Well B100 said in post #41 "...., but the point is the engine examples I mention have decent power to weight ratios that are stock and can maintain high power output all day without undue stress! So you can increase power levels safely between 20 to 25% and some makers actually offer that as an option! But you dont need to , because the power is there already....so correct me if I´m wrong take off on 80 to 100% power for 2 minutes, then back of to 75 to 80 % on climb , and cruise on 60 to 65 % power...
In a current diesel engine that translates into 3600 to 4000 rpm then back of to 3000 to 3200 rpm and cruise at 2400 to 2600 rpm..."
This statement makes sense to me.
However, I agree the fuel economy gap is getting smaller, so a Diesel may only make sense if the fuel choice is limited. Also agree that engine durability suffers with higher pressures, and a diesel piston is beefier than a gasoline piston of similar size, as are most other stressed parts. So the weight penalty is undeniable. I am also doubting that one can just run a diesel on jet fuel without any changes. Is the cetane number the same? We made SI DI engines that run on jet fuel, but not on diesel.
Diesel popularity in Europe is not only driven by frugality, however. The fact that a high torque is available at low rpm and over a wider RPM range is enhancing driving pleasure, there is no doubt about that. You can shift up earlier and can stay in a higher gear longer. For an aircraft with a variable pitch prop this should translate into creating the same amount of thrust at a lower rpm, shouldn't it?
Well, my assessment of the U.S. diesel engine use is 10 years old and only based on my personal observations in the greater Detroit area and Wisconsin. I did notice on my holiday at the west coast that there were a lot more Japanese and European car makes in the mix
even back then. Things must have changed since then. I'm also not sure if a 80% portion of diesel engines is desirable, since they still are smellier and have these small particle emissions. I suppose the distribution between diesel and gasoline engines should match the distribution of diesel and gasoline due to the refinery process. I once read that there was a fixed ratio that determines how much of each comes out of a litre of crude oil, but that may be bollucks...
Hi Kingfisher while the fuel gap is indeed getting smaller this has not yet trickled down to real world everyday cars , but is rather still very much in the research realm ! Duel to technical limitations it never will, so the variables will be cost per liter and taxes !
Here is a link that exemplifies what I mean ;
Ten of the best used diesel cars | This is Money (remember to convert imperial gallons to US where applicable)
Now bare in mind that the UK is one o the few countries in the world where Diesel costs more than gas! ( an economic contradiction as diesel is cheaper to produce/refine)
In regard to more boost reducing engine life, that is true for most SI engines, not so for Diesels, as they are built from the ground to include those factors so the reliability is built in which explains that they are normally heavier Ltr for Ltr when compared to SI ! Besides in diesels power increase is more than just pushing up boost pressure . You can actually increase power and torque to reduce fuel consumption and eliminate turbo lag at low rpms (that why I chipped mine and it works great)
As for running a diesel on jetA without changes, you are right ! there are issues involved to consider!
I have actually researched this hands on, and can give you some good info on it!
Some years back I was contacted on a Biodiesel forum by a guy who asked me to teach him to make Biodiesel. He worked at the local international airport refuelling Jets and was able to "procure" (lol...free):ban: enough jet A to power his Mercedes (old 87 model) and the wife's VW Golf ! Problem was it didnt take long for his injection pump to break !
Repair shop told him it was very worn and that he should mix a little 2 stroke oil with the diesel for better lubrication! This problem became more common when Europe adopted ULSD, ultra low sulphur diesel in early 1990`s . Sulphur had a lubricating properties, but provoked acid rain, so when it was removed , it was replaced with an additive to restore the lost lubricity . This helped but it too was found to be carcigenous and toxic so in the late 1990´s The European union mandated a new enviroment green replacement, biodiesel! Now all diesel in Europe has at least 2% biodiesel as an additive !
The problem with Jet A or other types of jet fuel is two fold;
1- It has a lower cetane number that varies a bit from lot to lot , and this gets worse with other types specific for cold weather! which puts it way under the European 51 cetane minimum (remember its meant to be used by burning not CI!)
2-Its thinner and thus more aggressive to the injection system , having almost no lubricating properties .
After some experimenting we came to conclusion that a minimum of 10 % biodiesel mix was required to up cetane and lubrication properties to acceptable levels , 20% and up was even better!
I supplied him small amounts of Biodiesel for the mix, until he eventually made his own ....and lived happily ever after...lol
With these factors in mind and based on hands on experience, I would only use Jet A in a Diesel auto conversion aircraft engine in an emergency, or with a very small dose of 2 stroke oil , but ideally with road diesel or a blend of diesel and biodiesel , being the latter the best option due to higher cetane and less engine/injection system wear.
That being said since the introduction of common rail injection systems resistance to wear from less lubricating fuel has improved somewhat. I also remember back from my Military days that a NATO standard came into force that stipulated all machines on the battlefield should be able to operate on the same fuel! This implied that a jet could run on road diesel in an emergency, and all other combustion engines on Jet fuel if need be !
As for smell....well diesel will always stink! except if it mixed with at least 20% biodiesel.
or more.....then it smells good ...lol....:gig:
In the last years diesels have become cleaner then SI engines which in some countries contributes to lower taxes and lower running costs and helps explain the popularity of Diesel.
Refining crude depends on how a refinery is set up! but diesel is always cheaper to produce as it requires less energy to refine . Older refineries would be set up to produce diesel , and gasoline was a by product , don't forget that the world runs on Diesel, or diesel type fuels be that trains, boats and planes lol...as the song goes! These days most refineries are set up for diesel od diesel type fuels , like jet fuel ! To sum it up , if gasoline disappeared today the world wouldn't stop , but if Diesel ended it would all stop!
....can you elaborate more on the mentioned product you developed involving a 2,0 CR Diesel ? Just curious? unless you cant divulge more info, or consider Im not worthy......
