Cetane numbers?

[dodge man]

I understand the vague premise of what a cetane number is, vaguely similar to octane number for gas. What I don't understand is how a higher cetane number gives you more power/economy.

In a modern gas engine, higher octane can allow the computer to dial up the ignition a little bit, based on the knock sensors, and give you a little more power and gas mileage. In the old days if you had a higher octane fuel, you always dialed up the intial timing a little bit and you could feel this in the seat of your pants when you drove the car.

In a diesel engine in a tractor, there is no computer, so what does the higher cetane rating mean? Does it just give a little bit better combustion, there by giving you more power and economy?

 

[jlrsn]

A good explanation can be found at the following URL

Cetane number - Wikipedia, the free encyclopedia

Jim

 

[oldballs]

Heck, where can one find the cetane value of the fuel one purchases? It's not on the pump, and if you really want a laugh, ask an attendant. I use BP ULSD but no cetane number is found at the station or at their web site.

 

[Skyco]

I've seen it posted at some pumps around here...usually at 40.
That concerns me because that is less than recommended for many engines.

 

[oldballs]

The workshop manual for the BX2660 says the cetane number should be "45 minimum" and greater than 50 when the temp is below -4 deg F and when at elevations above 5,000 feet. Mine has run fine on diesel from my local BP station at zero temps (with Power Service)...but it would still be nice to know what their statement of cetane value is.

 

[Charolais]

I add cetane to all diesel fuel in my bulk tank. Since I bought my first Deutz Fahr I started asking questions to my bulk supplier. First I got a MSDS sheet from them and then ordered cetane by the case to add. My fuel is delivered with 45 cetane. Deutz says a min. of 46. I bring it up to about 54. After doing that I found the other diesel engines here start easier in the winter on that higher cetane.

I also add to heating oil. Get more heat per gallon.

Have one fuel supplier in this area that sells fuel at 38 cetane and may be lower. If you throw some on a fire it'll put the fire out. The 45 cetane fuel will blaze up. Any place you buy fuel should have a MSDS sheet and should either let you read it or copy it.

 

[LBrown59]

I add cetane to all diesel fuel in my bulk tank. Since I bought my first Deutz Fahr I started asking questions to my bulk supplier. First I got a MSDS sheet from them and then ordered cetane by the case to add. My fuel is delivered with 45 cetane. Deutz says a min. of 46. I bring it up to about 54. After doing that I found the other diesel engines here start easier in the winter on that higher cetane.

I also add to heating oil. Get more heat per gallon.

Have one fuel supplier in this area that sells fuel at 38 cetane and may be lower. If you throw some on a fire it'll put the fire out. The 45 cetane fuel will blaze up. Any place you buy fuel should have a MSDS sheet and should either let you read it or copy it.

Around here diesel and home heating oil are the same thing.

 

[Jerry/MT]

I understand the vague premise of what a cetane number is, vaguely similar to octane number for gas. What I don't understand is how a higher cetane number gives you more power/economy.

In a modern gas engine, higher octane can allow the computer to dial up the ignition a little bit, based on the knock sensors, and give you a little more power and gas mileage. In the old days if you had a higher octane fuel, you always dialed up the intial timing a little bit and you could feel this in the seat of your pants when you drove the car.

In a diesel engine in a tractor, there is no computer, so what does the higher cetane rating mean? Does it just give a little bit better combustion, there by giving you more power and economy?

Cetane number is like the opposite of gasoline octane rating. With gas the higher the octane the less the tendency to knock or detonate. With the cetane number, the higher the cetane number the more easily the fuel will detonate. That's what causes diesel to burn without a specific ignition source.
You don't get any more power out of a higher cetane number. The power output per unit displacement is determined by compression ratio. It does make it easier to start, however.

 

[Diamondpilot]

This is why the diesel sold here is such junk compared to the rest of the world. We treat diesel like a secondary fuel for just truckers and farmers while the rest of the world uses it as its primary fuel.

I read somewhere once on a Ford Diesel Guide that making the trucks run well here was tougher than anywhere else in the world because the fuel varied so much.

Chris

 

[jlrsn]

The last time I was in Europe I had a choice of basic or hi-test diesel fuel at the fueling station for my rental car.

Jim