GT40 vs GT40R

[CTX-SLPR]

Howdy,

Is there a major difference in the physical mounting and associated plumbing between the ball bearing and non-ball bearing center sections of the GT40 turbo? In an effort to get my engine completed I'm considering going with a GT40 to start with and then upgrading to a GT40R later when I can afford an $1800 turbo.

Thanks,

 

[John Wilde]

Howdy,

Is there a major difference in the physical mounting and associated plumbing between the ball bearing and non-ball bearing center sections of the GT40 turbo? In an effort to get my engine completed I'm considering going with a GT40 to start with and then upgrading to a GT40R later when I can afford an $1800 turbo.

Thanks,

The only difference that I know is that you will have to run the water lines on the R turbo for a street application.

 

[Taffy]

Howdy,

Is there a major difference in the physical mounting and associated plumbing between the ball bearing and non-ball bearing center sections of the GT40 turbo? In an effort to get my engine completed I'm considering going with a GT40 to start with and then upgrading to a GT40R later when I can afford an $1800 turbo.

Thanks,

The GT40R is not an upgrade over the GT40. The GT40 actually has a larger inducer (technically smaller wheel), but the same exducer. You will make more power with the GT40 than with the 40R. If you have enough stall to spool this turbo 3200+, then you do not even need to worry about the difference in spool time between the two. You are going to have to pedal the gas anyways to get traction.

 

[CTX-SLPR]

Well its in a 4000lb car, that make much of a difference? This is also a street car over a race car and with a 256" Buick V6 I think that the smaller GT35R would be a choke on the engine rather than a good street turbo. I want to keep the stall down to around 2400, though I'm debating a Gear Vendors SP400 combo instead of a TH200-4R due to the durablity factor and the ability to incrimentally upgrade vs buying everything at once with the TH200-4R. I want a ball bearing water cooled turbo as I see it as the best turbo for the street.

 

[John Wilde]

Well its in a 4000lb car, that make much of a difference? This is also a street car over a race car and with a 256" Buick V6 I think that the smaller GT35R would be a choke on the engine rather than a good street turbo. I want to keep the stall down to around 2400, though I'm debating a Gear Vendors SP400 combo instead of a TH200-4R due to the durablity factor and the ability to incrimentally upgrade vs buying everything at once with the TH200-4R. I want a ball bearing water cooled turbo as I see it as the best turbo for the street.

If you want to keep a lower stall, maybe you should consider 9.5 compession.
That would allow you to spool a average sized turbo with a stock type converter. I have heard that you can run the PT-61 BB with the stock converter have you considered that? This of course has the same 61MM wheel as the GT35R and can make around 630-650HP.

Best regards,

 

[CTX-SLPR]

Well the short block is already built and I'm not doing through the expense of having another custom set of pistons made. Its lower than I originally wanted but I can run thinner gaskets if I could find a set for the 4.1 since the pistons are almost 0.020" in the hole. Unfortunately its only 8.3:1.

 

[John Wilde]

Well the short block is already built and I'm not doing through the expense of having another custom set of pistons made. Its lower than I originally wanted but I can run thinner gaskets if I could find a set for the 4.1 since the pistons are almost 0.020" in the hole. Unfortunately its only 8.3:1.

I still think you can do it with the PT61 BB.

http://www.fullthrottlespeed.com/items~Cc~ptebb.htm


A full ball bearing turbo with the proven GT61 compressor and the popular P-Trim turbine wheel. This would be considered a step up from the GT6152 (non-BB) Only it spools faster and make more power due to the bigger turbine. Comes with "E" compressor cover 3" inlet 2 " outlet. "S" compressor cover with 4" inlet and 2.5" outlet available at no extra charge. Actuator optional please specify standard or high boost

All Garrett based BB turbos are water cooled and will require a water line kit be installed. We have kits available. The stock oil feed line is not compatable with the BB turbos a -4 line is required but the "Turbo Saver" oiling system is highly recommended

 

[CTX-SLPR]

Now that sounds more like it. I was thinking the GT wheels would help on the street but ya'll are the people with the knowledge in this regards. I'd want an external gate in any case, Is this a 3-bolt turbo?

 

[White Out]

Couldn't you run a smaller exhaust housing on the 40/40R for quicker spool?
I have a 35R on my STi with the .82 exhaust housing. I chose it for decent spool and great top end. I know that there is a .63 and 1.06 exhaust housings for the 35R wich allow for either quick spool or big top end. I assume that the 40/40R have this same options.

Nick