Ambitious Project: Fuel Injected 1275

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Ambitious Project: Fuel Injected 1275

Postby badboypolar » Tue Apr 28, 2009 5:51 pm

I like the melding of old and new. Since I don't like carbs and am familiar with tuning FI engines, and to be honest I've always wanted to play with a MegaSquirt, I am going to fuel inject the 1275 going into the Bugeye. If you don't like this, please feel free to exit this thread now.

So here's the plan:

- Fab up new intake manifold; which will consist of the runners from the weber carb kit and some motorcycle throttle bodies. Motorcycle throttle bodies usually come with all the sensors and injectors. I will need to measure up the runners to see which TB will work best with the least modification. Sensors Needed: TPS (Throttle Position Sensor), MAP (Manifold Absolute Pressure), IAT (Intake Air Temperature), and possibly IACV (Idle Air Control Valve)
- Weld in an O2 bung into the headers
- Convert the ignition to the Pertonix system; however since I will be using a MegaSquirt for ignition I will need to lock out the advance mechinism
- Have to fab up a new fuel tank topper that needs fuel feed, fuel return, and fuel vapor recovery (maybe)
- Install new high pressure fuel pump (255 cc / 24 lbs: good up to roughly 200 HP); I will never use it all, however these pumps are many and quite cheap and easy to get
- Install new fuel pressure regulator; plus with this I can be sure to keep the fuel pressure in check
- Install new FI fuel filter
- hook up vacumm lines to vacumm log for sensors
- I might need vacumm canister
- Will need to install a coolant temp sensor somewhere

I plan on using the following in the engine:
-257/214 Cam
-Moss Header
-Lucas or Crane Coil
-Copper head gasket
-Shave head .010"
-New pistons (looking at .020" over)
-Lightweight flywheel
-Lightened/Balanced Crank (probably knife edge it)
-Duplex chain kit
-Will port match the intake and exhaust manifolds


This might sound difficult, however if you get an already built megasquirt and wireharness, then 1/4 your work is done already. MegaSquirt uses a bank fire system for fuel injectors. So one bank fires then the next bank fires. So you don't need to tune each individual injector. You need only tune the AFR. The trickier part will be how to setup the timing for a first fire tune, though I'm sure I figure that out. It won't be that difficult since I have the cam and valve timing values for the engine.

Now this may change, as I am only in the planning stage for this. I don't intend to build the motor for at least 8 months as I am doing body and suspension work first. As things develop I will keep this thread up to date. I will also try to post my costs for this if anyone else would care.

I'd love to hear your thoughts or ideas, as long as they are constructive and not bashing me for not doing the normal carb thing.
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Re: Ambitious Project: Fuel Injected 1275

Postby Rot » Tue Apr 28, 2009 6:16 pm

I can't wait to see the completed system - I can tune SU's pretty well but that's it for my expertise. Post lots of pics when you get going on the FI system, there is a slim chance I might learn something!
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Re: Ambitious Project: Fuel Injected 1275

Postby SteveC » Tue Apr 28, 2009 11:27 pm

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Re: Ambitious Project: Fuel Injected 1275

Postby Rot » Wed Apr 29, 2009 2:18 pm

That's just incredible to me. Very nice installation, mostly blends in like it was original equiment. Have to see what BadBoyPolar comes up with and I might get inspired to do FI on my 1275 BE. I really like the idea of the emmissions being a little lower, having more power and improved mileage - just more efficent!
Roy 8)
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Re: Ambitious Project: Fuel Injected 1275

Postby badboypolar » Tue May 05, 2009 4:56 pm

Here is what I think my manifold is going to look like. I will probably end up using mild steel for the U connectors, since that will be easy enough to mock up for a manifold connector. Also it will allow better air flow and I won't have to jimmy anything for the 4 injectors it should have. The greyish pattern is a heat shield between the header and intake manifold.

This is not to scale.

Image
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Re: Ambitious Project: Fuel Injected 1275

Postby Charlie Tolman » Wed May 06, 2009 9:33 am

Constructive comments, suggestions, and questions:

Your illustrated intake manifold design probably will not flow air very well, due to the curves, and probably will not flow as well as a stock manifold. Also, the injectors are a long distance from the valves in the head.

Would it be possible to use two straight intake runners, one for each port in the head, and use one fuel injector in each runner ? This might be possible with two injector timing wires going to one injector, and with a diode in each wire for isolation.

Or, use two straight runners, with two fuel injectors in each runner ?

Does the fuel injection electrical system need a crankshaft position sensor ?

Exhaust port matching will not help much, unless the manifold is smaller than the head port.
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A very interesting project.

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Re: Ambitious Project: Fuel Injected 1275

Postby trevor » Wed May 06, 2009 11:20 am

I'm considering a FI project, but I was going to do a simple throttle body injection, then later try to add a turbo charger after I had the TBI system worked out.
I've been told that there is little HP gain with FI.
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Re: Ambitious Project: Fuel Injected 1275

Postby badboypolar » Wed May 06, 2009 1:20 pm

Charlie Tolman wrote:Constructive comments, suggestions, and questions:

Your illustrated intake manifold design probably will not flow air very well, due to the curves, and probably will not flow as well as a stock manifold. Also, the injectors are a long distance from the valves in the head.

