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Discussion Starter #1
hi,
i've seen 2 superchargers for sale, not gonna say where cos i'm thinking about getting one! one's a brand new supercharger off a car that had a jcw conversion done literally 40 miles into it's life and has been sitting in his garage since - i've seen it looks brand new, the grey coating on the blades has no scratches not peeling.....and it's not on ebay, all the paperwork, part numbers check out, verified with BMW.

the other supercharger is a used teflon later supercharger that's done 45 000 miles. one or two small areas on the blades where the teflon coating has come away a little, but only a tiny amount.

both available for the same money.

which would you choose? is the teflon coating that a big a deal?
 

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Overly excited!!
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Pickup a nearly new Teflon coated one from eBay for around £100-150 if you really want one.
 

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Discussion Starter #3
these 2 superchargers, (not on ebay) are both going for a lot under £100, hence the question. how big a difference does the teflon coating actually make? there's 7 bhp difference between the old cooper s and the post facelift cooper s, how much of this is down to the supercharger?
 

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Most of that is supposed to be the facelift gearbox. The teflon coated 5th gen charger is supposed to be better.

Seems pointless to buy one thats not a 5th gen coated, or to buy a high milage 5th gen with peeling teflon unless you need to buy one as yours is failing.

How many miles has your car done? Is it a facelift model?
 

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I changed my S/C for a teflon coated one and noticed that the boost pressure raised much sooner up the rev range and held for longer compared to the one i took off.
 

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I've changed to a teflon one too. It gives about 0,1 bar higher pressure and withstands higher temperatures.

Be sure to get a good teflon one if you are planning on also jacking up the boost with smaller and bigger pulleys.

Try to find one with low milage because the cog wheels also wear down.

The costs of exchanging one again are probably higher than the lower price that you can get for the one with higher milage.
 

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The later supercharger with coating is the one to get ,provided the gear drive for the water pump is not damaged/worn ,
The coating is what is known as an abradeable coating ,ie it is designed to touch the casing and wear into size ,so it perfectly matches the outer with the rotor with a minimum gap.
This happens once the charger has got to its highest temperature and run for a few hundred miles .once set it should not change unless debris is passed through the charger or bearing surfaces alter-so a higher milage coated s/c would be better than a low mileage un-coated s/c all things being equal.
ps replace the oil before fitting
 

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Discussion Starter #8
The later supercharger with coating is the one to get ,provided the gear drive for the water pump is not damaged/worn ,
The coating is what is known as an abradeable coating ,ie it is designed to touch the casing and wear into size ,so it perfectly matches the outer with the rotor with a minimum gap.
This happens once the charger has got to its highest temperature and run for a few hundred miles .once set it should not change unless debris is passed through the charger or bearing surfaces alter-so a higher milage coated s/c would be better than a low mileage un-coated s/c all things being equal.
ps replace the oil before fitting
so what disadvantages would the older pre teflon coated superchargers confer?
 

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due to the larger gap between rotor and stator(case) they are more inefficient,so they produce less boost pressure and less flow ,and they are more affected by reverse flow,-thus the output air is hotter -less dense and less power
 

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due to the larger gap between rotor and stator(case) they are more inefficient,so they produce less boost pressure and less flow ,and they are more affected by reverse flow,-thus the output air is hotter -less dense and less power
excuse the ignorance but how is the supercharger cooled & lubricated, is it via the normal engine oil/ pressure & is it cooled with the engine cooling system or air cooled.
 

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Very primitive really ! internal oil bath and no cooling. it is a simple robust unit and has no internal compression so no heat generated internally due boost -its a pump only
 

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Very primitive really ! internal oil bath and no cooling. it is a simple robust unit and has no internal compression so no heat generated internally due boost -its a pump only
Thanks for that! is the oil in the oil bath somthing that should be changed..
 

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Basically yes - but it is not on the BMW service schedule- the same charger is used in various other applications and they have a scheule oil change around 60 000 miles
the chargers can also leak -tell tale marks under the charger
Why not on the service schedule? probably didnt want to publish an extra £500 job to the inpection schedule! ?
 

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The facelift model MCS's extra power came from an ECU tweak rather than any difference in supercharger, for what it's worth...
The extra power and shorter gear ratios helped knock a couple of tenths off the 0-60 and a second or two off the 0-100 times.
 

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I would think the ECU alteration was more connected with emissions and slightly more fuel due the charger change than as the stand alone increase through a better map -perhaps a better throttle response too
 
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