio for a given flow rate. If you have a higher VE (ported head, header, ect.) or a stroker it might make more sense to go with the 56 trim. Did I get that right? I've been sick...

 

[We're on Boost]

SRT guys are also running 2.4's, so it would make sense that they'd need less of a pressure ratio for a given flow rate. If you have a higher VE (ported head, header, ect.) or a stroker it might make more sense to go with the 56 trim. Did I get that right? I've been sick...

That's right, but I think there is also something else going on here. Take a look on turbobygarrett.com at the compressor map for the GT2871R with the 56 trim wheel and the 756021-2 compressor cover and compare it to the compressor maps for any of the GT3071R's. Notice anything mysterious? Same compressor wheel - same compressor cover - same or similar bearings - different compressor map - right? The 3071 goes way higher PR. Howcum?

http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT28/GT2871R_743347_2.htm

http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT30/GT3071R.htm

The 3071 goes higher PR because they show another speed line at 140,000 rpm that takes it up around 3.5 PR. From the 127,000 rpm line on down it looks pretty much like the map for the 2871. Howcum the extra speed line for the 3071 with the same wheel and same cover? Bearing system should be the same or similar. What's up?
I'm thinking they just didn't show the 140,000 rpm line for the 2871 for some funky reason like maybe they've never even mapped a 2871 with the 756021-2 cover, or they just wanted to be ultra conservative like MHI is with their maps. Robert@FP for instance has maps for the MHI turbos that show higher speed lines than the official MHI maps show and he calls them "valid speed lines" meaning reasonably safe to use.

Anyway, I don't know why the maps are different but I would like to find out. I think the compressor performance of the 28 and the 30 should be the same, just the hot side would be different.

Basically I'm saying, I bet the 56 trim in the big cover can do a lot higher PR than what they show in their 2871 map, and the 52 trim probably could too if it were available with the big cover.

Gary

 

[We're on Boost]

Basically I'm saying, I bet the 56 trim in the big cover can do a lot higher PR than what they show in their 2871 map

Yup that's the answer according to ATP. Here's their answer back to me:

Gary,

The 2871R is actually mapped with the small T04B class compressor housing and not the same T04E class housing mapped on the GT3071R wheel. That is the reason for the difference.

They sent me this answer on Friday night - amazing!
So anyway, when you buy a 2871 with the TO4E comp housing the garrett 2871 maps are no longer valid, you would then use the garrett 3071 map.

Gary