When do you shift?

[scotty777]

I usually drive the car around 3000-5000 when accelerating... For cruising I usually keep it between 2000 and 3000. Dropping lower than that is pointless.

Power band ekes out after 6000 iirc, but I don't go there too often. Heck, can't remember what my redline sits at :/

A bit useless??? Hmmm, I drive at speed limit (often 10km/h faster, I know the roads won't have traps ), and I keep up with traffic while not really doing over 2200 rpm... and I have a 1.4...

Jeez, that's a bit rough :/

Less known fact - driving at full open throttle at low RPM is also bad for your car. It puts a lot of strain on the drivetrain.

yes, I very seldom do that though, foot just tickles the throttle. You also wast fuel like that because the engine needs to make more torque (this is for engines with ECUs), to much torque on the drive train results in added strain of all your drive train (from tires to clutch).

Hmmm, seems like I get 550km's out of about 45 liters though, so i think I wast fuel on those seldom "joy rides". But, just a question, isn't it good to rev high and what not every now and then (not thrash your car, but rev it to 5000 rpm to get the oil flowing and what not)

 

[Fazda]

Nothing wrong with revving the engine every now and then scotty, as long as you are paying for the fuel in the end, it doesn't matter...only thing with revs is that the engine should be up to operating temperature before you do it...I just find it a pointless waste of money, unless I have to get out of a situation in a hurry...

 

[scotty777]

Nothing wrong with revving the engine every now and then scotty, as long as you are paying for the fuel in the end, it doesn't matter...only thing with revs is that the engine should be up to operating temperature before you do it...I just find it a pointless waste of money, unless I have to get out of a situation in a hurry...

Well, my folks give me two tanks a mouth period, if I use more then that then to bad for me... However, I find that I can get about 3 weeks out a tank (550km's) now (during school though, I was REAALLY on thin ice, 12km's to school, then 12 km's back, for 20 days a month, then on weekends I'd go out jolling ).

But yeah, sweet, I just don't wanna put extra strain on my car, it's done 159206km's! And I've gotta go down to Durbs at the end of Nov .

 

[Gnome]

Shift at 3000rpm when cold or in city, when I'm in a hurry 6500rpm, don't really feel it losing power, usually when I shift to second and third get wheel spin when shifting @ 6500rpm which I don't get so bad @ 5000rpm but I do have 272 cam among other things.

Need some bigger tires, my 15" can't handle it, in the rain it's like driving on ice, car has wheel spin from the start up to 2nd unless I drive like little miss daisy.

It's a Corsa B 1.6 so need to rev to get proper power.

 

[dj_jyno]

But yeah, sweet, I just don't wanna put extra strain on my car, it's done 159206km's! And I've gotta go down to Durbs at the end of Nov .

160 000km is not at all bad, considering the age of your car. This would mean it did mostly highway driving before you got it.

Hey, be glad you have to drive down to Durban... gives you the opportunity to clean out all the carbon deposited from city driving. Might even see an extra few kilometers per tank once you return to Joburg

 

[Pyro]

Shift at 3000rpm when cold or in city, when I'm in a hurry 6500rpm, don't really feel it losing power, usually when I shift to second and third get wheel spin when shifting @ 6500rpm which I don't get so bad @ 5000rpm but I do have 272 cam among other things.

Need some bigger tires, my 15" can't handle it, in the rain it's like driving on ice, car has wheel spin from the start up to 2nd unless I drive like little miss daisy.

It's a Corsa B 1.6 so need to rev to get proper power.

Bigger tyres don't neccesarily mean more grip. In the wet with wider tyres, you'll have to displace even more water with the same downforce, so you're more likely to lose grip.

My car can keep spinning in the wet until I lift off the throttle as well. I rather try to go miss daisy in the wet It's entertaining for a few seconds without chewing up rubber at least.

A bit useless??? Hmmm, I drive at speed limit (often 10km/h faster, I know the roads won't have traps ), and I keep up with traffic while not really doing over 2200 rpm... and I have a 1.4...

yes, I very seldom do that though, foot just tickles the throttle. You also wast fuel like that because the engine needs to make more torque (this is for engines with ECUs), to much torque on the drive train results in added strain of all your drive train (from tires to clutch).

Hmmm, seems like I get 550km's out of about 45 liters though, so i think I wast fuel on those seldom "joy rides". But, just a question, isn't it good to rev high and what not every now and then (not thrash your car, but rev it to 5000 rpm to get the oil flowing and what not)

Whether you're at low revs or high revs, your engine will have to burn more or less the same amount of fuel to get the same acceleration. Your engine might be slightly more efficient at certain rev ranges for certain throttle openings, and has slightly more pumping losses at higher revs, but otherwise there isn't really a difference between cruising at say 2200rpm and 2800rpm, other than the amount of noise the engine makes. Once you start going overboard - say cruising at 3500+ you might start seeing an impact on your fuel consumption.

