what fuel to use?
#1
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The last track weekend I ran, it cost me 280.00 in fuel for 28 gals of 100LL. This next race, I'd like to enter into 2 classes and am looking to save a buck (or a small fortune) in fuel costs.
I would like to look into other options:
I can cut 110 race gas (8.00/gal) with 50% 92 pump gas and get 100 octane for approx 6.00/gal. (would this cut the lead enough to work with O2 sensor?)
or, I can get 100LL Av gas for 5.65/gal.
I know that there are many racer opinions on what fuel makes the most power, etc. I'm more interested in knowing what the turbo miata racers have found.
What fuel grade have you run successfully/unsuccessfully on the track?
Does a standard race prepped 1.8 running 12# boost even require 100 octane?
I would like to look into other options:
I can cut 110 race gas (8.00/gal) with 50% 92 pump gas and get 100 octane for approx 6.00/gal. (would this cut the lead enough to work with O2 sensor?)
or, I can get 100LL Av gas for 5.65/gal.
I know that there are many racer opinions on what fuel makes the most power, etc. I'm more interested in knowing what the turbo miata racers have found.
What fuel grade have you run successfully/unsuccessfully on the track?
Does a standard race prepped 1.8 running 12# boost even require 100 octane?
#7
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Around these here parts we have 93 octane so we use it to tune. If I hit detonation, I take 4 degrees out depending upon the IATs when that det occurred. With low compression I think I can run 91 octane on my 93 octane tune because I never saw detonation, but I always take a few gallons of 93 when I go to OK to bring the octane up a little. I have too much money in this car to make mistakes like that.
#8
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Go to paint store, buy toluene by the drum, mix, win.
Quick find--> Vintage Triumph Register - VTR
Little bit of info
Formula #1 - Toluene
R+M/2.........114
Cost...........$2.50/gal
Mixtures with 92 Octane Premium
10%...........94.2 Octane
20%...........96.4 Octane
30%...........98.6 Octane
I use to mix 10% in my old 200sx SE-R for completely legal late night weekend races in warehouse districts. I could crank the timing up a lot before det. I don't honestly know how high of a mixture I could go. Quirt (guy i use to work for) said more than 10% could cause issues with the fuel system or filter. Or that was when we were mixing alcohol, can't remember. Now that this has come up I'm going to hunt around for local paint supply shops. I never had any issues, but I didn't run it ALL the time. Just for funs
Quick find--> Vintage Triumph Register - VTR
Little bit of info
Formula #1 - Toluene
R+M/2.........114
Cost...........$2.50/gal
Mixtures with 92 Octane Premium
10%...........94.2 Octane
20%...........96.4 Octane
30%...........98.6 Octane
I use to mix 10% in my old 200sx SE-R for completely legal late night weekend races in warehouse districts. I could crank the timing up a lot before det. I don't honestly know how high of a mixture I could go. Quirt (guy i use to work for) said more than 10% could cause issues with the fuel system or filter. Or that was when we were mixing alcohol, can't remember. Now that this has come up I'm going to hunt around for local paint supply shops. I never had any issues, but I didn't run it ALL the time. Just for funs
#10
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"Race Fuel" actually has somewhat slower flame propagation than "Pump Gas." The higher flash point and slower flame front are two of the things that help prevent detonation. but if your spark and fuel maps are not optimized for this there are literally THOUSANDS of back to back dyno runs that show "Race Gas" in a car tuned for "Pump Gas" will actually make LESS power.
#11
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AVGAS is designed to work on engines with huge pistons, long strokes and 2700 maximum RPM. Great octane, but you couldn't have picked a worse fuel for a Miata. Modern car engines try to prevent det by having a well-controlled fast burn. Mazda's Skyactive is one of the ultimate expressions of this.
Anyway, you're much better off with pump gas than with AVGAS. And that doesn't even include all the lead deposits.
I run some AVGAS in the 440 in my Sport Fury (mainly to get some lead to the exhaust valve seats), but even there I cut it. There are lots of old school anectodal stories about hot rodders running a tank of the old 130 purple avgas (designed for B-29 bombers) in their 442/GTO/GTX/fill in the blank and melting their mufflers. That's the wrong place for the heat.
The slow burn might help spool though. Hmmmm . . . .
#12
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"Race Fuel" actually has somewhat slower flame propagation than "Pump Gas." The higher flash point and slower flame front are two of the things that help prevent detonation. but if your spark and fuel maps are not optimized for this there are literally THOUSANDS of back to back dyno runs that show "Race Gas" in a car tuned for "Pump Gas" will actually make LESS power.
Honestly if you det on the track with the fuel you were tuned with I would look at your iat and/or ect spark compensation. I bet you need to pull more timing but only under the iat/ect conditions that it happens.
Last edited by Leafy; 08-02-2012 at 12:15 PM.
#17
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As for the OP, if E85 isn't possible, just use pump gas and a few gallons of high octane stuff for safety and adjust the tune accordingly.
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92 octane E0 is available at the Kwik Gas on MLK across the freeway from PIR. I find that my car likes E0 quite a bit more than E10 - I would get some pinging with E10 that isn't there with E0.
There's no need for 100 octane for you that I can see. Stock ecu (tweaked a bit), and moderate boost levels. Maybe throw in some toluene each tank.
There's no need for 100 octane for you that I can see. Stock ecu (tweaked a bit), and moderate boost levels. Maybe throw in some toluene each tank.