CLUBS & FORUMS
For the ones thinking of running with a "stacked" combination of pulleys, mentioned [HERE] in more detail, or simply wants to determine what crank / supercharger pulleys setup are equivalent to each other, and/or how fast their SRT-6 supercharger will be spinning, here is a equation that can be very useful to determine these data.
In pure English, this means the following:
Crank pulley diameter x Crank pulley RPM = SC diameter x SC RPM
EXAMPLE 1: RPM OF SUPERCHARGER
So, if I have got a 185mm crank pulley, a stock supercharger pulley (74mm), and the engine is running at redline (6,200 rpm in this case as it is raised due to ECU tuning), the Supercharger will be spinning at:
185 x 6200 = 74.2 x SRPM
SRPM = 15,458
EXAMPLE 2: SC PULLEY EQUAL TO CRANK PULLEY
Here is another calculation if you want to see what size a supercharger pulley would equal a 185 mm crank pulley:
154.4 x 6200 = SD x 15458
SD = 61.9 mm
EXAMPLE 3: CRANK PULLEY EQUAL TO SC PULLEY
Here is another calculation if you want to know what the crank pulley equivalent of a Code3 65mm SC pulley is:
154.4 x 6200 = 65 x SRPM
SRPM = 14,727
CD x 6200 = 74.2 x 14727
CD = 176.2 mm
Supercharger RPM safe max value: 15500 - 16000 rpm
Supercharger RPM max value: 20000 rpm
Engine RPM: 6000 rpm (stock) 6200 rpm (tuned)
Stock Crank Pulley diameter: 154.4 mm
Stock Supercharger Pulley diameter: 74.2 mm
Other: Click [HERE] to see more information on measurements of Supercharger Pulleys for the SRT-6 and [HERE] for measurements on the Crank Pulleys.
60 mm SC pulley is equivalent to 191.2 mm crank pulley
61 mm SC pulley is equivalent to 188.0 mm crank pulley
62 mm SC pulley is equivalent to 185.0 mm crank pulley
63 mm SC pulley is equivalent to 182.1 mm crank pulley
64 mm SC pulley is equivalent to 179.2 mm crank pulley
65 mm SC pulley is equivalent to 176.5 mm crank pulley
74 mm SC pulley is equivalent to 155.0 mm crank pulley
155 / 74 = (2.10) x 5.800 = 12,180 SC RPM (Factory)
178 / 74 = (2.41) x 6000 = 14,460 SC RPM
181 / 74 = (2.45) x 6000 = 14,700 SC RPM
185 / 74 = (2.50) x 6000 = 15,000 SC RPM
155 / 65 = (2.38) x 6000 = 14,280 SC RPM
178 / 65 = (2.74) x 6000 = 16,440 SC RPM (Stacked)
Picture above shows a diagram of testing the S105 supercharger. Relation between compression ratio and volume flow. Here you can also determine that the supercharger is not running quicker than 16000 rpm, so be careful not to overspin your superchargers.
Video above: Eurocharged 61.9 mm SRT-6 Supercharger whine testing.
Data table above shows a excel sheet with several data eg. crank and blower (sc) sizes, blower (sc) rpm, overdrive %, blower (sc) rpm at different engine revs. Credits: boostmonkey over at CrossfireForum. Click to enlarge.
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