Ok, I been driving around my 88 toyota MR2 supercharged for a while now, and once you've experenced boost you never want to go back to NA, So I have decided to supercharge my fairlane, I plan on using one of those short roots type Eaton M90 off 80s and 90s tbirds and fab up parts to make it blow thru the carb with the charger hanging off the side of the block, dump valve in between the carb and supercharger on the charge pipe, also its gonna be intercooled. Basically I can't affort a centrifugal type and I like to make stuff . the only problem I think i will encounter is crank pulley because its a serpentine belt drive, (perhapse use one of those Power steering bolt on pulley and weld a serpentine pulley on it), and the carburetor.

I have a holley 470 truck avenger, and I have no Idea how to make it work in a boosted application in a blow thru configuration, and maybe a 470 would be too small now, probably I am going to need a carb that flows at least 570cfm.  Also I have no idea how to retain the PCV system as the manifold will be under pressure then.

also if anyone know if theres a supercharger like the M90 price wise thats more compact?

Have you considered using a pull thru rather than a blow thru for the carb?  This would solve some issues surrounding the boost reference for the secondary diaphragm that comes about when going to a blow thru application.  If you pressurize the whole carb (similar to the 65/66 Shelbys), then boost referencing the secondaries gets easier but new problems crop up in sealing the accelerator pump linkage and any other connections that must get to the carburetor.  Depending upon the amount of boost, you'll definitely need a larger carb and a 570cfm would be marginal at best.  I'm thinking more in line with a 750 cfm if you're going with a vacuum secondary operation and a 650 cfm if going with a double pumper.

And definitely do some research on the camshaft.  Blower cams like a wider lobe centerline.  Chuck (MoonShadow) is currently working his way through this with his own blown application.

Lorena, Texas (South of Waco)

Holun,

     Further to what Ted said. Try to keep the static compression ratio around 8.5 to 1. You might want to go find a set of 471 heads. Y blocks seem to like more exhaust duration and lift with a blower, so work on the exhaust side.

    You can use a smaller carb if you blow thru it, but that creates it's own problems as Ted mentioned. Maybe consider finding one of the old spread bore Holleys, that would give you small primaries for some semblence of throttle response and enough airflow when you get serious.

                                           Frank

Frank/Rebop

Bristol, In ( by Elkhart) 

The enclosed carb setup would still be a blow through right? Just with the whole deal pressurized. I wouldn't have any idea how to set up a pull through carb on this rig. I don't think you can feed fuel through the McCullouch. I have considered the enclosure although the look changes from early McCulloch to a Paxton. I see carb enclosures on EBAY from time to time. They don't look that hard to hook up. Maybe that would be a good solution? Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I did some more research, Look like the Carter AFBs will be able to work as blow thru with out an enclosure with minor modification to the carb.



I looked at my engine bay over again today, I dont think the M90 is going to fit on the side of the block, I'll have to put it on top of the engine next to the carb. I guess I'll keep an eye out for some centrifugal type also while I am hunting for a M90 for a good price. or I can also go the turbo charge route, but I think tubo lag could be a problem.



and I just converted my car to a low pressure electric fuel pump too, guess I will need to get a high pressure pump and a regulator that have a pressure port to up the pressure with boost.

HoLun - 

Ever look at one of those WEIAND "Pro Street" roots blower set-ups? The blower has the carb mount machined into the top for a direct bolt on. The intake manifold has to be a simple open plenum and the nose shaft is extended out over the front of the engine to accomodate the belt drive. As designed, it actually has hood clearance on some vehicles - like a pickup. A "box" adapter might fit one onto a gutted "Y" 4 barrel manifold - but hood clearance will evaporate. The box could also be the aftercooler housing however. You always wanted a cowl induction set-up right? May have to find another hood to cut on ........................

What sort of inlet air temperatures occur on the "blow through" outfits that Hoosier and Frank are running? They don't have any aftercooling provision in their arrangements.   

 
 Steve Metzger       Tucson, Arizona

No, I never wanted cowl induction style hood, the reason I want to do blow thru is because of hood cleance, also the M90s are dirt cheap, and the M90 should give the whining noise too

actually, I have a spare hood in my backyard rotting away, its got some rust holes in it, maybe its time for some styling mods.

Steve,

       Never measured it, but you can feel the heat from the blower in the ducting. Hoosier's car will be cooler, he's running a cowl induction, sort of, using the cold air plenum in front of the windshield. I have to run the original air cleaner, underhood. The cars do like cooler temperatures.

                                                                       Frank

   

Frank/Rebop

Bristol, In ( by Elkhart) 

I just remember something, what 'bout the vacuume advance?  The vac advance pot is not sealed on the back side, so I cant just tap a nipple there to feed boost to it to make it work... hmm

HoLun:

First, I want to congratulate you on your grasping of the engine workings.  When you first started to post, and you were first learning, your questions were of the very basics of engine operation and repair.  Now you are thinking supercharged, and have a grasp of the little things that will be required to make it streetable.  ATTABOY!!!!

Now for the vacuum advance.  Just leave it unhooked and work out a suitable mechanical advance curve for it.  I know you have changed the distributor springs, so it may be as simple as changing to an initial advance setting that will give you about 34-36 degrees total advance.

John

John - "The Hoosier Hurricane"