Carb convert.

[Tamburinifan]

Read on the old FIM site that they Y-wired dual injectors on P8 Ducs but that is maybe wrong:

one way to overcome this problem is with dual injectors. The P8 computer (found on the '93 and 94 888s and the '95 916s) is capable of firing dual injectors sequentially, which is; one injector per cylinder is used at the 'map' injector time, up to a certain injector time (that point is set by the software on the 'chip'.)

From http://www.visi.com/~moperfserv/955_sps.htm .


I would like to see how a 900 2v w FCRs & the full ignition map from a ECU runs.....

[higgy]

OK, I'll take the bait...you're saying that F1, modern off road M/Cs, virtually 100% of auto and motorcycle racing where FI isn't explicitly prohibited are all wrong?

Not at all, Where you can use more than one injector per cylinder and money is no object a well developed sequential direct injection Fi system when combined with variable intakes and variable cam timing will in the end outperform even the best carb setups.
The limiting factor, performance wise and reliability wise in an FI system is the injectors. Only Direct Injection can beat the carb hp for hp.

The single advantage FI has over the carb is its ability to easily deal with large changes in fuel quality and even type of fuel,soon to be at the single combustion cycle level.

[higgy]

What Not one single argument Must be loosing my touch

Common Anglix, blast away...Sam nothing to say,Oh man,what a drag

[angelix]

......
The single advantage FI has over the carb is its ability to easily deal with large changes in fuel quality and even type of fuel,soon to be at the single combustion cycle level.

Actually this is only partially true

EFI is MUCH cheaper and MORE versatile that any carb setting.

if we look at the Marelli Production their EFIs were used in millions of vehicles and dozens of models in different markets (racing, Auto, motorcycle)

of course the investment and the development involves a lot of research and money, but once that is in place, the actual production is very cheap compared to the traditional carbs and can be done by ant company working in the electronic business.

Moreover, EFI it is self adjusting, basically it takes into account Air temperature, altitude, engine temperature, knocking.

It is cleaner than carbs in every aspect so less carbon footprint.

It is easier to maintain, does not get stuck, worn out, dirty, etc etc.

Last , but not least, it opens a new world... Traction control, anti spin, drive-by-wire, etc

what else to say?

[higgy]

EFI is MUCH cheaper and MORE versatile that any carb setting.

Cheaper? Have you lost your mind? Versatile? It may be that some day an injector will be developed that can match even the cheapest made carb in range of operation or application,That day is yet to arrive. Currently to match a carb requires multiple direct injectors. And lets be clear, it is the electronics not the injector that has come a long way,all of which could also be applied to a carb. Direct injectors are neither cheap nor easily maintained and are a very recent developement.

It is easier to maintain, does not get stuck, worn out, dirty, etc etc.

Maintainance wise there is little difference, It is advancement of filters and fuel additives that has improved the reliability of any fuel system

Last , but not least, it opens a new world... Traction control, anti spin, drive-by-wire, etc

what else to say?

All of which could be applied to a carb system equally as well.

Still, the reason for leaving the carb to history came down to emissions. There is just no way to adjust the mixture in a carb setup quickly enough to accomplish what needed to be done. Performance wise,speaking in terms of Ultimate hp,it has only been recently with the development of direct injection and multiply injectors per cylinder that EFI has matched and surpassed the performance of a carb.

[samandkimberly]

Sorry, I really meant to continue the debate but I've been stupidly busy at work. I've been reading the dialogue, though...

First, just for clarity - you mean multi-point, rather than throttle body injection when you say direct injection, right? This is not to be confused with direct, high pressure injection right into the combustion chamber. Modern Ducatis are multi point, I don't think anyone is doing direct injection yet on a M/C.

If that's the case, then we're pretty much in agreement. I might argue that EFI does have more tuning advantages in that you can tune for a wide variety of input changes other than manifold vacuum, but you could counter that you can do the same with a carb, to some extent. I do think EFI systems are generally less susceptible to change over time, but that's debatable. Carbs *do* get real complicated when you start adding lots of little solenoids and rheostats, etc.

EFI is still more expensive than cheap carbs, but not good ones - if they weren't competitive I can assure you we wouldn't be seeing them on the latest round of MX bikes. I think we're right at the price tipping point now.

I built my own EFI system about 10 years ago, it was a disaster; I lost 2 years of racing pushing my bike around the pits, because I didn't think I had the time to dyno tune it. I got it to work, but never well...the best performance I ever got was when I replaced my EFI with a set of FCRs. Still, eventually I'd like to replace the stock EFI on the 907 with a newer system, when I have the time. Just the controls, I think the stock hardware is perfectly fine. This time I'll schedule a few days on the dyno to get it going right.

Sam

[Tamburinifan]

I'd like to replace the stock EFI on the 907 with a newer system, when I have the time. Just the controls, I think the stock hardware is perfectly fine.

MyECU is bolt-on, if you like to fiddle yourself.
All parameters seen f e in Wordpad, as simple as it gets.
Had it over 2 years now, works fine.
But I still like the feeling on my Monster w FCR & Ignitech better.....

