MicroSquirt.com read only forum (Jan.15,2018)

The engine I have is a reed valve induction, air cooled, 2-cycle. This engine is designed for kart racing. It is run on methanol and has a usable rpm range from 10,000 rpms to 16,000 rpms. I am currently using 2 carbs. I want to switch this to fuel injecion to make it more user friendly. If ignition can be switched, fine.
I have NO idea where to start but I have access to my engine builder and an inertia dyno. I have read a good bit and I have a very basic understanding of what is needed. What I would like to do is gain some assistance from someone with MASTER KNOWLEDGE. Your time is valuable and compensation can most certainly be arranged.
If you are interested, please contact me.
Michael P Grady
South Charleston, WV

I should add that I need to be able to flow at least 60 hp of fuel. The reason I am requesting help is that I want to be sure my needs can be met by this system before I spend money on components.
Thanks,
Mike Grady

Curious to know what cc is it, any particular make and is it a twin or a single, (two carbs)
60hp over here is like a 250cc single with adequate tune, but don't see that high on the revs, sub 12,000, so assume it's a twin, but probably 200cc max to be able rev to 16,000!
A MicroSquirt is more than capable, but the thin edge of the wedge

It is a Parilla Sudam single cylinder 125cc engine, stroked to 131cc. It has a very peaky oval racing pipe. It is producing only about 53-54 hp but a large amount of the fuel is going out the pipe. That is why I gave an estimate need of 60hp worth of fuel. I expect the fuel inject will allow the pipe to be altered even more, creating more hp. The key is to be sure I can access fuel injectors and pump that can live on the methanol......and be able to purge them on gas. This is key. I expect that using 2 injectors will be KEY. That way, I can unplug one injector at a time and run gas through them so the alcohol can get out of the engine.
The true running RPMs will likely be 10,500 to 14,500 but from time to time, a track may require overspin in RPMs so that the clutch doesn't hit in the corner.
We are currently running against an Axiro wankle engine and they are flat awesome. If the FI doesn't help, I am in trouble.
Mike Grady

Is fuel injection allowed? FI is illegal in he racing that I do, I have been fighting like heck to get it to be allowed.

Yes, it is legal in the series I race in, although I would be the first one with it.

Why do you need to purge the system with gasoline?

Also there is probably a test mode that could be used for the purge, no need to even run the motor. Pull the injector and position over a catch can, go into test mode to run the pump and fire the injector, wait until it is all clear and shut it down.

You should be able to find many different motorcycle throttle bodies that will flow way more then 60hp, the injectors might be more difficult since you need methanol and oil premix (or are you oil injected?). Oil injected should make life a lot easier and you should be able to find several race oriented fuel pumps that or rated for alcohols, same with the injectors.

I have to purge because if you leave the alcohol in the engine, it will rust the crank, rod, and bearings. The purging with gasoline and Marvel Mystery Oil keeps it nice inside.
Mike Grady

Hey Mike, I think I know you from the 4 cycle forums.

Anyway the biggest obstacles I see are determining the motor load, since the motor is small and you are running WOT the only vacuum signal will be the reed resistance I don't think you will be able to use MAP to determine load and the pulsations will drive it crazy. You will have TPS, Cylinder head temp, IAT, you could use EGT (but it might need some logic for MS to use it) Perhaps someone has gone there already. I'm not sure there are enough parameters there to effectively control fuel delivery. Combining the EGT signal into the control loop might be the key and the key benefit as it would let the driver worry about his line and traffic and not have to think about twisting needles.

Some other ideas are, do the injectors need to be upstream of the reeds? They could be in the case. Is there a benefit from the mixture passing through the reeds? It seems they might pass more air if it was not weighted down with fuel. Spraying fuel with the piston on its way up would put the fuel in at the cases lowest pressure point and if the spray was directed at the cylinder and piston vaporization and engine cooling would be assisted.

Probably going to need plenty of Dyno time for the R&D and maybe a sixpack of pistons.

The best place to look for help would be motorcycle guys or some other small motor types ATV's, see what they have done. Don't limit your search to MicroSquirt as MegaSquirt has been around longer and uses the same controls. I know of one guy who used an MegaS2 on a Turbo'd, bored and stroked Bombardier on Alky and 10%nitro with NOS for cooling that he drag raced in the sand.

I have aluminum blanks that will mount a Suzuki street bike fuel pump good for ~130+HP on gas to most any tank.

11.5WFO wrote: Anyway the biggest obstacles I see are determining the motor load, since the motor is small and you are running WOT the only vacuum signal will be the reed resistance I don't think you will be able to use MAP to determine load and the pulsations will drive it crazy.

He would need to use alpha-N then, but there are quite a few two stroked MS machines out there.