Diesel fuel possibilities 3

[FahlinRacing]

I have been on the hunt for a buddy who runs truck pulls and was curious on what I could do to improve the burn cycle by engineering a performance fuel. I had seen Mr Primmer mentioning Acetone does help, however I believe it kind of dries out the Diesel fuel since it is a solvent. In turn needing a lube additive no matter what. I had the idea of Biod for its lube properties and high Cetane quality.

The ideas I have had so far are using BioD, methanol, ethonal or another that could be mixed in. But, some are saying I will need some equipment to mix it properly and efficiently on whatever I decide on. I believe methanol can only be injected, assuming ethanol is the same way? Along with other additives, I would like to use another actual fuel if I can.

Any insight would be greatly appreciated!

 

[patprimmer]

If your looking for power above all else, nitro-methane sure packs a punch. I have no idea how it reacts with dieso or how it lubes fuel injectors and pumps.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[140Airpower]

What is the efficacy of adding octane booster (Acetone, Ethanol, Methanol) to diesel fuel? Should make it harder to ignite. Cetane and octane have diametrically opposite scales of merit.

 

[ivymike]

Add propane?

 

[mattsooty]

There are stark contrasts between a 'performance' fuels for diesel & gasoline.

For a gasoline engine to produce more power generally the biggest constraint is the amount of air that one can cram into the combustion chamber - the limits being rich misfire & the knock limit.

With a diesel its more of how much fuel you can get into the cylinder and burn quickly & efficiently - the limits being exhaust temps & smoke.

The main attribute of a performance gasoline is its resistance to knocking (high octane number) whereas for diesel, which runs with excess air, it is the reduction in ignition delay of the fuel (high cetane number).

It is useful to remember that the combustion in a gasoline is laminar->turbulent whereas in a diesel it is a diffusion flame.

MS

 

[SomptingGuy]

pmax is also an design input for diesels.

- Steve

 

[mattsooty]

Yes, indeed, there are many factors that must be addressed - but I considered these over and above the fairly open question posed by the OP.

MS

 

[winfieldblue]

A shot of unleaded gasoline added to the diesel should give the engine some extra kick, 25-1 hasn't caused my engine/pump any obvious problems as yet!

 

[mattsooty]

Doubtful, since the cetane number of gasoline is usually less than 20...

MS

 

[winfieldblue]

I believe that the increase in performance comes from a faster burn, here's an interesting link for the O.P.

http://www.chipit.com.au/product-info/diesel-petrol-injection-system/

 

[FahlinRacing]

Wow, didn't expect this many replies! Thanks guys.

Things I have come across are Methanol seems to be the one most widely tested with diesel but has been known for eating up seals n the fuel system, although there are some that have done something with ethanol and diesel. Winfieldblue, thats what I am trying to achieve a faster burn cycle without reaching knock. If I remember right Methanol has a Cetane rating of 3.

I want to use a base fuel of No.2 Diesel because it has more BTU than No.1, but it, No.2, has a lower Cetane rating, thats where I need to improve the fuel. Now we haven't done any observing of the crown as far as just running with No.2 or 1 so I don't have any visuals to see. he is running around 3000rpms right now and the new engine will be between 3000 - 5000 operation range.

One person had mentioned microemulsion for mixing up fuel, then I will have to consult the manufacturer on if its safe to run a emulsified fuel in diesel, The only thing I have to think on some more is BioD, methanl and Ethanol are oxygenated which have less BTUs compared to Diesel, I had the thought of gasoline run by me on another forum, that brought the thought up of buying non-oxygenated gasoline, unless the oxygenated gasoline or methanol or enthanol will be benefit due to its cooling qualities because of the latent heat of vaporization since diesel is low in that department. Albeit, the diesel combustion phase is quite quick, so I am not sure if that characteristic will have an effect on horsepower production.

