When are we going to see it?  We've got fuel injection now but to really get horsepower out of these engines you need some serious engine management and serious engine management needs drive by wire.  Cars already do it, road going motorcycle already do it.  You guys are paying nearly $10g for a KTM dirt bike.  $12g buys you a world class 4-cylinder motorcycle with drive by wire throttle control.  Cost can't be the issue.

i've actually been thinking about this topic lately.  First of all it wouldnt be drive by wire, it would be throttle by wire.  The only real advantage that it MIGHT hold is weight savings.  You could redesign the throttle tube and incorporate a rotary pot sensor to send a signal to the EFI, but by the time you design a secondary system that pulls the throttle back after its released, there may not even be much of a weight savings (i also could be very wrong).

Of course there is always the tunability, but how much do you really need to tune it.  I mean, it would be nice to have the extra item to custom tune, but motion pro is basically doing that right now mechanically, anyway...

http://www.motionpro..._throttle_kits/

I guess im not going to go as far as to say its not a good idea.  If the increase in tunability that the system creates is even a miniscule speed advantage, you will start seeing top tier teams starting to do it.  In my honest opinion, if teams havent already atleast LOOKED into doing this, then they're lagging behind.  But for the everyday rider, this is not going to be a system that creates any sort of advantage until the day that rotory potentiometer sensors or string potentiometer sensors, newly designed throttle tubes, and wiring, become less priced than a the current throttle tubes and current cables.  

just my 2 cents...

We need to understand the primary benefits of drive by wire.  It is one component of a complete engine managment package.  Drive by wire throttle control is an important step in extracting maximum performance out of an engine.  It gives engine management total control over the throttle plates which helps make an agressively tuned engine perform more smoothely and makes it more rideable.  It also limits throttle position in situations that may be damaging to the engine such as a low rpm lug. Engine management is the reason 1000cc sport bikes are pushing in excess of 150 horsepower at the rear wheel and are still daily driveable.  Engine management is the reason pickup trucks are making 400 horsepower out of an engine package that was only approaching 300 horsepower 5 or 6 years ago.  Engine management is the reason cars are pushing 200 horsepower and getting 40 mpg.

the only fuel pedal I ever changed for a drivabilty problem was on an international truck but.... that particular pedal had an on/off switch and 2 rheostats ..... the on off switch tells the computer that the throttle is off idle and then the two rheostats must confirm each other for the computer to know throttle position.  so I am guessing at this point in time  money, complexity, space limitations  and durability are preventing it from making it on a position that is prone to a nasty environment.

I am getting old and cheap and I wouldn't want to see it happen. Too many bikes are crossing over technology gap while the simple trail/play/beginners bike are dropping off.  F1 technology is great but how many privateers  or weekend warriors  do you see in a F1 car

It's not F1 technology.  It's been on most cars after 2004 and is on most current sport bikes.  It's simple and reliable and has significant advantages to engine tuners.  My 2005 R1 has primary and secondary throttle butterflies.  The primaries are cable controlled and secondaries are computer controlled.  Newer versions of the bike have gone completely drive by wire and completely eliminated the secondary throttle.  In the way, it has made things simpler.

you probaby need a battery for the system to work, so ill pass on that. ill be happy with direct injection, but that will prolly need a battery also cause that requires alot of fuel pressure

Throttle by wire has been used in production vehicles for years, but not in the same capacity as required for racing vehicles. There is a distinct feeling you get from a throttle cable that you absolutely don't get from a throttle by wire system. I hated my throttle by wire in my BMW 330i sedan, it sucks, totally puts the driver out of the equation. My standard cable throttle BMW M Roadster (which was my autox race car) was so much easier to manage.

Needless to say, nobody seems to be complaining about the sportbike throttle by wire system and having felt many of those throttles myself, the manufacturers seem to have it licked. I'm not sure of the delay yet, but its probably minimal as computers today are pretty fast. The nice thing about throttle by wire is the simple ability to manage tuning and allow the ECU to keep the throttle open for anti-stall and on 4 strokes, it helps keep the engine breaking to a minimal.

