what are the roles of tachometer? I am not really sure about it. I just know that if it is in red tachometer zone, the vehicle should be slowed down. What are its other roles? Thanks for advices!!

 

The tach is a reading of your RPM level or revolutions per minute of the engine. When u start hitting red, or red lining, start to overwork you engine. Not good. if you have an automatic then ya it would probally be a good idea to slow down , but with a manual its an indication to shift gears.

 

so this is only role of tachometer? thanks

 

lets you know where your engine rpms are at. like stated above it can let you know if your overworking your engine. the only thing i use a tach for is knowing when to shift at the track.

 

If you have an automatic you wont really need to worry about a tachometer since gears are shifted for you. Now if you have a manual, its a nice feature to let you know if you arent revving to high. However, believe me, youll know if you are revving your engine too high... especially high enough to where it destructs. But in todays cars, that is unlikely because of a "rev limiter". Basically, it wont allow you to go above a certain RPM.

 

your tachometer tells you the engine speed.if your speedometer is broke,you would be able to tell your speed by the tach and what gear your in.

 

tach gives you shift points. simple as that.

is it possible to redline an auto?i was always under the impression that if it hit redline it shifted. i mean it usually shifts at like 3 or 4k anyway

 

you can also tell if your car is still running when your stereo is blasting off your ears. look at the tach, instead of hittin' the pedal to see if the car moves.. also much cooler than going to leave the light and slipping your clutch, cuz you cant hear your motor... i would not agree at all with shift points... red line is set at the point where your engine no longer produces viable power, or no increase.. usually caused by "valve float", meaning your valves can no longer seat themselves, so the combustion chamber can no longer seal, hence no power. the tach has nothing to do with points. those variate with weather, grade, driver preference, and lets face it, the drivers mood.

 

if it doesnt increce from there it means thats peak power, which makes it an optimal shift point (in racing apps anyway)

 

true, and some tachs have those diamonds,or a dot to indicate economical shift points