quadcam boat
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- Emerald, Qld Australia
I ran my M90 Eaton bown lexus engine and my max boost was 2.94psi!
I was hoping for 8psi.
Run the blower drive calculator off sprintex website (www.sprintex.com.au)and you just need to fill in 4 ltr engine, 7000rpm max and pick Eaton M90 from the supercharger list. I played around with the Boost required figure and found out the following
Drive ratio required to get 55kpa (8psi) = is 1.92
Drive ratio is 1.7 with the current pulleys I am running, so I played around with the boost required figure and found out that 37kpa (5.4psi) should be produced at a drive ratio of 1.7 It also says to increase boost or max RPM.
Thinking about that, the blower probably isn’t spinning fast enough and is operating inefficiently at the current low speed. That probably explains why the boost is lower than works out on the boost calculator, because the blower is spinning too slow and has too much leakage around the rotors at this speed. I don’t think to blower drive calculator takes this into account.
The difference between the 2 calculated pulleys is --
73mm diameter for 8psi
82mm diameter (current pulley) for theoretical 5.4psi which is 3psi actually.
THis is working on the drive pulley being 140mm (all pulleys measured on the outside of the grooves)
That’s bugger all difference for a huge effect!!!
Anyway will get one made with a drive ratio of 2.
Hope this info helps others doing the same thing.
Cheers,
Andrew
I was hoping for 8psi.
Run the blower drive calculator off sprintex website (www.sprintex.com.au)and you just need to fill in 4 ltr engine, 7000rpm max and pick Eaton M90 from the supercharger list. I played around with the Boost required figure and found out the following
Drive ratio required to get 55kpa (8psi) = is 1.92
Drive ratio is 1.7 with the current pulleys I am running, so I played around with the boost required figure and found out that 37kpa (5.4psi) should be produced at a drive ratio of 1.7 It also says to increase boost or max RPM.
Thinking about that, the blower probably isn’t spinning fast enough and is operating inefficiently at the current low speed. That probably explains why the boost is lower than works out on the boost calculator, because the blower is spinning too slow and has too much leakage around the rotors at this speed. I don’t think to blower drive calculator takes this into account.
The difference between the 2 calculated pulleys is --
73mm diameter for 8psi
82mm diameter (current pulley) for theoretical 5.4psi which is 3psi actually.
THis is working on the drive pulley being 140mm (all pulleys measured on the outside of the grooves)
That’s bugger all difference for a huge effect!!!
Anyway will get one made with a drive ratio of 2.
Hope this info helps others doing the same thing.
Cheers,
Andrew