Understanding Torque

[eschaider]

I have driven vehicles with CVT's, Patrickt. There is a considerable mortgage to be paid in terms of throttle response and acceleration for these types of vehicles. What they attempt to do is allow a small displacement engine that is operated closer to its torque peak to power a vehicle we would be reluctant to drive with a more typical transmission choice.

The effect is not a performance benefit it is a utility benefit perhaps allowing CAFE standards to be more easily accommodated. The CVT technology currently is definitely not a performance oriented option.


Ed

[Dominik]

I pressed "like" already before I even read the article.

In the 90s I had a 496 with a very flat torque curve and corresponding "low" hp.
My limitation were the tires.

No bike in the 90s could keep up from standstill to 160 mph. Not even a Duc 996 with power upgrade. A 900 cc Ninja with 160hp had NO chance. Well, it had no torque ;-)

[patrickt]

Funny how none of our professional engine builders want to even touch this thread.

[mikeinatlanta]

Originally Posted by Dominik

I pressed "like" already before I even read the article.

In the 90s I had a 496 with a very flat torque curve and corresponding "low" hp.
My limitation were the tires.

No bike in the 90s could keep up from standstill to 160 mph. Not even a Duc 996 with power upgrade. A 900 cc Ninja with 160hp had NO chance. Well, it had no torque ;-)

Lots has changed with modern bikes. A current liter class sport bike is good for about 80 lb peak torque. Looking at the graph you can see the MV4R makes that just off idle, and carries over 100 all the way to the rev limiter. BTW, it is a Katech developed pushrod V4 based largely on LS architecture. Long live the pushrod.

[olddog]

Mike,

Just a quick thought on the dyno chart. When torque drops off a cliff on top end, I would first suspect you are loosing control of your valves.

That does make determining your shift point more challenging. You may want to give up a bit of acceleration for longevity of the engine.

[mikeinatlanta]

Originally Posted by olddog

Mike,

Just a quick thought on the dyno chart. When torque drops off a cliff on top end, I would first suspect you are loosing control of your valves.

That does make determining your shift point more challenging. You may want to give up a bit of acceleration for longevity of the engine.

Agree, however, the manufacturer claims it's purely cam profile. Have to give it a look on the dyno with my own eyes and see what we have. As flat as the curve is, I can see shifting just after hitting peak hp, but we'll see.

EDIT: Bike has LS rockers, Ti valves, Ti keepers, Ti retainers, hydraulic lifters, and beehive springs. I read that the beehive springs tend to give up softly. Anyone have any experience pushing beehive springs to their limit? How do they behave at the limit?