Fuel consumption

[Jon Wildsmith]

I doubt there's much difference in air resistance between the two tents but I wonder if an unoccupied rack causes more turbulence that translates into more resistance than a rack with a nice smooth tent on top? Sounds plausible to me but maybe someone with actual knowledge of these things might comment More likely to be a difference in fuel quality or trip measurement if no work has been done on the truck?

 

[Chas]

I did wonder whether the bare rack would make a difference, but the consumption was the same as when the Airlander tent was on. No work has been done on the truck, so we could count that out, fuel quality I always go to the same garage (Sainsburys) at home to fill up, but the fill up that returned the good consumption was from a garage near BOAB (Didn't notice what brand) that I've never been to before, I've just filled up again from my usual garage so I'll keep an eye on it. Trip measurement was from the speedo and the receipt from the till for ltrs used, so it'd be difficult to get that wrong.

Very pleased with the new tent Jon, figured out a way to pull the front down easily, a rope running from the tents pull down handle under my roof light bar and pull from the front of the truck, works a treat

 

[Jon Wildsmith]

Glad you're pleased with the tent Chas, I really liked mine on our recent trip

 

[Gav Peter]

I doubt there's much difference in air resistance between the two tents but I wonder if an unoccupied rack causes more turbulence that translates into more resistance than a rack with a nice smooth tent on top? Sounds plausible to me but maybe someone with actual knowledge of these things might comment

Our Colorado has the ARB rack on it full time & I would agree with this theory... It seems to run a whole lot better when the rack is fully loaded with the load all wrapped up in a big blue tarp rather than when its nekid...

 

[chriscolleman]

Face the facts. There simply isn't any goodness left in our fuel.

Chris

Indeed the addition of those biofuels into the vehicle will lower mpg.
Recently I had a leaflet from one of the engine manufacturers that they will be adding ethanol to gas in the near future. MPG will suffer again.

Car manufacturers are trying to compensate by loosing lost space. Most noticable with the narrow headroom these modern cars are being delivered with. Another compensation is weight, every ounce you loose whilst accelerating is gained in mpg. So lower weight materials are used for about anything they can find.
Steel bumpers to "plastic", steel to alloy, etc...

Then we come along, adding every heavy duty item we can get our hands on, because these modern vehicles aren't the tractors we would like to have. And then try to fool the engine, tranny and gears into having great MPG. Contradictory.

Get everything on your engine into spec as per Toyota engineer, even the EGR valve on the more modern Toys. Treat your tranny and wheel hubs with care. And then get used to feeding it.

 

[Andrew Prince]

To continue the debate - Quoted from the Dieselplace:

We all know that diesel fuel has more BTU's than Gasoline right...

#2 Diesel .......................... 139,000 BTU's
Gasoline............................ 125,000 BTU's

So this is why diesel does more work (TQ) and has better MPG numbers compared to there gasoline brothers...

Here is some more to think about for BIO fuels... Small reduction but not bad...

Ethanol ............................. 76,000 BTU's
B20................................... 138,000 BTU's
B100.................................. 130,000 BTU's

Now for you common 3 diesel additives...

Naptha............................... 15,000 BTU's
Mineral Spirits...................... 19,000 BTU's
Xylene............................... 18,000 BTU's

So this proves the MORE fuel additives you use the LESS amount of HP/TQ and MPG your going to get from your truck... All its doing is washing out the fuel...

So how about 2 cycle oil...

2 cycle oil (avg).................... 138,000 BTU's

So 2 cycle oil isn't going to reduce the BTU value of diesel fuel. So its still a excellent choice as a fuel additive so far...

