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 Post subject: AMR 300
PostPosted: Sun Feb 27, 2011 10:19 am 
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Hi all,
Has anyone tried AMR 300 supercharger on a Mini before?
I know it is a small unit for a 1275 but I was thinking of putting one on my auto 1275.
I guess it would run out of breath very quick wouldn`t it?
Thanks for the feedbacks on advance.

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PostPosted: Sun Feb 27, 2011 10:46 am 
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There was a guy had one on a 998. I think he's from Stawell? Not sure if he is on ausmini. Aaron could be his name?? The car now has a BMW twin cam headded engine in it.

I believe it worked ok, but I think you'd be better off with an SC12 setup on a 1275.

I've always wanted to do a supercharged auto. :lol: Maybe mrs poeee will get a 998 supercharged auto (I have a Rover auto engine sitting here).


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PostPosted: Sun Feb 27, 2011 10:57 am 
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Hi,
Yes I have one 998 auto sitting too, I was thinking of using that as a template and put on the 1275.
I am planning to do Blown through set up on HIF(I think 38 )
I might go with AMR 500 not sure at the moment.

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PostPosted: Sun Feb 27, 2011 12:27 pm 
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You would have to use a turbo carb. Much easier with a suck through setup.


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PostPosted: Sun Feb 27, 2011 2:17 pm 
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why don't you use a SC14 blower. they are a bit bigger in size/cheaper /easier to buy, and you can drop the RPM of the blower to suit the required boost pressure.

I prefer a blow thru system than suck thru and if it is set up correctly with a large plenum/expansion chamber then the air will drop pressure and have a natural cooling effect. Then you run a equalizing valve/port between the dis-charge and the suction of the blower and this is set at the required pressure so that a constant pressure is maintained at various throttle openings.

The other most important thing is to get the correct air temp/volume into the engine and with the compression ratio of the engine make sure that the final comp temp is not too high.

As for most std carbys the fuel bowl and the fuel pressure must be equalized but the air loss around the butterfly shaft is a minor factor. I have set up SU's/keihin carbys with sealed safts, but if your air supply can over come any air leaks then it's not a big problem.

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PostPosted: Sun Feb 27, 2011 4:51 pm 
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david rosenthal wrote:
why don't you use a SC14 blower. they are a bit bigger in size/cheaper /easier to buy, and you can drop the RPM of the blower to suit the required boost pressure.

I prefer a blow thru system than suck thru and if it is set up correctly with a large plenum/expansion chamber then the air will drop pressure and have a natural cooling effect. Then you run a equalizing valve/port between the dis-charge and the suction of the blower and this is set at the required pressure so that a constant pressure is maintained at various throttle openings.

The other most important thing is to get the correct air temp/volume into the engine and with the compression ratio of the engine make sure that the final comp temp is not too high.

As for most std carbys the fuel bowl and the fuel pressure must be equalized but the air loss around the butterfly shaft is a minor factor. I have set up SU's/keihin carbys with sealed safts, but if your air supply can over come any air leaks then it's not a big problem.



Hi,
Thanks for the advice. I do value your knowledge (and all the others)
My idea of using AMR 300 or 500 is; only trying to be different.
But if it s a bad idea offcourse no need to try at all.
What would be the down side of using small supercharger?
Would not work at all
Would work but not efficiently
Would work only for small boost (I am planning to run not more than 5 PSI)
Once again thanks for your expert advice.

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PostPosted: Sun Feb 27, 2011 5:27 pm 
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Go the AMR500. They can be had for around $200-$250. These roots blowers have very low efficiency if run too slowly and and SC12 or SC14 really has to be run at or below 1:1 ratio with the crank. So at anything less than 3,000 rpm they are very inefficient and you won't get as much boost as you should.

An AMR500 will need to run at double crank speed or more so it will be less efficient at high revs but by then the engine is pulling hard all on its own. I reckon this will give good low-rev performance and instant response with a moderate top end. Not what you'd go for in a race car but perfect for the road.

Bigger isn't always better.

Oh, and with a roots blower that doesn't do any compression, an expansion chamber will smooth boost pulses by giving a bigger volume but won't create any cooling with expansion.

