Do lorry engines shut off fuel to some cylinders on motorway?

[Al R]

I think you could, my experience of that engine was limited and not in a lorry and I was the pup then

A cousin ran a few of them years ago in lorries and I can’t remember which order but it was something like 2 & 5 together then 3 & 4 then 1 & 6 once the rest were warm

 

[Wellpark]

A cousin ran a few of them years ago in lorries and I can’t remember which order but it was something like 2 & 5 together then 3 & 4 then 1 & 6 once the rest were warm

Don't know, It was a 5 cylinder that I knew , I have some thought it was 2 and 5 that shut of but It would probably be 40 years ago that it was scrapped

 

[Foxcover]

Scania eco cruise will put the gearbox in neutral before the crest of the hill, so you top the hill 3-4mph slower than the cruise is set, then pick up speed as you coast downhill. If you pick up to much speed it puts it back in gear so you get some engine braking.

Doesn’t make sense.
When you’re going down a hill if you leave it in gear the ecu will not inject fuel, whereas if you drop it into neutral the engine will have to use some fuel, albeit only a small amount, to keep the engine running. I never freewheel down a hill for this reason, just take my foot off the gas.

 

[Andrew]

Doesn’t make sense.
When you’re going down a hill if you leave it in gear the ecu will not inject fuel, whereas if you drop it into neutral the engine will have to use some fuel, albeit only a small amount, to keep the engine running. I never freewheel down a hill for this reason, just take my foot off the gas.

Depends how steep the hill is. Gentle gradients, if you leave the engine in gear the engine braking will cause you to slow down, so then you need to apply throttle to maintain speed. That uses more diesel than the engine would if it was in idle.
Steeper hills, where the gradient is enough to overcome the engine braking, the gearbox is left in gear.

 

[335d]

Cars have for some time cut fuel off to some cylinders, when coasting, or going downhill.
First seen it in V8,s, but has been fitted to VW’s 1.5 tsi for a few years. They go into two cylinder mode.

New VW Golf petrol engine promises to be as efficient as a diesel

Volkswagen has added a new 1.5-litre TSI ACT engine to the Golf range, which promises fuel consumption of 58mpg.

www.fleetnews.co.uk

 

[Username_Required]

Think a Cadilac V8 saloon shut off some cylinders to save fuel , talking back in early nineties from memory.

Guessing with the latest ecu's and engine management wouldn't be much of an advantage or saving to be made.

Some cars satnav and cruise control are linked perhaps Merc S class so similar to the Scania system.

I think it might have been the Northstar, they made some claim that it was the only car that could drop all of its coolant and still drive through death Valley.

As 335d says, it's been used on plenty of passenger cars over the past 10 years or so, by making fewer cylinders work harder you can reduce "pumping" losses at part-load - same idea as downsizing.

It has proportionally less benefit on diesels as they run lean, but still worth doing.

 

[Netherfield]

Starting them on a cold morning you could warm a Gardner up a few at a time could you not?

Only if you could see through the belching blue smoke they produced when cold.

 

[8100]

Only if you could see through the belching blue smoke they produced when cold.

My dad drove for Gordon Plant (Plants For Service ) nr Macclesfield when i was a kid they had a huge fleet of ERF with the old Gardner engines . The whole yard vanished in the morning under a cloud of smoke. I always loved it but when you think back on it now the pollution was horrific i suppose. No wonder ERF and Foden went with Cummins in the 80s

 

[fermerboy]

Don't know about lorry engines but my sisters Fiesta ST has a 3 cylinder 1.5 petrol that drops to 2 while on light load.
The bloody thing is a rocket, and you can't tell any odds or feel any change when you put the foot down.
Supposed to save fuel but difficult to say if it does gain much.