GT2860RS to GT2871R upgrade question

[Thomas800]

I am looking into updating from our GT2860RS to a GT2871R. I see that ATP offers an upgrade kit for $995. A brand new GT2871R is $1195. Does anyone on here know if we can just have our GT2860RS freshened with the 71mm compressor wheel and a new compressor housing? If we have to buy the upgrade kit (comes with a new CHRA) we might just as well buy a complete new turbo. Our current GT2860RS makes about 25# boost at 2100' 85f ambient. How much more boost capability does the GT2871R have over the GT28RS. I'm thinking that the 48 trim map looks about the best for this engine, but maybe some of you have some experience that says otherwise. I will make some phone calls to see what garrett has to say but I thought I would ask the questions here in case some of you have done this already.
Thank you Tom Ljuden

 

[TWIN TURBO]

I've been looking at the GT2871R map and if your going to run the boost up maybe 30 lbs. or so I think it will be better. Just make sure you move enough air through the system to stay far enough away from the surge line. I'd buy a complete turbo and keep your old one untill you are sure you won't need it. They can be purchased for less than $1195.

 

[Freak]

I can get you a new gt2871r for $1030 plus shipping if you decide to go that way.

 

[Thomas800]

Thanks for the replies guys. Do either of you have a feel for which trim you would go with on the compressor wheel? Which map were you looking at Twin Turbo? The 48 trim or the 56. I haven't found a map for the 52 yet. The reason for going with the 2871 is to "try" to get up to about 30 #, but I'm not sure if it will get us there. We are also running a fully ported head. Any thoughts? Thanks Tom

 

[TWIN TURBO]

I was looking at both the 48 and 56. It depends on how much air you can move. I would try the 56 and 30 lbs. if I had my way. Elevation is another consideration I'm at 700 with my dyno and 1600 feet in the field

 

[Freak]

I couldnt give you any rec's. I bought a 2871 with the 56 trim last year but sold it before I ever put it on. I was convinced that the lag would be way more than I wanted. So I stayed with the smaller turbo and sprayed it.

 

[TWIN TURBO]

You can get a GT2871R with different A/R rotios also. If you get it with a 0.64 A/R that would be better as far as response is concerned, but it will be slower to spool compared to the GT2860R. Look at the turbine side maps if your into maps.

 

[Thomas800]

We run mostly at 1800' to 2400' altitude. We also spray a .026" dry shot to pick the turbo up, so lag isn't really an issue for us. We hope to get down to a sea level track next spring to do some testing (read as "blow up some more belts"). We are going with a different clutch set up (overdrive 4 post Micro Belmont) and gearing to try to make our belts last a little better. We have a guy here that wants our 28RS, so we will probably update to a completely new unit. Freak, I will PM you once we are ready to buy the turbo. Thanks again Tom

 

[Thomas800]

Actually I love this stuff. I've been all over the maps for the last year or so. I made some excel files to do the air flow calcs for me so I could play with the different maps. I see someone has done the same thing, but taken it a step futher and overlaid the results directly over the maps. http://www.squirrelpf.com/site/files/te ... 2_beta.xls . It seems to come out with about the same data I had. We have been running with a .86 A/R on the turbine with the understanding that it could make a little more power but be slower to pick it's self up. We certainly haven't been dissappointed with how we've ran with the 28RS, but we always want a little more. Thanks Tom

 

[TWIN TURBO]

I guess I'm the same as you Tom, never seem to get tired of this stuff.
I'm wondering how the advance of the exhaust cam worked out for you. Did you notice any change because of that alone? I'm a drag racer so response means aliitle more to me than some others maybe.

 

[Thomas800]

To be honest with you, the cam timing I used was simply an educated (?) guess based on what I have for turbo theory. Being a Drag racer myself, I've played with cam timing a lot over the years, but mostly in automotive applications and never with turbos. With the drivetrain breakage we went though in the first half of the year, I never did get a change to play with the cam timing beyond what I did when I built the engine.. So did it help or hinder ??? Can't say. When I do get to do some testing I will let you know. Thanks Tom

 

[TURBO TURTLE]

GARRETT TURBO PRICES

TOM '' CALL ME WHEN YOU ARE READY TO BUY, THAT TURBO I CAN KNOCK A COUPLE OF HUNDRED OFF THAT PRICE. TURTLE/////////