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Discussion Starter · #1 ·
I am intrigued at the idea of supercharging a 1600 following this thread http://forums.aussieveedubbers.com/viewtopic.php?tid=65678 and some research I have done on Shoptalkforums.

The plan could be to possibly try this on a stock 1600 in an early bay..... pending calculations.

This is what I have found so far from some net research and trying to remember thermofluids/thermodynamics lectures from years back...

Based on a stock 1600cc
Eaton M45 Supercharger (from a mini cooper s)

Engine airflow max (cfm) = (engine Cubic inches x RPM x Volume Ratio x Volumetric effeciency x Pressure ratio)/1728

max airflow = 150.5 cfm = 255.7 m3/hour

Pressure ratio @ 7psi boost = (air pressure + boost pressure)/air pressure

Pressure ratio = (14.7 + 7)/14.7

Presure Ratio = 1.48



Looking at the M45 pergotmance graph that seems to prove the M45 would be suitable. Ok so my volumetric effeciency figure was a guess - need to do some more calculations on that.

I'll add my temp rise calculations tomorrow and inlet pipe diameter calculations- too tired right now.

I was planning a drawthrough system with a single carb very similar to the setup in the thread above.

Adrian..
 

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Interesting. I too have toyed with an M45 but on a 1303S bug but came to the conclusion that it would not fit anyway with the tinware. Have you enough height for the 'charger and the carb ontop? or are you laying the unit on its side.

Not wishing to hijack the thread but I think the topic is relevant - has anyone had direct experience of fitting a M45 out of a BMW Mini Cooper S or a Merc 180 Compressor? It does look fraught with difficulties because of the M45's rear inlet.

evilC
 

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Discussion Starter · #3 ·
Interesting. I too have toyed with an M45 but on a 1303S bug but came to the conclusion that it would not fit anyway with the tinware. Have you enough height for the 'charger and the carb ontop? or are you laying the unit on its side.

Not wishing to hijack the thread but I think the topic is relevant - has anyone had direct experience of fitting a M45 out of a BMW Mini Cooper S or a Merc 180 Compressor? It does look fraught with difficulties because of the M45's rear inlet.

evilC
That is something I need to look at. I have the dimensions of the M45, just need to measure up. I did know about the rea inlet issue..... don't have an answer on that yet.

There is definately more room in a bus engine bay so I am hoping I can find somewhere for it.....

cheers,

Adrian
 

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Hi Adrian,

i was just looking at the M45 measurements on the capa websites
its certainly a very compact unit
with some clever manifold design i think u could make it work quite easily
 

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The nose and rear inlet length on the BMW Mini 'charger are too long IMO for a T1. The M45 can be had with reductions on both using the Merc 230SLK Kompressor M45.

Check out: www.thefang.co.uk/eaton.htm

Alternatively, the base model M45 is available with a bare inlet and optional nose that is cut to length to provide a short unit. I still think Joel's SC12 is the route to go with the bug because a) its short nose, b) top inlet although I expect that configuration to be noisier than the M45. The problem for us POOR blighty buggers is that both the base M45 and SC12 are rarer than hens teeth here in s/h form.

evilC
 

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matty71 on here is currently supercharging a 1600 to put in a beetle. he has got a supercharger and carb, not sure what type though and I think is currently getting the mounted. May be worth seeing how he is doing it.
 

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Discussion Starter · #7 · (Edited)
The nose and rear inlet length on the BMW Mini 'charger are too long IMO for a T1. The M45 can be had with reductions on both using the Merc 230SLK Kompressor M45.

Check out: www.thefang.co.uk/eaton.htm

Alternatively, the base model M45 is available with a bare inlet and optional nose that is cut to length to provide a short unit. I still think Joel's SC12 is the route to go with the bug because a) its short nose, b) top inlet although I expect that configuration to be noisier than the M45. The problem for us POOR blighty buggers is that both the base M45 and SC12 are rarer than hens teeth here in s/h form.

evilC
It does look like a fair bit of work to get one to fit. This site shows how it has been fitted to an A series engine in a draw through setup.

http://www.vmaxscart.co.uk/supercharger.html

Either way it will require some serious manifold work..

The idea of the M45 is that they seem to be far more freely available compared with other units.

Keep the ideas/links etc coming.

