well, time for an update. The superchargers are, of course, driven off the crank. I calculated the belt loading and such for the pair of blowers, and need a 1.5:1 ratio to give me 5 PSI of blower boost over atmospheric, or, a pressure ratio of 1.35.
That may not sound like much, but, with compound boost, the ratios are
multiplied not added, so, if I run 10 PSI off the turbos, or, a pressur ratio of 1.7, I dont end up with 15 PSI of boost, I end up with 19 PSI of boost. It's important to let the turbos do most of the work, as the blowers are not as efficient, and, the point of the blowers is more to scavenge the cylinders than provide high boost.
The good news in all this is a co-worker of mine has an 8 rib 4.75" pulley, wich will give me a 1.47:1 drive ratio with the pulleys that are on the fronts of the blowers now, so, I've got my serp pulley setup nailed down. The problem is the crank pulley, and the fact that the blowers are too short to reach out past the end of the waterpump, AND, my AC air pump is alsoin going to be in the way, so, to get past all that, I plan to run a jackshaft. I'll have the crank turn a cog belt belt, which will turn one end of the jackshaft. The other end will have the serp belt and the 4.75" pulley. To get the cog belt and cog pulleys, I went out to the junkyard I scrounge and found a smucked Ford contour with the 2.0 DOHC Zetec. I snagged both cam cogs for the timing belt, then took the factory front pulley off the 400 and made some solid models in solidworks. I cooked up this assembly:
Green pulley is the stock 400 pulley. The red ring is the 36-1 toothed ring I'm going to use for the EFI to keep track of RPM and crank position. Grey hub is the part I need to have made, and the blue ring is the outside of one of the Zetec pulleys. I'll have a local shop make the adapter, and then machine the Zetec pulley for a light press fit, same with the red 36-1 ring.
hub will me made from aluminum. The 6 large holes are just to remove weight, while the 6 smaller ones will bolt it to the crank. The large hole in the middle is both to remove weight, as well as clear the stock crank snout bolt. The inner diameter will pilot on the crank snout, keeping it all concentric. I did the mass calculations in soldworks and it will weigh about 2.3 lbs.
And, a few cutaways showing the assembly:
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