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Glow plugs or inake air heaters are used to help preheat the air entering the engine to assist with cold starting only; they do NOT ever ignite the fuel.
The higher compression of the diesel engine is what ignites the fuel and eliminates the need for spark plugs.
1) "...A diesel truck is way more efficient than its gasoline counterpart. While a gasoline-powered engine will only use about 20% of the fuel to actually make it go, the diesel truck will use twice that or more."
- This is at least awkward wording. I understand what you meant was a diesel will uses its fuel more efficiently and will convert 40-percent of its fuel as motion, rather than heat. The direction is true, but the numbers aren't. A modern automotive gasoline engine is around 35-percent thermally efficient. Atkinson and Miller-cycle engines are a bit higher. Diesels are closer to 40-percent. In either, most of the fuel's energy goes out the tailpipe, the rest is used to heat up the coolant. The 20-percent figure may have come from an analysis of the flathead engine where compression ratios were around 5:1. A very thermally inefficient engine design to say the least.
2) "...the turbocharger on the diesel will suck in more of that oxygen-deprived air giving much better performance than the nearly winded gasoline counterpart."
- Just staying in the engine family; Ecoboost 2.3, 2.7, and 3.5. The turbo supercharger helps both diesel and gas engines both a sea level and at altitude.
3) "Diesel trucks have a very small carbon footprint compared to gasoline powered trucks. They produce much less carbon dioxide and run way more efficiently, especially at lower speeds..."
- This is true. A diesel can burn a lot less fuel at idle and low speed operation.
4). Kenworth and first diesel truck in US. Interesting fact.
5) The spark thing already mentioned above.
6) The fast Dodge. There are some spectacular tales of diesels in racing. Audi at Le Mans and such. The Banks Dodge is kind of the progenitor of modern diesel performance but diesels have come a long way since 2002.
7) Texans and diesels. Yeah, we live up to our stereotype in some regards. Trucks are more common here than any other state.
My own addendum on diesels. This goes toward the fuel efficiency and power diesels make. There are four distinct reasons diesels can be a better fit:
1) Diesels are more thermally-efficient than are gasoline engines. But not by much these days. The higher the compression ratio, the more energy the engine can extract from the fuel. Back in the terrible '70s and '80s, compression ratios in gasoline automotive engines were around 8:1, some lower, some higher. The reason for this was the nationwide switch to low and unleaded fuels. The reason for the chemical change in gasoline was the advent of catalytic converters, which were poisoned by the lead in gasoline. Taking the lead out of fuels dropped the fuel's octane rating, and engines of the day couldn't burn 87 (ron/mon) fuels with their 10:1 and higher compression ratios. In 1971, most manufactures dropped compression ratios in that 8:1 range. There was an irony here in that lowering compression ratios made for worse fuel economy right as we were on the door step of a nationwide fuel shortage. Back to the story: Today's gasoline engines enjoy much higher compression ratio...around 12:1, due to computer engine management and the same diesel benefit; direct injection. So gasoline engines are fairly close to diesels in thermal efficiency.
2) Diesel fuel has more energy content. My user name is in reference to the average 12 carbon and 24 hydrogen atoms making the long-chain hydrocarbon model in diesel fuel. Gasoline fuel is nearly half that. What this means is that by volume, diesel fuel has more energy to give to the combustion process. So you need less of the fuel to make the same power. There are alternative fuels with varying hydrocarbon content, alcohol fuels being the predominant one with higher energy content that gasoline, but it gets rather tricky due to the one significant variable: Stoichiometry.