I think on 4 stroke dirt bikes, throttle by wire is only a matter of time. On 2 strokes, I don't think we'll ever see it.

Kinda makes you wonder if the Factory MX bikes are doing it yet or not.  Especially in Europe.  Maybe there is not a rule against it, AMA or FIM.

Throttle by wire is especially useful when there are limitations on peak allowable compression pressures such as fuel restrictions.  What fuel do the top level MX riders run?

1987CR250R, on 25 January 2012 - 09:15 PM, said:

Fuels that eliminate those limitations.  Mostly.  Still has to be gasoline, so that pretty much eliminates the idea of running 15:1.

There is, as I understand it, a rule against "traction control", although I think some teams are stretching that one pretty thin with some of the timing controls they are using.  If the AMA decided fly-by-wire throttle control was traction control, it would be illegal, too.

What I am thinking is building engines with higher compression pressures that tend to cause detonation.  Detonation is damaging to engines at low rpms but isn't very detrimental once a certain piston speed is achieved.  So, drive by wire systems will limit throttle opening at mid rpms where cylinder pressures are high and likely to cause damaging detonation then allow full throttle again on top when detonation is nolonger detrimental.  Think NASCAR engines, they make as much power as they do on fairly low octane because they are tuned to have a very narrow powerband.  They run deep into detonation towards the top but the piston speeds are high enough that the pistons run away from the shockwave and there is no damage.  But, narrow powerbands are good for circle track and not offroad riding.

That was pretty obvious when you first said it. Electronic ignition advance control already accomplishes all of those same things, and has for years.  You can add a knock sensor and get sillier than shit with things, too.  I had a Turbo Volvo 760 for some years that I NEVER ran premium in, and it would not only spank a huge array of American V8's it never pinged.  Don't need fly-by-wire throttle controls for that.

I'm sure it will happen eventually it's a nice technology in cars. Soon dirtbikes will be as bad as cars to work on, there are benefits to it but they aren't huge in a n/a engine, maybe a faster throttle response. Turbocharged engines pretty much need them so you don't have so much turbo lag, it sucks when the throttle body goes bad though. I'm sure this is part of the reason why I'm able to safely run regular 87 octane in my car that has a turbo, along with the multiple other sensors. 700$+ plus part. I'll stick to my carb for now. Won't be long before dirt bikes are gonna be breaking 10 grand.

Edited by 79yamdt, 03 February 2012 - 04:07 PM.

grayracer513, on 26 January 2012 - 06:53 PM, said:

Electronic ignition control cannot control all of those things because it cannot control compression pressures.

there is a function of drive-by-wire throttle control that most people dont know about.when you let off the gas in a dbw car the ecm kills fuel to the injectors.but the ecm does not completely close the throttle blade.it is left open so the engine can pump air into the cat convertor.no need for a belt driven pump anymore.the ecm's on modern vehicles do other things- like evacuate the fuel tank while you are driving.Usually with a piston engine you get a big doce of unburnt hydrocarbons with a chopped throttle.the dbw eliminates this.As far as a dirt bike app the best use would be for traction control-but you would need speed sensors on both wheels.the ecm could be programmed for percentage of slip-a max % of overspeed on the rear wheel vs the front wheel.

1987CR250R, on 26 January 2012 - 05:42 PM, said:

Wouldn't the piston have to travel faster than the speed of sound to do that?

oldxr1, on 27 January 2012 - 04:16 PM, said:

Overrun fuel cut has been a standard feature of digital EFI practically since the inception of digital EFI decades ago. Many cars equipped with it (EFI) don't use smog pumps, either. How does TBW eliminate the rich spike on throttle chop, though? The only thing I can think of that would truly eliminate that without incurring some kind of lag is GDI.

