65 replies to this topic

[Spaceibiza]

I know there have been plenty of threads debating the supercharged vs turbocharged debate, but I'm just looking for a bit of experienced advice on my situation.

Firstly I have a blow through supercharger setup on my car built by Neil Slark. It uses an M45 charger mounted on the front of the block, going through an inter cooler and into a metro turbo plenum and carb. The engine itself has been built with forced induction in mind with a slark head and low compression forged omega pistons. Firstly I am very happy with the performance of the car. On Slarks rolling road it was putting out 152bhp and 150Ib's at 1.2 bar and is plenty fast enough for what I want so making it go faster is not my first priority. I just have 2 issues with it.

First of all the charging system. I don't have an alternator as the supercharger is mounted where the alternator normally fits. I did have a small motorcycle alternator mounted to the end of the charger as there is a drive for the waterpump on the bini, but this solution ended up not working as the alternator wasn't compatible with a Mini's charging system, and also the way it was driven from the supercharger created an horrendous rattling on idle. So at the minute, I'm just charging the battery up each time before I drive it which is not ideal. It's purely a fun weekend car so I'm not using it for work or anything.

Other thing for me is the noise. It sounds awesome from outside but from inside the whine from the supercharger is all I can hear. It might seem a bit silly to some, but I personally would like to hear the engine itself a bit more and actually hear the exhaust note a bit. I think I would enjoy the car more if I could.

With these 2 things in mind, I have been thinking should I go down the turbo route? I was thinking with a turbo, I could then just fit a standard mini alternator and have no charging issues. Also I think I would be able to hear the engine and exhaust note a bit more. I already have a metro turbo carb, plenum, an inter cooler and megajolt and low compression engine with forged omega pistons. I'm thinking it would be pretty straightforward to swap?

1 other thing is the bulkhead has not been cut. I could do this if I really needed to, but would prefer not to if I could get away with it!

I do like the idea of my current setup as it's a bit different from the norm, but wondered what people thought. Try and develop what I have or go for a turbo setup?

Thanks!

[mini13]

well there are probably a few things you can do about the alternator, I run a smallish 40-45 amp nippon denso alternator from a kuboto digger, a lot of people use these and they seem to work a treat.

http://www.ebay.co.u...=item1e77e52f5d

I have seen alternators turned round so they sit in the wheel arch area, but if your not running a flipfront, or have a side rad this is probably niot an option,

another thing that may be possible is to put the alternator up the back of the engine where the suck through chargers are normally positioned,

If you were starting fresh I would say go turbo charger, but as its already in and already working... why mess with it too much.... although with a turbo your likly to see a significant improvement in MPG.

got some pics, It might give me some more thoughts.

[Spaceibiza]

I do like how what I have at the minute is a bit more unique so if I could find another alternator solution that would definitely be a good option. I'm away from home until Sunday, but when I'm back I'll post up a couple of pics for you to look at and see if you have any ideas!

[freshairmini]

Do you have any sort of deadening or sound insulation/isolation on the bulkhead. Might help to cut down on the charger whine.

In regards to using a turbo, I believe with the right manifold you dont require any bulkhead mods. I think you can use the gt1548 and a mirage manifold. Not certain tho.

[Daviewonder]

although with a turbo your likly to see a significant improvement in MPG.

Why is this?

[Turbo Phil]

Because a supercharger {positive displacement type} is directly coupled to the engine the boost increases in relation to rpm & you'll usually see boost from very low down, so even driving at relatively low speeds the engine will be on boost, hence the decreased MPG.
Whereas a Turbo can be controlled with throttle position.

[mini13]

yep as phil says,

the charger is constantly consuming power, an the power consumed is proportional to the amount of boost, below is a power consumtion chart for the Eaton M45 from the Bini, from this your probably looking at about 2-4 bhp being consumed at cruise, considering it takes about 12 hp to push the mini through the air at 60 mph thats a big impact.

[mini13]

incidently, on a top fuel car the charger takes around 700hp to drive it!

[Spaceibiza]

Here are some pics of the supercharger installation. Any ideas about how i could mount a suitable alternator?

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•  IMG_3698.jpg   34.71K   141 downloads
•  IMG_3699.JPG   62.44K   160 downloads

[Nick Warwick]

Isn't this the blow through set up done by slark?

[Spaceibiza]

Yes it is. The supercharger system works fine, it's just the lack of alternator that's been a bit of a pain which was making me think about converting to a turbo so I could just use a standard mini alternator. From what people have said and having a good think about the situation myself, I think I would be silly to get rid of what I have, as it's all set up and running. I think I just need to find a solution to the alternator problem and maybe mount a small alternator in an alternative position somewhere. When it was done by Slarks, it used a motorbike alternator mounted to the end of the supercharger, but it didn't really work in the end and rattled like mad!

My other plan is to make some kind of intake airbox to hopefully silence some of the supercharger whine. I can then run a pipe from the by pass valve back into the airbox so it recirculates properly rather than blowing out to atmosphere. Not quite sure how to go about making that yet unless anyone has any good ideas?

[mini13]

any more info/ pics of the alternator,

i'm wondering if its a simple as a cooked regulator pack

[Spaceibiza]

 IMG_2710.JPG   79.43K   11 downloads

any more info/ pics of the alternator,

i'm wondering if its a simple as a cooked regulator pack

Its a denso alternator off a kawasaki ZX7R i believe. I bought another one from a bike breakers and tried that, but it was exactly the same. I took them both to an alternator specialist to be tested and he said they were unsuitable for use on a mini. Normally an alternator has a big thick cable coming off it, but this alternator just has 2 thin wires so i think he's right. It was a good idea to mount it on the end of the supercharger, but because it's effectively home made, the coupling rattled like mad on idle and sounded like my big ends were hanging out, so i think a belt drive would be a better way of doing it.

[Nick Warwick]

If i had this set up i would personally keep it and get the alternator sorted out.

Could you run it below the supercharger nose? so it can be belt driven.

[mini13]

I would look into putting the alternator over the back of the engine in a similar manner to where this charger is.



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