This one looks good. Any more info, from anyone?

I have all those parts in the shed

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Respect mine and I'll respect yours.

I do like this set up but I dont have a pressure carby
this more what I want to do but I was thinking of havind the super where the alternator is

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Don't under estimate the power of a Mini

1975 Supercharged Blue Mokezilla
1976 Fudge Moke
1967 BRG & White 67 Morris Deluxe
1974 Clubman Mini S
2005 Red Mini Cooper S
2009 Mitsubishi Outlander VRX

I didn't use a 'pressure carby' either. The carb in the photo is just a normal, late-ish model HS4. Just make sure the throttle shaft and bushes are in good nick and run a line from the inlet manifold back to the fuel bowl (so that fuel doesn't get blown back down the jet). You'll also need an electric fuel pump that can supply more pressure than the supercharger can and a rising rate fuel pressure regulator. You may also need to make a restrictor for the carb mouth to reinstate the venturi effect that draws fuel out of the jet. . .I made one out of bit of ally plate. I've never really understood why pressurising the air flow through the carby destroys the venturi effect - but it does!

wat sort of psi are these running at?

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

It shouldn't, as long as the fuel bowl is maintained at the same pressure as the incoming charge. That way the venturi formed at the carby bridge causes a pressure drop and fuel is drawn out of the jet as normal.

The pressure is all relative, as long as it's increased everywhere...

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Simon

The adventures of an owner builder in the Tallarook Ranges

If you mean the front mount Moke setup, it ran about 6psi from memory. . .that was with an AMR300 on a std 998.

I agree. . .but we're both wrong. . .
A restrictor in the carb mouth is definately required. . .have a look at the plenum of a factory Metro turbo. . .there's a little brass restrictor ring. . .



Oh, and I found another shot of the blow-through setup on my Moke:

SC14 blow thru at 3 bar and 6.8:1 comp ratio. Peter just watch out about talking about venturi's in a supercharger system. some dis-agree but guess what, as far as I am concerned even with 4 carbys with ram tubes ,you need one into the plenum chamber.

what boost/comp ratio are you running on yours.

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

Well, I'm not even going to start comparing your engine to mine. . .yours has had slightly more work done to it. . .

Mine was a very standard 998 with a AMR300 on it. . .so 8-point-something compression and about 6psi boost flat out. . .your is somewhat more developed. . .

Regardless of that, the air flow restrictor case is identical - and I'll argue until I'm blue in the face that the restrictor was necessary. . .I'm not entirely sure why but I know it was needed.

Without the restrictor, the car ran fine at light throttle (off boost) and for short periods on boost. . .but if you mashed your foot and held the throttle wide open, it would run out of fuel quite quickly. . .probably in about the time it took to empty the fuel bowl. Lift your foot and let it coast - the fuel bowl would fill, the car would run-start itself and off you go.
This was neatly and completely solved by putting a thin ally plate with about a 35mm hole in it between the inlet pipe and carby mouth. . .no problems at all at idle, light or heavy throttle from there on in. I read something about restrictor plates being used in a blow-through Weber carb setup and thought I'd give it a go. . .

I've never thought particularly deeply about it. . .fluid/air flow dynamicist I ain't. . .but I guess it has something to do with the fact that with forced induction the engine is no longer drawing air over the carb bridge, it's being pushed across instead. . .ie the pressure differential across the throttle plate is no longer negative with respect to the engine but positive. . .

That being said, I still don't understand why that should stop fuel being pulled through the jet (as long as the bowl is seeing the same pressure as the inlet).

different kettle of fish, but that's the same problem I had with my SC12 & HS6, except it's a suck through. I'd get about 10 seconds on boost and it'd die. I bought a high volume needle and seat (has a ~3mm hole in it) which solved it right away for me - I stuck with the standard electric SU fuel pump & no fuel reg. I tried another pump and some other ideas and my mate just said "what's the biggest restriction?"



I read somewhere that with a blower it's fine (and sometimes necessary?) to run a carb one size smaller than if it was n/a



I'd say you're on the money there



From my also limited understanding, it's the venturi effect of the air flowing over the bridge that draws the fuel out. The blower pressurises the whole intake (all of your black pipes) and the carb, the engine just gulps as it needs it

I would agree, other than we're talking about the fuel demands of a 998 making maybe 40hp at the wheels in SC form. . .I'm sure a std HS4 needle and seat could keep up with that.
Also - without any other changes, the restrictor plate fixed the problem. . .

At 3 bar the SC will not last long before the coating on the rotors melts off especially since it happens at about 1 bar.
Some pictures of this setup in a car running would be nice.

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4efte powered Clubman
supercharged 998 race car

yeah... and I went from ~60hp n/a with twins, so 2 float bowls, back to one float bowl with a lot more demand for fuel

The super in the moke is it on a standed engine?

If not what has been done to it?

_________________
Don't under estimate the power of a Mini

1975 Supercharged Blue Mokezilla
1976 Fudge Moke
1967 BRG & White 67 Morris Deluxe
1974 Clubman Mini S
2005 Red Mini Cooper S
2009 Mitsubishi Outlander VRX

Completely standard, normal old 998.

That setup has now been removed and replaced with a draw though SC12. The standard engine underneath still wont die.

Clean oil, not too much advance, plenty of fuel and a water injection system keep it alive. . .