Hi there

I recently got a hand me down sc12 blower, however i am missing specs on this....

- mine has a 125mm pulley

if anyone can help with the following

- max safe rpm these units can handle (****need this urgently****)

- what was the standard boost on the 4AGZE

- what was the standard size of the crank pulley

- i intend using it on a 2L 8V motor with stock internals want about 10psi would i need to inter-cool

- i already have an aftermarket fuel management system installed currently gatting 105kw @ wheels, what do you think i would get @ 10psi

 

regards

alu :bash:

http://www.rollaclub.com/board/?showtopic=24596 follow this link. theres some info on the SC12's i think.

 

also they reckon not to exceed 12,000rpm for these Superchargers

wow that was quick

thanks for the input

now the next question

- what is the max boost this unit can safely handle

 

thanks

alu :bash:

depends really, the more boost you run, the hotter everything runs and the shorter the life of the charger. If you find the equation for working out pulley sizes in that thread i linked you to.

 

FIRST CALCULATION (Engine Litres/min @ 0 Psi )

Multiply engine capacity (in litres) times maximum engine Rpm. E.g. 2 litres x 6000 rpm = 12,000 litres/minute. Divide this figure by two as engine only fills every second stroke. (12,000/2 = 6,000 litres/min.

This is the engines air requirements in litres/minute at 0 Psi boost.

 

SECOND CALCULATION (boost ratio)

Add the boost pressure desired (10 Psi) for the engine to 14.7 Psi (atmospheric pressure).

(10 psi boost desired +14.7 =24.7 psi)

Divide this answer by 14.7 and this gives the boost pressure ratio. (24.7/14.7=1.68) This is the boost pressure ratio above atmospheric pressure.

 

THIRD CALCULATION (Actual air requirements @ desired boost)

 

Multiply the boost ratio by the litres/minute obtained for 0 Psi and you get the actual air requirements in Litres/min for the engine at that boost. In our example this is 6000 litres/min X 1.68 = 10,080 litres/min for 10Psi boost.

 

To decide on the correct size of supercharger you need to know :-

1. The swept volume per revolution of the supercharger. (Eaton M62 1 litre/rev, SC14 from a 1G-GZE 1.5 litres/rev, SC12- 1.2 L/rev)

2. The maximum continuous safe operating speed for the supercharger. (Eaton M62 14000 rpm continuous, Toyota SC14 12000 rpm??)

3. The maximum pressure that can be safely produced by the supercharger continuously. (Eaton M62 12 psi, SC14 10-12Psi??? teflon on rotors melts??)

 

CALCULATION (Supercharger rotor speed)

Divide the desired air flow (5313.6 L/min) by the swept volume of the supercharger (SC12 from the 4A-GZE is 1.2 litres per revolution). This will tell you the maximum speed the supercharger rotors must be run at to produce the volume required.

10,080/1.2 litres = 8,400 rpm for the SC12.

 

So, to make your wanted 10psi happen, you need to spin the SC12 up to 8,400rpm while the Engine is doing 6,000rpm.

 

8,400 is well under 12,000 so youll be safe running that boost.

Its up to you how much boost you wanna run, but remember, the more boost you run, the more heat is created and the harder the charger has to work. SO, the harder you boost it, the shorter the chargers life will be due to heat and wear.

best bet is sell of the sc12 and buy a sc14, sc12 isnt the best sc out.

 

mine runs out of power in when i get to about 5k, stock boost for a 4agze is 8psi.

 

inter cooler is a must, anything after 6psi is blowing hot/warm air so you need to cool it down