itguy
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| posted on 1/9/06 at 12:14 PM |
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Eaton M45 supercharger
Hi Everyone
My winter plan is to fit an Eaton M45 Supercharger to my 1800 Zetec.
Now I've seen the pics on here of how this has been done before, but I wonder if anyone can answer me a simple question;
Is there a way to vary the boost pressure on one of these superchargers? Is there an actuator / restrictor or something or is it just a case of bolt
it on and 'you get what you get'?
Thinking of the initial stages of tuning / CR and also knock etc
Thanks
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rayward
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| posted on 1/9/06 at 12:18 PM |
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the pressure will be relevant to the RPM, so one way to increase/reduce the pressure is to change the size of the pulley on the suprcharger.
just check your not going to over rev it a full engine rpm if you fit a smaller pulley.
hth
Ray
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NS Dev
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| posted on 1/9/06 at 02:23 PM |
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absolutely no need to alter revs, just size the drive pulley right to start with!
If you can engineer the conversion you should be able to work the maths out in order to establish what speed to drive the compressor at relative to
the engine (use engine volumetric efficiency and swept volume vs supercharger pumping efficiency and supercharge level over and above atmospheric
pressure, remembering that because a supercharger is positive displacement you need to deliver atmospheric pressure to the engine before you even
start adding supercharge pressure!!!!!, easy to forget that one, you don't want to undercharge the engine!)
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 1/9/06 at 02:25 PM |
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ps just seen you are fairly local. If you need info get in touch.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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itguy
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| posted on 1/9/06 at 04:42 PM |
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Ok, thanks.
Have seen the graphs of the power requiements of the supercharger dependant on the PSI it is delivering, however just wondered how that is determined
as the graph I've seen has two lines on, one at 5psi and one at 10psi...
Do people usually fit some kind of bleed valve to regulate the overall quantity of air going in?
Will.
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bimbleuk
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| posted on 2/9/06 at 06:58 AM |
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Just some points to be aware of.
1. You don't need to limit max pressure on a fixed displacement supercharger. The pulley ratio does this.
2. The most efficient arrangement is filter, throttle, supercharger, intercooler, manifold.
3. Install a recirculating valve plumbed in before and after the supercharger. Relieves pressure spikes and reduces parasitic loses on part
throttle.
4. If you can find one then a clutch engaged supercharger is better. One (M62) recenty went for £112 on eBay off a Mercedes SLK.
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NS Dev
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| posted on 2/9/06 at 10:02 AM |
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completely agree with bimbleuk's comments. not sure about the necessity for the clutched drive but the M62 is a nicer size blower which you can
drive slower and thus heat the inlet charge a bit less.
re. the graphs, the lines at 5 and 10 psi give you a "guide". I.e. draw a matching line 3/5 of the way between them if you want 8 psi
supercharge.
To size the charger, work out what flow volume the engine requires at your required supercharge level (a typical aim will be around 8 psi, which
would, in very approiximate terms, be just over 50% more flow than the engine would require at 0% supercharge) and then aim for a supercharger that
can supply that flow at it's mid rpm range (i.e. for the M45, between 7000 and 11,000 rpm) If you look at the temp graph, you will see the delta
T for this rpm is quite small compared to higher revs.
hope this helps
Nat
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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02GF74
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| posted on 2/9/06 at 11:51 AM |
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does the CR of engine need to change?
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bimbleuk
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| posted on 4/9/06 at 01:07 PM |
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quote:
does the CR of engine need to change?
Too many variables to give a simple answer. Static compression is the easiest factor to measure but the effective compression is the main limit to
combustion pressures.
For example my 2ZZ-GE VVTLi engined Celica Sports M had 11.5:1 compression and produced 7PSI from an inefficient straight rotor roots blower. However
someone else I spoke to had a low compression 2.0L Pinto but was struggling to run with 10PSI from a very efficient Rotrex SC.
I guess my Celica's effective compression was lower due to very high lift, long duration cams and peak power at high RPM (less time for
detonation to occur). The Pinto was more limited due to the iron cylinder head being unable to dissapate the combustion energy quickly enough.
[Edited on 4/9/06 by bimbleuk]
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itguy
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| posted on 5/9/06 at 06:31 AM |
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I've also noticed that the supercharger kits in the states also don't lower the stock compression ratio until they get to the higher side
of 8.5psi...
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