Cheers,

Adrian
 

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Evilc, even in aus good SC12s are getting harder to find
i dunno when toyota stopped production of the 4AGZE engine but theres not many of them here either

it would be worth checking first that the eatons are ok to run draw thro

theres debate over the toyota ones as theory has it the flourine/teflon coating on the rotors lifts with fuel on them

others say the fuel is fine and actually helps the blower run cooler
ive had no problems with mine yet and my mate steves bus went for nearly 6 years with no probs at all

that said tho im about to re-invent mine at the moment
ive got a pair of renault carbs i wanna put on kadron manifolds and run blow thro with a WRX intercooler on top

this is mainly so i can crank the boost up alot more and intercool
current draw thro works well but boost is an evil addiction
 

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Evilc, even in aus good SC12s are getting harder to find
i dunno when toyota stopped production of the 4AGZE engine but theres not many of them here either

it would be worth checking first that the eatons are ok to run draw thro

theres debate over the toyota ones as theory has it the flourine/teflon coating on the rotors lifts with fuel on them

others say the fuel is fine and actually helps the blower run cooler
ive had no problems with mine yet and my mate steves bus went for nearly 6 years with no probs at all

that said tho im about to re-invent mine at the moment
ive got a pair of renault carbs i wanna put on kadron manifolds and run blow thro with a WRX intercooler on top

this is mainly so i can crank the boost up alot more and intercool
current draw thro works well but boost is an evil addiction
Joel, I suppose that in an ideal world its draw thro' for carbs and blow thro' for injection and thats probably why blow thro' is coming more to the fore as injection becomes ever more common.
I do take your point about rotor coating although nothing is mentioned on the Eaton web site for the M45 and therefore I would hope that it is not a specific problem otherwise Eaton would have highlighted it especially as the Yanks are such a litigious lot.
I must admit that roots blower supercharging does have distinct attractions over other forms of tuning for the aircooled engine especially as the VW engine is inherently slow running and the advantage of a roots type blower is the boost at low revs.
I have wondered if it was possible to relocate the inlet to the M45 to the opposite side of the blower to the outlet and accept the possible increase in noise generated. That would then solve quite a few problems but would mean the M45 case was fairly well butchered. Alternatively and a bit more radically is to develop twin porsche style fans to cool the both banks that would release space to fit the whole BMW Mini blower rear inlet and all with a carb on top of the standard blower inlet. A serpentine belt would then power it all.

evilC
 

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i didnt realise till after i did this the measure ments were in inches

but heres a very dodgy paint shop to show how i would setup the manifolds

the SC12 is 280mm all up

turns out the M45 is 330mm so its 50mm longer

so with a shorter snout it work easily

 

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Joel, the shortest dimension that Eaton quote for the o/a length less inlet (your 13.2" dim) is 8 1/4" (210mm) but generally we are all looking to use s/h units from some existing car source to moderate the costs. the shortest unit I think is the Merc 230CLK Kompressor that appears to be in the reagion of 13.2 - 13.5" long o/a including inlet (the standard BMW Mini one is substantially longer than this - say another 3-4"). This unit has the inlet and the outlet cast on the same side so I guess that the unit would have to be mounted on edge with a side draught carb plus a plenum to feed the two banks of cylinders.

of course the unit could be mounted upside down with a down draught carb plus plenum.

evilC
 

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Sorry - I have been so busy doing my job not had a moment to browse here.
I will take a squit when I have a moment but a 3 second look seems you do not need me.
:D
 

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<snippet>

Engine airflow max (cfm) = (engine Cubic inches x RPM x Volume Ratio x Volumetric effeciency x Pressure ratio)/1728

max airflow = 150.5 cfm = 255.7 m3/hour

Pressure ratio @ 7psi boost = (air pressure + boost pressure)/air pressure

Pressure ratio = (14.7 + 7)/14.7

Pressure Ratio = 1.48



I'll add my temp rise calculations tomorrow and inlet pipe diameter calculations- too tired right now.

Adrian..
Thinking out aloud

Pressure ratio @ 7psi boost = (air pressure + boost pressure)/air pressure

Pressure ratio = (14.7 + 7)/14.7

Pressure Ratio = 1.48

OK - calced in lb/sq inch - doesn't matter its a ratio

Engine size = 1600cc
RPM - say 3,000 and a bit gives 5,000 litres a minute

Volumetric efficiency of the S'charger - say90% as it is a Rootes type running at a low RPM - less I imagine than in a Mini. 0.9

The volume ratio - that is the compression in a supercharger as the air passes through? In a Rootes type there s no compression it just displacement so here is the volume of one rotation of the screw. Which I do not know. Say 500cc? = .5 litre

So if we do something like

5,000 x .5 x 0.9 x 148

Are we talking the same language here? ie are my assumptions correct here?
 

