Seeking Information About the Manussen Dual Supercharger Induction (Magnecharger)

I have a couple of pictures of a Pantera installation.

Blown, you are obviously in love and thus not entirely rational, so a couple of more facts. If you or someone reading this post finds one of these blowers for sale in which a screw or other metal object has gone through the rotors and scarred them or the cases, and you can get it cheap, do not throw it away or waste time trying to find a shop to weld and remachine the cases (which will hopelessly distort even from TIG-weld heat). Scarring is common with roots blowers both the aluminum and magnesium case ones. I have a close friend who builds blowers for big-name dragster guys. I asked how he fixes scarred cases, and he said, 'JB-Weld'!

Clean the scarred area with solvent, deburr if necessary and wipe on JB-Weld epoxy with a plastic bondo-scraper so the result is level and has no high spots. The cases & rotors never touch so there's no load on the repair. My friend says JB-Weld is fuel-proof once cured for a day or so, and if you're careful in applying the epoxy, the repair need not even be sanded.

Keep in mind most 351-Cs  have thin cylinder walls so you cannot safely increase cylinder pressures much. Sonic-test any donor blocks before considering supercharging; I personally blew a silver-dollar-sized piece of cylinder wall into the water jacket on an 11:1 c.r 351-C when it 'sneezed' on the start line of an event- probably due to not being fully warmed up. It had a fairly big flat tappet cam, a big Holley carb and aluminum heads but no nitrous or supercharging. This was on race gas, too. We later found the block had been bored 0.030" over and at the point of failure near the top of the bore, the failed cylinder wall was only 0.075" thick. We were lucky the rings originally seated- walls that thin flex a lot! Pro engine builders get nervous when cylinder walls get below 0.125" in a performance build and that excludes many (most?) 351-Cs. It's worthwhile to look for a good one.

teflon strips are not for street use

Sorry for the late reply. The engine that this blower is going on is SB Chevy not a Ford. I have now built the engine since this post and its a 388 cube SBC with Forged Crank, H-Beam rods and Forged flat tops. The compression is set to 9:5:1 and using AFR 220 Competitions heads. I have since changed the really crappy 1970's Edelbrock Street master manifold and purchased a weiand x-celerator which has much much bigger ports. The manifold has been port matched to the heads and will be a much better fit and not increase the blower height.

The blower is NOS so there is no damage to it as its never been used. I had it checked out also here in Melbourne by Fisher Superchargers.

I have also custom fitted a Snow water meth kit with dual nozzles to help with cooling. The Dello'rto 40mm were replaced with Dell'orto 48mm and these are my only concern whether they will flow enough. ..?  Anyone have experience with the DCOE carbs and power limits. I noticed a lot of people used the 50mm Weber carbs...
I do have the option of going EFI but if  have to...

The photos are before I put the AFR heads...target HP is 680HP to 700hp at the crank

Here are some more photos

HRM back in the '90s did a street blower test on six different street kits. A few things that stood out were, the Magnussen was the prettiest setup, probably the most complicated, and with the single pulley set back then, it delivered only 6.0 psi. Good that you have extra pulley ratios as that's not much boost these days. I've also heard that the idler pulleys sometimes give trouble.

One of our members had that setup on his Pantera for many years, and ran several side-draft carb setups. He finally settled on dual throttle body injectors from (I think) GM trucks, on a custom manifold. That's right- those TBIs don't care if they're run as down-draft or side-draft, they're cheap and they flow lots of air. He may chime in. .

Yeah, I have heaps of pulleys,. Apparently the highest overdrive combo that I have is capable of 12psi on 350cid. The test in the pic I've attached used only 40mm Dellorto and 130% overdrive for 8psi on 350cid and produced 560hp.

I have pulleys for  a lot more overdrive that this so we'll see.Here are my 48mm Dellorto ...

But There is a option for billet DCOE throttle-bodies from EFI Hardware in Melbourne.

I know of four different guys that ran them on 351-Cs. One used aluminum shear-studs to mount the blower to the intake, and sure enough- on one club run down south, the thing sneezed and lifted the blower. Took him a couple of hours to change studs but that was the only damage. On many roots type blowers, they use burst panels or some sort of valving to protect the blower from backfires, but with low-profile mounts, there may not be room, so shear-studs are a substitute.

You're moving a lot of air with these and the big danger is going lean. I would suggest a pair of 50 DCOEs or larger if you can find them. All the Ford kits were stagger-jetted on a dyno to get them to run right. And under even 6psi, crankcase pressurization used to blow oil mist past the main seals, eventually coating the engine... with no visible leaks. Not as easy an add-on as the brochures say.