Direct Injection on bikes - why not?

[spicy]

So I was pondering with my brother and friend a couple days ago and thought I'd ask the masses why nobody's tried to do DI on a motorcycle engine? Alternatively, why is it that bike engine tech lags so far behind car motor tech, particularly since 3 of the big 4 produce performance automotive engines.

My bro suggested that running the pump necessary to get 1200psi in the line for DI would be tough on such a small engine; our friend countered that probably wouldn't be too hard, and the reason for it was more cost not being worth it.

Most of the larger performance-oriented car manufacturers offer at least one DI engine, but maybe it's just not feasible for smaller production numbers that motorcycles are limited to.

Seems like it would break the stalemate on 600cc engine development. I was under the impression that DI allows for increased efficiency (and thereby power if you increase fuel/air) and reduces emissions (which would allow manufacturers to lessen all the heavy, strangling exhaust bullshit), but maybe that's incorrect...



I also posted this on SBN for increased exposure, just in case anyone is wondering why the redundant posting...

[imkindafkedup]

http://www.motorcycledaily.com/31march06_dinject.htm

it seems to just be cost as of right now, but they do see it foreseeable on mass produced bikes. Maybe suzuki will do it, but only after buell makes at least one DI bike.

[Sheppo]

The fact that Ski Doo has a DI engine now. I'll bet Buell wont be too far behind on the 1125.

[spicy]

ah, excellent. thanks mike, 'preciate it -- hope you're doing well.

[GixerJockey]

The fact that Ski Doo has a DI engine now.

Rotax had a DI 2-stroke going into Sea-Doo watercraft since '98 or so. They stoped using it in '03 I think.

[Ericthejet]

Gasoline direct injection

What is it? High pressure fuel injection into the combustion chamber of each cylinder. This is more efficient than injecting fuel into an intake port and from there channeling it to various cylinders.

When is it coming? Right now. VW and its Audi luxury brand have pioneered the wholesale adoption of direction injection and others are also in the game.


Detroit is dropping car models and budgets faster than a hot piece of iron. I would also think that with the current world wide economic slowdown that perhaps the motorcycle industry is looking at it's budgets a bit closer as well?

[Sheppo]

Rotax had a DI 2-stroke going into Sea-Doo watercraft since '98 or so. They stoped using it in '03 I think.

True, but they brought it back in the 2009 600HO Etec Sleds.

[Kurlon]

Aprilla has had clean burning DI two strokes for a few years now, and they are decidedly more powerful than their carb/efi brethren.

[schleppy]

I'm also wondering if the ECU is a contributing factor. I know some of the higher end superbikes have pretty advanced, units, but not all.

Also, most of the DI car motors I know about are also turbocharged (or super). I wonder if that's also a factor?

[richw]

I assumed it just allowed for more compression and therefore higher efficiency

mc we don't care of efficiency

was not sure what etec outboards are direct injection or just injected at the port

[spicy]

efficiency should always be at the forefront of concerns.

efficiency and power go hand in hand. you can either use less fuel to produce the same amount of power, or use the same amount of fuel to produce more power -- seems like it's always of interest to improve efficiency.

ericthejet -- yeah, you're right. i didn't really mean "WHY DON'T WE HAVE DI BIKES OMG WTF!!!" more just wondering why they haven't appeared yet (particularly since it's been around for a bit in car engines, and has pretty distinct advantages)... there must be reasons why nobody's bothered (cost, complexity, etc).

schleppy -- porsche just came out with the new 3.6 and 3.8 (S) engines for the 911. both are NA, but i think you're right in that DI is more beneficial for forced induction because the benefit of cooling the charge air is multiplied when you're compressing it (like with a turbo/SC).

[Kitt]

hey! I design GDI fuel pumps we don't have one customer that manufactures bikes.

[richw]

DI and 2 strokes would make great bikes

CARB take a pill

[CEO]

http://www.motorcycledaily.com/31march06_dinject.htm

it seems to just be cost as of right now, but they do see it foreseeable on mass produced bikes. Maybe suzuki will do it, but only after buell makes at least one DI bike.

I like how that article says that we will start seeing direct injection on bikes 'within the next two years' and the article is dated from 2.5 years ago...

[stoinkythepig]

I really don't think there's a stalemate in the 600cc class. All the makers know how to make more power and build lighter bikes, they just don't want to do it all at once because there's more money to be made with gradual improvements through multiple generations of bikes over a period of decades. Giant technological leaps forward cost a fortune and only produce market-leading sales until the competition catches up by copying the technology (which is much cheaper than developing it from scratch). Bike makers need to generate brand excitement and sales every 2-3 years when the improved models come out. By making gradual improvements every 2-3 years, makers have reasonable R&D costs and don't share any secrets with competition. Someday, there will likely be DI on a 600, but not until it does not cost a fortune to design and implement.

DI is used on marine two-strokes to meet emissions standards. It has the added benefit of dramatic efficiency improvements while retaining the light weight and simplicity of a two-stroke and the ballsy hole-shot advantage over most four-strokes. Evinrude decided to buck trends and concentrate solely on making DI two-strokes rather than build entirely new four-strokes from scratch. I'm pretty sure they are the only maker with this philosophy. If I were in the market for a big outboard, I'd buy one, they are really nice motors and I just love two-strokes.

AFAIK, the efficiency improvements of DI on a four-stroke are markedly less dramatic and it's mostly used solely to overcome pre-ignition issues related to excessive heat on engines with forced induction. Works great (and has for decades) on four-stroke diesels though...

[560smr]

The Bimota V-Due was a 500cc D.I. 2-stroke that was essentially a GP bike for the street.Shame they did not have the money to perfect them,it was the cause of their demise a few years ago.

[richw]

Remember your neighborhood EPA keep changing the rules

Devoloping something today doesn't mean it can used tomorrow

[Evil_Weasel]

The Bimota V-Due was a 500cc D.I. 2-stroke that was essentially a GP bike for the street.Shame they did not have the money to perfect them,it was the cause of their demise a few years ago.

they should build that bike again but with todays technology. it was killed because 1990s F.I electronics couldn't keep up with a 2-strokes firing every stroke. a 2-stroke turning 10K rpm is like a 4-stroke turning 20K when it comes to injector and spark firing.