View Single Post
kenikh kenikh is offline
3 restos WIP = psycho
kenikh's Avatar
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,729
I have been fiddling with this and it seems that the 2860RS is a bit too big for your application. You aren't generating enough air to run the turbo in the middle of the efficiency sweet spot, although it appears that it does work OK. They are spot on for a 7000 RPM redline 3.6, or so says the Squirrel.

The Garrett 2056, based on Squirrel's calcs, seems to be a better match, since although they blow less peak air, they still support what you need for 500HP:

As far as a final solution, you would likely be best served talking to an expert like Blouch or Forced Performance:
Forced Performance...
Blouch Turbo...

Take a look at Forced Performance and the work they are doing. They have some pretty amazing TD05 and Garrett variants:
Forced Performance Turbochargers: FP Turbochargers

Given what the tuners are getting out of customized Garretts, their attention to detail and the fact that Garrett's reliability has come into question of late, anyone needing a Garrett turbo should really look at the above:
Forced Performance Turbochargers: Garrett Turbochargers

They could do some pretty amazing work to your existing Disco Potatos (GT2860RS) to fine tune it to your application without needing to reinvent the wheel (no pun intended ):
Forced Performance Turbochargers: Garrett GT2860RS Turbo - "The Disco Potato"

BTW, this is FPs new "Beast from Hell" turbo for the Evo crowd and will blow 600HP all day on pump gas:
Forced Performance Turbochargers: FP BLACK Turbocharger for the Mitsubishi Evolution IX

IMHO, I'd seriously consider having your turbos modded by one of the above, using the 2056s, using a variant of the FP custom turbos as single/dual or the single turbo I went with.

Mine is based on the TD05HR-16G6, which you can map on Squirrel, too. It is a twin scroll turbo that would work great with RarlyL8s headers, since these turbos require equal length, segregated headers before the turbo. Here's how your motor plots to that turbo:

The variant part is that that Chad Block Racing Development has been working with Blouch on modding these turbos by swapping the turbine and compressor to push more air, yet keep the spool time very low.

Their latest BBK XL (I am using the BBK Full), uses the same turbine as the Full, with a more aggressive compressor wheel. If you can imagine the above compressor map (with your lines stationary), but with the map stretched to the right...that would be along the lines of the Full and XL. (Edit) The XL, since renamed the BBK-B support 58 lbs/min which translates to about 700 CFM, which is 3076R territory, keeping in mind that the left side of the compressor map looks much more like the TD05 than the Garrett (more responsive).

Here's a dyno of a 2.3 liter EVO VIII running this turbo, albeit on e85:

This is net WHEEL HP.

It's making power about 300-500 RPM quicker than the same 2.3L motor on a GT3076.

They only downside is that the turbo is watercooled and don't know anyone who has tried running these oil cooled only. I am going to run water cooling for the turbo on my car.

Here's a comparative boost plot of the Full versus the XL in a 3rd gear pull:

I believe that the boost levels won't be as high on a bigger motor.

Net-net, all of these turbos are streetable on a 2 liter 4 banger, so a 3.2L six would see MUCH better off idle boost response. Something to think about!

Anyway, that's a lot of rambling to read over. My 2 cents in a nutshell:
GT2860RS are too big in stock trim
Either send them to a tuner to quicken them up or
Get some smaller duals like the 2056s or
Get a custom, purpose specced single turbo from a tuner

The benefit of using a tuner is that you can leverage their expertise to customize the turbos to your needs, versus being stuck with the one-size-fits-all trim of the off the shelf turbos.

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930

Last edited by kenikh; 05-17-2010 at 12:26 PM..
Old 05-17-2010, 11:50 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)