Ducati "no redline" history

[red_ryder]

I was just reading the Dream Rides article in Motorcyclist and they mention that the no-redline tachometer is a signature of Massimo Tamburini...This is on the MV Agusta F4 as well as Ducati's, as far as I know.

What's the history/ reason behind this? Just to force the rider to ride by feel/ listening to the engine? Just curious..





Thanks

[bevel450]

If the max engine speed is regulated by the engine control unit, isn't it just academic ? A romantic carry over from old tech ?

Originally Posted by red_ryder

I was just reading the Dream Rides article in Motorcyclist and they mention that the no-redline tachometer is a signature of Massimo Tamburini...This is on the MV Agusta F4 as well as Ducati's, as far as I know.

What's the history/ reason behind this? Just to force the rider to ride by feel/ listening to the engine? Just curious..





Thanks

[grendels_arm]

I think it's more along the lines of a SBK being for racing and racers don't need redlines I would think.

A few times last season I misshifted and the bike was at 11K. The top safe rpm is supposed to be 10K on my 916 I believe. So unless the tach is wrong.....

At 150mph if I downshift into 2nd gear will the ECU will prevent my motor from revving to 15000? Cool thing to try when I get my slipper clutch I guess.

[kaos]

no it won't stop it from revving to 15,000,it will only stop it fireing the sparkplugs

[bevel450]

+1

Originally Posted by kaos

no it won't stop it from revving to 15,000,it will only stop it fireing the sparkplugs

[blade625CT]

there is red line on my tach...cause I PUT it there [I love red duct tape ]
I had to. Hitting the rev-limiter costs precious time.

[nathanTX]

-raises hand- Oooh, oooh, I know this one! Actually, the fact that the F4 doesn't have one is pure styling and possibly a nod to the Tamburini connection. But the fact that some/most Ducs don't is actually based in theoretical mechanical physics.

What redline actually represents is the point at which valve float becomes a problem. In a motor with valve springs, the cam(s) open the valves and the force from the valve springs closes them. As the motor spins faster, the valves open and close at ever increasing extreme rates of speed. Eventually, the force of the springs is not enough not close the valves completely before the next stroke cycle comes around and you have valve float. At that point, the combustion chamber isn't sealed, intake and exhaust don't take place properly, valves can even remain open far enough to slam into the piston on upstroke, and basically all internal combustion processes go to sh!t in a hurry.

On a motor with desmodromically operated valves, there of course are no valve springs. One cam opens the valves and another cam closes them. Theoretically, as fast as you can open the valve with one cam, the closing cam also shuts it. So, you never get valve float, and therefore have no valve float dictated redline.

Now, I say theoretically because there are other factors to redline such as friction mitigation, piston velocity and g-forces during BDC and TDC (the piston is a heavy slug that has to be accellerated and decellerated under EXTREME forces because of the speed of up and down movement). So, even with desmo motors, there is a practical limit to how fast the motor can spin. And the ECU is programmed to retard or eliminate ignition at a certain rpm to prevent these other problems from arising, which becomes the unindicated redline but very real rev limiter. But the fact that there is no possible valve float means that the traditional "redline" factor is not present.

So, sort of as a subtle slap in the face of the competition, it is my understanding that many Ducs do not show a redline in a reference to the desmo actuated valves. Like I said, they still have a very real practical limit that the rev limiter enforces. But, it's a clever indicator that Ducs are something special. IIRC, the MVs have more traditional valve springs. But, perhaps the F4s don't have an indicated rev limiter sort of as a nod to Tamburini?? Or maybe it's just marketing so that it falsely appears that the highest rpm indicated is how high the motor can rev??? Sort of the, "ooooh...look daddy, the speedometer goes to 200" effect.

edit: oh, and yes, racers need an indicator for redline more than anybody else does. Many racers add a redline or better yet a shift light. Especially if they electronically remove the rev limiter for safety and overrev reasons. Gotta know if you are about to grenade your motor when you go to heel it over at the end of Daytona's banking!

