Direct Injection

[Lord_Bragle]

I wonder why we don't see it on motorcycles? Its increased efficiency in car engines vastly and yet no bike makers moved on it yet, seems daft when I can easily get 60 miles to the gallon out of my direct injection car carrying 4 passengers, yet my Monster does sub 40 if I thrash it.

[Turf]

Aprilia's SR50 and RS50 are direct injection, but they're strokers and it helps keep them clean.

I've never thought about this, I cant think of a reason why bikes arent.

Ferrari was talking about a DI rule change for the 2013 F1 rule change

/not helping

[zarn02]

I think I remember reading either here on the board, or somewhere else, that DI was banned in MotoGP (and/or Superbike).

For companies that make sport bikes, it may not make sense to throw money at something that won't be useful in racing. And as we know, a lot of tech that ends up in your street bike is just slow trickle-down from the race machines.

[Drunken Monkey]

I know some scooters are using it, as well as some outboard motors.

In motogp they limit fuel pressure to 10 BAR (~140 PSI) and since that's nowhere near enough pressure for a direct injection system it's effectively outlawed.

[brad black]

i think the di systems use mechaincal fuel pumps to supply the pressure (basically common rail diesel set up) and that may be a packaging issue on a bike.  the aprilia scooters use the orbital system (ditech?), didn't spend enough time working on them to find out much about it.

[WarrenJ]

There was a link on here a while ago on Motus motorcycles.  They were developing a direct injection engine and are in the process of building a sport touring bike - looks interesting.


http://www.motusmotorcycles.com/index.html

[Lord_Bragle]

I didn't know D.I. was outlawed in racing… seems a bit bonkers considering all top level race bikes and cars are alowed and use pneumatic valve actuation (sept for Ducati's Desmo of course) and that air valves ain't even applicable to road usage.  I can't get my head around it it don't make sense? u would think DI would be wanted in racing to push the technology forward.

[Porsche Monkey]

i think the di systems use mechaincal fuel pumps to supply the pressure (basically common rail diesel set up) and that may be a packaging issue on a bike.  the aprilia scooters use the orbital system (ditech?), didn't spend enough time working on them to find out much about it.

DI systems use a low pressure pump (60 psi) to supply a high pressure pump (1700+ psi) very similar to a common rail diesel.  The low pressure pump would be an electric in tank unit and the high pressure is mechanical usually driven off a camshaft.  The problem with gasoline is when a high pressure line ruptures the fuel comes out in a very fine, very combustible mist.  Imagine the excitement when one of those lights off in a crash.

[Drunken Monkey]

The orbital system (AFAIK) combines fuel with high pressure air and then injects both of those into the combustion chamber.

The added air is supposed to aid with the dispersal of the fuel and since the fuel pressures are lower, I can't see motogp having an issue with it.

[caperix]

I would think packaging would be hard on a bike.  The piezo injectors most modern automotive direct injection setups are about the size of a sparkplug and coil.  On a 4 valve per cylinder small displacement bike engine theres not alot of extra room.  Though I would not be surpised to see it showing up on large touring bikes in the near future.

[Porsche Monkey]

I would think packaging would be hard on a bike.  The piezo injectors most modern automotive direct injection setups are about the size of a sparkplug and coil.  On a 4 valve per cylinder small displacement bike engine theres not alot of extra room.  Though I would not be surpised to see it showing up on large touring bikes in the near future.

The DFI injectors I play with are no bigger than a standard MPI injector.

The orbital system (AFAIK) combines fuel with high pressure air and then injects both of those into the combustion chamber.

The added air is supposed to aid with the dispersal of the fuel and since the fuel pressures are lower, I can't see motogp having an issue with it.

I have no experience with this setup but it sounds intriguing.