Change-up RPM - make some noise

[beetlebloke]

When I was learning to drive ('01), I was taught to use 3rd for 20mph, 4th for 30, 5th for 50; because it's "safer". Another one of those 'learner' traits that I dropped as soon as I passed. It's like using only the very middle of a saw...

Beetle

[hemibum]

You should come here, (Nigeria) for an eye opener on gear selection. To the Nigerian driver, if a car has a 4 speed box, then 4th. is the "fastest" gear. The other 3 are simply a means of reaching no.4. It makes for some pretty interesting overtaking when they get stuck behind a lumbering truck at 40mph, then pull out with foot flat down, engine pinking, and another truck coming the other way! Tip: buy a car with a very deep footwell.

[Polarbert]

beetlebloke said:

When I was learning to drive ('01), I was taught to use 3rd for 20mph, 4th for 30, 5th for 50; because it's "safer". Another one of those 'learner' traits that I dropped as soon as I passed. It's like using only the very middle of a saw... Beetle

I was taught that as well. Was over 3 years ago mind. Was also taught on the IAM to use 3rd @ 30, 4th @ 40. Which I disagreed with. My observer was unsure so asked someone in the know, said they would fail me if I didn't use their system. I understand the advantages of using 3rd at 30, but its more economical and just as safe in my eyes to use 4th.

[trevorh]

It all depends on the car, and the 'system' should take that into account.
My Elise will run and pull smoothly from 25mph to max in 5th, whereas less than 35 is difficult in 4th in my Passat diesel.
Trying to prescribe in advance what gear to use at what speed seems a little daft.

[Nick_Chim]

Polarbert said:

Was also taught on the IAM to use 3rd @ 30, 4th @ 40. Which I disagreed with. My observer was unsure so asked someone in the know, said they would fail me if I didn't use their system. I understand the advantages of using 3rd at 30, but its more economical and just as safe in my eyes to use 4th.

they weren't in the know! 3rd @ 30, 4th @ 40 is a guideline only - you won't get failed for not doing it provided that what you are doing is justified and sensible. As Trevor rightly says, there is no 'one size fits all' prescription, but people do generally short-shift meaning that the engine is labouring and the delay between throttle movement and increase in power output from the engine is longer. If this means that you are spending longer at larger throttle openings to get the reaction you need, then this can be less economical than using a lower gear.

[pbirkett]

I think this is why a lot of people these days seem to think diesels are fast, because a lot of their power and grunt occurs low down in the rev range, and so they mistakenly think they are "so much faster than a petrol" - and yes, I have heard people say this!

Even then, I have seen some people drive even things like diesels wrong. I have seen people who constantly drive below the point where the turbo kicks in, and almost as soon as it does, they change gear!

Unfortunately, I think there is a culture of people who believe revving an engine is a bad thing, and should not be done under any circumstances (hence their love of diesels). One of my friends ideas of driving fast seems to be going no more than about 3500 rpm and aggressively forcing his way through the gears as fast as he can.

Some people actually seem to genuinely believe that revving their cars hard damages them. Personally, my car spends much of its time over 4000 rpm on the open road, at all times, and doesnt seem to do it any harm. When I use my car for work, I rarely get to rev it that hard (although when I can, I do), but once its been driving around town for a while, it seems to feel somewhat sluggish, and often I feel it needs a good thrashing to get it good again.

I once heard someone say that if you never rev your engine hard, it can somehow become "clogged up". Dont know how true that is, but if it is, my engine should be pretty clean

[Jspesh]

My mum is the worst for this. Constantly driving around in 6th gear in her 150bhp TDI MK4 Golf!

I've tried to explain to her she'll make more progress by shifting at more than 2000rpm but she thinks the car will "go too fast". She is by far the worst driver I know. Always scared of hitting the car in front so maintains a 'safe' distance of roughly 6 miles. That's fine but on the rare occasion she overtakes, she'll get past the car on the left (very slowly usually) and then immediatley pull in front of it and brake - because she's scared of the next car.

If i try to comment I get accused of 'criticising' and she gets angry at me! I want to send her on an advanced driving course but I think she might be beyond help with her 30ish years of driving behind her?

[mph999]

pbirkett said:

Some people actually seem to genuinely believe that revving their cars hard damages them.

If a car is never taken up the revs range, and then after a few thousand miles (quite a few though) is reved higher it might break the piston rings.

As wear occurs, you end up with a slight edge on the cylinder wall, as at higher engine speeds, the piston travels a tiny bit further, of course, if this never happens you get a area that hasn't worn.

Martin

[TripleS]

pbirkett said:

Some people actually seem to genuinely believe that revving their cars hard damages them. Personally, my car spends much of its time over 4000 rpm on the open road, at all times, and doesnt seem to do it any harm. When I use my car for work, I rarely get to rev it that hard (although when I can, I do), but once its been driving around town for a while, it seems to feel somewhat sluggish, and often I feel it needs a good thrashing to get it good again. I once heard someone say that if you never rev your engine hard, it can somehow become "clogged up". Dont know how true that is, but if it is, my engine should be pretty clean

I would guess that modern fuels and lubricants keep engines generally cleaner than used to be the case, without the need to take the car out for a good belting periodically!.

Many years ago it used to be said that some of the less respectable elements of the motor trade (which I'm sure we don't have now!) had a quick and easy method of de-coking an engine. What they used to do (so the story goes) was put a load of Redex down each plug hole, let it soak in for a while and then take the car out for a good blast to get rid of some of the carbon deposits around valve heads etc. This would make it breathe better and thus feel more lively thereafter. The final detail was to run a scriber round the cylinder head/block joint to clear away the dirt so it looked as if the cylinder head had been off!

Tricks of the trade eh?

Best wishes all,
Dave.

[gridgway]

in a previous house, I lived in a road where a small car trader operated from home. It was a bit of a pita, but he was a nice guy. I always knew when he was de-coking as the road was filled with white smoke after the redex treatment. Not sure if he did the pretent head-off thing though!

Graham
PS that's small as in low volume, not his stature nor the types of cars he traded in!

[hugh_]

I personally don't make a problem using the rev's, I've even managed to persuade my Mum that when overtaking it is much safer to use full throttle and most of the revs where conditions permit.

From what I've seen the route of the problem is driving instructors. When I was learning I given guide speed limits when to change gear:
1st-2nd: 5mph
2nd-3rd: 15mph
3rd-4th: 25mph
4th-5th: 35mph.

I was also told to drop a cog for overtaking. So overtaking at just over 35 I should be in 4th, in a 1L micra The only thing I overtook while I was with my instructor was a tractor, and then I held onto 3rd until about 45 and got an earful for doing that! People need to be learn that using the rev's isn't a problem. But equally with driving standards often being very low before the test then I can see why instructors don't want to create opportunities for situation to develope faster than the student can react/cope with them.

[GreenV8S]

I think it's a mistake to talk about what gear you should be in versus speed, because it differs so much between cars. It makes more sense IMO to talk about which part of the rev range you should be keeping the engine according to how hard you want it to work.

[seanlazyass]

I was always under the impression that you should accelerate upto the speed limit (obviously depending on road conditions and hazards) as quickly and as smoothly as you wanted regardless of what gear you are in?

Why is using the whole rev range of your engine seen as a bad thing to do?

You are making use of the tools you have to make appropriate/desired progress. As long as it is in a safe and controlled manner I dont see the problem.

Sean