3) Stoichiometry for diesel fuel is 14.6:1. Gasoline stoich is 14.7:1. Pretty close, really. Stoichiometry only refers to the chemically perfect combustion environment where all the fuel is consumed. If such a condition existed, the only byproduct out the exhaust pipe being water. But we live in the real world. Both gasoline and diesels are not running under stoichiometric conditions normally. Either engine design will run much richer ratios under heavy load, while lighter loads can put the air/fuel ratios above stoich. The difference is the tolerance level. Gasoline engine range full rich at around 10:1 a/f ratio and full lean around 16:1. It can vary greatly by combustion chamber design. Diesels, on the other hand, due to being throttled by fuel, rather than air, have a much bigger spread. A full rich ratio can be as low as 7:1 and full lean ratio gets above 70:1. So, at idle or low throttle setting, a gasoline engine being throttled by air is going to be sitting at stoich: 14.7 pounds of air to One pound of fuel. The diesel being throttled by fuel will be idling along at that 70 and over ratio. Yeah, baby! That difference is huge! Throttle by fuel is the way to go. Oh, and that alternative fuel...alcohol? Stoich for alcohol is around 8:1, meaning when compared to gasoline, you have to burn nearly twice as much by volume to match gasoline. But alcohol, particularly methanol, has higher energy content and you can make more power on alcohol than gasoline. This is why it has found a use in racing. And you can't ignore the 120 octane rating of alcohol with is very beneficial with static compression ratios of 14:1 and higher. Now, this throttled by fuel thing gets really interesting when you look back and forward. Forward looking: Labs around the world are bringing gasoline engines into the diesel realm by having the gas engine operating as a diesel at light loads. What this means is the engine switches from air throttling to fuel throttling under light loads and sipping fuel at ratios above gasoline stoich without adverse affects. In looking back, you want to dig into the Continental multi-fuel engine used in military trucks. This is really interesting because the engine is primarily a diesel but in reality, it can burn anything from gasoline to jet fuel. The reason for this is if you have a truck on the battle field and you don't have any diesel, just dump some gasoline into it. If you do this with a gasoline engine you'll do poorly but a high-compression engine throttle by fuel can do it. You know the other engine throttled by fuel that can burn just about anything and work? Gas turbine.
4) The other benefit to throttling by fuel is an operating condition referred to as pumping losses. Pumping loss is the energy lost just keeping an engine spinning. Pumping losses are friction from engine and drive accessories and overcoming intake tract restriction. Pumping losses are a huge component to fuel economy, particularly at idle and at low throttle settings. A gasoline engine runs at idle with the throttle nearly closed. The pistons are creating a tremendous vacuum in the intake tract just trying to keep itself going. At idle and lower throttle setting, the engine is in fact working pretty hard just pulling a vacuum. A diesel has frictional losses and no or very little intake tract restriction for the engine to work against. And the bigger the engine, the higher the pumping losses, though in a diesel, it's primarily just a slight increase in friction. A big displacement gasoline engine at idle...and by big I'm thinking of the 500ci Cadillac and 460 Ford days...sucks down gas like a wino on Sunset Boulevard.
So, yes there are plenty of reasons why diesels are great and I've only scratched the surface but there's my take nonetheless.
Seven good things to know about diesel pick up trucks, my version. Myversion.my version may or may not fit your situation.
1. Diesels are capable of getting more miles per gallon because: have less pumping losses as stated. They do not have to overcome the vacuum imposed by a throttle, the power to drive accessories such as pumps, alternator water pump etc are not pumping losses, moving the air around the crankcase as the pistons move is, diesel fuel has more energy per gallon.
2. Diesels have a smaller carbon foot print only because you choose to use miles per gallon as your measure. I think if you took into consideration all the factors of a carbon foot print such as energy used to produce the more complicated and robust Diesel engine, DEF production and distribution, larger quantity of oil needed for an oil change, keeping them warm for winter starts...vs a gasoline counter part it wouldn't hold up
3. Diesel is dirty and smelly, not the new engines, they actually smell nice to me, but the fuel itself. Diesel fuel islands are dirty because the fuel doesn't rapidly evaporate collecting air born dust. The oily nature of diesel fuel makes it cling to your hands (and clothes if you have an oops) so you get to smell it longer.
4, 5, 6, 7.
Since my beloved wife likes to drive my F 150 (its communal property):
you paid 9 thousand dollars just for the Diesel engine option and I have to plug it in so it will start this winter, I have to unplug it, I have to wait until that curly symbol light goes out before starting it, not only do I have to fill it at that nasty diesel fuel island I might have to put DEF in also and so help me if I get that smelly stuff on me or my clothes... and what's this? oil change and filter $200!
Just sayin'. They have there place. If you do a fair comparison, for most gasoline engines do just fine. Unless your manl man ego needs power stroking?
1. Reliable, long-lasting gas engines can be made with MUCH less weight than diesel engines and in a smaller size than a comparable diesel engine. Diesel engines have heavy cast iron blocks and a low specific output, due to the low flame propagation front from the not very volatile diesel fuel limiting redlines significantly. Gassers can rev much higher and make a lot more power per displacement as a result, and you can make a very reliable gasser with an aluminum engine, not so with a diesel.
