Whats "Perfect" Air/Fuel Ratio???
#1311457
09/27/12 12:37 PM
09/27/12 12:37 PM
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Joined: Sep 2003
Posts: 2,008 Sweet Home Alabama
MRMOPAR622
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Running Ron's Terminators on alcohol with 15.5 CR whats the perfect air/fuel ratio? While on dyno might as well get everything as close to "Perfect" as possible,I have been doing my tuning by the ET slips but while I'm spending the Big $$$ for the dyno time I want to get all I can.
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: MRMOPAR622]
#1311458
09/27/12 01:02 PM
09/27/12 01:02 PM
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Joined: Jan 2003
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440Jim
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There is no "perfect" air/fuel ratio. Each engine will like a slightly different value, since the BSFC (a measure of efficiency making power from fuel) will be different. But with a Ron's alcohol injection, a good starting point is Lambda = 0.835 Methanol scale = 5.35 (5.2 to 5.5) Gasoline scale = 12.3 (12.0 to 12.6) What values have you seen on the track so far? I highly recommend talking to James or Scott at www.killerrons.com
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: MRMOPAR622]
#1311459
09/27/12 01:12 PM
09/27/12 01:12 PM
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Joined: Oct 2007
Posts: 4,205 New York
polyspheric
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master
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One big advantage of running methanol is that too rich loses very little power (compared to gas). What is occasionally described as "perfect" is the stoichiometric ratio, which is what proportions of air and fuel are needed for there to be none of either substance left over when combustion is complete. It's interesting to read, but has no practical application.
Boffin Emeritus
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: MRMOPAR622]
#1311461
09/27/12 02:24 PM
09/27/12 02:24 PM
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Joined: Aug 2003
Posts: 43,095 Bend,OR USA
Cab_Burge
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I Win
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Quote:
Running Ron's Terminators on alcohol with 15.5 CR whats the perfect air/fuel ratio? While on dyno might as well get everything as close to "Perfect" as possible,I have been doing my tuning by the ET slips but while I'm spending the Big $$$ for the dyno time I want to get all I can.
Don't waste your time and money trying to find the perfect tune on the engine dyno, we don't race dyno's Get it close to max so you have a base line to start with,make sure and get the weather data, baro. pressure, temp and humidity as well as the actual altitude of the dyno cell your using, then when you put the motor back in tha car you have a decent starting point The type of alcholol can vary batch to batch so make sure you have a alcholol hydrometer to keep track of the specific gravity of the alcholol you buy and then tune off of the time slip and spark plug If your going to use a wide ban system to tune off of make sure you buy the correct NTK brand and part number sensor for alcholol, they are not as cheap as the Bosch and other gasoline sensors so don't be suprised on the price of them There worth the extra money if you want a very accurate reading from your AFR system
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: GomangoCuda]
#1311463
09/27/12 05:12 PM
09/27/12 05:12 PM
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Joined: May 2003
Posts: 6,558 Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
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Downtown Roebuck Ont
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Quote:
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One big advantage of running methanol is that too rich loses very little power (compared to gas). What is occasionally described as "perfect" is the stoichiometric ratio, which is what proportions of air and fuel are needed for there to be none of either substance left over when combustion is complete. It's interesting to read, but has no practical application.
which would be 14.7:1.
All of the posts above yours were refering to methanol. 14.7 is stoic for gasoline which is much different than meth. Besides stoic is a lab experiment not a drag race. Like Poly said "it has no practical application". You'll find 440jim's numbers far more useful.
No practical application for this discussion perhaps but it does have its place.
Kevin
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: 440Jim]
#1311465
09/27/12 08:48 PM
09/27/12 08:48 PM
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Joined: Jan 2003
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440Jim
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I Live Here
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Quote:
But with a Ron's alcohol injection, a good starting point is Lambda = 0.835 Methanol scale = 5.35 (5.2 to 5.5) Gasoline scale = 12.3 (12.0 to 12.6)
Trust me. I run a Ron's Toilet. If you don't have track data to do any different, this will be close. Like somebody posted, methanol will allow error on the rich side of my range with little difference.
