Author Topic: Fuel injection retrofit  (Read 30544 times)

gpineau

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Re: Fuel injection retrofit
« Reply #20 on: March 01, 2018, 08:12:31 PM »
From what I have read you want to open the injector just after the intake valve opens and the piston is on the down stroke. That would not change ever unless there was a variable cam.

But you are right the spark timing advances with rpm so the injectors should be timed to the crankshaft sensor and not the spark. I dont think it is critical timing. The next thing that happens after the spark fires is that an intake valve is going to open and a cylinder will begin to suck in air and fuel.  Of course you would like there to be a stream of air to inject the fuel into but I don't think it is that big a deal to fire the injector a little early. What is most important it the amount of fuel you inject . If it is a bit early it will maybe wet the intake valve a little but in milliseconds it will be sucked into the cylinder anyway.
« Last Edit: March 02, 2018, 09:16:23 AM by gpineau »

Offline B.D.F.

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Re: Fuel injection retrofit
« Reply #21 on: March 02, 2018, 10:11:10 AM »
What you are talking about is timed fuel injection Ted, and it is not usually done that way for the simple reason that fuel injectors are sized to be open around 85% of the time when the engine is using the maximum amount of fuel that it can. And no valve on any engine is ever open 85% of the time, so a great deal of an injector's open cycle occurs with the intake valve closed anyway, no matter when the injection cycle is started. On top of that, the benefits of timed fuel injection are not that great when applied to normal road vehicles, and there is always the risk of stratifying the fuel / air charge inside the combustion chamber if injection cycles are too short at very high engine speeds. In other words, if a much larger injector is used so that only, say, 20% of the injector's capacity is used so that it can deliver a full fuel volume when the intake valve is open.

These concepts get really complicated really quickly. I find the best way to deal with them in general is to basically just do what everyone else already does and use the method in common use for the vehicle in question.

Brian

You sed; its injector should be triggered just a few degrees after his companion was ignited for the power stroke.

Question; as the timing changes as RPM's increase. Do you want to control injectors by the signal to the plug (that changes) , or the signal at the pick up Coil (which doesn't change)?
ie; Do injectors also change their firing point, based on RPM?

Ride safe, Ted
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Offline connie_rider

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Re: Fuel injection retrofit
« Reply #22 on: March 03, 2018, 08:59:05 AM »
Thanks Brian.
It's taking me some time to absorb what you said.
Still not sure I have it all, but I'll keep pondering it.  :banghead:
NOTE: This is not my build it is gpineau's.
            I'm just enjoying the discussion/learning..

Our previous discussion was just about the trigger point for the injectors.
  gpineau had stated he planed to base his trigger point, of the fire signal (that signal would change with the timing),
  I made the point that the signal from the pick up coil might be better because that signal would not change with
         the ignition timing.
    We agreed that the pick up signal would be the best trigger source.

Still trying to wrap your 85% point, into the plan to use 1 injector to fuel 2 cylinders.. ie; Pondering continues.  :nuts:
      I know 1 injector per pair of cylinders will work, but when to spray the fuel, and for how long is confusing...
         My assumptions are; the (1)  injector will fire each time one of those (2) cylinders is on a intake stroke.
         At 10,000 RPM's, this will happen 10,000 times per minute. {each cylinder would have 5,000 intake strokes)
          An injector sprays at a constant rate, so pulse width determines how much fuel is delivered.
          As RPM's increase, the time that the valve is open becomes shorter.
          If the delivery is a constant rate, but the amount of time is less at higher RPM's, you would have to spray fuel into the
            intake before the valve opens.. (to ensure enough fuel is available when the valve is open)
          Opening the throttle allows more air, so fuel quantity must also increase. (ie; longer pulse width)
          In my mind that suggests your 85% figure indicates; a properly sized injector fires 85% of each rotate {at WOT}.
            That 85% of one rotation needs to be before (and during) the time that the valve is open.
         At 10,000 RPM's, this has to happen 10,000 times per minute, with pulse width, and injector timing varying. {as RPM's change}.
                    Am I on the right track??

NOTE: I am not speaking for gpineau. Just trying to understand a bit more...
          Both of you know more about this than I.
          I particularly want to hear what gpineau thinks about my pondering..
               Good discussion!!

Ride safe, Ted
« Last Edit: March 03, 2018, 10:56:52 AM by connie_rider »

gpineau

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Re: Fuel injection retrofit
« Reply #23 on: March 03, 2018, 09:24:41 AM »
Connie_rider.

Those are some good thoughts and are along the same thought I had when I first started thinking about this.  Maybe I am reading too much or thinking too much or both.
But I have come to the conclusion (in my feeble mind) that timing is not that important. What IS important is to get the air/fuel ratio correct. Its not just air and its not just fuel that make things work. Its maintaining the proper air/fuel ratio. If the air flow increases then so must the fuel being injected. If it takes keeping the injector open 100% of the time then that is what needs to be done or get a larger injector.