Would it be possible to use two straight intake runners, one for each port in the head, and use one fuel injector in each runner ? This might be possible with two injector timing wires going to one injector, and with a diode in each wire for isolation.

Or, use two straight runners, with two fuel injectors in each runner ?

Does the fuel injection electrical system need a crankshaft position sensor ?

Exhaust port matching will not help much, unless the manifold is smaller than the head port.
_______________________________
A very interesting project.

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H/P 40 (Retired)


Charlie,

I had thought about having one runner with two injectors, however that adds more complication of fabbing a fuel rail, and I don't feel that one injector per runner would sufficently fuel the engine as it would have to fire twice as often. While a motorcycle engine injector might handle that I'm not sure that would be the correct path to pursue.

While the injectors are further from the head, I don't think that will be a problem if using proper injectors that atonimize the fuel correctly. If it is done correctly there will be no ill effects during combustion.

I realize some of the flow issues with the design of the manifold, but I think that it will have double the flow available coming in that it will offset the curves and merge that it will have.

This first rendition is only theory so far. So It might change based on viable feedback such as your own.

The megasquirt system can actually run of the stock points system from the distributor, though I may choose to go to a crank mag wheel setup.
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Re: Ambitious Project: Fuel Injected 1275

Postby SteveC » Thu May 07, 2009 12:02 am

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Re: Ambitious Project: Fuel Injected 1275

Postby Charlie Tolman » Thu May 07, 2009 1:15 am

If you are planning on using a certain fuel rail, then this places design restrictions on the intake manifold. If this is the plan, and using four injectors, then I would design an intake manifold that has a non-curved "Y" shape for each of the two intake ports. The base of the "Y" would be short, and the "V" shape of the "Y" would be as narrow as possible, for the best air flow near the 2-into-1 junction. This probably means that the "V" section would have long runners, which would then match the spacing of the injectors on the fuel rail.

Having two runners merge into one runner will not double the net air flow into the head port.

Even though the intake valves slightly overlap during their open periods on neighboring cylinders 2-1 and 3-4, with the amount depending on the lobe duration and angular spacing (lobe center), the required maximum air flow is basically that for only one cylinder at a time. Four throttle bodies might look impressive, but it all depends on what you consider to be important.

If I was undertaking this type of project, I would use a straight intake runner for each of the two intake ports, use either the single-injector or the double-injector arrangement for each runner, and place my design and fabrication efforts on creating a special fuel rail.

I wish you success with your project.

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Re: Ambitious Project: Fuel Injected 1275

Postby Charlie Tolman » Thu May 07, 2009 9:34 am

One last(?) thought:

With "Y" style intake manifolds, each time an intake valve opens, air will be drawn through both branches of a "Y". One branch will flow one-half of the air, and the other branch will flow one-half of the air plus the fuel. I wonder if this arrangement will work well ?

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Re: Ambitious Project: Fuel Injected 1275

Postby hpmowog » Fri May 08, 2009 11:59 am

For some more reference information, here's some guys who've done an FI set-up for an MGB (also siamese port). It uses two ITB's as replacements for the stock HS4's on the stock manifold.

http://extrudabody.com/TechInfo/Installations.html

Poke around their site. You might get some ideas.
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Re: Ambitious Project: Fuel Injected 1275

Postby Charlie Tolman » Fri May 08, 2009 5:46 pm

A comment from my friend, who has an early (classic) and a late Mini:

Later classic Minis had F.I. There was single point fuel injection, and the last couple of years (late 90's through 2000) they had twin point. A lot of people have converted those to carb engines due to the computer controls not being able to cope with much in the way of engine performance enhancements. Perhaps that could be researched to see what may be available via ebay or some of the Mini message boards.

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Re: Ambitious Project: Fuel Injected 1275

Postby mmacquee » Tue May 12, 2009 3:41 pm

The set-up used on injected minis in the UK seems to consist of a Weber manifold plus a Jenvey throttle body, set up for two injectors.
Also, the Brits seem to favor an Omex (spelling) ECU for the mapable injection. I'm thinking FI also, I've already installed a Megajolt mapable crank trigger ignition on my 1275, so the hardware is in place for that. I'm just waiting for the Eaton M45 used supercharger I bought on ebay to arrive and see how feasible that looks for install on a BE
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Re: Ambitious Project: Fuel Injected 1275

Postby PHerder » Sun May 17, 2009 8:59 pm

I, too, have a plan to use Fuel Injection and electric ignition on my 1275.

Here is a couple of pictures of the Throttle bodies on a manifold I got from Moss.UK for a "A" engine to 1 1/2" HS4 carbs.

Image
Image

I have a couple of MegaSquirt computers and the necessary parts to change my points over to electronic (LED) ignition (thanks Glen!).

It will be a while before I get there as I am currently getting rid of rust on my tub...

Image

;)

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