Which ECU should I consider

[74Dusted]

I joined years ago, looking for some info on MS, and the project stalled for a long time. At the time I wanted to run Fuel Injection on a Roots 6-71 Blown (Supercharged) 340 in a '74 Plymouth Duster-Twister. I ran out of money after building the engine, and the car needed parts, so the engine sat on the stand for 4 years. I got impatient and dropped the engine in my '73 Duster, with a pair of carbs and drove it like that.

Fuel Injection is a foreign world to me, so I have no idea what to look for when pricing or ordering stuff like the ECU, and I have no idea how I should set it up (Batch Fire, I would think).

Currently I have a pair of 750cfm Carter AVS Carbs on top of the Blower, which would be replaced with an Enderle "Bugcatcher" Hat and Injector Plate fitted with Electronic Injectors. MPFI isn't an option, since the blower is cooled by the fuel going through it. I'd imagine I would need Batch Fire for a setup like that, wouldn't I? It would be the equivalent of a pair of massive TBI units.

What MS Controller would I be looking for, for my setup? Basically just looking for a standalone fuel controller since my ignition system already handles the vital stuff, Timing Locked Out at 30.1 Degrees Advanced (No Mechanical or Vacuum Advance), Ignition Box retards the timing for Starting, and pulls out timing as the boost increases (Boost Proportional Timing Retard).

She's not very friendly on the street (it hunts for an idle half the time, idles in neutral, requires a foot on the throttle when in gear, idle can't be adjusted up any higher and be friendly on drivetrain components) , and I'm hoping the swap to Fuel Injection might tame her down a little bit.

[billr]

I always suggest the MS3, it is only about $100 more than the MS2 and has a lot more features and room for growth. You will probably also want the MS3X, but that is an easy add-on and you don't have to commit to that right away. Isn't that extra $100 trivial when compared to the over-all costs of a project like this?

[74Dusted]

You're right about that, $100 doesn't even put a dent in the amount I've got sunk in that motor ($3,500 for the engine block, $3,800 for for the Blower, $900 in the Ignition System, I forget how much for the Pistons, Rods, Crank, etc).


At this point, converting to EFI is only going to cost a bit more than a pair of high quality carbs for on top of the blower. (okay, a couple hundred more than a pair of great carbs, with none of the cold blooded issues)... And my car is definitely cold blooded (especially with no chokes and locked out timing), anyone with a Blown engine knows this, you have to let the blower heat up before the engine will run correctly.


Would you run it as Batch Fire though? Sequential wouldn't make sense (at least I don't think it would), since it's all spraying into the blower and most likely wouldn't supply enough fuel as Sequential. Could the Distributor (Cam Signal) be used as the only signal communicating with the MS Box? I don't have the space for a Wheel on the Crank, with my SFI Balancer, V Belt Pulleys and Gilmer Drive Sprocket I'm pretty much tight against the radiator already and have no room to spare to add a Wheel anywhere in that combo.


Can the MS Box share the same MAP and O2 Sensors that my Ignition System and Wideband use for their own systems/gauges? Or do I have to add another MAP for the MS and another set of O2 Sensors for the MS?

[Matt Cramer]

Would you run it as Batch Fire though? Sequential wouldn't make sense (at least I don't think it would), since it's all spraying into the blower and most likely wouldn't supply enough fuel as Sequential.

You could do sequential injectors under the blower plus a second bank to bank stage above the blower, but that may be more expense than it's worth. I would start out with bank to bank above the blower and see how you like the results.

Could the Distributor (Cam Signal) be used as the only signal communicating with the MS Box? I don't have the space for a Wheel on the Crank, with my SFI Balancer, V Belt Pulleys and Gilmer Drive Sprocket I'm pretty much tight against the radiator already and have no room to spare to add a Wheel anywhere in that combo.

The stock distributor will work fine for bank to bank - I'm using a Lean Burn distributor on a turbocharged Dart myself.

Sequential would require putting a more complex trigger wheel arrangement inside the distributor, such as a dual sync setup.

Can the MS Box share the same MAP and O2 Sensors that my Ignition System and Wideband use for their own systems/gauges? Or do I have to add another MAP for the MS and another set of O2 Sensors for the MS?

Yes, although most MS variants have a built in MAP sensor.

[74Dusted]

Ok, been a while since I've posted. I've been saving up cash and gathering up small odds & ends parts for this project.

Something came to mind. Roots Blowers (4-71, 6-71, 8-71, etc) have to heat up a lot before the engine will run. How is megasquirt going to handle this? Is it going to have a heart attack when it can't get the engine to idle because the blower hasn't got hot yet? On a carbureted application, you have to keep smacking the throttle for 5 minutes or so, keeping it high in the rpms until the blower gets hot enough for the engine to run. (adjusting the mixture and idle to idle with a cold blower is equal to a 3,500 rpm idle on a hot blower)

I learned that one the hard way, when I first installed the blower over a year ago. I adjusted everything to idle on a cold blower, and once the blower got hot I couldn't figure out why I was holding both feet on the brake pedal and doing a 3,500 RPM burnout at a redlight without touching the throttle.


Am I going to have to just babysit the car for 5 minutes, manually keeping the rpms up until the blower heats up enough for her to run? Or can the MS adjust to run on a cold or hot blower?

[elutionsdesign]

Clearly you want the intake air temperature sensor (IAT) downstream of the blower. I'm positive the fuel injection will be more friendly than the carbs have been.

[billr]

Is this an issue of the blower rotors having to thermally expand, so that tip clearance is minimal and efficiency is proper? Regardless, MS has several ways to "automatically babysit" for you, i think that will no longer be a problem.

[74Dusted]

Yeah it's an issue of the rotors having to thermally expand. Cool that the MS can do the "babysitting"


For a setup like mine (Batch Fire, No Ignition Control) What all will I need to gather up to put this system together. This is going to be my Winter Project/Upgrade for the car.

MS3 unit
Injectors and Injector Rails/Lines
Fuel Pump
TPS (can a Mopar Magnum 5.2/5.9L TPS be used?)
Idle Control Motor (Can a Magnum 5.2/5.9L Idle Control be used?)
Air Intake Temperature Sensor (Can a Mopar unit be used?)


Locating Mopar Magnum parts is easy and they're on the shelf everywhere, if the car ever leaves me walking to locate parts, and if I can use all Mopar stuff it makes it easy to remember (since I could just order the stuff for my Dakota) The only reason I ask, is almost all aftermarket/custom stuff uses GM spec Parts to do upgrades/modifications. Does MS care if it's connected to GM EFI Parts or Mopar EFI Parts?