If you think about it that is what a carburetor does. It does not time anything. I is tuned to mix the proper amount of fuel with the incoming air regardless of the amount of air flowing through. Just keeping the mix right.

I went back and looked at some of the earliest injector designs and they did not time anything. The injector was just a means of spraying fuel into the air. They just sent the proper amount of fuel into the manifold to keep the mix right and it seemed to work pretty well.

So going forward I don't want to overthink this and just stick the the basic idea of delivering fuel to the manifold based on the measured/calculated air flow.

So now I m going to begin. I have been collecting ideas and parts for the past year and now it is time to do something. I am going to start on the manifold. I pulled the carbs yesterday and took some measurements and determined that I can use 1.5 inch pipe to get from the manifold to the intake ports and I am thinking I will use a 4 inch pipe for the manifold/air-box. It will all fit with some room to spare.  I will post some drawing when i get closer to the final design. 

Offline connie_rider

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Re: Fuel injection retrofit
« Reply #24 on: March 03, 2018, 11:15:05 AM »
I agree about the manifold first.
Also I agree about AFR.
But you can't spray continuously as the mixture would be rich at Idle, and lean at WOT.
  (Carbs, draw fuel at the correct AFR with each intake).
I think; Injector Pulse widths have to adjust with throttle opening, rpm's, (plus others) to maintain AFR.
            If they vary, injection timing has to vary as well. (longer pulses initiate sooner/before the intake stroke)

Just realized your planning 2 throttle bodies.
So, each will have an injector built into it. Good plan..
Have you determined which throttle bodies you'll use?

Ride safe, Ted
« Last Edit: March 05, 2018, 08:07:02 AM by connie_rider »

gpineau

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Re: Fuel injection retrofit
« Reply #25 on: March 03, 2018, 06:51:57 PM »
I think I will use one throttle body.  I have a number of carburetors laying around that I could cannibalize to make a throttle body. I have a Volkswagen carb that is just begging to be cut in half. 

The prototype is going to be ugly.
A 4 inch sewer pipe .
Four  1.5 inch pipes to the intake ports.
Dont know if I will mount the throttle body to the side or the top.  Just depends on how it all fits.  Still thinking.
You know if I mount the injectors very close to the intake ports then the throttle body can be anywhere in the vicinity.

Offline connie_rider

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Re: Fuel injection retrofit
« Reply #26 on: March 03, 2018, 07:50:35 PM »
Now, I'm really baffled...

Ride safe, Ted

gpineau

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Re: Fuel injection retrofit
« Reply #27 on: March 03, 2018, 08:46:50 PM »
Baffled about?

Something like this manifold.  Its for an inline 4 cyl (like a Connie). But imagine it with holes on both sides of the big pipe to mate up with a V4.
The throttle body can be mounted on top or it could be mounted at  one end .

Gerry

Offline connie_rider

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Re: Fuel injection retrofit
« Reply #28 on: March 04, 2018, 05:52:15 AM »
Sounds like your talking about using a single downdraft or maybe side draft carb body?
An actual throttle body, with TPS sensor would seem to be easier.
Plus I think you'll need MAP or MAS sensors?

(Downdraft) I just can't figure how it will fit under the gas tank.
2 Injectors? Located where? Probably need to be near the valves.

I'm not saying don't do it. Just don't understand how you can make it work.
NOTE: Not familiar with intake port layout on a Magna.

Ride safe, Ted

gpineau

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Re: Fuel injection retrofit
« Reply #29 on: March 04, 2018, 09:10:57 AM »
I have several ideas in my head. but have a look at this picture. Imagine all the room you have when you remove the carbs and air box. I mean its not a huge but there is plenty of room for a throttle-body and a manifold. The space above the carbs is not all tank. There is a wide opening toward the front of the tank where the air box and filter is now.  Down draft, side draft or obtuse angle ...it doesn't matter.  Just where ever it will fit. There are no carbs or floats or fuel levels to worry about. Just air. 

I plan to use a map sensor mounted somewhere on the manifold.

I have a throttle body off a 95 Hyundai. I will use it because it has the throttle sensor attached . 

The way I see it here are the important pieces of the plumbing. 
1. injectors close to the  intake ports. (although  I have see some designs where the injectors are in the manifold below the throttle body)
2. Throttle body and manifold
3. plumbing to connect 1 and 2.

I'm off today so I have time to move the bikes around and get the victim into the garage to start making real measurements.

This is a multi phase project. There is the mechanical design and fabrication, the electronics piece and then the software programming. I don't expect to finish this for at least a year.  Maybe by the time I finish I will be educated enough to claim I know what i am doing.  :D
 

Offline connie_rider

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Re: Fuel injection retrofit
« Reply #30 on: March 04, 2018, 10:33:01 AM »
Ok, keep us posted on the progress.

