I've got this supercharged 3800 series II engine out of my Bonneville just sitting here. I got to thinking today if it would be possible to modify it to work on my 300?



As you can see its designed to be mounted on the intake manifold. I thought I could build an adapter to bolt to where the manifold would be, then into a pipe running to the carb.

I don't remember exactly how much boost these chargers make but I believe it to be about 6psi.

- Is this possible?

- Would having an adapter into a pipe further increase boost? (I don't want to have too much.)

- What CFM do you think would be necessary to support around 6psi boost?

 

Are you going to be doing a draw though carb setup or potential a blow through setup of some kind? I can see the charger getting mounted up just fine with an adapter plate of some kind, now as for boost I'm not sure what kind of carb would be best. i would think based upon the setup something around the lines of a 650 CFM carb and watch it with a wide-band O2 sensor to keep the setup from leaning out if you could do something like a draw through carb. I am curious because a setup like this could cure my need for a dirty but cheap way to supercharge my own vehicles without a boatload of excess fabrication work.

 

If I do a draw thru setup that would eliminate the need for an expensive blow thru carb. But, I've heard that the bearings in the M90 are not meant to see fuel. Some say they will be fine, others say it will break at some point. Bearings are cheap so it may be worth it to try and do a draw thru.

I can fab all the adapters at work so that won't be an issue. And these superchargers can be had for around $100-200. If it can be made to work it's an extremely cost efficient way to force charge the 300!

 

If they are that cheap I say try it with a draw threw carb. The worst that could happen is that you kill it and have to buy another for 200 bucks. That's cheap for a supercharger. as compared to some prices and if you can source them for ease than even better. As for fuel killing the bearing, I say its one of those deals where I guess you pull a cover every so often and make sure whatever lubes said bearings or gears for the rotors is not full of fuel and has good grease and oil, mind you my knowledge is limited on superchargers but if it were mine that would be my thinking.

 

Yea crazy cheap, the junkyards are loaded with them and they are all over ebay/craigslist. The M90s were used on all the 3800 series Bonnevilles, Grand Prixs, Impalas, etc. I have to agree, just try it and if it breaks, well not much invested. I still need to figure out what to run for ignition/fuel.. needing more fuel pressure as boost rises. I've never supercharged anything before, all new to me.

 

I'd do it blow thru, I can't recollect anything special about a blow thru carb if you do it "right". How it's best done depends on the carb of course, I assume you want to use what you have to save money but you haven't said what you have.


The most sure way of course, in particular with our application and that blower is to just put the carb in a box. Build a box large enough to enclose the carb completely that mounts to the manifold on the bottom, and the blower mounts to the top of the box. The you just need to put a filter on the back of the blower. Add a boost pressure adjusting fuel pressure regulator and a belt and you're done.


The box isn't THAT simple, but it's not too complicated either.

 

check rotation, gm had some components rotate backwards. fuel may attack surface coatings inside compressor, along with seals and bearings. blow thru would be safest, o-ringed throttle shafts and boost referenced fuel pump.

 

If you do a blow thru carb system, you also have to raise the fuel pressure at the fuel inlet the same PSI as the boost. Say you run 7 PSI normally, and 5 PSI of boost. You would need to increase the fuel pressure to 12 PSI to compensate for the boost.