Landracing Forum
Tech Information => EFI Questions => Topic started by: JimL on September 14, 2008, 01:13:13 AM
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E Fuel class engine (about 250 cubic inch), Hilborn system, methanol only....does anyone have a suggestion how much fuel tank capacity is best? This "non-gasoline" stuff is all new to me! :?
Thanks in advance for sharing your experience.
JimL
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Jim,
Gasoline - air/fuel ratio = 13/1
Methanol - air/fuel ratio = 10/1
60 cu in Harley Davidson engine, I use 2/10 of a gallon on the 5 mile course, towing to and from ... Joe
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Hello All, :-D
Just had to reply quickly when I read the A/F ratio for Methanol.....WOW! The correct number would be closer to 5:1 than the 10 listed.
Not trying to be a wisenheimer :mrgreen:, but was afraid that one would slip by and hole a few pistons. :x
Running toward the rich side is always better than using aluminum for additional fuel. :roll: 8-)
Regards to All,
HB2 :-)
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And I forgot to add comments about the tank sizing: :-o
The return fuel needs to enter the tank so that it does not aerate the suction line. So make sure the return line is located in a place that will not disturb the suction line.
Sometimes the size of the fabricated tank is dictated by the real estate that is required for fittings and mounting more than how much fuel the thing needs to carry. Obviously it does not take too much volume for the task. Plan on a MINIMUM number at about 1lb/hp-hr which would be at an A/F ratio of about 6:1 and the preferred target of 5:1 would yield about 20% more fuel use. Consider having enough fuel on board to absolutely not encourage vortex generation (whirlpools) when the fuel level is low. :cheers:
Regards to All,
HB2 :-)
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JML,
The capacity related to the amount of fuel that you use is really not important, as stated by Harold the really important thing is to make the tank so that it provides your fuel pump with sufficient inlet conditions such that the pump does not cavitate. This includes making sure that the return line from the return jet (pill) is brought into the tank away from the port that is the pump inlet also this port must be below the normal level of the fuel in the tank. If the tank is very far from the pump make the tank tall so that the fuel level is above the inlet for the pump if possible, also placing the tank in front of the engine will provide some additional pump inlet charge from the acceleration of the car. A basic rule is that the size of the inlet line to the pump cannot be to big. Even if the pump only has a -8 inlet going with a -12 or -16 line will assist the pump inlet conditions. If you make the tank cylindrical and you take the fuel from the bottom, be sure to add a baffle across the tank near the bottom to prevent any vortexing. Lastly don't forget to put a breather in it to allow air to enter as the fuel level drops.
Rex
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My experiences is 2 to 1 on the ratio on the starting point. If you are making a tank and using aluminum have it HARD anidized (SP?) If your are planning on using a lot of gears and spinning it hard make sure you have enough. Pay attention to that inlet to the pump like the others said. Mine is a -12 with 300 inches and get enough pump to run at least 50%...You know you want to do.....Good luck
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I got to thinking how big a tank we'd need over our 5-gallon one to run alcohol rather than gas. Our C motor uses about 1 to 1 1/2 gallons a run including warm-up.
Then it dawned on me. We have to have the tank sealed because of the gas. With alcohol you could just fill it yourself after each run -- duh!
Actually you could use the same size tank for gas or alcohol because of this.
Stan Back
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I got to thinking how big a tank we'd need over our 5-gallon one to run alcohol rather than gas. Our C motor uses about 1 to 1 1/2 gallons a run including warm-up.
Then it dawned on me. We have to have the tank sealed because of the gas. With alcohol you could just fill it yourself after each run -- duh!
Actually you could use the same size tank for gas or alcohol because of this.
Stan Back
The sealed tank with gas is what made me design one big enough for hopefully a couple runs before I have to go back to the line at the fuel truck.
Hey you can line up behind me again as I got the oiling/smoking problem fixed on the truck finally :-D. What a mess that was :cry:.
c ya,
Sum
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Gasoline 20,943 BTU’s/lb - 14.7:1 air/fuel ratio - 1415 BTU’s/lb of air
Methanol 9,770 BTU’s/lb - 6.4 air/fuel ratio - 1527 BTU’s/lb of air.
Not as good a heat source as gasoline, but you can run more of it.
Methanol gets you about 22% more bang and runs much cooler. You will see ice on the fuel system on a cool day.
Roughly twice as much methanol as gasoline.
Nitromethane 5,160 BTU’s/lb - 1.7:1 air/fuel ratio - 3035 BTU’s/lb of air.
Nitromethane gets you 123% more heat. Even a little adds a bunch of power.
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Running toward the rich side is always better than using aluminum for additional fuel. :roll: 8-)
UNLESS, you're in my line of work :-D
Nick 3rd.
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Racing engines like all kind of things for fuel. If you are a little lean the engine witll just turn to other "stuff" into fuel... Pistons are easier because of the density. Rings are nice, valves are harder so it takes a little longer. Alumimun heads make quite a tasty meal and keep a lot of shops in business. I think a copper gasket might make nice little desert.................Good Luck
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I was looking at the engine and realized it's about 3/4 of a 327 Chevy Hilborn setup. I still have a question...is it ok to use the poly tanks or is anodized aluminum the only choice?
Thanks for all the help. We sure keep each other entertained with this hobby!!
I'll try to attach a quick pic of the engine sitting on the bench.
Thanks for all the help, again.
JimL
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Running toward the rich side is always better than using aluminum for additional fuel. :roll: 8-)
UNLESS, you're in my line of work :-D
Nick 3rd.
Boy have I learned that lesson.... got 2 sets of 3 pistons from Nick decorating my basement, my engine just likes to eat just one....
(http://mmeierle.com/images/Max/Red%20Engine/Number%203%20piston%203.jpg)
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The very reason I usually buy 6 pistons for my 4 cylinder motor.
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Many use poly. I don't know how the "foam" will react with methanol if you use it. Make sure you have an adequate mounting for the tank and hold downs can secure it during an accident. Good Luck. Nice looking engine.....as for pistons I always buy 8 for my six...............JD
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Gasoline 20,943 BTU’s/lb - 14.7:1 air/fuel ratio - 1415 BTU’s/lb of air
Methanol 9,770 BTU’s/lb - 6.4 air/fuel ratio - 1527 BTU’s/lb of air.
Not as good a heat source as gasoline, but you can run more of it.
Methanol gets you about 22% more bang and runs much cooler. You will see ice on the fuel system on a cool day.
Roughly twice as much methanol as gasoline.
Nitromethane 5,160 BTU’s/lb - 1.7:1 air/fuel ratio - 3035 BTU’s/lb of air.
Nitromethane gets you 123% more heat. Even a little adds a bunch of power.
On a previous team I was told it was
gas: 13:1
methanol: 8:1
70% nitro/29% methanol/1% benzene: 2:1
By Dean's numbers, we would have been rich on gas and lean everywhere else. From what I have seen here, I'd use 6.5:1 as a planning figure. Although I would never run methanol over a lambda of 1.1 for fear of washing the oil film off. JMHO.