leaded/oxygenated racing fuel vs. methonal
leaded/oxygenated racing fuel vs. methonal
(OP)
I currently have a project I am part of we are contemplating on the switch to vp's m5 methonal. We originally were looking into ethonal/e98 but we have yet to see substantial gains over vp's q16.
The project is a 2.3ltr engine making 60lbs of boost, on the fuel we currently run we are making roughly 1250hp. Has anyone made a switch over to methonal and have any data on actual gains?
We are fully aware of the fuel system requirements to make the change over and are willing to do so if need be.
The project is a 2.3ltr engine making 60lbs of boost, on the fuel we currently run we are making roughly 1250hp. Has anyone made a switch over to methonal and have any data on actual gains?
We are fully aware of the fuel system requirements to make the change over and are willing to do so if need be.





RE: leaded/oxygenated racing fuel vs. methonal
A second advantage of methanol is the clean burning and the lack of plug fouling even when very rich. This allows extra fuel to suppress detonation which in turn allows more spark advance or more boost, so you only find that if you optimise correctly.
The extra fuel required for a stoichiometric mixture then further enhanced by the ability to run even richer gives a significant reduction in charge temperature all the way to ignition point.
I have seen power losses with methanol if the ignition system is not up to lighting the charge. This is a very common problem with people who claim methanol will not give a power boost. A really good magneto with really tight plug gaps still works best in my experience. Second best is an electronic system with coil on plug but I have yet to see one match a good maggy under really high loads.
The only practical (well kinda), available (well kinda), legal (well kinda) fuel I have seen out power methanol on a properly optimised engine is nitro methane.
I have never been able to reconcile VPs claims and premium prices over 99.9% pure industrial grade methanol.
They sell some extra powerful methanol, but that is actually a nitro blend. If you can legally run that, you can legally run your own blend with the same level of nitro.
If you want a less abrasive fuel than 99.9% methanol, you can add castor oil or some other proprietary methanol compatible lubricant.
Regards
Pat
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RE: leaded/oxygenated racing fuel vs. methonal
RE: leaded/oxygenated racing fuel vs. methonal
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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RE: leaded/oxygenated racing fuel vs. methonal
RE: leaded/oxygenated racing fuel vs. methonal
RE: leaded/oxygenated racing fuel vs. methonal
Although alcohol contains oxygen, it is not really the way we want it. In general, the higher the oxygen content, the lower the energy content.
RE: leaded/oxygenated racing fuel vs. methonal
Let me check the numbers (I may have a MathCad file lying around somewhere which I made for similar purpose) and get back on this (with admission of guilt or otherwise).
RE: leaded/oxygenated racing fuel vs. methonal
RE: leaded/oxygenated racing fuel vs. methonal
I'm enclosing the comparison of heating values (assuming his numbers for the fuel low heating values) as picture, and will try to see how numbers differ when viewed more 'realisticaly'. But I suspect they will be similar to those per kg of air.
RE: leaded/oxygenated racing fuel vs. methonal
RE: leaded/oxygenated racing fuel vs. methonal
Heywood lists sAFR = 14.6 and 6.47 for gasoline and methanol, respectively. So using those along with his values of lower-heating values per kg of fuel, (for consistency), one gets 2.821 and 2.677 MJ per kg of mix, (which seem to agree w/ the values in his table), and 3.014 and 3.091 MJ per kg of air, respectively.
Eric
RE: leaded/oxygenated racing fuel vs. methonal
In case of low heating value per kg of mixture I got 105,27% higher for methanol, and in case per cubic meter of mixture I've calculated 105,27%... HTH
RE: leaded/oxygenated racing fuel vs. methonal
Using Qlhv = 32.808 and 120.971 MJ/kg for carbon and hydrogen, respectively, I came up with 44.79 and 19.91 MJ/kg for gasoline (approx as C8H15) and methanol (C1H4O1). For stoich mass ratios, I was coming out with 14.609 and 6.473, respectively.
So using those numbers, I get 3.066 and 3.076 MJ/kg_air for gasoline and methanol at stoich. So 0.3% higher. So at least tipping in the same direction as Pat had seen reported.
Per kg of mix, it comes out to 2.87 and 2.664 MJ/kg_mix, which are not too much different than in Heywood's table.
RE: leaded/oxygenated racing fuel vs. methonal
Now that we've solved the mystery of energy stored in the mixture, another thing is intriguing me. Looking at those numbers, it's apparent that in case of methanol the weight of mixture should be more than twice the weight of gasoline mixture- I wonder how does that affect intake cycle, mixture formation, &c.
RE: leaded/oxygenated racing fuel vs. methonal
It is due to a) the increased charge density due to the increased evaporative cooling of the methanol, b) the ability to configure and tune the engine much more aggressively in terms of manifold pressure, peak cylinder pressure, and heat release rate, without destructive combustion knock (due to the internal cooling effect of fuel evaporation, and methanol's superior antiknock properties), and c) a subtle but positive effect of the specific heat ratio of the charge during compressiom vs that during expansion that favors methanol over gasoline.
RE: leaded/oxygenated racing fuel vs. methonal
In addition, methanol also has a higher burn velocity. The shorter burn duration results in a more constant-volume like cycle, which improves thermal efficiency. It also tends to reduce MBT timing. And since the end gas is consumed more quickly, there's less chance of detonation, as a result.
Not only does the higher latent heat of vaporization help prevent knock, but the lower temperatures throughout the cycle also result in less heat loss to the cooling system. This also helps thermal efficiency.
I agree that the difference in cp/cv may be subtle. While I have looked at that for the case of ethanol, I have not done so with ethanol.
There are probably other things I'm forgetting So yes...lots of other effects to consider, other than just the energy content of the fuel, hemi. It's good to mention them.
(Woof woof.)
RE: leaded/oxygenated racing fuel vs. methonal
RE: leaded/oxygenated racing fuel vs. methonal
Regards
Pat
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