Fuel Related Performance

[Autoholic]

Without diving too much into the reasons behind this question just yet, I was wondering if anyone with hands-on experience using different fuels can comment on power relative to the fuel used. So for a specific engine or in general, how much power was gained from shifting to ethanol from gasoline, E85 from gasoline, methanol from gasoline, nitro from gasoline, E10 from gasoline? I'm working on something that won't be focusing on the power gained but I'll most likely end up mentioning as a percentage, the power gained. Due to the universal nature of the writing, the spec-less engine will not try to maximize performance using a specific fuel but rather what would happen to the performance of a spec-less engine from just changing the fuel. The real focus will be on fuel consumption. All of this will be done from the theoretical chemical properties of the fuels, so engine specifics don't matter. Yes, realistically the engine specs make or break the engine's performance, fuel economy and emissions.

[cammerfe]

When I first started ECTA land speed racing, I departed into 'fuel' classes by using nitrous oxide and, of course, gasoline. Then I put in a stand-alone fuel system to go with the nitrous oxide and filled it with methanol. The fuel-injected engine was, therefore, running on C116 through the factory fuel system, and when I activated the nitrous oxide system, as I went into third gear I was also adding methanol as well.

In that configuration I was running 'fuel competition Coupe/Sedan' and I set the record in that class. On the next run I added a couple of jet sizes of methanol and went a bit faster. I did the same thing again and once more went a bit faster. I don't know how many more times I could have done the same thing because I ran out of incrementally-larger jets. The next size on hand was about eight sizes larger and I thought it made good sense to stop at that point.

I drained the methanol out of the fuel cell and replaced it with C116. Doing so made it possible for me to run in 'Super Street' class rather than 'Competition Coupe/Sedan'. I set that record also---but it was almost four miles slower than what I'd done an hour before with methanol in the cell.

I could have gone faster by playing with the nitrous oxide jets in both classes, and by varying when I flipped the 'spray' switch on but I was mindful of my factory pistons and rods.

All of the above is a somewhat long-winded way of saying that under the given conditions, the substitution of methanol for C116 made about four MPH difference in one mile. Top speed for the combination was a tick over 140 MPH. That record still stands.

KS

[Autoholic]

Interesting story. I wonder how much more power you made? The paper I'm writing will be focusing on AFR and energy density, the goal will be to show that there is a misconception about the role energy density plays in fuel consumption.

[cammerfe]

There's probably a way of figuring out the difference in fuel volume from each jet change. I DO have my notes, put away, and could probably interpolate as to the jet size numbers I used on each run. But the info isn't at my finger tips.

KS

[Autoholic]

With the size of the jets and the pressure, you can find out how much is flowing.

[cammerfe]

One of the arcane facts regarding jets is that there is more to them than just the size of the hole. The shape of the approach to and departure from the hole also has a significant effect. Methanol pressure was set at 65 pounds on the gauge just prior to the regulator. When I get over to the storage where everything is located at present, I'll dig out my notes if you like.

KS

[TorinoBP88]

Trouble is each fuel has a different ideal compression ratio and air fuel ratio.

If you look only a power per gallon (usually related to carbon content) diesel is the highest.  But as we know 18:1 CR is requires.

Regular gas is actually more powerful than premium but trouble is it mar burns too fast in some engines so you can't use all the heat.  That's why premium is useful, also handles more compression.  Power is related to compression ratio.

Alcohol is much less dense so it takes a bunch more fuel volume to match the power, again up the flow and compression = more power. But a stock engine might be less power.

Methanol is of course a total different animal.  Top fuel runs almost at hydro lock! That's a lot of fuel.

[Autoholic]

One of the arcane facts regarding jets is that there is more to them than just the size of the hole. The shape of the approach to and departure from the hole also has a significant effect. Methanol pressure was set at 65 pounds on the gauge just prior to the regulator. When I get over to the storage where everything is located at present, I'll dig out my notes if you like.

KS

I'd appreciate it. My research into the topic is based on the chemical side of the problem, lots of math involved in order to make sure the comparison makes sense.


The purpose of the paper I'm writing is to show that there is a misconception about the energy density as to why there is an increase in fuel consumption for a given engine. I do cover the fact that a spec-less engine is not realistic. This is analyzing the fuel properties themselves, so looking at the root of the issue that no amount of tuning and engine design will be able to overcome in a large percentage.

[Falcon67]

Here's a fuel ratio calculator, from memory mentioned in a chart in a Car Craft article. 

http://www.wallaceracing.com/air-fuel-lambda.php


http://www.smokemup.com/tech/fuels.php

http://www.brighthubengineering.com/machine-design/15235-the-stoichiometric-air-fuel-ratio/

"When the composition of a fuel is known, this method can be used to derive the stoichiometric air-fuel ratio. For the most common fuels, this, however, is not necessary because the ratios are known:

Natural gas: 17.2
Gasoline: 14.7
Propane: 15.5
Ethanol: 9
Methanol: 6.4
Hydrogen: 34
Diesel: 14.6"

Note, IIRC best power ration is about 2.0 numbers lower than "ideal".  Methanol I know makes best power around 4 or so.

[Autoholic]

Thanks, I already have all the info though.

I'm looking for comparisons in power gained due to any fuel conversions. The chemical comparison side I already have down.

[jayb]

Generally, a switch from racing gasoline to methanol will pick you up about 5% peak torque, and a little less than 5% HP, based on my somewhat limited experience...

[machoneman]

BTU's are your friends! 

http://www.smokemup.com/tech/fuels.php

[Autoholic]

Energy density only gets you so far. Each fuel has thermal to mechanical inefficiencies as well, influenced by various factors. I can focus on just the chemical properties but I wanted to get a real life idea as well. Right now, I'm seeing about 4.5%? increase in power switching to ethanol (e100).

[Devil69]

Autoholic,

        I have made a reply to your post in a new post here, http://fepower.net/simplemachinesforum/index.php?topic=3493.0#new.

Calvin

[Qikbbstang]

          Comparing Ethanol, Methanol, Gasoline and Nitro Methane is difficult since the "optimum/specialized" engines for each fuel are as different as the fuels. Running Gas in an Engine built for Alcohol shortchanges the Gas and vice-versa. Taken to the extreme, can you imagine taking a 500 Cu In 10,000 HP AA/F motor and running it on gasoline? .....