[mgriffiths303]

Hello Everyone,

I thought I'd share my progress developing an EFI system for my EX-500 powered Land Speed Racer "RailGun".

So why, why, why would anyone develop an EFI system for the EX-500?? Well, plainly, I've got some time on my hands, and something to prove. I could have tried to adapt something like the very fine MicroSquirt system, but honestly I felt I build a simpler(cheaper) system.

My "model" for the system is the basic mechanical injection system which works stupendously well with just a pump, a throttle valve, and some metering. For Bonneville, which is basically Wide-Open-Throttle in a "preset" environment I don't think I need more sophistication. a "preset" environment meaning I can access the atmospheric data (temp, dewpoint, pressure) from Wendover Airport and dial it in to the EFI, then make trim adjustments as needed.

I also did not want to mess with timing wheels so I pick up the injector timing directly from the ignition timing. The stock EX-500 ignition fires at 37 degrees BTDC (full advance), and the intake valve opens at 45 degrees BTDC, so the injector opens just a little after the intake valve starts to open (but on the intake stroke, not the compression stroke). In my view this is the perfect strategy but obviously it's early days. And to clarify the injectors fire only once per
two revolutions.


I've made a number of approximations in the software:
- The air flow percentage based on the throttle position (100 steps)
- The Volumetric efficiency of the engine at all RPMs (based on normalized torque curves)
- The "load" approximator which increases fuel based upon RPM and apparent acceleration.
- The "accelerator pump", which increases fuel based on acceleration of the TPS. Ie.
it compensates for the initial lean condition when the throttle butterfly is opened.
- I have a manual system for switching firing phases, and I have an idea for something
automated using a piezo sensor, but we'll see.

The hardware is comprised of:
- Custom throttle bodies using Ninja 650 shafts, butterfly valves, injectors, TPS sensors and harness
connectors.

- An Arduino based micro-controller with a voltage regulator and a couple of heavy FETS (Literally
around $25 in parts

- A basic fuel delivery system, with a boost pressure regulator for the future turbo.

In terms of calibration, I just needed the minimum (i.e. mechanical) injector open time, flow rate of the injectors at 42PSI, and to set the TPS min/max points.

I did have some initial teething problems, mostly from having very slow serial diagnostic output messing
the injector times, but all is well at this point.

For reference, here is the bike/rig

And the Injection System

Videos
The initial calibration rig Calibration Rig

The Fuel Injection Walkaround EFI Walk around

And the initial startup EFI Startup

Shoot any questions my way,
Cheers, Mike

 

[po18guy]

Nice work! Your clear advantage over carbs is software tunability. Being able to tune on the spot for the variables is a huge benefit. Do you have an EGT? Imagine also that you start rich and lean out from there?

 

[K-woppa]

It may be a "basic fuel delivery system" but the execution of this project is far from simple. I do hope you keep us updated because I'm excited to see how this goes.

 

[ducatiman]

nice execution of your specialty concept! You've gotta have a lot of hours into this (as you've referenced)....but how much $$$ into it would you estimate? (or admit to?) I'd have to guess in your unique situation that $$ has been deemed no object.

 

[mgriffiths303]

Nice work! Your clear advantage over carbs is software tunability. Being able to tune on the spot for the variables is a huge benefit. Do you have an EGT? Imagine also that you start rich and lean out from there?

Thanks. I believe I'll be able to get very good power delivery just with the basics I've described, but to get the final couple of percentage points I will need to add (2) wide band sensors. There is an issue in that the sensors (in this configuration) will be very erratic until the RPM climbs well above 6000 RPM, but this should be okay since I'm really trying to optimize tuning in the 8000-10000 RPM range. I will dyno the current configuration and make a baseline, and then we'll see about adding the sensors and the feedback loop.

 

[mgriffiths303]

It may be a "basic fuel delivery system" but the execution of this project is far from simple. I do hope you keep us updated because I'm excited to see how this goes.

Thanks, and I will. When I first started this project in 2013 I learned a lot from this forum and I felt I could contribute something back.

 

[mgriffiths303]

nice execution of your specialty concept! You've gotta have a lot of hours into this (as you've referenced)....but how much $$$ into it would you estimate? (or admit to?) I'd have to guess in your unique situation that $$ has been deemed no object.

Thanks. You can tell this is a project based on my passions, and I'm retired so this is really what I like to spend my time and talents on. In dollar terms it's not been that expensive because I make everything myself when I can, and I use OEM EX-500 parts where possible. I have a friend with a lathe who helped with the steering head, rear pivot, throttle bodies and fork sliders. The only part "we" could not make ourselves was the triple tree clamp(s), which I farmed out to a local CNC shop. Adding up just the stuff I've bought, is probably less that 5 or 6 grand, and 1K of that is the triple tree clamps(s)

Cheers, Mike

 

[po18guy]

If you ever do turbo it, I would think that it needs a copper gasket, or O-ring the cylinders and get some ARP head bolts or studs. Dunno if there's enough room to go with 12mm bolts or not.

 

[mgriffiths303]

If you ever do turbo it, I would think that it needs a copper gasket, or O-ring the cylinders and get some ARP head bolts or studs. Dunno if there's enough room to go with 12mm bolts or not.

I think your right that the head sealing will be the weak point, and thank you for your suggestions. I'm not planning to go too crazy on the turbo boost though, I've got a little RHB31 Turbo which is good for 100HP at 8PSI (given an optimum installation). I developed the turbo a few years back but I gave up trying to get it to work well with any carburetor setup, either blow through, or pull through. I'm going to get back to it right after I'm happy with the EFI. The good news is that I developed the RailGun chassis around the turbo, so it's literally going to be a bolt on.

Cheers, Mike