SC12 Supercharger on 1098 Clubby Estate
Turbo Mini Forums

I have been piecing together a sc12 kit, some from Ben, some from other places. I landed a very low mileage sc12 super charger with only 45k original Miles, and now I will have 2. I just bought a slightly used complete setup, the only problem is he lost the 6psi crank pulley and had a 12psi pulley fabbed. So my questions are this.

I have a bog standard 1098 A-Series with 145 compression. Runs good, shifts good, etc. I wanted to pop this kit on here and "take it easy". I'm not gonna be doing clutch drops, just fun cruising. The kit comes with a trigger wheel and sensor bracket (and ultimately I am planning on going to Mega Jolt).

1. Would you be nervous of dropping a 12psi crank pulley on a 1098, what will the boost levels look like under 5k rpms in the real world, I'll certainly keep it below that if not 4500rpms. Am I better off buying a new 6psi pulley from Ben? Are the 1275/998/1098 crank pulleys interchangeable? I have seen others run this kit on 998's, so I assume they are.

2. Megajolt I know is the way forward, should I even waste my time with a 2nd hand MSD Boost Retard box to get me through Spring/Summer?

3. The tappet cover breather needs to be ditched. How many breathers are necessary? I was gonna blank the tappet cover, and maybe use the mechanical fuel pump blank to go into a catch can.

Any other suggestions? I am excited, but I also don't want to cook a good motor.
Cheers!

I have a 7psi pulley spare

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

With the trigger wheel kit!

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Graham, I may be very interested in that from you, if your willing to part with it. Any thoughts on the rest of it? I don't understand the relationship of a 12psi pulley, and different engine sizes, etc, what that would mean at what rpm. Is the 12 gonna make a full 12 at 6k, 5k? Or am I only gonna be seeing 6 pounds of boost at 4.5k rpms? Any easy way to do a calc? My gut is telling me to start with the smaller pulley and have fun with that, then when I have the cash to fix what will eventually break, go for the 12....

What size engine is the 12/6 psi designed for ?

A Rootes air pump doesn't actually compress the air, it just moves a certain amount of air per revolution, ultimate boot pressure is dependant on engine size.

Metric is for people who can't do fractions.

1. I think 12psi on a standard motor is too much. You want to drop the c/r to run that much with no intercoolers and clockwork ignition.

2. Just fit MJ

3. As many as possible.

Also is 12psi calculated on a 1275? If so you will get more then 12psi with 1098.

I have pm'd you about the spares that I have

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I'd really like that fixed pulley fast carl did for a buddy/customer as well.

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[quote=Has anyone ever drilled out the flywheel breather on the small bore? Is it worth it?[/quote]

using that location as the main way my engine breathes and for the turbo oil drain too also got a 3/8 or 1/2 take off from the rocker cover thats not doing much it connects into the same clutch cover breather location

seems to be fine ill try get a pic of it

There will be more boost on a 1098 because your trying to squeeze the same amount of air into a smaller space.

The speed of the blower dictates how much it will pump. If you make the engine smaller the blower will still be pumping the same amount per revolution of the engine but you will be trying to cram it all in smaller cylinders so you will have more pressure.

To work it out you really need the compressor map which dont have to hand for the SC12. As you spin the blower faster and ask it to pump more pressure it looses efficiency so you have to compensate for this. (but its probably over complicating things for your use)

While I know this is not ideal, I did end up tracking down a MSD 5462 Boost Master Timer, this is the universal one they stopped making that works with stock distributor/coil. My question is, would you leave vacuum connected (can you get away with it), or plug the vacuum advance. From looking at the vacuum setup on the supercharger, is it my understanding that all the ports on the supercharger are t-ed together, then the vacuum to the carb? So they are all together?

I looked at it years ago and went with megajolt

On 9th Feb, 2015 notabmw1 said:
While I know this is not ideal, I did end up tracking down a MSD 5462 Boost Master Timer, this is the universal one they stopped making that works with stock distributor/coil. My question is, would you leave vacuum connected (can you get away with it), or plug the vacuum advance. From looking at the vacuum setup on the supercharger, is it my understanding that all the ports on the supercharger are t-ed together, then the vacuum to the carb? So they are all together?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Had time to get it mocked up, working on tappet covers right now to add breathers and waiting on new gaskets. Also waiting for some other odds and ends.







MSD Boost Timing Master

That's a nice picture of my Kitchen Table you have there.

Edited by notabmw1 on 19th Feb, 2015.

I was working on the smaller details while waiting on some parts (tappet covers to mod, 10psi crank pulley, catch can, boost gauge, and speakers). So I fabbed up this 1/2" heater hose line to bring the return line to the other side so it is clear of the supercharger. I think it turned out good. Just waiting on 1/2" bulk head plate to run heater hoses through.





Painted green. Thinking about putting some crinkle black on the supercharger, we will see.