Well, gas prices are going up, and I finally have some money to spend on geeky things. Instead of making a 400WHP RX-7, I think I may spend a bit of cash on improving the Subaru, in my own geeky way.

 

So, questions.

 

1. How difficult is a MPFI swap onto a SPFI engine? I would assume it's more or less a straight bolt-on mod physically, and electrically will be handled separately. Also, where does one find a MPFI manifold? Are they easy to come by?

 

2. MSD6A/Crane HI-6: Who is using one, and what kind of benefits do you see? I'd be using this to make sure everything burns nicely.

 

3. Megasquirt/etc: Again, what kind of benefits are seen? I'm hoping to put a Megasquirt in charge of all the ignition/fuel, with a wideband O2 sensor and possibly an ion sensing setup for combustion chamber pressures.

 

4. Switching to a crank angle sensor: Is there a good way to do this, or do the SPFI engines already have something? With the megasquirt & such, I'd like to be able to do some pretty fancy timing advance if needed.

 

5. Switching to a direct fire setup: Can I use a waste spark arrangement? RX-7 twin coil packs are a dime a dozen in my world. :-)

 

6. Higher compression pistons: IIRC, the EA71 pistons are higher compression when put in an EA82. Are they still non-interferance?

 

Thanks!

 

-=Russ=-

Well, gas prices are going up, and I finally have some money to spend on geeky things. Instead of making a 400WHP RX-7, I think I may spend a bit of cash on improving the Subaru, in my own geeky way.

 

So, questions.

 

1. How difficult is a MPFI swap onto a SPFI engine? I would assume it's more or less a straight bolt-on mod physically, and electrically will be handled separately. Also, where does one find a MPFI manifold? Are they easy to come by?

 

2. MSD6A/Crane HI-6: Who is using one, and what kind of benefits do you see? I'd be using this to make sure everything burns nicely.

 

3. Megasquirt/etc: Again, what kind of benefits are seen? I'm hoping to put a Megasquirt in charge of all the ignition/fuel, with a wideband O2 sensor and possibly an ion sensing setup for combustion chamber pressures.

 

4. Switching to a crank angle sensor: Is there a good way to do this, or do the SPFI engines already have something? With the megasquirt & such, I'd like to be able to do some pretty fancy timing advance if needed.

 

5. Switching to a direct fire setup: Can I use a waste spark arrangement? RX-7 twin coil packs are a dime a dozen in my world. :-)

 

6. Higher compression pistons: IIRC, the EA71 pistons are higher compression when put in an EA82. Are they still non-interferance?

 

Thanks!

 

-=Russ=-

 

 

1. You would need a N/A MPFI heads, Intake, wiring harnes & ECU. N/A MPFI engines were most commonly found in non-turbo XTs, there are some found in 2wd GL10s too.

 

2. Not sure

 

3, 4, 5. Track down the board members who are unning megasquirt.

 

6. Since you have a SPFI engine you're already have a 9.5:1 compression ratio.

well since i run the full on ms and edis setup i guess i better reply

i am still adjusting my fuel and timing maps but i would say its a big improvement in mileage

i am using a narrow band o2 sensor and program that reads my datalogs i make on the way to and from work <about 30 miles each way>

and it then readjusts my fuel maps when i have the logs ran thru the program

 

as far as the crank angle sensor goes i used the ford edis setup and had my crank pulley modified to fit the timing ring onto and the edis module will control pretty much any wasted spark coil pack you put on it

 

it certainly makes a big gain all by itself back when i was using stock ecu for fuel and the ms to run the edis ignition

check my profile my names i use for msn messenger and few others i think are in there

 

and i can send you the maps i have so far

to give you a start eventually i will be using a wideband but.. those cost money

What kind of economy are you seeing?

 

-=Russ=-

well as long as i stay out of it i would guess its close to 25-30 ish maybe more mpg with my not so refined fuel maps right now

1. You would need a N/A MPFI heads...

Shouldn't need N/A heads, as turbos should work, too. I do not hink that there are any differences between turbo/non on disty-side head, and the non-disty side just has some extra passages/fittings. Heads swap side to side, and there are more disty-side heads floating around (as non-disty seem to die from exhaust port cracks more often).

 

Might consider using the turbo cams with less valve overlap. Not so great for N/A power, but better for economy and emissions.

 

Turbo manifolds should be plentiful. No real difference between them and a non-turbo MPFI, except maybe an extra fitting or two.

 

The multiple-spark advantage of MSD goes away with increasing RPM (not sure where with MSD), but still MSD might be an improvement over stock system. Single-spark CDI is good for fouled plugs, but its short duration spark is not so good for normal conditions.

 

EDIS is wasted spark. The system used on EJs is wasted spark. How about sending a couple of thiose "dime a dozen" coil packs my way??

oh and the edis setup also has the multiple spark discharge function depending on the module you get out of the junkyard

 

and i happen to have 2 mpfi intakes in my garage