badcoupe

wasn't the gt-40 wheel the one I wanted?

Pauerman

Mike,

According the turbo builder I deal with, the only GT-40 compressor wheel available is the 56 trim, 82mm wheel - no other trims of this wheel are available. Funny that Garrett posts many compressor wheels on their site, yet they don't make them all available to their distributors.

Mike, we looked at the 88mm, 54 trim, GT-40 wheel which is unfortunately n/a.

It was recommed to me that the GT-40 wheel is slightly large for our 2.5 but that's not to say that people aren't using it in applications even down to 2.0 litres. I was told that when this wheel is mated to a small turbine wheel/housing, the faster spool time makes it very prone to surge.

I'm using the GT-40, 56 trim wheel for my 3.0L project and was recommended to mate it to a Stg 5 wheel. I'm hoping for good results.

jimbo1111

Posted by Pauerman: The GTS61 - aka GT61, SC61 uses a GT40 (56 trim) compressor wheel. This same compressor wheel is used in the ball bearing GT35R turbo and is rated for the 400-600 hp range.
I have never denied what compressor trim I'm using. The gts61 is a little different than the gt61,sc61 and gt40 because of the mods done to it. Keep in mined that most larger compressors will tend to surge when used on smaller displacement motors no mater how efficient the compressor is. The gts 61 is rated for 650 to 700 hp and spools up like a 50 trim. The compressor is mated to a T4 turbine and is efficient to 60 lbs boost. This trim is only used by race teams and its not sold to the public. It might be in a couple of years when newer tech is released. LR sells the sc61. I believe they call it there super 65.

Pauerman

Jimbo,
I wasn't implying that you were trying to hide your turbo's configuration - I was following up on info you have previously posted.

Here's the map you posted:
Looks like a T61 - 60 lbs/min
Inducer: 2.400" = 60.96mm
Exducer: 3.540" = 89.92mm



Here's the GT-40 map, 65lbs/min (used in the GT35R)
Inducer: 2.416" = 61.37mm
Exducer: 3.227" = 81.97mm

ehall

can someone give a quick "how to" on reading compressor charts? Ie the x axis equals what info and the Y equals what info. Together what does the info tell me?

NZ951

Elliott,

The x axis is the corrected air flow in pounds/minute, the y axis is the pressure ratio (boost). Now we know what kind of boost you want to run, so reading the y axis is easy... but we have to assume or best guess the air flow. I have heard some say 32lbs/min on the 944 turbo. Now, you essentially want to read the junction of the boost and air flow on the chart... you want this line to be as close as possible to the high efficiency island. Some say anything below 70% efficiency and the map is not desirable. The bigger the "island" of high efficiency in the boost range you want to run, the better as you are more likely to be distant from the surge line. Remember the less efficient the compression, the hotter the air will be. And hot air is prone to detonation...

NZ951

E,

Given that, which of the above two maps would you prefer and why?

ehall

looks like the bottom, at 32#/min., 2 bar is where you want to be, so the bottom graph.

NZ951

Look at the efficiency percentages... also look at the shape of the island. Keep in mind 2 bar is 1 bar of boost. You may want to look at what happens at 2.5 as well.

ehall

ah I forgot about 2 bar one bar.

ehall

32, 2.5 neither one is in the island, so the conclusion is neither? Doesn't it depend on the level of boost you want to run? I'm looking for the best efficiency at 17 to 20 psi of boost.

NZ951

Read the top one again...

And yes it totally depends on the boost you want to run. You want to run at the highest efficiency possible, again, more efficient = heat heat = less prone to detonation.

fast951

You mean more efficient < (less) heat ???

NZ951

lol yes I do... thanks JJ. Brain working faster than fingers.

Joseph Imports

Ok, 32lbs (Air Flow) is ideal for the 951. Would +32 or -32 is more accurate?
If a kkk #8 hot housing with a stage 3 wheel is used, how does it change a particular map?
Map 1 is more efficient at @ 25 psi (2.7 PR) than Map 2. At 25 psi, map 1 is in the full efficiency island. Although @ 15 psi ( 2 PR) map 1 is less efficient.
Map 1

Map 2


Does higher boost = more lag?

Also is running closer to the surge line = less lag?