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PostPosted: Tue Jun 14, 2022 8:53 pm 
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Hello chaps
I’m Greg I’m 19 and I’m new here
My first and only car is “Steve” my 1974 Leyland mini clubman I welded in basically an entire new floor. It’s got the works done to it, a 1275 engine and gearbox built by readspeed, disk brakes, twin tanks, hilos, stiffer doughnuts, fully adjustable front end, walnut dashboard with 7 dials and 10x6 Cooper s rims. Oh on not to forget the roof basket from a Kombi I chopped down and tig welded back together, it makes it super useful at work and the various Bunnings trips

Enough about that.
Recently my mate Tom who has a 73 clubman with a 998 engine. he has fitted a vmaxscart supercharger and I was well impressed by the results, so I naturally want a piece of the action. Being on a budget I’ve decided to go down the route of the sc12 supercharger kit on mini sport (I haven’t bought the kit yet, I’m currently saving up). I’ve managed to get my hands on a sc12 supercharger and I’ve got some questions.

1. What do I need to modify/do to make the supercharger and the said kit off minisport fit my 1275 engine? I know I need a decompression plate

2.. The sc12 superchargers have some sort of clutch on the pulley which allows you to engage and disengage it (much like the interceptor from mad max) if I fit said supercharger to my mini will I be able to turn in on and off and the engine keep running? If so how to I set it up to do that?

3. will I be able to use my current 1 3/4 su carburettor on the supercharger?

Any advice tips and knowledge from people who have done such a thing before would be greatly appreciated.

I’ve attached an image of my mini hopefully you guys can see it
Thanks as always
Greg


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PostPosted: Wed Jun 15, 2022 9:34 pm 
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998cc
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Joined: Tue May 13, 2008 12:40 pm
Posts: 864
Location: Queensland
I would speak to Read speed about it if he built your engine which i believe is a fairly hot engine prob best to build a new engine to suit supercharger


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PostPosted: Wed Jun 15, 2022 10:16 pm 
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Joined: Wed Sep 08, 2004 9:27 pm
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Location: Wodonga - Vic/NSW border
awesome fun to drive, horrible to own...

I had an SC12 on my car for a few years, initially I used an 1 3/4" and it was OK-ish, but not ideal because SU carbs don't have a throttle pump - you get a lean spike on sudden throttle opening - different springs/needles/oil etc. will go some way to fixing it but it's all compromises. I injected it after a little while and it was better but still not great, fuelling into the cold side before the blower means the fuel doesn't stay atomised and falls out of the air. Obviously can't intercool it so I was getting 100°C+ intake temperatures, I water injected it to help with that, but the water was only on while boosting so driving off boost had very hot intake air.

The first engine I had it on was a typical warm 1275 plus something, I had a thick copper head gasket made (maybe 2mm?) by a mob in Melbourne, I just rang them up and said I wanted one for a 1275 mini and the bloke said "yep, no worries" and it arrived in the post soon after. That engine didn't last long - a valve seat insert (aka "unleaded conversion") fell out - it jammed the valve open and destroyed a piston and one chamber. I built another motor with around 9.4:1 compression which was happier, but it was always painful, again, just too many compromises.

The clutch on an SC12 engages/disengages on the 4AGZE motor in conjunction with a bypass that opens to let air into the plenum without going through the blower. You don't have that luxury. When I injected it I made a smaller, fixed pulley, but initially I used the clutched pulley and I could turn it off - air being pulled in by the engine would make the blower turn - but didn't run very well... especially given the fuel has to go through the blower as well.

I spent a very long time trying to get it to be reliable, but the best thing I did was take the blower off - I now have the most reliable, easy to drive mini - I can leave it for months and months and it just starts right up and is happy, I basically only use it for competition and I haven't touched the motor in 7 or 8 years except for changing the oil... though I did have to top up the dashpot oil a few weeks ago... tsk tsk..

As with all modifications, it's the devils trifecta - performance, low cost, reliability - choose any two...

I'd do it again, but only on a 7 port head where I could intercool out of the blower and inject into each intake port. So my advice, save up and get a 7 port head with webers, then save up some more and inject it, then save up some more and a bit more and put the blower on, or a turbo, and run an intercooler.

edit: here's my build thread: viewtopic.php?f=5&t=66558 the pictures are doing something odd, right click and open them in a new tab is fine so.. ?

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PostPosted: Thu Jun 16, 2022 12:35 pm 
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Joined: Tue Jun 14, 2022 2:59 pm
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Thanks Simon k and I got a mini
I’ve had a chat to Matt read at readspeed about supercharging my mini. Matt says he knows how to set them up to run like a Swiss watch. He has a special cam just for the application and so on. For the meantime I’ll have it running around as usual as I save up the funds. Thanks for all your advice
Greg


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PostPosted: Fri Sep 02, 2022 4:07 pm 
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Joined: Wed Oct 22, 2008 5:06 pm
Posts: 199
Location: Coffs Harbour
Hi Greg

Bit late on the post but I run an sc12 at 12-15psi with good results. No water injection, low compression pistons. I found a lot of initial ignition advance was the trick to helping the lean stumble, along with hours of needle filing. (Im using a Mikuni HSR but same principle as the SU).
Hard to tune a compromise for good fuel economy at cruise and no lean stumble though.
I am running super rich but hey, i didn't build it for economy and it helps to cool the blower.
Only prob that I currently have is plug foul/rich stumble off the line when only just touching the throttle. (Gets to 9:1 and blow some black) (This only happens when sitting idle at the lights for some time and the blower gets to about engine temp). Gone hotter on the plugs to NGK 5s and has helped but will need to make a new needle that is a bit leaner i reckon. Just go to find the time!!. SC12 pulley is locked but at low boost I used to run the clutch and could turn the blower off or an and it did run ok turned off.

Hope I haven't scared you out of it. I would like to try the vmax scart kit. I love the dcoe weber tunability.

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1310 SC 1969 Morris Deluxe - 15psi boost
1293 1968 Morris Deluxe Miglia - 45 Weber
HSV Maloo Z Series - Comp Cam - 300rwkw


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PostPosted: Fri Sep 02, 2022 8:08 pm 
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Joined: Wed Sep 08, 2004 9:27 pm
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Location: Wodonga - Vic/NSW border
MINI66 wrote:
. (Im using a Mikuni HSR but same principle as the SU).


Mikuni has a throttle pump doesn't it?

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PostPosted: Sat Sep 03, 2022 11:23 pm 
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Joined: Wed Oct 22, 2008 5:06 pm
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Location: Coffs Harbour
Yeah it does, and mine has an oversize pump bore from vperformance but it really doesnt have a major effect. It doesnt shoot quantity like a dcoe weber for instance. Its still all in the needle profiling

_________________
1310 SC 1969 Morris Deluxe - 15psi boost
1293 1968 Morris Deluxe Miglia - 45 Weber
HSV Maloo Z Series - Comp Cam - 300rwkw


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