my idea for a supercharger...

[crshbndct 0]

this is for my e30 325i.

i am putting an sc14 onto my m20b25. i have already started megasquirting it, and i am almost done with that, it is going to be a perfectly running ms'd car n/a before i start boosting it.

i am currently using 360cc injectors.(35lbs give or take)

i am going to also redo the head bolts before carrying on with the b00st.

as for the guys who say sc14 is too smal... an eaton m90 puts out 1.47 litres of air per revolution, sc14 puts out 1.42.

so thats the background.

there are 3 ways (from what i can see) to do the plumbing:

1: air filter -> throttle body -> blower -> intercooler -> intake manifold this way is the most costly, and leads to a bit of throttle "lag". also requires the blower to be constantly driven.

2: air filter -> blower -> intercooler -> BOV -> throttle body>intake the BOV wil have a low pressure spring which will vent excess boost more than the 8 or so psi i want. NOW before y'all go "TEHRE WANT BE A PSHHH NOISE YOU CANT USE BLOW OFF VLAVE TURBOS ARE MAD PHAT THEY GO PSHHH" i am not using the blow off valve to make a noise, just to vent off excess boost i.e. just as boost control. also required blower to be constantly driven

3: (preferred choice) air filter>blower>intercooler>throttle body>intake. between the throttle body and intercooler there will be a T off the line to another air filter, which will have some sort of one way valve, or check valve in it (anyone have ideas what i can use?) so that the engine sucks air through that until boost forces it closed and the motor is running on the supercharger. this way i can have the blower clutch hooked up to an output driver on megasquirt which controls its function. i.e. a tps switch, or something similiar. it can also be disable with a cabin mounted switch for sitting in trafic so that it doesnt engage/disengage constantly with town driving.

has anyone done any of these 3? what can i use for the one way/check valve behind the second air filter?

i am open to ideas here, so all/any input is helpful.

calculations show that with 70% ve, i should be able to get around 200hp at the wheels and so far all my parts have set me back less than $900 (although the injectors were free, so i guess that helped.) from here all i need is brackets to mount blower, piping, and time to finish the job.. its going on the back burner after my baby is born though.

[Hartage 0]

Been thinking about this as well, been told that the clutch on the SC14 will not handle the on/off if using the TPS.

Been done before and failed.

I think the SC14 is the way to go! Keep us up with how you go!

[bravo 35]

Sorry, can't answer your questions, but would love a full write up when its done (or even part way through). Seems like it may be alot cheaper than turbocharging, and although less gains, I'm only after slightly higher numbers than you suggested you'll be getting.

[crshbndct 0]

280hp(crank) should be attainable with the sc14, which is really enought to make an e30 come alive, especially given that the cars weigh bugger all.

e30tech has some great info under supercharging section.

there are also some pretty much fool proof guides to fitting megasquirt to an e30. using the guides posted there i had the car u an running (including installation of megasquirt) on a saturday morning. essential to get a widebnd o2 sensor though.

Edited August 14, 2007 by crshbndct

[bravo 35]

Rough total projected cost including tuning, excluding out-sourced labour?

[crshbndct 0]

there is no outsourced labour... about 1600 all up. but thats with hook ups - expect 2k-2.5k and if you need someone to install everything for you expect to get raped without lube

self tuned with megasquirt and wideband o2, and dyno run or two just to make sure everything is tip top

Edited August 14, 2007 by crshbndct

[bezzal 1]

expect to get raped without lube

Och!

[bravo 35]

Yeah, would be doing most myself, hence the cost without labour.

Cheers

[rowanhol 0]

here is a link to the bypass valve i got from ebay

http://cgi.ebay.com/ebaymotors/Bosch-Turbo...1QQcmdZViewItem

inlet size is 20mm, the piston then steps up to 42mm-thats just the part thats under vacum. outlet is 20mm aswell

i liked the idea of this over a blow off valve because a BOV only opens when you abruptly close the throttle body, i think you can modify the spring on a BOV so that it works like the porsche unit but its easier to just buy the porsche one..

the porsche unit stays open at idle and steady throttle,cruising on the open road, and when you close the throttle. ie more pressure in the piping than the inlet manifold which pushes from the bottom and and sucks the piston from the top to an open position

It closes when you sart to put your foot down, ie when there is positive pressure in the inlet manifold pushing down on the piston. I'm bad at explaining things but you should be able to get my drift

[crshbndct 0]

just managed to score a lysholm twin screw supercharger for $250..

much more efficient, and much lower out put temps than conventional roots blowers.

sweet....