I think people work with the higher gear faster approach, mainly because you automatically accelerate slower in higher gears.

I don't think you don't need excessively high revs to get the crud burned out, but a high speed cruise could probably do your engine a tonne of good if you often sit in traffic like me

My fuel consumption is probably closer to 500km/45l, and that's in a heavier 1.7 combined with a heavier than neccesary foot. If I get on highways that shoots up significantly.

 

[UtterNutter]

Don't some (all?) of the BMWs have a variable red with LEDs? I'm not a BMW fan, so I can't remember offhand, but I recall something about red line at 6,000rpm and as you drive and the car get's warmer, this moves to 8,200rpms or something.

That's the M range.

 

[FarligOpptreden]

I dare you to inch your way along for 2 hours in Jhb traffic in a manual 330 with that frikkin' heavy clutch and not get cramps in your leg...

+1gazillion

Anyone stating that an auto is "ghei" hasn't experienced the full wrath of JHB traffic yet...

 

[Slootvreter]

That's the M range.

That's pretty fscking nifty!

 

[SlinkyMike]

Less known fact - driving at full open throttle at low RPM is also bad for your car. It puts a lot of strain on the drivetrain.

Ha! had never thought of it... makes good sense though... nice one.

 

[Palimino]

Bigger tyres don't neccesarily mean more grip. In the wet with wider tyres, you'll have to displace even more water with the same downforce, so you're more likely to lose grip.

I don’t buy that. The tyre manufacturers claim that the tread pattern on their wet weather tyres prevent hydroplaning by ‘squirting’ the water out of the tread grooves. So the more tyre surface area (wide tyres) that you can put on the road, the better. Your remark would only be true if you were running slicks or your tyres were so badly worn that little tread was left. You should still drive carefully in the wet though.

 

[Pyro]

I don’t buy that. The tyre manufacturers claim that the tread pattern on their wet weather tyres prevent hydroplaning by ‘squirting’ the water out of the tread grooves. So the more tyre surface area (wide tyres) that you can put on the road, the better. Your remark would only be true if you were running slicks or your tyres were so badly worn that little tread was left. You should still drive carefully in the wet though.

The slimmer tyres are also designed to displace the water.

Thicker tyres would mean you need to displace MORE water, and you're spreading the same downforce over a wider area. The effective pressure on the surface is thus lower, and you have to move the water further before it's completely out contact area.

Say you go from 15cm to 20cm wide tyres. You now have to displace 33% extra water, and move it 33% further. Up until the thread area gets overwhelmed you should be fine in both cases, but as soon as those holes fill up, the thinner tyres are better off. The holes make up ... what? 20% of the area? And the thread would hopefull be at least 2mm. So once the water is more than 0.4mm deep, you're pushing the car off the ground with all the extra water you're pushing to the side. So by the simple fact that the wider tyre has more to 'push' out of the way, it'll be easier to lift off the road surface and start aquaplaning.

 

[rurapente]

At what RPM do you usually shift between gears?

I shift at 3000rpm on gears 1,2,3

gears 4 and 5 i will shift at 5000rpm

Thats how I drive

how about you?

around 2-3k mostly, and redline if I'm in a rush although the diesel engine dies at 4k anyway.

 

[Palimino]

The slimmer tyres are also designed to displace the water.

Marie Biscuit tyres displace water because of the tread pattern designed (your word) into them. Tyres ultimately present a very small surface area to the road (sq. cm. only). As small as it is, wider tyres present more surface area to the road.

Thicker tyres would mean you need to displace MORE water, and you're spreading the same downforce over a wider area. The effective pressure on the surface is thus lower, and you have to move the water further before it's completely out contact area.

I presume ‘thicker’ = ‘wider’?

Water would have to be pretty deep for that. No tyre is designed for those functions at speed (you should always be in control when water is that deep). I am talking about little more than a rain-slicked surface. Even so, it seems intuitive that a hydroplaning vehicle with wide tyres would have more ‘bite’ than a vehicle with Marie Biscuit tyres.

 

[JK8]

Ok now I change at 2000 - 2500rpm, I have tons of torque!!
If I change at 2000 - 2500 I reach 120kmph in 4th!!!!

 

[kkza]

+1gazillion

Anyone stating that an auto is "ghei" hasn't experienced the full wrath of JHB traffic yet...

