Maximum fuel economy: Piaggio Purejet (a.k.a. Ditech?)

[spasticteapot]

I'm on a team building a vehicle for a fuel economy competition, and I'm hoping to replace the Honda four-stroke with something a little more advanced. I even went so far as to consider building a complete fuel injection system from scratch, complete with MAP and exhaust oxygen sensor.

However, while searching the internet, I found the Piaggio Purejet engine - a 50cc unit that not only has EFI, but direct injection, too! This would seem to be an excellent starting point for a maximum economy engine, and the fuel injection system might make it possible to add a heavily modified Megasquirt system for that little bit of added economy.

I do, however, have a few questions:
1. What sensors are already on the engine? Is it like a motorcycle engine, which does not have an exhaust oxygen sensor?
2. How much horsepower does the engine produce out of the box?
3. Are there any aftermarket upgrades, such as ceramic bearings, I might want to apply?
4. What kind of ignition does it use?
5. What compression ratio does it use?

Thanks for the help!

 

[Browni]

I'm on a team building a vehicle for a fuel economy competition, and I'm hoping to replace the Honda four-stroke with something a little more advanced. I even went so far as to consider building a complete fuel injection system from scratch, complete with MAP and exhaust oxygen sensor.

However, while searching the internet, I found the Piaggio Purejet engine - a 50cc unit that not only has EFI, but direct injection, too! This would seem to be an excellent starting point for a maximum economy engine, and the fuel injection system might make it possible to add a heavily modified Megasquirt system for that little bit of added economy.

I do, however, have a few questions:
1. What sensors are already on the engine? Is it like a motorcycle engine, which does not have an exhaust oxygen sensor?
2. How much horsepower does the engine produce out of the box?
3. Are there any aftermarket upgrades, such as ceramic bearings, I might want to apply?
4. What kind of ignition does it use?
5. What compression ratio does it use?

Thanks for the help!

1. It doesn't have an oxygen sensor. It has got a throttle (butterfly) postition sensor. So it's quite simple. Also read this (this is the Aprilia Ditech engine, but the two technologys are quite similar).
2. check the 157.pdf below
3. If you mean crankshaft bearings I think no, because Piaggio uses special size crank bearings. Maybe you can buy ceramic balls, and convert the existing bearings, or you can do serious modifications.. If you would like to decrease the internal friction, you can remove one piston ring (but it's recommended only if the bike will have a min 7-8000 1/min operating rpm
etc..
4. check the 157.pdf below + (magnetic flywheel, induction type-pickup, CDI+ ECU (elctronic controll unit) -> controlls the injector and the ignition timing.
5. I don't know!

http://www.engines.piaggio.com/bank/4/157.pdf

If you would like to modify the injected charge, you should re-program the ECU or modify the fuel pressure regulator. (changing the spring preload).

There are two tuning kits for this engine. I think you don't want it because they are 70cc conversion kits, but you can find some usefull pictures:

Malossi (page 16 exploded view)
http://www.malossi.com/Archivio_Files/MONTAGGIO/7312043.pdf

Polini
http://it.catalogo.polini.it/en/pagina_710.132.html