We're not talking the GT40R with it's ball bearing center section...just the plain jane version with it's regular CRHA.



A bit of background first...I currently run a GT40 (88mm) compressor wheel in my GReddy T78. The compressor housing is machined out to mate the new wheel. This turbo has incredible top end power and it pulls until the cows come home. Problem is, with my current setup, I'm not seeing full boost til about 5K rpm maybe a bit later. I have a collected exhaust manifold (not fully divided in other words).



So...with some people saying the 35/40's choke on top, why not just run a regular GT40 with it's T4 exhaust housing? I remember Magnus Motorsports saying there wasn't anything offered that would work well with a rotary motor.



I posted a similar question on the other forum and received an answer but after talking with others, I feel the recommendation might be too "drag" oriented for my tastes/goals which are:



1)an easy 425+ hp at 15psi, shooting for mid-400's and then some

2)full boost 1000rpm than I'm seeing it now

3)at least 8psi by 3krpm and excellent street performance

4)easily rebuildable

5)Something I'll be able to take up to 22psi or so on race gas and push 500+ hp



Now the non-divided manifold may make this tough. I've been told that running the largest turbine housing a/r would be a no-no but I'd like others opinions. If I can get the hp with the .94a/r then great.



Others who have this hybrind turbo combo (T78 turbine/GT40 compressor) say the top end is better than the stock T78. I need better response than what I'm getting now and something a bit more modern than a stock T78.



If push comes to shove, I'll switch to a fully divided manifold. Problem is, there arent' too many out there for the third gen that are south of the $1K range and if they are, they're typically mild steel.



I've been quoted at $1000 for a plain bearing GT40, any trim combo, and $1900 for the ball bearing version by a local shop. Good? Bad?



I'm going to post the compressor map, GT40 options, etc...I'm looking for what would be best for a street ported 13B=RE (Cosmo). Secondary ports are quite large and primaries are just cleaned up a bit. I'm est. 35-40 lbs min. in flow. Correct me if I'm wrong.



So which would be best (theoreticallY)?

 

compressor map

 

hot side...

 

Anything look good here? I'm just wondering why people haven't jumped on this turbo before...seems to be more efficient than a T04 series at a similar cost.

 

because new turbos are expensive turbos.......

 

True...but this thing has been out for a few years. Hey, why you at home this late on a Saturday night? Looks like you and I have no life.

 

yeah i know and there is no bolt on kit



actually. i just called ihor silver 93. he is in NJ for the weekend. i'm going to the bar with him

 

Got any turbine or compressor information on the T78, stock?



So if you like what the GT40 compressor wheel does with your T78 turbine,

and the GT40R turbine will spool quicker than the T78 based on the BBs,

do you think there is 1000rpm quicker response in the difference between the turbine map?



I do, Michel.

 

There IS a bolt on kit. Ask Ihor when you see him.

 

i forgot to ask him. all he talked about was the Gotham Racing Turbo Kit and how he was gonna woop my *** lol