On the topic of traction control, it can be implemented without wheel speed sensors by monitoring changes in engine RPM. The ECU can limit output when engine RPM/time exceeds a threshold value. I doubt wheel speed sensors would easy to use on a bike anyway. Situations where the rear is not slipping and the front is off the ground, using throttle to control flight dynamics, and using throttle to steer the bike come to mind.

HeadTrauma, on 03 February 2012 - 01:10 PM, said:

In response to a "throttle chop" input at the gas pedal, the system reacts by cutting fuel, but "rolling" the throttle closed, so air follows the fuel through and out.

HeadTrauma, on 03 February 2012 - 01:10 PM, said:

Yes they would, and no they don't, not even close.  A 5.7 Chevy with 6 inch rods turning 9500 RPM will generate PEAK piston speeds in the realm of 9000 fpm, and sound in air moves at 66,986.22 fpm.  The statement is ludicrous on its face anyway, since it is the pressure of the advancing flame against the piston that causes detonation in the first place.  High RPM engines can utilize relatively low octane fuel if they avoid low speed operation.  That simply elevates piston speed to the point that the piston moves fast enough to avert detonation in the first place.  Good ignition controls can prevent that anyway.

79yamdt, on 26 January 2012 - 07:22 PM, said:

drive by wire in no way affects turbo lag, let alone reduces it...

hi_im_sean, on 03 February 2012 - 02:45 PM, said:

There is no human in this world that can respond as fast as a computer does or understand what the engine needs at a certain point as fast as a computer. It may not do anything more than an experienced driver can do but it does it faster. It opens the cars throttle body further and faster when you give it some throttle to help in the reduction of turbo lag. Lets say your move your throttle input from like 25% to 50%, the driveby wire system on most turbo cars actually overcompensates for your throttle input and will open the throttle further than that 50% momentarily. This would cause the turbo to build boost quicker compared to just giving it 50% throttle.   You could do the same by giving it more gas than you need than backing off but the person that drives their car everyday from point a to point b will appreciate this feature. And your not gonna be able to do it faster than a computerized system can anyways.

This is my understanding of it anyways as far as the saab Trionic 7 engine management system. Maybe other cars don't but I wouldn't see why other cars with drive by wire systems and turbos wouldn't have a engine management program that did this.

Quote

Borrowed from here..  http://saabworld.net...elease-usa-283/

Edited by 79yamdt, 03 February 2012 - 04:02 PM.

Drive-by-wire does not in any way allow a race engine to make more power. A drive-by-wire throttle wide open is the same as a cable throttle wide open. Air flow is the same, fuel requirements are the same, and the only position where you can make peak power is WOT.

You do not need drive-by-wire to limit detonation because all modern bikes have a 3D programable spark advance system, and the EFI ones probably reference manifold pressure as well. There are two ways to control combustion pressure - throttle opening, and spark timing. Retard the timing and combustion pressures go down.

Most of the gains on modern vehicles are coming from variable valve timing, and far more precise fuel control from better air-flow sensors and wide-band oxygen sensors. Not drive-by-wire. Cams with lots of overlap make big power, but have poor low end torque,  and quite poor emissions. Variable valve timing allows the use of very aggressive cam profiles, but during idle, low RPM, and cruise, they phase the camshaft timing apart to pretty much eliminate valve overlap, which grealy improves emissions. The main benifets of drive-by-wire are that it allows the computer much more control over engine power for things ilke traction control, and vehicle stability control, and during cruise it can cut the throttle blade opening slightly when the EGR opens, or the valve timing switches into EGR-like mode. I suspect it's mainly a traction and emissions thing in bikes as well.

Race engines were making 150HP/L well before the days of fuel injection, let alone drive-by-wire EFI. Even the carb'd 450s can be made to make 65HP at the wheel without too much effort, and still be quite rideable. That's 144HP/L from a single cylinder, carbureted engine.

Edited by Lead Head, 06 February 2012 - 03:05 PM.