Stroke oil in diesel fuel

Mopar1973Man said:
This is also why the engine gets quieter becuase it burning slower and pushing longer through the power stroke hence the gain.
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Higher cetane makes diesel engine quieter. If the burn is slower the efficiency drops because you are wasting energy out of exhaust as a heat.

So, 2-stroke oil must raise cetane number. Someone should send diesel/2-stroke mix to lab and let them test cetane number.
 
Leiffi said:
Higher cetane makes diesel engine quieter. If the burn is slower the efficiency drops because you are wasting energy out of exhaust as a heat.

So, 2-stroke oil must raise cetane number. Someone should send diesel/2-stroke mix to lab and let them test cetane number.
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Backwards.

Higher cetane burns faster and with a knock. 2 cycle Oil is a cetane reducer and BTU booster so it burns slower and longer is why 2 cycle oil is quieter.
 
Information from ASTM Testing Labs...

cetane-btu.jpg


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 is why in the winter time when diesel fuel cetane rises to meet winter conditions and MPG's start to fall because of the loss of BTU content. Hence why ASTM states lower the cetane the better.

Point of reference gasoline is just below the BTU scale at 115,000 BTU's. So the higher you make cetane the closer and closer to gasoline your making the fuel.

cetane-btu3.jpg
 
I've used 2stroke in all my trucks and have had no issues. Now I think people are over thinking having the ratio exact. Mainly cause we do t have plugs to foul :hehe: I normally have a good cleaned out Dr Pepper bottle that works amazing for storage.
 
Kick Start said:
Your speed is not what matters. Your rpm is.
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so you are saying if my gearing is high enough then i can drive 140 mph uphill at 1500 rpms and still get the same mileage as driving 50 mph downhill at 1500 rpms?
 
Mopar1973Man said:
Backwards.

Higher cetane burns faster and with a knock. 2 cycle Oil is a cetane reducer and BTU booster so it burns slower and longer is why 2 cycle oil is quieter.
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Wrong.

Diesel knock comes from low cetane fuel because it accumulates more to cylinder before igniting, then all that fuel ignites at once, makes a loud knock. High cetane fuel runs smoother because it ignites almost immediately when sprayed into cylinder, no pressure spikes, no knock.

Better study diesel combustion principles before trying to teach people.

I have used 2-stroke oil, didn't give any mpg benefits, better calculate your mpg again. Good for lubricity if that is a problem, nothing else.
 
Leiffi said:
Wrong.

Diesel knock comes from low cetane fuel because it accumulates more to cylinder before igniting, then all that fuel ignites at once, makes a loud knock. High cetane fuel runs smoother because it ignites almost immediately when sprayed into cylinder, no pressure spikes, no knock.

Better study diesel combustion principles before trying to teach people.

I have used 2-stroke oil, didn't give any mpg benefits, better calculate your mpg again. Good for lubricity if that is a problem, nothing else.
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Criticizing without helpful guidance does not help the situation either...

Some reading for anyone who has time and it may or may not be of help

http://www.chevron.com/documents/pdf/DieselFuelTechReview.pdf

Check out Page 10, 60 for Cetane

:Cheer:
 
Leiffi said:
Wrong.

Diesel knock comes from low cetane fuel because it accumulates more to cylinder before igniting, then all that fuel ignites at once, makes a loud knock. High cetane fuel runs smoother because it ignites almost immediately when sprayed into cylinder, no pressure spikes, no knock.

Better study diesel combustion principles before trying to teach people.

I have used 2-stroke oil, didn't give any mpg benefits, better calculate your mpg again. Good for lubricity if that is a problem, nothing else.
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Ok... Then change ASTM labs results then...
http://www.astm.org/

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."

cetane-btu.jpg


As for fuel logs I've got over 200k worth of them... All done on a spread sheet.
 
Ltk said:
so you are saying if my gearing is high enough then i can drive 140 mph uphill at 1500 rpms and still get the same mileage as driving 50 mph downhill at 1500 rpms?
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What gradient is the hill?
 
Seriously no one is even considering rotational mass and wind drag forces. So the whole idea of rolling 140 MPH with a truck that has a drag co-efficient of about 0.41 to 0.49 I hardly doubt it will happen.
 
Mopar1973Man said:
Seriously no one is even considering rotational mass and wind drag forces. So the whole idea of rolling 140 MPH with a truck that has a drag co-efficient of about 0.41 to 0.49 I hardly doubt it will happen.
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little off-topic, but ive noticed you mention 55 mph being your golden speed for fuel economy. have you done or seen any tests between 55 and 60 or 55 and 65? im curious how much 5 or 10 more mph alters your fuel economy
 
Ltk said:
little off-topic, but ive noticed you mention 55 mph being your golden speed for fuel economy. have you done or seen any tests between 55 and 60 or 55 and 65? im curious how much 5 or 10 more mph alters your fuel economy
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Actually I have. I've checked 45, 55 and 65 MPH. But the problem is wind drag on a 6'9" tall truck and when you do the math the drag curve is really low but jumps exponentially as speed increases from 55 MPH.

