Sunday, March 30, 2008

Perfect Shift Point

Manual transmission is the one to have if you love driving or riding. That's because, manual transmissions allow you to have full control over the engine power delivery, which cannot be asked of an automatic or a CVT.

Engine power delivery is nothing but how much of the engine power goes to the driven wheels. This can be controlled by altering the shifting point of each of the gears of the transmission system.

We'll first see the two extreme cases of shifting with an example: shifting to 5th gear at 20 kph in any vehicle forms one extreme of shifting point. When you do this, transmission snatch occurs. When the clutch is fully engaged and you give full gas, the engine might even stall. This is a scenario of the torque delivery being unable to match the torque requirement. Pressing on to 60 kph in 1st gear is the other extreme of shifting point. Here the engine revs too high and in most cases, even bounces off the rev-limiter.

The optimum shift point lies in between these two cases and that is a bit tricky to find. One must first decide the mode of driving--to conserve fuel or wring maximum performance from the engine. It is depending on this that the optimum shift point is determined. In cars, when a gear too high for the current speed is selected, the whole car will rattle. This can be had as an indication for a bad shifting point. Many drivers do this thinking that it will give good fuel economy. But the truth is, the mileage actually decreases. What actually happens is, the amount of fuel intake increases but with the volume of air sucked in remaining constant. This makes the mixture rich leading to incomplete combustion. This obviously wastes fuel and pollutes the environment.

At the same time, the engine should not be revved too high either. As a thumb rule, for fuel efficient driving, the optimum shift point can be the RPM which is just over half the redline RPM. For performance driving, the gear should be shifted at exactly the RPM where the manufacturer says the engine develops maximum power. This data can be had from the owner's manual.

|Add to Google Reader or HomepageAdd to My Yahoo!Subscribe in NewsGator OnlineAdd to My AOL|

| Add to The Free Dictionary                                                                               |

^IF YOU'RE PASSIONATE ABOUT FORMULA 1, YOU MIGHT ALSO WANT TO HAVE A LOOK AT THIS.

^STAY IN TOUCH WITH WHEELS OF RAM. CLICK HERE. 

2 comments:

Standardshifter said...

Glad to see a manual transmission fan blogging.

Are you a member of http://www.standardshift.com/ yet? Good group of manual transmission fans all gathered in one place.

Anonymous said...

The optimum shifting point is not the rpm where we have the maximum power, it is influenced by the torque curve and gear ratios and in general is slightly higher that the point were you have the maxim power.