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Crank Pulley List (Price, Weight, Part #'s)

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I've been very impressed Virtual Dyno and with how consistent the power can be day to day even as long as Ambient temp and barometric pressure is very close to the first run. It wasn't always like this, this car gave me some of the most inconsistent power graphs for the first couple years, things like D learning leaning out, Timing compensations on two cylinders, false feedback knock etc. Once I got rid of most of the compensations, and fixed the rattles, my runs started to be as consistent as a real dyno.


One big factor still is ambient temperatures and how MAF's work. Even today if I do a log at 85*F and 60*F I will have different power outputs simply because engine load g/rev will go into different timing columns, which might not be as optimally tuned for that boost level.

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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A couple of additions to the list:

Cosmo Racing out of Toronto. The crank pulley is a true underdrive at 10CM (3.937") diameter. At least that's the size they emailed me from a tech support question. They didn't send me the weight but no doubt it's very light.



Go Fast Bits also makes several true underdrive crank pulley kits, but not all their kits use underdrive crank pulleys. I've asked them for specs with no response, but you can see in this video that the crank pulley is smaller diameter than oem:


I still run Fluidamper on my cars though....

Nothing like a race track to find the weak points in man and machine.

"Good Judgement comes from Experience. Experience comes from Bad Judgement"

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Added! More info on go fast bits ones: https://smyperformance.com/go-fast-bits-underdrive-pulley-kit-w-belts-2008-2014-wrx-2008-2020-sti.html


Stock Crank Pulley : 5.51lb (STI) / 4.63lb (WRX)
GFB Crank Pulley : .86lb

Stock Power Steering Pulley : .81lb
GFB Power Steering Pulley : .37lb

Stock Alternator Pulley : .36lb
GFB Alternator Pulley : .14lb

Alternator Underdrive: 16.5%
Power Steering Underdrive:  18%


That's really tempting, since the car can be a bit of a dog off boost around town and I freed up a lot of amps by switching to LED's.

Edited by covertrussian

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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