As for why on the speed. This is not directed at you but I've wrote a article for this purpose.
http://articles.mopar1973man.com/members-rides/17-mopar1973man/459-speed-mpg

As for...
75 MPH = roughly 14-16 MPG
65 MPH = roughly 16-18 MPG
55 MPH = roughly 20-23 MPG
 
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Mopar1973Man said:
Actually I have. I've checked 45, 55 and 65 MPH. But the problem is wind drag on a 6'9" tall truck and when you do the math the drag curve is really low but jumps exponentially as speed increases from 55 MPH.

As for why on the speed. This is not directed at you but I've wrote a article for this purpose.
http://articles.mopar1973man.com/members-rides/17-mopar1973man/459-speed-mpg

As for...
75 MPH = roughly 14-16 MPG
65 MPH = roughly 16-18 MPG
55 MPH = roughly 20-23 MPG
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thanks for the info, Michael!
 
I just read this long thread and I think there's some confusion or assumptions about cetane, auto ignition and the diesel combustion process. But I'm certainly no expert on the subject.

Cetane number as mentioned indicates diesel fuel's ability to auto ignite, the lower the number the greater the rotation of the crankshaft before combustion starts, and when it does it burns more violently because there is more fuel loaded in the cylinder.

I have never read or heard where cetane value has any correlation with how fast or hot fuel burns in the cylinder, other than higher BTU fuel will create a little more heat energy per X volume of fuel. Diesel fuel burns vigorously in the cylinder, it is only controlled by the continuous and steady spray of the injector over several degrees of crank rotation. It is very different than gasoline combustion where all the fuel needed for a combustion event is present and then set off with a spark and burns evenly across the chamber.

This varies based on size and model of engines, but you could say there are 3 phases of combustion in a diesel engine. First is ignition delay, fuel is sprayed in and loads up but does not yet ignite. Next is uncontrolled and rapid combustion, when all that initial volume of fuel burns rapidly all at once, the chatter/knock you hear. It's practically an explosion. That is followed by controlled combustion, where fuel spraying from the injector tip burns steadily and evenly for the rest of the injection duration
http://petrolsmell.com/wp-content/uploads/2012/07/premixed_combustion_TDC_ignition_diesel.jpg

There's a multitude of variables between diesel engines when it comes to injection rate, volume and duration, these all play a part in how cetane number affects an engine performance and sound. A 12 valve has a slower injection rate (fuel flow rate coming from the injector) compared to a 24V, so therefore less fuel will be in the cylinder when autoignition occurs. That is why a 24V chatters more loudly. Because a 24V injects fuel rapidly (especially an HO) this engine will benefit more from a higher cetane value than a 12V, especially if operated at higher RPM.
 
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I know that this is a stale thread, but thought I would point out a couple things just because this is kind of my thing... being I get paid to know this garbage.

Both Night whatever and Mopar man are correct, I just think they overlap a little. Higher cetane does in general lower knock because of lowering the incidents of pressure spikes by igniting the fuel more quickly. Generally speaking it will also burn more completely to a degree (depending on the package that the additive manufactures uses). BTU is lowered with a higher cetane level for sure, but BTU and pressure spikes are kind of different animals. The adding of 2 stroke oil is helping mpg's because of a few reasons. It may or may not raise BTU, no way to actually tell without testing of the fuel in a lab. It does help lubricity, and more than likely helps the injectors and pumps stay cleaner. There are a ton of variables in this because of the different additive packs in some 2 stroke oils. So saying anything is absolute here could be misleading.

Pour point depressants are not the same in fuel as they are in a lubricant. PPD's work by separating the wax crystals formed at lower temps in a lubricant as well as in diesel fuel. However, the polymer constructs are different for different lubricants let alone for fuel. They may or may not work, depending on the fuel formulation and temperature. As well as about a thousand different variables, mostly in the 2 stroke oil you decide to add. And group 4 synthetics don't generally have PPD's because they have such a high viscosity index that they do not require them, however high quality gorup 2 and group3' mineral base stocks may not have PPD's either because of their inherit high VI as well, or the massive amounts of VI improvers that some lubricant companies dump in to get the test numbers that they need to pass a certain spec or make themselves look better on paper.

I agree with most of what yall are saying though, great work Mopar on years of data collection and testing, I love that kind of attention to detail!
 
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