AndyFloyd

Let me first start off by saying that I am currently running a GT3271 turbo with a 71mm 52 trim compressor and a .78a/r divided 63mm 73 trim turbine. This is being used on a Mazda BP 1.8L engine, and my goal is 350whp. I am going to be upgrading my compressor wheel to a 76mm because the 71mm wheel in the GT32 is marginal for 350whp. Since Ill be operating near the choke limit of the map ( turbo is rated to 420whp, but I would rather more efficent to redline ). I contacted ATP about getting a compressor wheel upgrade to 76mm. Thats where I have a question....there are 2 very similar 76mm compressor wheels, one is the GT35 based 76mm 52 trim BCI-18 compressor wheel, and the other is the GT37 / GT3076R based 76.2mm 56 trim compressor wheel. I told ATP that I would prefer to use the GT37 based wheel since I know people have great success with the GT3076R on this forum, and I have plotted it on a compressor map and it finishes right at 78% efficient at my redline (7400 rpm).

The compressor maps for both wheel are VERY similar, they both flow right over 50lb/min and seem to both fit my engine quite well. I just wonder if the GT37 based wheel is somehow superior to the GT35 based wheel in some way. I want to use the most efficient wheel for what my goals are. Also, how well does the 63mm 73 trim GT32 turbine match to a 76mm compressor wheel? It looks like my turbine will flow just as much as the GT3076R .63a/r 60mm turbine, so I would figure that my turbo would greatly benefit from the compressor upgrade. I am looking to find out which wheel is better, they will both get me 350whp....I just like to overnanalyize everything

AndyFloyd

Another interesting note, it seems that the 52 trim has 7 blades and the 56 trim has 6 blades on the compressor wheel. I have geard that the HKS Gt3037 uses the 52 trim compressor, but Im not 100% sure of that.

AndyFloyd

nobody?

seen4ever

andy,

what's the turbine wheel flow in lb/min? you want a turbine wheel to flow around half of your compressor wheel for a good flow.

i'd personally shoot for the gt35 wheel, just based on the great success people have had with that wheel compared to the gt37 turbos.

also, i was sure the gt35 compressor flowed 65lbs/min, but maybe that was just the true gt35.

AndyFloyd

Sean, Im talking about the GT35 wheel, not the famed GT35R wheel. The Regular GT35 wheel is a 76mm 52 trim and is an upgrade for my turbo. My turbine flows about 21lb/min and the bigger wheel flows about 50lb/min...my goal is 350whp and for that the turbine will work perfectly, it flows approx the same as the .63 GT3076R turbine does so I feel good about the turbine/compressor match. I found that both wheels are 6/12 blade GT wheels and not 7/14 T04S wheels ( less efficient ). I just thought one of the turbo gurus on here would know more about the GT35 and GT37 76mm wheels.

discopotato03

Andy there's some confusion here .

Don't confuse turbo numbers with compressor numbers . Turbo numbers are based on turbine family numbers ie GT25/28/30/32/35/37/40 etc . To give you some idea a GT3037 means GT30 series turbine and GT37 series compressor . The garrett marketed version is called GT30R or GT3076R . This means GT30 turbine with 76mm or GT37 compressor . Because its a GT30R doesn't mean t uses a GT30 compressor .
I'll make it easy for compressors :
GT30 = 60.1mm .
GT35 = 71.1mm .
GT37 = 76.2mm .
GT40 = 82 or 88mm .

FactionR

it sounds like a 76.2 mm gt3076r compressor will work great for you app. id say go for it.