i have a supercharger set up off an 90 supercoupe 3.8 ford , any ideas or past attempts at a 12a carb conversion? car is 83 with very healthy mazda reman, any ideas appriciated, tia trevor

 

the first thing I would concern myself with would be the drive gear ratio.

the redline of the original engine was something like 4000 rpm wasn't it ? the 12a is more like 7000.

a pump has an individual pressure/flow/RPM curve.

and you have TWO pumps, the blower and the rotary, with two different curves that you need to match.

the hassle I see is the likelihood that the curve of the blower is tailored for the curve of a 4000rpm redline engine, so that the pressure/flow of the blower drops away at higher rpms, where the 12a is just starting to kick in.

so you need the gearing to extend the range of the blower to match the redline of the engine, sort of thing.

odds are that there are going to be lumps and hollows in the combined pressure curves that you will need to cope with once you get the gearing sorted.

pressure humps from the blower can be dumped or recirculated, hollows {where the engine wants more air than the blower can deliver } are much more difficult to cope with and so should be dealt with mostly by gearing, bumping the overall curve up so there are humps and not hollows.

 

Tia do a search using "Eaton" by username "Sterling". I have alot of old posts here about it where I have alot of questions answered by people here, as well as calculate the ratio and possible boost pressure.

I have plans to mate the M-90 to my 12a and replicate the brackets for sale to others like us.

 

Um.. or you could do like people normally do with superchargers, and change the size of the pulley. RPM has nothing to do with it, it's aiflow into the engine. RPM can be changed easily.

 

my concern at this point is how to set the stock carb up for a blowthrough what would be fuel pump requirements ? ill limit it to 6 psi at firsst , its not gonna take much to lite lite my yellow fire i also have a couple msd s and a boost regulated timing reetard with knock sensor capibility, i thinks for ease of fabrication and ability to adjust boost levels easily plus the eatons self contained lube and if i use the ford inlet it full bypasses until you drop the hammer thus getting instant boost,
i love the 12a at 7000 k i just get a little bored geting there,ill screw with it after i get my paint straightened out. tis trevor

 

They, Them, Those people...

Well, at least it's not a V8, right? Just how the heck is your own personal prototype ride with the Eaton going, sterling? It seems like forever when you first introduced the idea and beat everyone with a bat when they kept telling you to go turbo...

 

i think his name was Trevor, and he was saying thanks in advance. unless he meant tia as in the spanish word for aunt :-P

you ever see turbo mikes twin supercharged fox body tbird?
http://www.toohighpsi.com/SCTC/sctc.htm
hes done lots of pulley changing so im sure he knows what size pully flows at x rpm

found a link to these pics from mikes page too:
http://home.att.net/%7Eampikas/PicPage.html