I have never seen one of these for a car, but a friend was showing me some tests in a motorcycle magazine. this is a thrust graph:




As was said above, the thrust (acceleration) is mainly a function of torque and gearing. You can see that for each gear, the curve looks like the torque curve stretched out or squeezed, and raised or lowered. Looking at this graph, it looks like all the bike should be shifted at the limiter in the first couple of gears. For the ducati, it looks like 4th and 5th don't need to go all the way to the limiter, and the same goes for the honda in 5th. The triumph on the other hand, looks like it should always shift at the top for peak acceleration.

 

The comparison is really interesting and you can see the different characteristics for each bike and gear. The Honda doesn't seem to have a rev limiter and the end of the Honda curves seem to more smoothly meet the curve for the next gear.

Between 1st and 2nd gear you can see the 2nd gear peak thrust for the Ducati occurs at about 60mph and before the rev limiter kicks in at about 68 mph in 1st gear, so you'd shift at 60 in order to ride up 2nd gear to its peak?? The Ducati's peaks trail the intersections in the early gears. Bad design???

The Triumph, however, between 1st and 2nd is the reverse, 1st gear maxs at about 69 mph, while the peak for 2nd doesn't occur until about 78 mph, so shift at the 1st gear rev limit of 69mph?? The peak for the gears on the Triumph seem to be after or at the intersection.

The Honda peaks, like the Ducati, are before the intersections in the early gears.

Wonder what the Z's curves look like?????

Modifying with Turbo or SC would change all this - How???

Thanks for the posts guys.

Bill

 

Shift points are easy to calculate. I did this way back in May of 2002 under the id 'msink' Unfortunately, I can not get ANYONE on this forum to respond to my emaisl about my ID not working. Anyway, you shift when drive wheel torque in the next higher gear = drive wheel torque in the current gear. When you view this thread, look for the Drive Wheel Torque plot. Keep in mind, this is a CALCULATED dyno plot, we didnt have real numbers back then, but this is close, and will at least give you an idea of what I am talking about.

https://my350z.com/forum/showthread.php?threadid=249

 

Thanks a lot Mark. Printed your prior thread and reviewing the curves. Will post thoughts/questions.

Bill

 

For strictly max accereration you want to shift where the curves cross or at readline if they don't intersect. On a road course you might want to shift sooner to avoid having to shift in the middle of a corner (particularly on a bike). The Ducati's torque peaks being below the optimum shift point RPM is a little bad for 1/4 mile times but it works very well in the real world where it is hard to be up at the top of the tach all the time.

Usually turbos are tuned for a fat midrange because that's the most usable on the street, particularly when you factor in turbo lag. A turbo tuned this way really reduces the need to downshift when you want to pull out and pass. If your at an engine speed where you can get full boost just floor it. You make power through boost and not really high engine speed. That being said, the old F1 turbos made over 1000 HP form 1.5 liters at about 14,000 RPM! Of course, it took the best drivers in the world to keep them on the track. Jackie Stewart, three time world driving champion from the pre-turbo era tried to do a track test for one of the car mags and looped a turbo McLauren (?) about 3 times before they took it away from him. Those cars were faster from 100 to 160 MPH than they were 0-60 because of the additional traction from the aerodynamics kept the wheels from spinning at the higher speed. But I digress ...