Fuel losing BTU's and HP in Black tank?

[JCasper]

So I just ordered a black transfer flow tank and a couple people have told me that fuel in a black tank loses BTU's and HP. I guess from heat.



Any truth to this or is it not anything to worry about?

 

[rbattelle]

Sounds iffy to me. A fuel "losing" BTUs? That doesn't seem right.

What color do these people say the tank needs to be? Pink?

Ryan

 

[JCasper]

Sounds iffy to me. A fuel "losing" BTUs? That doesn't seem right.



What color do these people say the tank needs to be? Pink?



Ryan

LMAO, pink, that's funny.



I think they are thinking it should be aluminum. I doubt it's an issue and the more I talk with them they are thinking the temps aren't high enough to matter.

 

[TAbbott]

A black tank will absorb heat. Hot fuel has less specific energy per unit than cold fuel. So, if you let your truck sit in the sun all day and significantly warm the fuel, you could theoretically lose some energy.

 

[JCasper]

A black tank will absorb heat. Hot fuel has less specific energy per unit than cold fuel. So, if you let your truck sit in the sun all day and significantly warm the fuel, you could theoretically lose some energy.

But is it enough to worry about?

 

[catdsl]

i wouldnt worry a bit about it

 

[JCasper]

i wouldnt worry a bit about it

Good, then I won't

 

[JDiepstra]

I am no expert but I have read about this a while ago. I think what it is is that in a hot black tank the fuel will expand. Thus, one gallon of hot diesel is "less" than one gallon of cold diesel. That is where the idea of less BTU's comes from. You can read about it on page 61 of TDR issue 58. And it sounds like from the article it may be enough to make a diffeerence over time.

 

[DPellegrin]

There is some validity to the claim that as the fuel heats up it looses heating value. However, there is an analytical way to determine whether or not the tank transfers enough heat to make any difference. To measure a fuel's heating value (energy content) you use an API thermohydrometer. This little device of course reads in API units and will tell you the temperature of that sample. Just take a sample of fuel in the black tank and compare it the a sample of the fuel in the regular tank. API publishes tables that convert API units to BTUs.



I do know from my days of doing SAE Type II fuel economy testing on heavy -duty vehicles at GM Mesa proving grounds we never measured the fuel used by volume, we first weighed the day tank then drove the operating cycle and then weighed the tank again. We converted this weight to a standard temperature and got the volume used at that temperature. I know this sounds complicated but I really do not think in the end you will be able to tell the difference in fuel economy from the black tank vs. any other tank. BTW an API thermohydrometer will probably set you back 100 bucks or you might ask your local fuel supplier to borrow one.



Regards,

 

[jwgary]

While the energy content per gallon will decrease as the fuel heats up, the volume of fuel will increase by the same amount. You will have the same mass and therefore the same amount of stored energy.

The problem you get is when you buy fuel and it is hot. You are paying per gallon, but energy content is mass based not volume based.

The only problem I could possibly see from using a black tank and heating the fuel is vaporizing more of the easily burned light hydrocarbons. If the tank is vented you could loose some of those.

 

[EKlem]

Hot fuel expands a tiny bit so a black tank will lead to the expansion. You will not loose any energy but you will have slightly less energy per volume until it cools down again.



If you are really worried about getting every last horsepower out of the truck, you won't be able to on hot sunny days(even without a black tank you get hurt some). If you are really worried that much about it, you could cover over it with something that is white. The bigger deal about fuel temperature is when you buy it. You want to buy cold fuel but even then, the difference is incredibly small.

 

[tgordon]

One other thing to keep in mind, and I doubt this is an issue you will deal with, is getting the fuel to hot. This was covered in TDR when a class 8 truck was converted to a motor home and one fuel tank removed. Fuel got hot enough the engine would not run until it cooled down as the fuel returned to the tank also acts to cool the pump and injectors.



But as your fuel will be returned to your OEM tank you should be just fine unless you are driving around all day in Death Valley at max load.



If you are worried about it you can always get a spray bomb and make it pink

 

[obert]

The OEM tank is black, so even if there is a problem, you already have it.



Unless your planning on mounting the new tank on the roof and spend your days drinving back & fourth across death valley, any HP loss would have to be as noticeable as a fart in a tornado.



Oh, wait, you still wouldnt notice because YOU ALREADY HAVE A BLACK TANK!!!! :-laf:-laf

 

[DPellegrin]

jwgary- you are correct in your assesment. This is exactly why as the fuel heats up the power of the engine will fall off a bit. Remember the injector only knows volume. It does not know density (mass). Therefore less energy is injected per injection cycle and the resulting lower power output.



Regards,

 

[JCasper]

Oh, wait, you still wouldnt notice because YOU ALREADY HAVE A BLACK TANK!!!! :-laf:-laf

:-laf:-laf

 

[mhenon]

jwgary- you are correct in your assesment. This is exactly why as the fuel heats up the power of the engine will fall off a bit. Remember the injector only knows volume. It does not know density (mass). Therefore less energy is injected per injection cycle and the resulting lower power output.

Regards,

I thought the computer controlled engines sense fuel temp and adjust accordingly.

Mike