Ride safe, Ted

gpineau

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Re: Fuel injection retrofit
« Reply #31 on: March 04, 2018, 12:16:53 PM »
Spent an hour rearranging all the bikes to so could get this one into the garage. I laid one of my Connies down in the yard cause I  got stuck in the soft grass.
Got the magna in place and looking in side where the carbs and breather normally would be there is lots of room for experiments.
« Last Edit: March 04, 2018, 07:48:17 PM by gpineau »

gpineau

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Re: Fuel injection retrofit
« Reply #32 on: March 04, 2018, 06:14:52 PM »
I did some yard work today before getting started in the garage. 
Building a mock up of different ideas for a manifold. 
intake ports are 1.5 inch pipe.
the  small looking manifold is a propane tank.
the larger manifold is a 4 inch PVC pipe. ( I like it better and it will be easier to work with. )

Offline kzz1king

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Re: Fuel injection retrofit
« Reply #33 on: March 04, 2018, 08:54:41 PM »
Turbo it. Draw thru with one carb
2010 CONCOURS
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Offline connie_rider

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Re: Fuel injection retrofit
« Reply #34 on: March 05, 2018, 08:34:35 AM »
OK, I understand the layout better now. There is more room than I thought.
TB will be on 1 side...

One concern, I think the plenum I.D. and runner I.D.'s may be too big.
To keep a good flow velocity, I think: you'll need to use the smaller plenum, or even a smaller one.
                                                       & you may need to go to a thick wall on the runners.

Geez, where's the folks that know about things like this?
I'm totally guessing... But enjoying the discussion.

Ride safe, Ted

gpineau

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Re: Fuel injection retrofit
« Reply #35 on: March 05, 2018, 08:46:05 AM »
kzz1king,

That was my first thought last year. Just put a single carb on top of the manifold. I presented that idea on the V4 Muscle bike forum and was nearly laughed out or the place. They thought it was devolving the bike. Even though I explained that I was sick and tired of cleaning the carbs of the green goop from Colorado gas.  That's when I  decided that I need to do an injector design before they would accept it as a worthy modification.

But I am really doing it for the experience and the education. I will use what I learn to make another for a Concours.  Who knows if i make it good enough it may turn into a product..Ha ha.


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gpineau

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Re: Fuel injection retrofit
« Reply #36 on: March 05, 2018, 09:20:15 AM »
connie_rider,

So we are talking apples to apples
let's call the plenum the box/pipe/container where everything is connected.
let's call the runners the pipe connecting the intake port to the plenum,
let's call the manifold the plenum and the runners connected together as a single unit.

I'm thinking about what you said about velocity and trying to imagine it in my mind where the velocity is created in a carburetor system. It seems to me that in a carburetor motor there is an air-box connected in some way to the carburetors either directly or through tubes. When connected directly i find there is a tube from the carb into the air box a inch or two long. I think in both cases  the purpose of the tubes is to create velocity into the throat of the carb before mixing with the fuel????

So i think (just thinking) that if there is a few inches of tubing (runners) between the plenum and the injectors the velocity will increase sufficiently to mix the fuel droplets. What do you think of this???

Look at the attached photo. The air-box and velocity tubes on this magna is every bit as big as my makeshift plenum.  Maybe i can include a flare on top of the runners ?

Offline connie_rider

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Re: Fuel injection retrofit
« Reply #37 on: March 05, 2018, 11:27:56 AM »
You sed;
So we are talking apples to apples
let's call the plenum the box/pipe/container where everything is connected.
let's call the runners the pipe connecting the intake port to the plenum,
let's call the manifold the plenum and the runners connected together as a single unit.

 {We're in agreement; I've been using the same names}

On the stock system each carb has a runner that is about 1" long x 1 1/4" ID.
      So the vacuum pulse from intake valve to carb is almost instant...
On your new system, the manifold is; 4 runners 3" long x 1 3/8" I.D., plus you have a 5" long x 3" I.D. plenum.
      (ie; the total area inside your manifold is huge compared to what you had).
        I think everything needs to be small enough; to keep the air moving quickly in the manifold runners, and to keep pulse timing (at the TB) closer to valve opening.

I'm not saying it right, but each time a valve opens, you will be pulling air from the entire manifold, not just 1 runner.
  (ie; Sounds like an RPM manifold instead of a Torque manifold).

Lastly, your 2 injectors will be where? (In the plenum? in the runners?)

All of this should be stated: "I think", because I'm totally guessing..
  {repeat; Geez, where's the folks that know about things like this?}

Ride safe, Ted

Offline tweeter55

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Re: Fuel injection retrofit
« Reply #38 on: March 05, 2018, 11:39:22 AM »
Just throwing this out there (where?) there. If you design the intake runners too small (to speed thinks up) will you sacrifice top end power because of that restriction?
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Offline connie_rider

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Re: Fuel injection retrofit
« Reply #39 on: March 05, 2018, 12:44:44 PM »
Agreed.
I'm just saying, do not make them bigger than the I.D. of the stock Runner.

Ride safe, Ted
« Last Edit: March 05, 2018, 04:54:54 PM by connie_rider »