Supercharger Info - Drouin Roots Type

I had a few members request a few more details on my bikes supercharger. This is a high level approach to that questions. Feel free to ask... I may actually have an answer.





This is a Drouin roots-type supercharger.

Drouin Background:
Drouin appeared to have copied the Magnuson blower. Drouin advertised them nationally in magazines and sold them in the earlier 80s, when I actually purchased this unit. What Tom Drouin didn't tell the buyers is that it was a design and not manufactured at the time!

After about 14 months and many shipments of parts... usually one at a time, I had a complete supercharger. I only know of about 6 people who got the full blower kits.

Drouin was investigated for US Mail Fraud, since he took money and shipped some parts though the US MAIL. I withdrew my part in that since I finally received the product. I recall Drouin filing for bankruptcy relief over this.

GREAT product - bad business strategies.

Fuel Delivery:
The unit is NOT carbureted, but instead uses a butterfly fuel injector... a giant throttle body similar to the older Hilborn Fuel Injector systems... probably a knock-off of that.


Water/Alcohol Injection:
There was an upgrade to add a water/alcohol injection system to the Drouin package, and opted for that. The system was a basic container that sits below the supercharger and holds the liquid. The tank is pressurized as the manifold pressure increases, thus pushing the liquid into the throttle body with the gas and air. The purpose of this unit it to use the water and or alcohol to cool the fuel, making it more dense in the combustion chamber.

Running:
Idle is tough, probably due to the drag on the unit through the clutch basket. I have got it to run as low as 2,000 at idle, below that it blips high and low. I may investigate now that I know a bit more, to see if the idle can be reduced through better fuel management.
Video with Sound of it running HERE (note manual choke was the box top :lol:

Boost:
Currently the pulleys are set to produce a max of 7 lbs of boost. I was fortunate enough to have many discussions with Tom Drouin and also received the pulleys to produce 15 lbs of boost.

I elect not to use the 15 lbs boost system, since I never welded the crank on this engine. I am under the impression that the added boost could slip the crank, although I have heard from turbo guys who push large boost without welding the crank... at least the first time:ohmy:

Results:
The results of all this... A really fast KZ that screams attention from the whine of the blower spinning, to the bulk of the drive unit, to the actual performance. When I built this bike there were many street racers... shitty looking bikes, with HUGE investments in the engine. I watched people lose their bikes in races to seemingly ratty bikes. I wanted to protect my bike and my ego... so the supercharger went on. Nobody wanted to race me for money!

In comparison to today’s sportbikes... I don't really think this blown bike can outperform them, but as an Old School Ride, it sure it beautiful!


More images are n our gallery here and offsite HERE!

"In comparison to today’s sportbikes... I don't really think this blown bike can outperform them, but as an Old School Ride, it sure it beautiful!"

Prolly would give them a run for their money! And beautiful is an understatement

At speeds of 120mph lets just say this was not as stable as my 1997 Honda 900RR, nevermind the newer stuff.

I am considering Dyno testing it.
I never did in the past since, there was not one locally and I was broke after building the bike.

Now my only hesitation is to push it and blow it up... that would not be fun.

It looks like it's getting it's power from the center of the clutch, can you elaborate a little on the blower drive attachment to the motor??

Yes, the premise of a supercharger, like a turbo is to force the fuel mixture into the cylinders to make more power. A supercharger is a direct drive unit, which spins as the engine spins. Most race applications are driven via belt off the crank, and you lose the alternator (stator). This application, along with Magnuson's for the KZ, used a drive off the clutch basket. This provides an instant response, as opposed to a turbo, which uses exhaust gas to turn the blower... so you need to be producing more exhaust gas for more boost - hence the turbo "lag time" for the blower to kick in.

You may know that the clutch basket has slots for the clutch plates. This blower drive unit has fingers that engage into the clutch basket and spin the blower based on the clutch basket spinning.

So, as the clucth basket spins, the drive unit spins the belt, which through a set of pulleys, regulates the ratio at which the blower spins. The faster the blower spins, the most boost (pressure) into the cylinders.

A Roots Type blower is easily explained HERE at Wikipedia

I kind of figured it was driven by the slots in the clutch basket, but I wondered if they used a modified clutch basket or the stock one. Don't seem like there would be much room for drive fingers on a stock basket.

I keep reading people discussing an Eaton M90 or M45 on a KZ, but still haven't read of anyone actually doing it. I'm not sure a centrifugal supercharger wouldn't be better than the Eatons.

To be honest, I don't remember the basket adaptation. I think it was simply remove on clutch plate, use HD springs, add the modified end plate... and that was it.

The small Eatons are the same type as this. The difference is in the lobe design which has a twisted helix design instead of straight lobes. The twist increases the compression.. pressure... boost... power. It would not take a huge amount of engineering to adapt one, just some machine time. The manifold does play a HUGE role in delivering the pressurized mixture to the cylinders, but that would only provide peak performance. Let's face it, even a poor design would be inefficient and still add 100+bhp.

The centrifugal blowers are more compact, but have to spin WAY faster to make the same boost. Something like 250,000 RPM over the roots type 25,000RPM (not exact). Also the centrifugals has a smaller output that now usually traves to its destination instead of a dump into the manifold. The travel heats and distorts molecular design of the mixture. ...Again a loss that may not be worth discussing if you are adding 100+bhp.

Are these the same units that are made for the British bikes. I can only find info and I have only seen used ones for the British bikes. I was going turbo but I have always wanted to go blower but knowbody was doing it and I could not get any support. I want all the info you can possibly share,please. I saw the video, did you get it to idle. Do you have a video clip of it. I really want to hear that blower wine. How about performance. How does it compare to turbos?

Are they rebuildable?

Who else made kits or still makes them?

Yes, Drouin made the supercharger for the Nortons. That was a differnt technology - centrifigal and not roots type. I do believe he made them prior to this model. He has been out of business, and I could not find him...

The only video at this time: VIDEO CLICK HERE

They are rebuildable, but 'should' last reasonably long. Car blowers with the same technology last 50,000-80,000 miles. I would think the engine would give first if constant hard boost is used. Getting main parts for this unit will be very difficult. I have spare belts, pulleys and bearings, but a housing or rotor... it will be trash.

In theory, the supercharger can lengthen engine life by making it easier to run. But that is when superchargers are used for efficiency rather than performance. Some Magnuson car blowers actually add MPG and run cleaner with blower then without. This is current 2008 models and not used for performance.. cruising highway speeds.

Current blowers. The only ones I have found were for drag use. They are not built to fit the bike...

How does the Drouin type differ from Magnusom superchargers? I have been wanting to do superharger but I could not find any support so I have switched to turbo. But you have inspired me again to go supercharge. There was a guy on here that had a Z1R with a big block/supercharger combo and he said he got 300hp. You have to take some more pics and videos. You can't just tease us.