Author Topic: question about m45 supercharger  (Read 4483 times)

Offline subaru

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question about m45 supercharger
« on: October 31, 2008, 01:32:45 am »
Hello.

I don t have a g 40 but like this car very much, and i am new at this forum so first want to sy hello to everibody.

A few months ago I had the crazy idea to supercharge a 1200 cm3 engine of a corsa C, and the first thing that came into my mind was buying a g lader from a g40.
After some reserach including the posts from this forum i knocked at eaton web site and saw the m45 supercharger, and the boost map. The smallest air flow value is 100 m3/h, and the biggest value i measured wit an OBD diagnostic interface on corsa C z12XE engine is 45 m3/h at 6000 rpm, and i think that the g40 with aprox 1300 cm3 engine, obviously with a bigger air flow value, is still far from 100 m3/h.

Is m45 supercharger too big for this displacements?

I mad this question to eaton engineers too but didn t had an answer. Hope someone can answer something .
Thanks.

juan

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Re: question about m45 supercharger
« Reply #1 on: October 31, 2008, 08:25:17 am »
the eaton m45 is fine for the g40 engines :) its less efficient than the g-ladder but can produce more boost :)

Offline subaru

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Re: question about m45 supercharger
« Reply #2 on: October 31, 2008, 12:24:11 pm »
Ok thanks juan. And what do you propose for the engine I talked? The g lader or the m45?
Thanks again

Offline hayesey

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Re: question about m45 supercharger
« Reply #3 on: October 31, 2008, 02:28:37 pm »
I'd use an Eaton, purely for the fact that they're easier to get hold of and stronger. 

I would have thought the whole point of supercharging is to force more air into the engine than the engine can flow naturally?  Maybe I'm misunderstanding what you are saying but if you put a charger on which flows the same amount of air as the engine does naturally then it wont make any difference to it?

Offline subaru

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Re: question about m45 supercharger
« Reply #4 on: October 31, 2008, 05:41:26 pm »
I m folowing corky bell's book to size the right charger for this specific aplication.

It says that max eficiency point of the compressor should fall at the useful range of engine rev, for other words betwen max torque rpm and max power rpm, I have:

max torque rpm: more less 4000 rpm

max power rpm: more less 6000 rpm

So i d say that max efic charger point corresponding to 5000 rpm would be good, the air flow for this engine (atmospheric) corresponding to 5000 rpm is roughly 33 m3/h.

I want to start with a 0.6 bar boost, so the PR is 1.6, multiplying for 33 i have more less 53 m3/h, a bit less with corrected formula usualy on boost maps.

So my starting point for choose the right boost map is 53 m3/h and PR of 1.6, that should fall at a good charger eficiency. If u look at m45 boost map the minimum is 100 m3/h, so  it can t even enter this value on the boost map.


Thats my big doubt. I am confused :-[. Thanks

Offline giorgio

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Re: question about m45 supercharger
« Reply #5 on: November 01, 2008, 12:15:29 pm »
Are you thinking the M45 produces too much boost for your application?

At 6,000 rpm the eaton flows ~240m3/hr.

At 6,000 rpm the Z12XE takes 45m3/hr

This gives a theoretical 'boost' of 195m3/hr

Like Hayesey says - If you were to get a charger to flow the 45m3/hr you calculated there would be no boost.