M


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PostPosted: Sun Feb 27, 2011 10:23 pm 
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I had a thread on this in "A series mods" http://www.ausmini.com/forums/viewtopic ... percharger basically an AMR300 comes off a 600cc engine and the AMR500 comes off a 800cc engine. If you were to use either one of these I wouldn't go any bigger than a 998 A series (maybe stretch up to a .40 or .60 thou overbore). From what I calculated an AMR300 on a 998cc engine would need to spin at 1.3 times to the engine to make standard boost which I think was around 5-8 psi plus the max rpm of the AMR series has to be considered to. Simply it's on a bigger engine than it was designed for so it will have to work harder to do the same job which will wear it out quicker.
The SC12 is a good blower for a big A series (1100-1275 or bigger), It comes off a 1.4L engine so is a good cheap blower and running at factory ratios will easily make nice boost.
I still want to use the AMR300 on a 998 so I'm not saying it's a bad idea just needs to be limited and the entire set up needs to be well thought out and calculated.
I'm planning on putting a SC14 on to my 1275 auto engine but that's another story.

Also for comparison I have a SC14 on (off a 1.6L) and it's now on a Feroza (also 1.6L) I'm not 100% sure what ratio it's spinning at compared to the engine but it's only creating between 5 and 8psi between 4000rpm and 5600rpm. Also it only really starts to boost around 1800rpm - 2000rpm. Thread... http://www.ausmini.com/forums/viewtopic.php?t=35493

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PostPosted: Mon Feb 28, 2011 2:22 am 
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Mokesta wrote:
Go the AMR500. They can be had for around $200-$250. These roots blowers have very low efficiency if run too slowly and and SC12 or SC14 really has to be run at or below 1:1 ratio with the crank. So at anything less than 3,000 rpm they are very inefficient and you won't get as much boost as you should.

An AMR500 will need to run at double crank speed or more so it will be less efficient at high revs but by then the engine is pulling hard all on its own. I reckon this will give good low-rev performance and instant response with a moderate top end. Not what you'd go for in a race car but perfect for the road.

Bigger isn't always better.

Oh, and with a roots blower that doesn't do any compression, an expansion chamber will smooth boost pulses by giving a bigger volume but won't create any cooling with expansion.

M


interesting ? why are sc12 and 14 ineffecient at lower than 3000 rpm unless they are worn out.

If a roots blower does NOT do any compression of the air into the engine then what is it actually doing.

And inregards to lowering the air temp you must have prooved that the 'ideal gas laws ' are no longer a law of physics.
P1xV1xT1=P2xV2xT2 or PxVxT =constant.

so if you increase the pressure for a constant volume the temperature increases. stick you hand on the outlet of a air compressor to the tank. conversely if the pressure drops the temperature drops,feel the temperature of the air coming out of the tank. . So the idea of a expansion chamber is to get the air to flow from the blower thru a venturi [IE increase the velocity] then into a larger volume [temp drop] and then when it enters the inlet to the plenum chamber[carbys] you have another venturi and increase the velocity again. This will drop the temperature.

and while we are on the subject of forced induction, do you alter the compression ratio of a engine when you increase the volume of air into the engine.

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PostPosted: Mon Feb 28, 2011 7:21 pm 
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david rosenthal wrote:
and while we are on the subject of forced induction, do you alter the compression ratio of a engine when you increase the volume of air into the engine.

Oh you bugger....now my brain hurts :roll:
Correct me if I'm wrong but a lower comp forced engine allows more air into the cylinder so more to burn therefore more power, correct?
Say the engine has 8:1 comp ratio and is forced. Your pushing more air in that it would normally suck in if it were NA sooooo yes it will be a higher compression in the cylinder while it's running BUT the engine will still be a 8:1 comp ratio when dismantled and volumes are calculated.......So if I think properly the answer to your question is NO you do not alter the compression ratio of a engine.

baahhhh I don't know :evil:

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PostPosted: Tue Mar 01, 2011 1:15 pm 
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Kennomini wrote:
david rosenthal wrote:
and while we are on the subject of forced induction, do you alter the compression ratio of a engine when you increase the volume of air into the engine.