[Tamburinifan]

my 89 851 ran very nicely with a p8 and possibly a std 888 eprom from memory. i had to ride it once and the original ecu was away.

So P8 work on P7 engines but they have to have a P8 chip.
http://www.ducati851and888.com/showthread.php?t=3161

I`ll test a P8 w custom maps on mine this weekend.

[higgy]

First, just for clarity - you mean multi-point, rather than throttle body injection when you say direct injection, right?

Actually no, While sequential multi point injection was a vast improvement,intake injection sustems all suffer from the same issue,that is the fuel tends to collect in the intake port. Only the advent of direct(into the cylinder) injection has allowed EFI to at last surpass the carb performance wise. Gee it only took a little over one hundred years.

[samandkimberly]

Actually no, While sequential multi point injection was a vast improvement,intake injection sustems all suffer from the same issue,that is the fuel tends to collect in the intake port. Only the advent of direct(into the cylinder) injection has allowed EFI to at last surpass the carb performance wise. Gee it only took a little over one hundred years.

There we would disagree. Nearly all modern multi point EFI systems are better than most carburetors. *Some* multi point injections systems (in particular dual injector and showerhead injector designs, but even well placed single injector setups) are better than *any* carburetor could be. As easy to set up - probably not, but better in terms of driveability, power, economy and flexibility.

Sam

[higgy]

but even well placed single injector setups) are better than *any* carburetor could be

Nope,never happen,not in this universe

[Tamburinifan]

Anyone has some hard facts, like one engine w carbs & injection on a Dyno?
Any motor will do, would be real interesting.

[samandkimberly]

Anyone has some hard facts, like one engine w carbs & injection on a Dyno?
Any motor will do, would be real interesting.

It's not that simple because dynos only show part of the story - peak HP at full throttle. If you surf the web you can find dyno charts showing that a carb makes more power, and others showing that FI makes power. Fact is, both do a pretty good job of getting maximum power out of an engine. I would argue that a well placed pair of injectors, or showerhead injector (one aimed directly down the intake) can actually increase flow to the point of increasing HP by a few percent, but I can't produce the evidence, and I wouldn't bet my 907 on it. I think the real issue in the FI vs carb debate is drivability when not at full throttle.

Where even basic multi point injection systems have a major edge over carburetors is in their flexibility. Fuel mixture can be (and typically is) based on ignition timing, RPM, air temperature, engine temperature, air density, throttle position, and more. Furthermore, they can be tuned for volumetric efficiency at given RPM/throttle positions. Carbs depend on one thing - pressure differential between the airbox and the inlet manifold. This is a very accurate way to measure air volume intake, and 100 years of development have made the modern carburetor incredibly adaptable. I would never argue that, in a typical street tuned engine, carbs do a nearly perfect job of delivering maximum drivability and performance.

But in bring radical cams, ultra high compression, tuned intake exhaust systems (or the most extreme example, turbocharging) and carbs can start having problems. If they're sized for maximum flow at full RPM, then their idle circuits may not get enough flow to deliver a smooth idle. If hot cams and a tuned intake system create a volumetric efficiency jump at a particular point then with carbs you very well might have to live with a flat spot that could be tuned out in an FI engine by tweeking the fuel map. And - with FI, you can get similar drivability across the board and still stay on the lean end of stochiometric efficiency because you have more control over the fuel mixture.

All these variables are also why FI systems often fall short of carbs. As Dale Quarterly once mentioned about suspension setup - "if you have 10 compression settings and 20 rebound settings on a shock that means you have a total of 199 wrong settings and only one right one." If you can get 95% of the way with carbs by playing with maybe a half dozen jets, a couple of needles, and a couple of screw adjustments, as opposed to 100s, maybe 1000s of hours tweaking and tuning both on the dyno and the track to get to 99% with FI, carbs seem to be the way to go.

Pick your poison. The 907 is a great example of a FI system that's OK, but no near as good as the state of the art in carbs. I have little doubt that bolting a set of FCRs will yield better drivability and performance. But I also have no doubt that someone with access to a dyno could make a *better* running M/C by bolting in and properly tuning a more modern EFI control system. MyEcu looks good, but I think Micro Squirt might be even better.

That said, the person who puts the FCRs on will be riding a lot sooner than the fool who take the EFI route...

Sam

[higgy]

Well said Sam I would agree on every point excepting one. That would be that a single point injector located in the intake has more control over the mixture than a well jetted carb

[907pasonut]

That said, the person who puts the FCRs on will be riding a lot sooner than the fool who take the EFI route...

Sam

first of all, I find this an interesting subject, but Sam I dont agree with your last quote...we are talking about a 907 here...and to fit carbs on a 907 its a major job, and would take ages...I went for a ride last saturday and bike went well...on the open roads it goes very well, I agree there are a few small issues with the FI system on the 907...but its miles better than the weeber setup on the 906...
instead of arguing about which is better, why not some of you brain heads (I mean this in a nice way) try to work out a way to improve the FI system and bring the 'last paso model' into the 21st cantury...now that would be nice