Freight Dog:
If its been this week it matches the cold air mass the UK has been steeped in.
Cold air hammers mpg, especially on diesels.
1/ cold air is denser, the engine MAF/ECU determines mass airflow and regulates more fuel to achieve correct mixture.
2/ thermal effiecency reasons. Low environmental temp, low air intake temp and higher fuel flows lead to longer warm up times. Diesels are less efficient when operating below working temp.
3/ higher loads on engine through accessories. Heating elements, blowers etc.
Point3- looks good to me.
Point1- with more air (weight) per stroke and a proportionally equal amount more fuel I can see that an engine will perform better with cold air (thats why we have intercoolers on turbos). I can’t see why it would be greatly less efficient?
Edit
Point2- engines may take longer to reach temp but they still get there ok.
Hi Franglais
Point 1
Unlike petrols, Diesels don’t typically regulate the mass air inflow at idle.The MAF sensed mass of air being colder at the intake manifold is greater. The ECU regulates more fuel flow to achieve a correct mixture. It will indeed perform better as a result of increased mass airflow/fuel but the mpg will be poorer. Cold day, engine performs well, loads of power, but sips more gas.
Intercoolers are fitted for the reasons at the opposite end of the spectrum, to remove excessive heat created by compression and promote a more efficient combustion. This negates the need to use forced induction to cool the precharge to acceptable levels prior to ignition.
Point 2/
They do get there perfectly fine, but the time spent operating at sub optimum combustion is greater. It is during this period that combustion is poorest.
Freight Dog:
If its been this week it matches the cold air mass the UK has been steeped in.
Cold air hammers mpg, especially on diesels.
1/ cold air is denser, the engine MAF/ECU determines mass airflow and regulates more fuel to achieve correct mixture.
2/ thermal effiecency reasons. Low environmental temp, low air intake temp and higher fuel flows lead to longer warm up times. Diesels are less efficient when operating below working temp.
3/ higher loads on engine through accessories. Heating elements, blowers etc.
Point3- looks good to me.
Point1- with more air (weight) per stroke and a proportionally equal amount more fuel I can see that an engine will perform better with cold air (thats why we have intercoolers on turbos). I can’t see why it would be greatly less efficient?
Edit
Point2- engines may take longer to reach temp but they still get there ok.
Hi Franglais
Point 1
The MAF sensed mass of air being colder at the intake manifold is greater. The ECU regulates more fuel flow to achieve a correct mixture. It will indeed perform better as a result of increased mass airflow/fuel but the mpg will be poorer. Cold day, engine performs well, loads of power, but sips more gas.
Point 2/
They do get there perfectly fine, but the time spent operating at sub optimum combustion is greater. It is during this period that combustion is poorest.
I can see the logic in what you’re saying. I wonder if that’s enough to account for a noticeable (10% or more?) difference in fuel consumption.
I don’t know if we’re talking about a real fuel consumption increase from the OP, or a random variation? If there is a genuine increase is it weather related?
Mind you, lack of fscts never gets in the way of us TNUK ers does it? [emoji12] [emoji2]
Freight Dog:
If its been this week it matches the cold air mass the UK has been steeped in.
Cold air hammers mpg, especially on diesels.
1/ cold air is denser, the engine MAF/ECU determines mass airflow and regulates more fuel to achieve correct mixture.
2/ thermal effiecency reasons. Low environmental temp, low air intake temp and higher fuel flows lead to longer warm up times. Diesels are less efficient when operating below working temp.
3/ higher loads on engine through accessories. Heating elements, blowers etc.
Point3- looks good to me.
Point1- with more air (weight) per stroke and a proportionally equal amount more fuel I can see that an engine will perform better with cold air (thats why we have intercoolers on turbos). I can’t see why it would be greatly less efficient?
Edit
Point2- engines may take longer to reach temp but they still get there ok.
Hi Franglais
Point 1
The MAF sensed mass of air being colder at the intake manifold is greater. The ECU regulates more fuel flow to achieve a correct mixture. It will indeed perform better as a result of increased mass airflow/fuel but the mpg will be poorer. Cold day, engine performs well, loads of power, but sips more gas.
Point 2/
They do get there perfectly fine, but the time spent operating at sub optimum combustion is greater. It is during this period that combustion is poorest.
I can see the logic in what you’re saying. I wonder if that’s enough to account for a noticeable (10% or more?) difference in fuel consumption.
I don’t know if we’re talking about a real fuel consumption increase from the OP, or a random variation? If there is a genuine increase is it weather related?
Mind you, lack of fscts never gets in the way of us TNUK ers does it? [emoji12] [emoji2]
Sent from my GT-S7275R using Tapatalk
Yeah, I honestly don’t know, I’ve heard of people saying it’s quite noticeable. Not sure how noticeable
Maybe Juddian will agree to send in another application for a research grant for us? We can work out the exact relevance of weather to truckers. And Juddian is not only an excellent writer, but has admirable skills dealing with bureaucrats.
toonsy:
Tyre pressures is unlikely because we have to drive over a pressure sensing plate which pings up warnings if the PSI is outside a certain tolerance. Running Scania btw. Never normally near the weight limits (It’s normally foam insulation boards) as the loads have been bulky rather than heavy.