Oh you bugger....now my brain hurts :roll:
Correct me if I'm wrong but a lower comp forced engine allows more air into the cylinder so more to burn therefore more power, correct?
Say the engine has 8:1 comp ratio and is forced. Your pushing more air in that it would normally suck in if it were NA sooooo yes it will be a higher compression in the cylinder while it's running BUT the engine will still be a 8:1 comp ratio when dismantled and volumes are calculated.......So if I think properly the answer to your question is NO you do not alter the compression ratio of a engine.

baahhhh I don't know :evil:


the compression ratio is not the critical factor. The engine must not have a air/fuel compression temp. that reaches 240-260 deg C. Auto ignition temp of air/petrol.
so if you can control the air temp then you can pressurize the cylinder to the maximum.

The air is heated by the action of compression and the heat is the thing that causes ignition of diesel fuel. The problem with petrol/air mix is that ignition can occur at a point earlier than the optimum ignition point. Then if the spark plug also then starts ignition, you have detonation [two flame fronts colliding]
A diesel has only air then the fuel is injected in at a precise point so a diesel can heat the air to more than auto ignition temp[ higher comp ratio] but a petrol engine has a mixture of air and fuel.

pressure in cylinder [at inlet v/v closing] x temp of air in cylinder at that point = pressure of air at maximum compression x temp at that point.
P1xT1 divided by P2 = T2

Final pressure[IE peak pressure] after combustion is then calculated[and measured] at 14 deg after TDC. IE location of peak pressure.

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PostPosted: Tue Mar 01, 2011 1:34 pm 
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Kenno, the SC12 is off the 1.6L 4cyl 4AGZE engine as found in some MR2's and Corolla derivatives.

The SC14 is off the 2.0L 6cyl 1GGZE engine as found in some Crestas, Mark II and Soarers.

Cheers,

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PostPosted: Wed Mar 02, 2011 1:01 pm 
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A Roots blower is a simple device that moves air from one side to the other. The volume of the air chambers within the blower do not change as they move from one side to the other so the air is not compressed at all inside the blower. This style of pump can, therefore, be used for pumping liquids.

A screw compressor is very similar but the air chambers reduce in volume during the stroke so the air comes out compressed.

The pressure increase from a roots blower is because it is stuffing air into a volume faster than the air is being removed. So, an Eaton M45 with 0.69 litres of displacement per revolution is stuffing that amount of air into the intake plenum. If the plenum is very small, say 1.5 l, then the pressure fluctuation at each pulse of the supercharger will be high but also the rise of pressure at fast throttle openings will be fast. If the intake plenum is large, say 4 l then adding another 0.69 l of air doesn't raise the pressure as much. The larger volume plenum results in a much more steady plenum pressure with the actions of a pulsing blower and discrete intake valve opening events. Larger plenum = more "lag" but easier to tune.

If a compressed air line is connected to a large expansion chamber, held at low pressure (ie not sealed), there will be a sudden pressure drop into the chamber and yes, there will be a temperature decrease. This is certainly the case if you have a turbo or screw compressor connected to a narrow pipe, then an expansion chamber. It is not the case with a roots blower because there is no pressure at the outlet of the blower unless there is a restriction to cause that pressure. If you were to connect a roots blower to a restrictive pipe or a pipe with a restriction at the end, then discharge that into an expansion chamber, you would get a decrease in temp. That would be counter productive though because you only got the high temp/pressure due to an unnecessary restriction in the first place.

Roots blowers have moving parts in contact with air. To ensure un-lubricated parts don't wear, they don't actually touch. There is a gap between the lobes and between the lobes and the housing. This gap must be maintained under all loads and temperature (expansion) effects so it can be a reasonable clearance. These gaps allow back leakage, reducing the blower's efficiency at low revs. Performance curves are not available for AMR300 AMR500 SC12 or SC14 blowers but are available for the Eaton range. If you look at the M45 curves, you will see that there is a sweet spot on the blower curve where maximum boost for minimum heat generation occurs. At low revs the efficiency is bad (but hard to determine because of limits to published data) and at high revs efficiency is bad too but acceptable up to the max revs of the unit.

See below for 5th generation curve. This is a much more efficient charger than the ones you'd get off a MINI. The older performance curve is around but I haven't searched for it for a long time.
http://www.eaton.com/EatonCom/ProductsS ... /index.htm

Some older data here: (also see the MP45 page)
http://www.capa.com.au/eaton_m45data.htm

All of the above curves bottom out at 4,000 rpm charger speed, which says to me that this is the lower end of where they are designed to operate. I don't think the theory of using a big charger so it is lazily producing boost is a good one. (Could be very wrong and very happy to receive test data for actual installations)

Now an M45 has slightly twisted rotors which reduces outlet pulsing but it doesn't have any coating on the lobes. The Eaton blower range has end inlet and side dischanrge. The AMR and SC blowers do have a teflon coating and have side entry and discharge. In the absence of curves for all, it is not possible to say whether the AMR and SC range are more or less efficient than Eaton. It could well be that the teflon coated lobes allow much better low speed efficiency?

