Short Car Journeys — Higher Revs Beneficial?

paperclap

Hi all,

Firstly, not sure where to post this. Couldn’t find a vehicle-related category!

As we all know, short journeys aren’t ideal for vehicles. Less time for the battery to recharge, less time for internals to fully warm up, less time for internal condensation to dissipate, so on and so forth.

With that in mind, would it therefore be more beneficial to the vehicle’s health to keep revs higher (by not shifting up a gear)?

For example, doing:
30mph, in third gear at 2,300 rpm

Instead of:
30mph, in fourth gear at 1,700 rpm

From my understanding, the higher the revs, the faster the battery recharges, the faster the vehicle heats up, etc.

Thoughts?

Alanp

There is a motoring section, maybe the mods will move it

over revving an engine uses more fuel and creates greater wear when cold, best just to drive smoothly and try not to let the engine labour, or over Rev, it’s all about being in the right gear for the speed limit of the road

Section62

laurencewhymark said:

From my understanding, the higher the revs, the faster the battery recharges, the faster the vehicle heats up, etc.

Back in the days of dynamos, the power output (hence the rate the battery could be charged) depended on engine speed.

But that doesn't apply to modern cars with alternator systems.  And if the car isn't modern enough to have an alternator then the engine needs to be treated with more care and respect than to run it fast when cold.

So no, it isn't a good idea to use high revs to charge the battery quicker on short journeys - it's either pointless, or damaging.

Grumpy_chap

laurencewhymark said:

Hi all,

Firstly, not sure where to post this. Couldn’t find a vehicle-related category!

As we all know, short journeys aren’t ideal for vehicles. Less time for the battery to recharge, less time for internals to fully warm up, less time for internal condensation to dissipate, so on and so forth.

With that in mind, would it therefore be more beneficial to the vehicle’s health to keep revs higher (by not shifting up a gear)?

For example, doing:
30mph, in third gear at 2,300 rpm

Instead of:
30mph, in fourth gear at 1,700 rpm

From my understanding, the higher the revs, the faster the battery recharges, the faster the vehicle heats up, etc.

Thoughts?

No.
Always drive in the optimum gear for the moment, with consideration for the next move.

AdrianC

Section62 said:

Back in the days of dynamos, the power output (hence the rate the battery could be charged) depended on engine speed.

But that doesn't apply to modern cars with alternator systems.  And if the car isn't modern enough to have an alternator then the engine needs to be treated with more care and respect than to run it fast when cold.

And, to clarify, alternators were pretty much universal by the mid 1970s...

The simple solution is not to routinely use your car for short journeys. There are simply better ways of getting around if you're routinely doing journeys of just a mile or so.

Car_54

Alanp said:

There is a motoring section, maybe the mods will move it

over revving an engine uses more fuel and creates greater wear when cold, best just to drive smoothly and try not to let the engine labour, or over Rev, it’s all about being in the right gear for the speed limit of the road

The speed limit has nothing to do with it.

daveyjp

Car_54 said:

Alanp said:

There is a motoring section, maybe the mods will move it

over revving an engine uses more fuel and creates greater wear when cold, best just to drive smoothly and try not to let the engine labour, or over Rev, it’s all about being in the right gear for the speed limit of the road

The speed limit has nothing to do with it.

So you would happily use 6th gear in a 20mph limit street with a severe gradient?

cattom

no is the answer to your op. the best thing is to drive according to the conditions, and of course the speed limits. if you drive revving the engine up to max revs before changing up, all you doing is using extra fuel, putting pressure on the engine and clutch, and wearing your brakes out quicker.

chrisw

Although a vehicle mainly used for short journeys may benefit from the occasional blast holding the revs higher in a lower gear. More to blow through the system rather than charge the battery though.

The classic Italian tune up.

Section62

daveyjp said:

So you would happily use 6th gear in a 20mph limit street with a severe gradient?

I think Car_54's point was the gear should be right for the speed you are driving at, in the prevailing conditions (with consideration for the next move, as per Grumpy_Chap's post)....

...not the arbitrary speed limit assigned to that particular stretch of road by legislation or traffic engineers.  The correct or necessary speed is often much lower than the limit.

facade

Automatics tend to hold the lower gears when first started so that the higher engine speeds can warm the engine and catalyst quicker and get the emissions down.

I suppose it keeps the load on the engine lighter too.