8 replies to this topic

[JonBooth]

Hello,

Just wondering if anyone knows the boost of an Eaton 45 supercharger when it uses the standard pulley? I currently have the Vmaxscart kit fitted to my Mini, it's a 1275 with standard internals apart from 1.5 roller tip rockers and double valve springs. I'm just wondering if I could put on a reduction pulley or would it up the boost too much and cause me to have to upgrade the engine internals?

Thanks in advance,

Jon.

[Wil_h]

what is the standard pulley ratio, and what is the higher pulley ratio?

I can do a quick calc that will get a ballpark figure.

[Grahamxx]

Hello,

Just wondering if anyone knows the boost of an Eaton 45 supercharger when it uses the standard pulley? I currently have the Vmaxscart kit fitted to my Mini, it's a 1275 with standard internals apart from 1.5 roller tip rockers and double valve springs. I'm just wondering if I could put on a reduction pulley or would it up the boost too much and cause me to have to upgrade the engine internals?

Thanks in advance,

Jon.

Standard pulley 8-10psi, 15% pulley 12-14psi, 17% pulley upto 18 psi. However it all depends how well the head has been reworked. I have a 260bhp Bimmi (3 different rolling roads) and use a 17% pulley and only see max of 15.5psi. Bypass valve can play a key roll in boost with the Bimmi, I've adjusted mine correctly. You won't need a bypass valve on your classic however...

Our classic is running standard pulley and I'm seeing 8-10psi..

Edited by Grahamxx, 19 November 2010 - 05:38 PM.

[JonBooth]

I'm not sure what the standard ratio pulley is I'm afraid... Ah right cool stuff. The head is standard apart from the rocker gear, it just has a decompression plate fitted at the moment which I think adds 12cc to lower the compression ratio to about 9:1. If I was to put a 15% reduction pulley on do you recon there would be any performance advantage after it's been set up without reworking the head?

[Turbo Phil]

If the compression ratio is already 9-1 I wouldn't like to put any more boost into it without lowering the compression a bit more. The M45 isn't very efficient after 10psi or so anyway so there's probably not much to be gained .....

[Grahamxx]

The M45 isn't very efficient after 10psi or so anyway so there's probably not much to be gained .....

Interesting quote Phil, my Bimmi is running 15.5 psi with no problems, I know of cars running 18psi and aren't suffering any ill effects either as long as the ACT's (Air Charge Temps) are kept within limits...

[Turbo Phil]

Yes, but how do you keep the temps down when you're running a suck through like these kits are, obviously you can't intercool ......
So without using water injection etc you're a bit stuck. Obviously if it's blow through then it's a whole different ball game.

[mini13]

Also, you cant compare a Bini running 15psi to a mini running 15psi,

they will be flowing a different amount, and therefore be running in a different part of the compressor map and be at a different efficiency, eitherway they will be right off the top of the map and chucking out 100degC+

http://www.eaton.com...t/ct_128483.gif

[Wil_h]

Correct Mini13, 160cc and 1275 will be at different points in the map. The differance inpower between 10psi and 15psi will be small compared to the differance between 5 and 10psi.

You can't get away from the fact that at 15psi the efficiency is well below 60%.