direct injection on a desmodue?

[Dirty Duc]

There are air-cooled diesels and a diesel combustion event is much hotter than a gasoline combustion event.

It's all physics and metallurgy.

[Dirty Duc]

Although you never specified air-cooled  desmodue

and it would allow a useful turbocharger (as opposed to a gargantuan one that piles on the power at 6k, a nice little one that spools early and maybe has variable vanes to maintain boost throughout the RPM range a la BMW).

[ducatiz]

Although you never specified air-cooled  desmodue

and it would allow a useful turbocharger (as opposed to a gargantuan one that piles on the power at 6k, a nice little one that spools early and maybe has variable vanes to maintain boost throughout the RPM range a la BMW).

i don't know of any desmodue except the ST2 that is not air or air/oil cooled, do you?  and there were only about 10,000 st2's on the road to my knowledge, in the whole world.

i think most ppl assumed it was the commoner air cooled, no?

[Dirty Duc]

Yeah, I know... damn lack of written tone!

I was referring to the ST2.  10k built, ever?  hmmm... I like things that are rare.  Is there a reference for that?

[ducatiz]

Yeah, I know... damn lack of written tone!

I was referring to the ST2.  10k built, ever?  hmmm... I like things that are rare.  Is there a reference for that?

Ducati apparently released it:

http://eastcoastducaticlub.sslpowered.com/eastcoastducaticlub.com/Forumbb3/phpBB3/viewtopic.php?f=2&t=310

[Dirty Duc]

Very cool.

Now I just have to unload my other "collector" item.

[ducatiz]

Very cool.

Now I just have to unload my other "collector" item.

welll.. rarity doesn't make it a collector item...  my 500 GTL only had about 5000 worldwide with 1400 imported to the USA.  likewise, my Alazzurra is more common, but still rare..  I wouldn't call them collector items.  maybe in 50 years.

More accurately, they are accumulator items.

[Dirty Duc]

Value is in the eye of the beholder.  I wouldn't pay Barrett-Jackson prices for an ST, especially as I tend to use my cool stuff as it was intended.  Cars should be driven, motorcycles should be ridden. 

I just like the "one of XX with XXX,XXX miles on it and still running" concept.   [moto]

[Duck-Stew]

I think the DI Porsche's run something insane like 1500psi for the fuel... 

PM DesmoPorsche.  He's wrenched on them.

[ducatiz]

I think the DI Porsche's run something insane like 1500psi for the fuel... 

PM DesmoPorsche.  He's wrenched on them.

chresus jist, what kind of pump do they have?!

[Dirty Duc]

You have to run high pressure to overcome the pressure inside the cylinder, and to spray all that fuel in the much shorter time.

[ducatiz]

You have to run high pressure to overcome the pressure inside the cylinder, and to spray all that fuel in the much shorter time.

sure, but Porsches don't have THAT much chamber pressure.

[bikepilot]

I don't think cooling is a major issue - and it hasn't been done on liquid cooled bikes (other than Motus) either.  Motos generally lag about a decade behind mainstream cages in engine technologies, especially ones of this type.  With less stringent environmental regulations, smaller production volumes and much higher requirements for performance and response it makes sense.  I suspect we'll gradually start to see direct injection bikes, but I don't think its going to happen quickly or anytime soon.  The R&D costs will be significant and the manufacturing costs are higher as well.  Not a huge amount higher, but still more and margins on bikes are extremely thin already.  (ford reportedly left standard injection on the new 5.0 v8 because DI would have added $200 to production costs - dunno if its true or not, think I saw that on autoblogg, but could have been somewhere else).  I think dialing in the throttle response so its just right will be more difficult, though certainly not impossible, with DI.


I don't know what sort of pressures most DI engines run, but its pretty high.  I know diesels run around 2,000 psi.  Pump tech varies.  My old ford uses a positive-displacement rotory pump.  My dad's powerstroke uses engine oil as a hydrolic fluid that's pumped to injectors.  the injectors use a solinoid to pump the engine oil which acts in a compound way to squirt the fuel (so more volume of engine oil moves in an injector than fuel).

[Langanobob]

.. for a one-off maybe.  But if this was part of the design by the factory, there is no reason it would be significantly more expensive.  Is there?

As discussed, the required injection pump pressure is very high.  I think MotoGP rules limit the max fuel system pressure to 10 bar (very roughly 150 psi) which is way to low for direct injection.  I don't know if this rule is based on legitimate technical or safety reasons or politics.

It could be that the factory does not want to mess with the high fuel pressure for safety/liability reasons. This is pure conjecture on my part though.

You've been on a roll lately with your posts - could it be that we have our own budding Erik Buell/John Britten right here on the DMF?

Bob

[Dirty Duc]

According to some people compression ratio of 9.8 is good for ~200 psi at 16 degrees ATDC at full load (measured at the spark event).

Plus, as you have a very small window to get fuel into the chamber...

SBK rules state the fuel pressure can be no more than .5 bar above homologated pressure.