Drouin Supercharged Zed makeover.

10:1 comp 1075 cc kit? or blower compression pistons?

I had a Eaton Supercharger I was going to put on a 10:1 comp 1200cc kit but I did the math and found out it took 60HP to spin that blower. I also figured it needed a 50mm carb to feed it, so ended up selling all those parts to a import car guy, actually gained value over the few years I had the stuff!

The guy I bought the blower from had it on a RX7 1.3L rotary and it made 8-10 PSI of boost.

I figured it would run more efficient on a 1400cc kit with a big throttle body.

The other reason for selling is I would have had to fabricate a lot of custom parts to mount it on the engine. Was planning on running it off the crank end.
 

Injected wrote:

10:1 comp 1075 cc kit? or blower compression pistons?

 

Yes! 1075 Wisecos at 8 to 1 comp.
These Drouins came with a 55m Hilborn style injector which i never had so the nearest carb i could find was the Super G.
I did run the smaller super B at first that i already had from a turbo kit but you could feel that it didn't flow enough and stifled the top end.

A few years after selling the supercharger gear I came across some snowmobile guys that offer huge flat slide carbs that take Mikuni jets.

thecrankshopvt.com/crank-shop-t-style-flat-slide-carburetors

They start at 48 and go up to 60mm!
 

Injected wrote:

A few years after selling the supercharger gear I came across some snowmobile guys that offer huge flat slide carbs that take Mikuni jets.

thecrankshopvt.com/crank-shop-t-style-flat-slide-carburetors

They start at 48 and go up to 60mm!

 

I would very much prefer a large flat slide over the crude S&S but as you can see from this pic there is no room to fit anything taller unless the intake was modified and the manifold dropped lower than the blower intake which probably isn't a good idea.

I think you have done a very good job in making that carb fit in the available space. The S&S seems to be the most compact carb with a throat above 50mm, those flat slides sit very tall. The S&S also has a very big float bowl on it so starvation will not be a issue.

When you fabricated the lockup plate and arms did you have to shim out the clutch cover?

On conventional setups you need about 1" of clearance but it could be less if you design the arms shallower than a MRE or MTC kit.

 

Injected wrote:

When you fabricated the lockup plate and arms did you have to shim out the clutch cover?

On conventional setups you need about 1" of clearance but it could be less if you design the arms shallower than a MRE or MTC kit.


 

No! Due to the design of the blowers spider drive which engages with the clutch basket there is no scope for spacing the cover and the spider sits so close to the stock pressure plate i originally had to skim over 1mm off the plate to stop the spider shaving shards of aluminium off it when the clutch was pulled in so when i made this it had to be at least 1mm lower than the stock clutch pack and the weights had to contained within the hub.
I've actually managed to sink the modified hub and top hat pressure plate a further 3mm into the basket whilst still allowing for the full 4mm of wear that's possible if all the frictions wore down to their service limit.

Here is a pic of the main parts.
You can see that the lock up fingers are enclosed within the top hat pressure plate when it's bolted in and push on the raised centre when the weights fly outwards.
The raised center of the pressure plate also has a steel ring pressed on with 5 steel pads bronze welded on so that the lock up fingers are not running on bare ally.
The top hat also has various slots and windows for clearance so that the weights don't foul the bottom or the sides.
It was so tight for space that the diameter of the centre is smaller than the stock clutch pusher so i used a Suzuki Hayabusa radial thrust bearing pusher and turned its 12mm diameter shaft down to 10mm to fit the Zeds input shaft.




 

Thanks for that explanation, a lot more machining work required to gain the arm clearance. Opposite of those bolt on kits and covers.