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Another calculation which might help to work out pulley diameters - which is what you are after I assume in the end.

If we look at the ratio of engine air requirement and what the supercharger can give we can ignore rpm for the moment

So engine requirement is something like this
Engine displacement x (boost pressure required + atomos press + somethingfor inefficiency etc) = A

Supercharger delivery
Volume of supercharger x atmos pressure x 2 = B
The 2 is because on a 4 stroke engine the engine goes around twice to use all 4 cylinders

So the ratio of rpm crank to s'charger is along the lines of A/B

So now the discusion point is the efficiency of the engine etc. Depends on the lumpyness of the cam and the engines pumping losses. So for a standard Beetele with its nice quiet cam and the 1600 fairly decent head and low rpm say 0.3 (30% lossy)

So if you care to use my 0.3 for somethingfor inefficiency etc, and find teh volume of your eaton you can tell what ratio ypur pullies nee dto be.

Closer to engine speed is good. I doubt wether you will get near the slough nor compression lines on the graph.


Does any of this help at all?
 

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Discussion Starter · #15 ·
So then based on your figures and feeding that into the equation I had above.

5000 lpm = 305 118.7 cubic inches per min

Therefore max airflow = 118 m3/hour

Which would render the M45 pretty useless on a stock 1600 at 3000rpm. My first calculation was based on the redline of 4500 which I guess is an unrealistic figure. I never get near that....

That begs the question of how come the superchager is useful on the mini cooper s ? Would it be just down to its max RPM being far higher than a 1600 type 1?

Cheers,

Adrian
 

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Discussion Starter · #16 ·
Scrap that.... I was still in cfm rather than m3/hour

It is actually 200.5 m3/hour for a stock 1600

A 2l type 4 at 3000rpm would be 240 m3/hour

Adrian
 

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Discussion Starter · #17 ·
Here are some better calculations now I have woken up.

This is the airflow plotted against the engine rpm.

Airflow (m3/hour) =

(engine CC x RPM x 0.9 x 0.75 x 1.48)/16666.666666



Pulley ratio based on no losses will be

((14.7+Boost) / 14.7) x (engine liters / 2)) / Supercharger Size liters = Theoretical Pully Ratio

= (1.48x(1.6/2))/0.75 = 1.58:1

If we assume 30% losses then this would be 2.05:1

Rough calculation on potential power increase from stock = 74 bhp !

I'd be intersted to know the torque increase ....

Adrian
 

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That begs the question of how come the superchager is useful on the mini cooper s ? Would it be just down to its max RPM being far higher than a 1600 type 1?

Cheers,

Adrian
Pulley ratios I guess and the Eaton is efficient at a high rpm.

This does depend on what the 'displaced' volume of the Eaton is. Normally bigger s'charger the bigger the displaced volume.

A simple way would be to look at the pulley ratios on the Mini, and then multiply the ratio by say 90% of max revs of the Mini and there you have the rpm of the Eaton required.

Say pulleys in a 1:1.3 ratio and the Mini runs at 5,000 at 90% of top revs.
The Eaton has to run at 6,500 rpm which you can take as your max.
With the swept volume know you can work out how much air it is pumping per rpm an dthen from that you get an idea of how much you reduce the ratio to suit the slow running VW.

You do not need much boost at all to feel the difference
 

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Here are some better calculations now I have woken up.

This is the airflow plotted against the engine rpm.

Airflow (m3/hour) =

(engine CC x RPM x 0.9 x 0.75 x 1.48)/16666.666666



Pulley ratio based on no losses will be

((14.7+Boost) / 14.7) x (engine liters / 2)) / Supercharger Size liters = Theoretical Pully Ratio

= (1.48x(1.6/2))/0.75 = 1.58:1

If we assume 30% losses then this would be 2.05:1

Rough calculation on potential power increase from stock = 74 bhp !

I'd be intersted to know the torque increase ....

Adrian
2:1 appears to be a big ratio to me. But if th Eaton has a small volume for your max rpm it could be of the right order.
 
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