I do deliveries and get stuck in traffic on a fairly regular basis, ive been on the freeway when its been crawling along at 2kmh and ive sat in dead stop traffic, driven through town when all the lights are out and its a free-for-all, Im fine with my manual thanks.

 

[rabbiddog]

750 - 16000rpm
500 - 12000rpm
bakkie - 3000rpm

 

[kevinswan007]

The slimmer tyres are also designed to displace the water.

Thicker tyres would mean you need to displace MORE water, and you're spreading the same downforce over a wider area. The effective pressure on the surface is thus lower, and you have to move the water further before it's completely out contact area.

Say you go from 15cm to 20cm wide tyres. You now have to displace 33% extra water, and move it 33% further. Up until the thread area gets overwhelmed you should be fine in both cases, but as soon as those holes fill up, the thinner tyres are better off. The holes make up ... what? 20% of the area? And the thread would hopefull be at least 2mm. So once the water is more than 0.4mm deep, you're pushing the car off the ground with all the extra water you're pushing to the side. So by the simple fact that the wider tyre has more to 'push' out of the way, it'll be easier to lift off the road surface and start aquaplaning.

http://en.wikipedia.org/wiki/Hydroplaning_(tires)

Vehicle sensitivity factors
The driver's speed, acceleration, braking, and steering
Tire tread wear and contact patch shape
The longer and thinner the contact patch, the less likely a tire will hydroplane. Tires that present the greatest risk are wide, lightly loaded, and small in diameter. Deeper tread dissipates water more easily.
Ratio of tire load to inflation pressure
Underinflated tires are more prone to hydroplaning, especially as vehicle weight increases.
Vehicle type
Combination vehicles like semi-trailers are more likely to experience uneven hydroplaning caused by uneven weight distribution. An unloaded trailer will hydroplane sooner than the cab pulling it. Pickups towing RVs present similar problems.
There is no precise equation to determine the speed at which a vehicle will hydroplane. Existing efforts have derived rules of thumb from empirical testing in the 1960s and 1970s.[4] In general, cars hydroplane at speeds above 45 MPH (72 km/h), where water ponds to a depth of at least 1/10 of an inch (2,5 mm) over a distance of 30 feet (9 meters) or more.

 

[Brawler]

gear 1,2,3 @ 3000rpm and gear 4,5 at 4000rpm.

 

[Pyro]

Marie Biscuit tyres displace water because of the tread pattern designed (your word) into them. Tyres ultimately present a very small surface area to the road (sq. cm. only). As small as it is, wider tyres present more surface area to the road.

So what are you trying to say? Wider means you'll have a lower surface pressure since the contact patch is wider, but you'll also need to displace more water to get to the road surface. Even if it's a tiny difference, that water you have to displace means you're effectively losing grip.

I presume ‘thicker’ = ‘wider’?

Water would have to be pretty deep for that. No tyre is designed for those functions at speed (you should always be in control when water is that deep). I am talking about little more than a rain-slicked surface. Even so, it seems intuitive that a hydroplaning vehicle with wide tyres would have more ‘bite’ than a vehicle with Marie Biscuit tyres.

Yes, wider, as mentioned in that same sentence. The deeper the water, the more water needs to be moved out of the way before the tyre can touch the ground. Like I said, a 20cm tyre would need to move 33% more water away than a 15cm tyre.

--- Kevin gives a more 'accurate' quote.

http://en.wikipedia.org/wiki/Hydroplaning_(tires)

Vehicle sensitivity factors
The driver's speed, acceleration, braking, and steering
Tire tread wear and contact patch shape
The longer and thinner the contact patch, the less likely a tire will hydroplane. Tires that present the greatest risk are wide, lightly loaded, and small in diameter. Deeper tread dissipates water more easily.
Ratio of tire load to inflation pressure
Underinflated tires are more prone to hydroplaning, especially as vehicle weight increases.
Vehicle type
Combination vehicles like semi-trailers are more likely to experience uneven hydroplaning caused by uneven weight distribution. An unloaded trailer will hydroplane sooner than the cab pulling it. Pickups towing RVs present similar problems.
There is no precise equation to determine the speed at which a vehicle will hydroplane. Existing efforts have derived rules of thumb from empirical testing in the 1960s and 1970s.[4] In general, cars hydroplane at speeds above 45 MPH (72 km/h), where water ponds to a depth of at least 1/10 of an inch (2,5 mm) over a distance of 30 feet (9 meters) or more.

That's it - "Tires that present the greatest risk are wide, lightly loaded, and small in diameter." You're unlikely to change the actual diameter of your car's tyres, because it'll mess with your gear ratios, so I wasn't referring to that.