I can’t see how a pressure sensing plate on the ground could determine tyre pressure, could you find some more about about this? I’m curious
Pretty sure there is one at Keele Services for cars.
I have heard of bus companies using them as well.
learn something everyday, I had never heard of such a thing before, would love to know how they work, unless the expected footprint of the tyre is known I don’t get how they could calc the air pressure ?
This is a very basic explanation of it but basically each vehicle has a recommended PSI for the tyres. This is fed into a system and tied to a number plate. When each vehicle goes over it a number plate recognition camera picks up the plate so as you go over each tyre is compared to these parameters. If it’s outside a set tolerance it’ll flag up a digital report for the fitters which tells them what tyre is outside the parameter and they’ll go check it out.
We used to fill the tyres with Nitrogen on the Honda SP1 I used to race in endurance races. I always assumed that it was used as it doesn’t expand when hot therefore giving better control over tyre pressure. Obviously I may be wrong, it happened once in 1987 so I have got previous!
the maoster:
We used to fill the tyres with Nitrogen on the Honda SP1 I used to race in endurance races. I always assumed that it was used as it doesn’t expand when hot therefore giving better control over tyre pressure. Obviously I may be wrong, it happened once in 1987 so I have got previous!
It does expand when hot, but it’s more consistent than normal compressed air where the moisture content varies as its dependant the ambient conditions when the tyre was fitted.
As I said in an earlier post I haven’t used nitrogen in race tyres for years, as most of the tyre manufactures turn up with the kit to produce air dry enough to give consistent results. Also as far as I’m aware, not all F1 teams use nitrogen in their tyres these days.
You do still see nitrogen used by some race teams, especially if the tyres haven’t been fitted by a manufacture supported set-up with all the air drying equipment. But to do it properly you need equipment that can remove the air from the tyres and refill with nitrogen without allowing any of the ambient air to enter the tyre and introduce some moisture content.
the maoster:
We used to fill the tyres with Nitrogen on the Honda SP1 I used to race in endurance races. I always assumed that it was used as it doesn’t expand when hot therefore giving better control over tyre pressure. Obviously I may be wrong, it happened once in 1987 so I have got previous!
It does expand when hot, but it’s more consistent than normal compressed air where the moisture content varies as its dependant the ambient conditions when the tyre was fitted.
As I said in an earlier post I haven’t used nitrogen in race tyres for years, as most of the tyre manufactures turn up with the kit to produce air dry enough to give consistent results. Also as far as I’m aware, not all F1 teams use nitrogen in their tyres these days.
You do still see nitrogen used by some race teams, especially if the tyres haven’t been fitted by a manufacture supported set-up with all the air drying equipment. But to do it properly you need equipment that can remove the air from the tyres and refill with nitrogen without allowing any of the ambient air to enter the tyre and introduce some moisture content.
Is it not nitrogen heats quicker due to the size of the molecules, as it heats it expands giving the tyre its maximum performance in less time than an air filled tyre ?
the maoster:
We used to fill the tyres with Nitrogen on the Honda SP1 I used to race in endurance races. I always assumed that it was used as it doesn’t expand when hot therefore giving better control over tyre pressure. Obviously I may be wrong, it happened once in 1987 so I have got previous!
It does expand when hot, but it’s more consistent than normal compressed air where the moisture content varies as its dependant the ambient conditions when the tyre was fitted.
As I said in an earlier post I haven’t used nitrogen in race tyres for years, as most of the tyre manufactures turn up with the kit to produce air dry enough to give consistent results. Also as far as I’m aware, not all F1 teams use nitrogen in their tyres these days.
You do still see nitrogen used by some race teams, especially if the tyres haven’t been fitted by a manufacture supported set-up with all the air drying equipment. But to do it properly you need equipment that can remove the air from the tyres and refill with nitrogen without allowing any of the ambient air to enter the tyre and introduce some moisture content.
Is it not nitrogen heats quicker due to the size of the molecules, as it heats it expands giving the tyre its maximum performance in less time than an air filled tyre ?
My understanding is it’s to do with the variable moisture content of normal compressed air not being consistent and not giving predictable results on pressures as they heat up, which is why when you get a full tyre manufactures set-up with proper dry air you don’t need to run nitrogen, I’ve have back to back tested nitrogen and dry air and there was no difference in the results.
Also in a lot of racing you heat the tyres, in ovens or blankets, before they go onto the car, so the heating them up quickly doesn’t matter, in fact F1 teams heat up their tyres over a period of hours, stepping the temperature up in increments.
