This question is directed to anyone who knows anything about SC12 superchargers. . .
What do the three 'vents' on the supercharger unit actually do?
Anyone who has an SC12 will know what I'm talking about - two vents at the pulley end and one at the other, generally connected together and (upon Ben Afford's recommendation) connected to the carb vac advance port on a Mini draw-through application.
Where do they connect on the original Toyota setup - are they meant to see boost pressure to equalise pressure across seals or something like that?
Any info would be great!

i would imagine they'd be emssions / ecu related..

perhaps toyota put a boost cut on it's Super chargered cars as well and the hair driers...

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i thought they were just breathers, but im often wrong

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does that mean you're often right?

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They need to be connected to the carby.

Not 100% sure why. But it needs to be or something dodgy happens.

I first thought, meh emmission, who cares. But it runs better with it connected (no oil flying out! and it was pulling air in which is wierd??)
and cos Ben told me to connect it.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

Yes they are ment to equalize pressure on either side of the seal so boost when under boost and vacuume when vacuume via an electric valve. So originally when I started playing arouynd with these I connected the pipes to the inlet to head manifold, see's boost and vac when required good but I found that after a little while the oil would disappear from the gear train in the end of the blower not real good so connected the pipes to the carby this stopped and blower's seem to run fine oil level doesn't move and have had no problem with seals and that is how I left it.

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4efte powered Clubman
supercharged 998 race car

Brilliant - that's the answer I was looking for Ben. . .might have a bit of a 'play' and see what different setups do. . .
Thanks!

Gentlemen, whilst not a Mini owner, I am planning on fitting an SC12 to a 1934 PA MG, and am finding it very hard to get any information and/or specifications on this blower. Does anyone have any such data, or can tell me where to find it?

I'd really like to know how to rig it up to an SU carbie - perhaps just plug the pressure equaliser ports and hope for the best? Any help would be greatly appreciated, thanks.

Pete.

the ecu controls them in the levin, i think it opens them on boost and closes them at idle, they did it to get a smoother idle

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backyard performance............. Aint it the best

Gentlemen, further to my request I've found a page of stuff on the SC12 which may be of interest to many of you. It's sort of what I was after. Try http://shell.deru.com/~sgn1/AW11/Scnotes.htm.

I am going to have to run my SC12 upside down, plugging the dipstick hole and air vent into the gear case and making a new oil filler plug set-up.

I think I will plug all the air vents and underdrive it a bit to keep the temperature down. Original s/cs on Pre-War MGs didn't have any of this stuff. Then again, come to think of it, they didn't seem to be that reliable either!

Pete.

Does anyone know how to identify an sc12. A mate has a toyota SC that he said I can have, but I am not sure which one it is? Does anyone have the correct dimensions or where to look etc?

Regards
Smarty

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68 Mini
70 Moke

The SC12 has this cast into the body of the unit at top right above the outlet port.

Smarty - the SC12 has SC12 cast on to the case - easy to see.

Peter - scroll further down on this forum and you'll find :
http://www.mr2.com/TEXT/SuperChargerInfo.html

Thanks 69elf. I found that site after I'd posted my request for info - his boost levels and oil discussion were particularly helpful, but he won't answer e-mails! My 847cc OHC engine requires about 6-8lb of boost, for which a used SC12 is perfect driven at engine speed or close to it.

The SC12 is not that easy to get in Australia, but for those of you who want one, they come up all the time on TradeMe, a New Zealand based auction site similar to eBay, but restricted to Kiwis and Aussies only. You can pick them up there and have them posted here for way less than you'd pay in Australia. Find TradeMe on Google and type in "sc12 supercharger" in the Search field for Cars, Bikes and Boats.

Pete.

On a 847cc engine you will want it to run at a lot slower than engine speed to achieve 6-8 psi of boost on a 998 at about 80 percent engine revs it will get about 9psi

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4efte powered Clubman
supercharged 998 race car