 

[FahlinRacing]

After doing some reading Mr Gale Banks suggests to leave the Propane for the stove, however he does state that there is a power gain with propane. This particular class is not allowing any fuel systems besides the stock one, but you can build a pump up and use different injectors. Back to my research though....

 

[mattsooty]

No need for oxygenated fuels - the richer than stoih afr makes this irrelevant. The oxygenated taking up
High cetane number means short ignition delay in premixed regions & effectively shortens the burn duration, with the charge being consumed, via diffusion flame, quickly & progressively.

 

[mattsooty]

Kin ell sent from my phone & full of typos!
Leaner than stoich makes it irrelevant, why waste fuel volume with something you aren't short of in the first instance.
Reduced ignition delay means potentially more fuel burnt more quickly, giving a mre progressive heat release but, with CR, allowing for better control thereof. Only issue then becomes gradient of rate of pressure rise. Much more than 3bar degree becomes harsh & inefficient.

Ms

 

[FahlinRacing]

Thanks Matt,
So it would be better to use a non-oxygenated gasoline with a low octane like the basic grade 87? or would it be beneficial to test different grades up to 93 octane etc for mixing with No.2. Since these pumps get turned up, I think we aren't in a lean situation, I would say more around stoichiometric or slightly richer.

Yes, in the general sense of reducing the ignition delay along with probably adjusting the injection timing point is what I am looking at.

 

[FahlinRacing]

Another person I have spoken to mentioned at higher rpms, he thought just the basic Diesel may be beneficial, but with the No.2's lower Cetane rating than No.1, the ignition delay may be too long and miss the point of peak pressure as well as having a less smooth combustion phase due to the lower Cetane number.

 

[mechanic6]

using gasoline is not a good idea,for one gas has less btu/lb than diesel fuel.
if you could get your hands on some GTL diesel fuel,that would greatly help in your situation.
GTL diesel is made from natural gas,it has 30% more lubricity than ordinary diesel,it has a cetane rating in excess
of 65(depending on origin,Shell claims up to 70)
now the problem ,i don't think GTL is available in the USA.
however it is widely used in Europe,either straight or mixed with oil derived diesel fuel.
i think i saw an info sheet from Shell that said GTL has more BTU/LB than regular but cannot recall how much.
i hope this does not cause too much confusion for you.
just an aside,you can increase the density of GTL by cooling it,it has no wax in it so it
so it will not cloud up,and the viscosity changes very little.
you could really max out your fuel flow this way..

 

[patprimmer]

For maximum power, it's not btu per lb of fuel. it's btu per lb of air available. That is why methanol makes more power than petrol even though it has less btu per lb.

From memory, it has just over 1/2 the btu per lb but needs to be a bit more than twice as rich at stoich.

That is why I kinda tongue in cheek mentioned nitro methane earlier. It has a huge amount of btu per lb of air, like about twice that of typical hydrocarbon fuels, but it is 1.9:1 air fuel ratio at stoich. I have no idea as to its cetane or burn rate or autoignition point or how it mixes with diesel fuel or how it lubricates fuel pumps and injectors.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[mattsooty]

It's not quite as easy as that with CI engines Pat; a fuel with a high calorific value may still be sub optimal, if you cannot get all of it burnt in the right window - hence the requirement of a high cetane number, without which you end up with high exhaust temps & loads of smoke. However, the opposite end of the spectrum is 'diesel knock' with similar consequences to a gasoline engine.

It's must be borne in mind that the charge will be heteorogenous in nature & burn only occurs in areas that are locally combustible.

As for lubricity. Not my bag.

MS

 

[patprimmer]

Matt

I realised that, but I have no idea of the cetane for nitro or if it can be mixed to give an optimal cetane. I just threw it in their for discussion. It is an unlikely fuel additive for a diesel as they are normally chasing BSFC not power density and of course nitro is great for power density, but really bad for BSFC. Also it needs to run so rich, it can be in danger of hydraulic lock even at 10:1 so more like 20:1 certainly won't help in that regard.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules