Odd one out... Mopar, Indy, Kuhl, Hilborn, Street, Propane, Megasquirt

[BigBlockMopar]

Now my fun blowermotor buildup is slowly progressing again I find myself daydreaming and wondering about how to properly fuel it.

Some specs:
500ci - Indy heads - 8.5cr - solid .630" rollercam 112/114 - 8/71 blower - Hilborn ShotGun injector scoop- streetonly use

To get the motor running at all at first, I will use regular carbs and just have fun for awhile. (Probably until the next fill-up 2 days later that is.)

In the end, this is what I'll have to decide about;
Fuel type will be Propane. It's half the price of gasoline with good octane, so that's a nobrainer. Fuel will be fed either through '425' propane carbs, or vapour injectors and EFI.
Either way, it will cost a fair amount of dough getting this setup working. Propane carbs run at 200,- Euros a piece ($270). I need at least 2. Also need valveplates under the propane carb as they come without.
I've been known as cheap (think 'squirrel-cheap'), and since the 'E' in EFI still stands for Expensive in my book, I will be trying to do 'CFI' instead. Nonetheless I'm leaning to EFI, or CFI my motor.

When I choose injection, I think a MS2 would be sufficient as I only want to control fuel for now. (Correct if I'm wrong.)
Ignition will be a stock MoparPerformance distributor and ECU. Perhaps I will use an older Jacobs CD ignition later on if Megasquirt can trigger it properly through the Jacobs inline sensing wire. I think it can.
I want to inject the vapourized propane into the intake by using the existing nitrous holes.
To turn (enough) liquid propane into a vapour, I will have to use 2 convertors and 2 sets of 4 Valtek34- propane injectors. Although I'm not sure those injectors can properly feed a hungry 500ci motor. Maybe I need 16, but then I wonder if the MS2 can control all those.

I've got a Hilborn 'shotgun' injector scoop which I really like to use directly on top of the blower. So no carbs.
I need to figure out a way to filter the air and find out how 'easy' it will be for the huge twin injector scoop-valves to control/meter airflow with streetuse. Probably not. I think I'll have to convert the somewhat linear movement of the throttle-pedal into a semi-parabolic arc at the injector scoop to prevent the huge valves from opening too wide too fast.

Another thing I'm wondering about if the MAP-sensor can cope with the varying amounts of vacuum and pressure in the intake because of the fairly big cam.


Holy cow, I thi k my key oard j st br ke. What was the question again?

Oh yeah, is the MegaSquirt II a good idea for this little streetmotor?
And is an injector scoop at all usuable even for just metering airflow with streetuse?

[CDMBill]

I saw a pick up truck built by Art Chrisman last weekend with a 392 hemi and an 8-71 with a Hilborn four hole "mailbox" scoop. It was using four large gas injectors, 80 lb/hr units, linear linkage, sounded great and semed to drive well when the guy left. Another buddy did some of the plumbing on it and I oculd get more details. Chrisman has built a number of these traditional looking efi blower motors, but I'm unsure about any usinh porpane.

One other note none of his stuff is anywhere near 'cheap'.

[dieselgeek]

Megasquirt will work no matter how many vapor injectors you have to drive - worst case scenario you spend another $30-60 assembling or purchasing an external injector driver to match the current you need to drive. What is the impedance of the injectors you plan on using? bonus points for high impedance (ohms over 12), but low impedance is no problem either.

As long as the stock ignition doesn't cost you anything to leave alone, I agree with going "fuel only" for Phase One of your plans. It's a lot less debugging work for Fuel Only, then spend a weekend after it's running good converting the ignition.

The default megasquirt MAP sensor will be fine with any cam you choose, it's the boost you want to run to be concerned about - 22psi is around the max for the default MS MAP sensor which comes with the kit or preassembled unit.

You should think about how you will trigger the megasquirt's RPM input. You can slave it off a tachometer drive, or you can read off the distributor pickup (no matter if it's Hall, Optical, or Inductive/VR). Slave it off the tach if you run a separate ignition system IMO, the tach output of any Jacobs/MSD/whatever CDI ignition box will be a nice clean signal.

Sounds like a fun project. I've tuned a few hemis and they love EFI just like the other engines. Propane tuning should be a breeze, it's a relatively forgiving fuel.

[BigBlockMopar]

I think I've read the Valtek 34's are about 2-3 Ohm. But the only reason I said I will use Valteks is because they seem to be readily used with LPG-injection. If there are 'better' ones available I'm willing to look into that aswell.

I have had this Jacobs CD-ignition on a daily driver once before. But for the sake of simplicity I indeed want to keep the first startup as simple as possible as this is a freshly built new engine except for the block.
I'm even going to let the motor run first by installing a large carb-adapter plate over the blower-intake so I can just mount a carb on there.

The Jacobs ignition is a very simple setup however which is installed "inline" with the current setup. The Jacobs' trigger-signal is taken from the HV-output of the stock coil, and the CD-output goes directly to the distributor.

http://image.fourwheeler.com/f/18899496+w750+st0/129_0207_02_z+jacobs_omni_ignitions+top.jpg

I think it shouldn't be much of a problem of letting the MS control timing aswell perhaps.
For tach-input I could have a triggerwheel lasercut(?).

I'm pretty sure the blower will never make upto 22psi on this motor. The car is not set up for that kind of 'violence'.

[BigBlockMopar]

2 months later I can post a little update;
I've bought an Innovate MTX-L sensor gaugekit, 2 'Magic' LPG vaporisers and 8 'Magic 3' vapour injectors.

Not sure yet which motor will be the first to run on injected propane, the blower motor, or the 5.7Hemi, but I think the blowermotor has the edge at the moment.
I also still have to buy a MegaSquirt controller.
There's a built MSII-v3.0 for sale locally, supposedly brand new, also cheaper than new. But if I buy that one, I will not use it on the Hemi.

In the mean time I will be welding a couple of injector bungs on some cars of mine, so I can play with that lambda-gauge a bit.