Back to the sizing. If you use an M45 with 0.69 l per rev on a 1.3l motor with peak revs of 6,500, then the charger is bigger than optimum. If you set it up to spin to max revs when the engine is at max revs, then it will be above it's allowable boost level. If you set it up to reasonable boost levels, then it speds much of it's time at below 4,000 revs where it may be very inefficient. BUT, it may well be operating at peak efficiency when the engine is at peak revs so it could be a fantastic match for a peak-power engine.

Factory installations and common kits for M45s are on 1.6 or 1.8 motors and all produce around 135-150 kW (180-200 Hp). If you are aiming for that power from a mini then it is the right choice. If you simply want a cheapish charger and accept is isn't a perfect match it is also a right choice.

I have used an M45 on a 1.8 l motor and the boost level at just off idle was great but measurably lower than at peak power. I think that on a 1.3 l motor, aiming for about 8lb of max boost, then the boost off idle may be quite poor (but I can't comfirm and would really like someone to publish results).

So if an AMR500 has similar performce to an M45 but is 0.5 l per rev instead of 0.69 l and can also be spun to 15,000 rpm then it appears to be an entirely appropriate size for a 1.3 l motor intended for about 8lb of boost and with torque not peak power as the aim so redlined at 6,500.

As stated above, an SC12 is from a 1.6l (4AGZE) making about 130kw (173 Hp). If your aim is to have a mini engine with 110Hp but lots of torque then really you only need a charger 2/3 the size of an SC12. You certainly don't need an SC14.

Personally, I'd prefer a (semi)screw compressor ( http://www.sprintex.com.au/sprintex/wp- ... eSpecs.pdf ) with substantially higher efficiency than any roots type but who has $2050 for the base charger?

M


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PostPosted: Wed Mar 02, 2011 2:06 pm 
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Hi all,
thanks for all the input every one is giving.
I have been testing couple of bracket ideas for the AMR 500 for the last few days. Honestly none of them seems quite there yet and one of them I need to remove my air/con(which is not goinfg to happen lol)
Then suddenly I had an another idea; using turo instead of supercharger(possiably primary turbo out of a Subaru Liberty and set it up to 4 or 5 PSI)
Using similar manifold to Mirage Motorsport one and still blow throug http://www.miragemotorsport.com/ this will make the hole st up very dicrit.
Now I wil play with both ideas see which one appeals more at the end.

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PostPosted: Thu Mar 03, 2011 2:53 am 
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well mokesta you have been doing some reading, so now put that info with the basics of pressure ,volume and temperature and look at the whole system.
I agree that a blower is not going to compress any air with in the body of the blower, but it compresses the air on the discharge side if the volume of air being transfered exceeds the volume of air being used. This causes a pressure increase between the blower and the engine.If it didn't then the pressure would not increase above 1 atmosphere.

As for temp drop have a look at bernouilli's principle of a venturi. So as the air passes from the blower and comes up against a higher pressure more energy is required to move the air and that energy is dissapated as heat. Then if the air is passed thru a venturi it will increase the velocity and when it passes into a larger volume the pressure will drop. So in other words you have a venturi between the blower discharge and the entrance to the expansion chamber. You will find that this also increases the effeciency of the blower as you are accelerating the air.
Then you have a similar set-up from the expansion chamber to the carbys.

As for blower effiency have a look at some of the more modern types other than just car engines ones. There are liquid ring seal types and expansion seal types that are used as a compressor. IE they are sealed and take air at 1 bar and discharge into a chamber and increase the pressure upto 3 bar in the chamber. These are fitted to some big marine 2 stroke engines that are turbo charged as well.

All you are doing is transfering air from 1 atmosphere into a contained system and if you supply more air that what is used then there will be a increase in pressure, and if your blower has a capacity greater than the engine requirements under full load ,and the camber between the blower and the engine has a pressure activated bypass then that pressure with in the discharge system will remain constant.

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