[bevel450]

Well, sort of-

The red line indicates the engineer's warning of problems ahead. It doesn't necessarily have to do with valve float. ( In fact, where on earth did that one come from...must be about twenty years ago. I haven't heard of valve float problems from any race engineer in years, so that can't be the reason for a red line, eh ?) It is addressing the mechanical limits of the engine. And don't go dissing valve springs. Desmo is fun and Desmo is a lot of things, but no one has demonstrated that it is superior to valve springs. ( It is simply Ducati's "brand" way of doing, and as technical writers say, they make it work.)

And sometimes a tach it isn't even necessary. On the pre-twin spark Monster engines, you couldn't overrev them because they would just run out of steam, and Monster riders would just accelerate until there wasn't any more...and then shift. Ducati later made an accessory tach available but it was there for $how. ( I'll sell you mine, cheap.)

If you want to have some fun, take whatever redline is available to you and back calculate that to the piston speed. Thats where the limits of material science get to be interesting. Piston speed is where the fun begins as all of those loads of accleration have to be stopped and turned the other way. It makes things interesting.

Lastly, painting a higher redline on your tach is a nice way of mind f**king with the competition or the posers. ( A big redline means as much as the top speed painted on your speedo. Utterly meaningless.)

Ah...one other thing. I noticed on superbikeplanet.com today that the new Yamaha 600 doesn't rev to the limits shown on the tach, and there doesn't seem to be much concurrence between the PR office and Yamaha engineering as to why it won't. Bad tachs ? Bad settings on the engine control ? WTF ? But it won't go to 17,500 as they advertise.

Originally Posted by nathanTX

-raises hand- Oooh, oooh, I know this one! Actually, the fact that the F4 doesn't have one is pure styling and possibly a nod to the Tamburini connection. But the fact that some/most Ducs don't is actually based in theoretical mechanical physics.

What redline actually represents is the point at which valve float becomes a problem. In a motor with valve springs, the cam(s) open the valves and the force from the valve springs closes them. As the motor spins faster, the valves open and close at ever increasing extreme rates of speed. Eventually, the force of the springs is not enough not close the valves completely before the next stroke cycle comes around and you have valve float. At that point, the combustion chamber isn't sealed, intake and exhaust don't take place properly, valves can even remain open far enough to slam into the piston on upstroke, and basically all internal combustion processes go to sh!t in a hurry.

On a motor with desmodromically operated valves, there of course are no valve springs. One cam opens the valves and another cam closes them. Theoretically, as fast as you can open the valve with one cam, the closing cam also shuts it. So, you never get valve float, and therefore have no valve float dictated redline.

Now, I say theoretically because there are other factors to redline such as friction mitigation, piston velocity and g-forces during BDC and TDC (the piston is a heavy slug that has to be accellerated and decellerated under EXTREME forces because of the speed of up and down movement). So, even with desmo motors, there is a practical limit to how fast the motor can spin. And the ECU is programmed to retard or eliminate ignition at a certain rpm to prevent these other problems from arising, which becomes the unindicated redline but very real rev limiter. But the fact that there is no possible valve float means that the traditional "redline" factor is not present.

So, sort of as a subtle slap in the face of the competition, it is my understanding that many Ducs do not show a redline in a reference to the desmo actuated valves. Like I said, they still have a very real practical limit that the rev limiter enforces. But, it's a clever indicator that Ducs are something special. IIRC, the MVs have more traditional valve springs. But, perhaps the F4s don't have an indicated rev limiter sort of as a nod to Tamburini?? Or maybe it's just marketing so that it falsely appears that the highest rpm indicated is how high the motor can rev??? Sort of the, "ooooh...look daddy, the speedometer goes to 200" effect.

edit: oh, and yes, racers need an indicator for redline more than anybody else does. Many racers add a redline or better yet a shift light. Especially if they electronically remove the rev limiter for safety and overrev reasons. Gotta know if you are about to grenade your motor when you go to heel it over at the end of Daytona's banking!

[DukeDesmo]

My understanding of why there is no Red-line is that as a bike that is built to be 'raced' rev limits are variable from bike to bike (state of tune etc) and so this was why they had no red-line, this has carried on as a link to the racing heritage.

But the cynic in me says it's a cost saving exercise - so they could use the same tacho on a 996 and a 748.........

[grendels_arm]

17500 is the redline on the Yamaha? Wow. You like never need 5th or 6th gear.