There is no benefit to using a higher cetane number fuel than is specified by the engine's manufacturer.The ASTM Standard Specification for Diesel Fuel Oils (D-975) states, "The cetane number requirements depend on engine design, size, nature of speed and load variations, and on starting and atmospheric conditions. Increase in cetane number over values actually required does not materially improve engine performance. Accordingly, the cetane number specified should be as low as possible to insure maximum fuel availability." This quote underscores the importance of matching engine cetane requirements with fuel cetane number!!!
So adding cetane boosters are not going to improve the performance of the engine and/or fuel.
Cetane improvers modify combustion in the engine. They encourage early ignition of the fuel. They encourage premature combustion and excessive rate of pressure increase in the combustion cycle.
Look at the materials they use in most cetane boosters. Mineral Spirits, Xylene, and Naptha none of these chemicals are even close to the diesel fuel family. They also have very low flash points like gasoline! Every one of them are used for degreasing and cleaning solvents.
Cetane Number is a measure of the ignition quality of a diesel fuel. It is often mistaken as a measure of fuel quality. Cetane number is actually a measure of a fuel's ignition delay. This is the time period between the start of injection and start of combustion (ignition) of the fuel. In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower cetane fuels.
Cetane booster tend to advance the timing of ignition. Hence the ignition knock that you hear. The lower the cetane number the less ignition knock you'll hear. Also the flash point and the auto-ignition temps of the fuel is reduced greatly.
Cetane number should not be considered alone when evaluating diesel fuel quality. API gravity, BTU content, distillation range, sulfur content, stability and flash point are very important. In colder weather, cloud point and low temperature filter plugging point may be critical factors.
All of the cetane boosters on the market tend to reduce the BTU content of the fuel. Hence it reduces the MPG and the HP/TQ numbers. Sulfur content is been reduced national to 520 HFRR (<15 PPM Sulfur) which mean less lubricity of the fuel. Cetane boosters tend to de-stabilize the flash point. Go back to my Chemical definition page and look at the flash points of the different chemicals."

There's a lot more interesting reading, in amongst the trolling on that forum.

 

[Graham]

Hi Andrew,

Very interesting reading.

As my brother now has my old LC, he is running it with new vegetable oil as an addition.

When he fills up, his procedure is that he pours a 5 liter veggie oil in while he is filling with standard diesel. This lets the oil mix better with the incoming diesel.
So he will fill with about 70 liters of standard diesel, and 5 liters of new vegetable oil.
He says the difference in fuel economy is hear nor there, but he is more than impressed with the way the oil quietens the engine down.

From the exhaust, you can smell nothing of the oil, as it is so diluted by the diesel, but it then also has enough lubricant to give the engine back it's smoothness.

Where to find the BTU of vegetable oil?


Gra.

edit, vegetable oil = 130,000 btu 35 to 45 cetan number

http://www.ag.ndsu.edu/pubs/ageng/machine/ae1240w.htm

 

[Chas]

When he fills up, his procedure is that he pours a 5 liter veggie oil in while he is filling with standard diesel. This lets the oil mix better with the incoming diesel.
but he is more than impressed with the way the oil quietens the engine down.

How quickly does veggie oil assimilate with diesel? when I use VO i just put about 10ltr in the tank and then fill up with diesel, I thought the diesel pouring in would mix it a bit and then the driving would slosh it about a bit more, should it be mixed more thoroughly?
I can't say that I notice the engine being quieter by using VO, but I did notice a big difference when I started adding 2 stroke, 500ml per fill up.

 

[Andrew Prince]

How quickly does veggie oil assimilate with diesel? when I use VO i just put about 10ltr in the tank and then fill up with diesel, I thought the diesel pouring in would mix it a bit and then the driving would slosh it about a bit more, should it be mixed more thoroughly?

Chas, I think the trite answer is "it should be mixed as thoroughly as possible" - I understand from what I read that it will separate in time, which isn't ideal. Proper bio-disel and derv should mix readily without (much) separation over time. If you're filling up and then using the tankful in a day or 2, I'm sure you'd never notice any effects of separation. But left standing for a month and in cold weather, the SVO may be difficult to pump if it has separated significantly.

I guess you could test it by pouring SVO into a clear container full of derv and see how much mixing the pouring creates? And let it stand and see whether it mixes or separates. And then swirl the mixture around to replicate your driving motion and see whether mixing improves.

The 2stroke I'm sure mixes easily with the sloshing in the tank.

 

[Chas]

As you probably know my 80 has been standing at Julian V's since our last Lincomb gathering,

I can't actually remember if there is any VO in the tank at the mo, but a few days ago I was up there and she started and ran fine, well after we had put some electrickery in the batteries anyway, so I just had to reacquaint myself and had a little drive around the farm

I was amazed at how light the steering was compared with the Lexus I'm driving now, and how much slower, that Lexus goes like sh*t off a shovel.
I have never noticed in the past any problems with not thoroughly mixing first.

 

[Andrew Prince]

Yes, I reckon chances of any noticeable issues on low SVO mixes is minimal. The scaremongers (or the unlucky few that have had issues) do build things up a bit. Fair enough to point out the pitfalls I guess