2. Emissions of a gas engine are less and much easier to control than emissions of a diesel engine. Modern gas engine emissions controls (PCV, evap canister, and catalysts) are very reliable and have a negligible impact on performance. Can't say the same for current diesels with the Tier IV soot traps, EGRs, and DEF systems.
3. Gas engines are much easier to start in the well below zero cold weather seen in northern states than diesels.
4. Cost per mile to fuel a gasoline engine is less than that of a diesel with current fuel prices, where diesel costs significantly more than gasoline.
5. Maintenance costs of a gasoline engine are notably less than that of a diesel engine.
6. Purchase costs of a gasoline engine are notably less than that of a diesel engine.
1. Reliable, long-lasting gas engines can be made with MUCH less weight than diesel engines and in a smaller size than a comparable diesel engine. Diesel engines have heavy cast iron blocks and a low specific output, due to the low flame propagation front from the not very volatile diesel fuel limiting redlines significantly. Gassers can rev much higher and make a lot more power per displacement as a result, and you can make a very reliable gasser with an aluminum engine, not so with a diesel.
2. Emissions of a gas engine are less and much easier to control than emissions of a diesel engine. Modern gas engine emissions controls (PCV, evap canister, and catalysts) are very reliable and have a negligible impact on performance. Can't say the same for current diesels with the Tier IV soot traps, EGRs, and DEF systems.
3. Gas engines are much easier to start in the well below zero cold weather seen in northern states than diesels.
4. Cost per mile to fuel a gasoline engine is less than that of a diesel with current fuel prices, where diesel costs significantly more than gasoline.
5. Maintenance costs of a gasoline engine are notably less than that of a diesel engine.
6. Purchase costs of a gasoline engine are notably less than that of a diesel engine.
yup! This too. Just wondering if all the diesel pickup hype is promoted by those trying to justify the price of admission and extra effort of diesel ownership?
All are correct. Why buy a diesel and take the price hit up front?
If you tow, a diesel engine is more effective and fuel efficient than there gas counterparts as they generate more torque at a lower RPM.
Engines are more robustly built to withstand the higher compression ratios and thermal issues.
Maintenance costs are lower due to longer intervals, especially true in "severe" conditions. I.E. Towing
Downsides:
Diesel fuel is more expensive
Cold starts are an issue.
DEF,DPF and SCR systems are expensive to maintain and repair.
My .02. Former diesel 3/4 ton: 10-11 towing my TT. As high as mid 18’s empty. Average all around 14ish
My gas 3/4ton: 8’s towing,14-15.5 hiway empty; 12.9 all around...
gas .35-.48 cents per gallon cheaper around here.
loved towing/driving all my diesels but you don’t have to use your toes to do that math. Modern diesels DO NOT have a significant mpg advantage anymore over gas in fuel efficiency. What’s more under load they LOSE a greater % of their efficiency. These are not my estimates: these # are hand ( and feet) calculated
Just anecdotal, but didn’t diesel used to be alot cheaper than gas at the pump many many years ago? If my recollection is correct, that was also one positive (now a negative).
It’s all relative to the new emissions. It’s questionable whether the new emissions burning significantly more fuel is really better lol. I guess I’m jaded but most companies using diesel here are just fixing up old ones rather than buying new... that kinda hints at something me thinks🤔.
My ‘06 DIesel truck all stock had no pblm keeping mpg in the hi 16-17 range. On long interstate runs it was hi 19’s.... My ‘10 was 14-15’s as long as I babied. I did get some 17-18 on longer trips but the DD was a 2-3 mpg diff.... all emissions related I’m sure.
I didn't even watch the video, I spent more time reading and then re-reading CI2H24's post, because he really does get it... He mentions Atkinson design engines, and guess what? An F150 is running around with an Achates Engine right now. Diesel? Yes, Gas? Yes, other fuels? likely... Spark Plugs? NO
I'm waiting for that power plant for my next light duty truck...
The future is not in batteries... Just ask GM how well their Volt worked...
Sorry, I'm a GM hater, and they clean sheet designed that thing while they were taking bailout money, screwing their shareholders, and running a full Nascar program. Hell, they might as well had their own money printing plant...
02-22-2018, 11:47 AM
