What does your rev counter tell you

[obi_waynne]

What does your rev counter tell you?

The information that this humble dial imparts should be useful to the driver but whilst I have my own ideas as to why we have them I thought I would throw it open and ask you all what you use yours for?

I'm planning a great in depth philosphical debate here and I just know that someone, somewhere is going to come back with the blindingly obvious answer! PLEASE RESIST!

 

[rockape]

basically to see what the car is reving at in relation to the speed i'm doing.
eg prior to the superchip, at 80mph rpm was 4000. post superechip 80mph rpm 3500 much better

 

[obi_waynne]

Thats a surprise but it makes sense - more power at the lower RPM means you can maintain your speed with less effort! (I hope that this is 80mpg on the track or a private road!) So you use the rev counter as a mark of the cars improvement after a remap.

 

[HDi fun]

Rockape - is your Coupe automatic?

If not then RPM will track road speed according to the gear you're in and nothing else unless you have clutch slipping problems.

My 406 is running 2500 at 80mph, before and after ECU remap. But it would be, because the gear ratios haven't changed at all.

 

[rockape]

definately on the track

 

[rockape]

no mate it's manual . it just seems a lot smoother since the remap, i just put this down to the fact it wasn't reving so high. but i'm no expert

 

[HDi fun]

The revs definitely won't change with a remap.

It's interesting that you mention smoother power delivery after a remap. My car gave a similar result after a remap, which is something that is not usually found with plug in boxes.

And the power went up to 192bhp. not bad for a 2.2 diesel.

 

[old-git]

A biker friend of mine said that the japanese word at the bottom of the dial, although acually the dial maker's name, really said 'change gear now!'

 

[HDi fun]

Yeah - who needs a redline after all. Once that needle's invisible you're close to upchange point. Not sure my car will stand it though. I reckon that the sixteen valve stems sticking up through the bonnet lid would bear me out.

Rgds,

P.

 

[lutonmatt]

you can use your revs when if your speedo cable goes like rock said his does 80 at 3500 so if the speedo stoped he was in 5th gear on the motorway and he got to 3500 he would know he is going to fast


and now the power bit more for racing (and sorry for the spelling on this one)
when racing (on a track) you use your revs to get the best out of the engine as a engine is at its best before the red line so say its redlining at 7k most likey best power is at 5.5 6 as any more it will not make it have any more power and more waer and stress on the engine so thats why all sports models have rev counters and base modles dont
but to find the best you need a dyno ect if it makes sense

 

[HDi fun]

Redline and rev limiters are always set above the peak power output. The reason for using the last 500rpm say before the limiter kicks in is if you really need a bit of headroom to complete a manoeuvre and don't have time to grab another gear.

Also, in road cars which in general have WIDELY spaced ratios you can get a bit more by hanging on to a gear beyond peak power so that you land right on it with the next upchange.

My Nissan redlined at 7300, and would upchange at 6800 under full throttle. (auto BTW). But in kickdown it hung on until the red. Not much difference, but you hit the next gear at nearly 6000rpm, right on the power peak.

 

[obi_waynne]

Knowing my Torque curve I can use the rev counter to determine the peak power bands.

This firstly enables me to find economical driving speeds in each gear (just over 3000rpm).

Secondly I know where the engine is most flexible for overtaking, with sound deadening you just can't guess the engine speed.

Thirdly it allows me to plan gearchanges to maintain the power band. So I have come to rely on the rev counter as the tool it is.

 

[Gangsta]

It can also help you diagnose problems with your car, as you most likely know your car, and if for the last year - your car idled at 800rpm (give or take) and you jump in one day and its revving at 900 or 1000 then you should be thinking 'what caused that then?' mabey you have burst a vaccum pipe and have a small vacuum leak. You will also be able to see if your engine is 'hunting', even if you cant hear it - as the needle will rise and fall repeatededly. if you have air con, you can tell if your aircon pressure switch and pump is working, when you hit the aircon button, the revs should drop a little, then a few moments later, they should rise when the pressure switch kicks in, holding our engine slightly higher than normal idle.

The same applies to the powersteering pressure switch, when you 'full lock' the steering wheel, (if your in a ford you'll hear a squeel) and a the revs will drop, followed quickly by the revs rising a tad above normal idle.

Im sure there are other diagnostic purposes too. But as my daily driver is an auto, the only thing its good for is looking at, or driving in manual mode, as if its in 'economy' you take the revs up to 2k and it will go from 0-90ish with the revs only dropping by about 150rpm between changes (which is bearly noticable on the needle)

 

[obi_waynne]

Thats true, the Rover had a vacuum leak which I first noticed through the rev counter. It was only 200 rpm higher but on a warm engine I saw that something was not right.

Eco mode in my car is 2300-3800 rpm (any more or less and the MPG drops considerably!)

 

[Prince]

The rev counter tells you how hard the engine is working. As mine's a Honda I have to work it harder. I generally shift at about 5000rpm!

 

[steve09]

it tells you the revs

 

[Prince]

Someone had to do it!

 

[bigdon23]

as i drive a rover i watch it to make sure my revs dont get too high and blow my head gasket lol

 

[obi_waynne]

I know that feeling bigdon23.

Steveo09 I guess we did well to get as many posts as we did without someone saying that!

 

[steve09]

i know. i thought some one else would have said it but as they didnt i just couldnt help it lol