Going back to the original question, and following the original hypothesis that if all else is similar couls weather greatly affect fuel usage, how much difference does rain make to fuel use? There must be some research out there? As we drive along our vehicles displace tons of water as spray, that too must affect fuel use. We feel the drag when we go through a deep puddle, so there is drag fron driving through a shallower puddle hundreds of miles long. And shoving heavier, rainy air out of the way, also must have an effect.
Franglais:
Going back to the original question, and following the original hypothesis that if all else is similar couls weather greatly affect fuel usage, how much difference does rain make to fuel use? There must be some research out there? As we drive along our vehicles displace tons of water as spray, that too must affect fuel use. We feel the drag when we go through a deep puddle, so there is drag fron driving through a shallower puddle hundreds of miles long. And shoving heavier, rainy air out of the way, also must have an effect.
Sent from my GT-S7275R using Tapatalk
Water displacement is a tyre manufacturer’s area and not vehicle performance, it would be impossible to have a report made by each company for every vehicle with different performing tyres, the mindset of fleet when it comes to tyres is Mid Range and re cut them to death.
Franglais:
Going back to the original question, and following the original hypothesis that if all else is similar couls weather greatly affect fuel usage, how much difference does rain make to fuel use? There must be some research out there? As we drive along our vehicles displace tons of water as spray, that too must affect fuel use. We feel the drag when we go through a deep puddle, so there is drag fron driving through a shallower puddle hundreds of miles long. And shoving heavier, rainy air out of the way, also must have an effect.
Sent from my GT-S7275R using Tapatalk
Water displacement is a tyre manufacturer’s area and not vehicle performance, it would be impossible to have a report made by each company for every vehicle with different performing tyres, the mindset of fleet when it comes to tyres is Mid Range and re cut them to death.
All true.
But maybe it is a partial answer to the O.P.?
Franglais:
Going back to the original question, and following the original hypothesis that if all else is similar couls weather greatly affect fuel usage, how much difference does rain make to fuel use? There must be some research out there? As we drive along our vehicles displace tons of water as spray, that too must affect fuel use. We feel the drag when we go through a deep puddle, so there is drag fron driving through a shallower puddle hundreds of miles long. And shoving heavier, rainy air out of the way, also must have an effect.
Sent from my GT-S7275R using Tapatalk
Water displacement is a tyre manufacturer’s area and not vehicle performance, it would be impossible to have a report made by each company for every vehicle with different performing tyres, the mindset of fleet when it comes to tyres is Mid Range and re cut them to death.
All true.
But maybe it is a partial answer to the O.P.?
Sent from my GT-S7275R using Tapatalk
I was taught that drag plays a major part with increased fuel consumption, I’ve always driven with a close coupling, ensured the curtains are pulled as tight as possible from front to rear then the same with the curtain buckles making sure it’s tight top to bottom, the buckle tails I always tuck away, tyres I check weekly, loads I try to keep weight distributed evenly which isn’t always possible.
Franglais:
Going back to the original question, and following the original hypothesis that if all else is similar couls weather greatly affect fuel usage, how much difference does rain make to fuel use? There must be some research out there? As we drive along our vehicles displace tons of water as spray, that too must affect fuel use. We feel the drag when we go through a deep puddle, so there is drag fron driving through a shallower puddle hundreds of miles long. And shoving heavier, rainy air out of the way, also must have an effect.
Sent from my GT-S7275R using Tapatalk
Water displacement is a tyre manufacturer’s area and not vehicle performance, it would be impossible to have a report made by each company for every vehicle with different performing tyres, the mindset of fleet when it comes to tyres is Mid Range and re cut them to death.
All true.
But maybe it is a partial answer to the O.P.?
Sent from my GT-S7275R using Tapatalk
I was taught that drag plays a major part with increased fuel consumption, I’ve always driven with a close coupling, ensured the curtains are pulled as tight as possible from front to rear then the same with the curtain buckles making sure it’s tight top to bottom, the buckle tails I always tuck away, tyres I check weekly, loads I try to keep weight distributed evenly which isn’t always possible.
Drag / wind was my previous suggestion and I reckon it’s likely to be a major factor.
Still waiting for the grant to start the TNUK research laboratories.
When we get the grant there’s a site available next to Mr Zappa’s
Utility Muffin Facilities I think.
Grumpy Dad:
I was taught that drag plays a major part with increased fuel consumption, I’ve always driven with a close coupling, ensured the curtains are pulled as tight as possible from front to rear then the same with the curtain buckles making sure it’s tight top to bottom, the buckle tails I always tuck away, tyres I check weekly, loads I try to keep weight distributed evenly which isn’t always possible.
Drag / wind was my previous suggestion and I reckon it’s likely to be a major factor.
Still waiting for the grant to start the TNUK research laboratories.
When we get the grant there’s a site available next to Mr Zappa’s
Utility Muffin Facilities I think.
The issuing body will see the request “the fuel efficiency of trucks and the resistance of drag” and the thick barstewards will send out a box of frocks