What CID and rpm do you cross the finish line at? In some applications (head limited), those systems can go rich near the finish line. They have a high speed (rpm) bypass to avoid going rich (less than 0.81 Lambda)
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: 440Jim]
#1311471
09/28/12 10:24 AM
09/28/12 10:24 AM
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Joined: Jan 2004
Posts: 903 Saskatchewan, Canada
cudabin
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super stock
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As usual, 440 Jim is giving great advice. My 15.5 to 1 Alky motor made best power on the Dyno with a 37 nz, 76 pill combination. At the track, it ran a lot faster with 38 nz, 76 pill. Richer worked better to accelerate the car all the way down track... Alky is very forgiving on the tune up, so have fun and let us know what you learn. Arnie
67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...)
70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: cudabin]
#1311472
09/28/12 08:19 PM
09/28/12 08:19 PM
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Joined: Sep 2003
Posts: 2,008 Sweet Home Alabama
MRMOPAR622
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Thanks everyone for the Great advice I always say the ET slip is the only True tuning tool.But it will be nice to have a little more insight going into the dyno session. I have found also alcohol has a wider tuning range and is more forgiving than gas. As for reading the plugs running alcohol I'm lost they always look new no discoloration except on the treads. They have discoloration about 2 1/2-3 treads up on the plug,which I have been told by the Tech's @ Ron's is fine. I had Rons set mine up so I was close at the start on the tune up,and just fatten it up a little going to a smaller pill in the return.Again THANKS everyone
Last edited by MRMOPAR622; 09/28/12 08:20 PM.
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: MRMOPAR622]
#1311473
09/28/12 09:04 PM
09/28/12 09:04 PM
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Joined: Jan 2004
Posts: 903 Saskatchewan, Canada
cudabin
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super stock
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If you start at 30 degrees total timing and go up 2 degrees at a time, you should be able to find the spot where the plug strap coating is burnt off just at or slighty past the curve towards the base of the strap...
For my Indy -1 heads that turned out to be 34 degrees total using NGK -9 heat range plugs.
What nozzle/pill are you starting at, and which pump? Mine is the black 0 -1/2 gear pump.
Keep us posted!
Arnie
67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...)
70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: 440Jim]
#1311474
09/29/12 01:42 AM
09/29/12 01:42 AM
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Joined: Jul 2010
Posts: 1,491 Oologah, Oklahoma
Big Squeeze
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As you know, it's the same process.... whatever makes the most hp is usually what you shoot for although that sometimes isn't the fastest way down the track and if the car leaves very hard the tuning process starts all over again at the track...
In my car with alcohol injection, I found slightly richer made more torque and improved the ET in the very beginning 60, 330. But slightly leaner made more mph, ie hp. But still in the ranges I posted.
If it was me, I would record the fuel curve (and tq/hp) vs rpm for several barrel valve bypass pills. That way you know what each change will do at the track. Typically in those systems, a 4 number change (76 to 80) in the bypass pill is one step; but a 2 number change could be optimal.
That's another good point that most people don't know/understand...as the RPM goes up there's less fuel fallout so you don't need as much fuel at the top of the RPM curve...depending on how big the sweep is and how fast the motor revs, you can go .5 to 1 full point richer in the fuel curve...and that's the exact same reason why you can go leaner on nitrous than you can naturally aspirated...
If you can't handle the truth, you're living a lie.......
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Re: Whats "Perfect" Air/Fuel Ratio???
[Re: Big Squeeze]
#1311475
10/01/12 06:27 PM
10/01/12 06:27 PM
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Joined: Sep 2003
Posts: 2,008 Sweet Home Alabama
MRMOPAR622
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I have been running alcohol for about 3 years now and I'm just not happy with anything other than perfection. In order to have perfection you must have knowledge and the more the better,so I have really been putting a lot into learning and trying to figure out this alcohol lately.If I can fine tune one on gas I should be able to do it on alcohol as well.I think I have figured out my spark plug problem...well not a problem but burning so clean they look new and make it almost impossible to tune the engine reading the plugs. I think the alcohol is washing,cleaning the plugs. I may have to try something other than the Champion plugs to see if I can get a better reading of them. Also talked to a dyno operator and he said he knew of no way to measure the air & fuel coming through the injectors to get the correct ratio injection like on carbs. now looking for another dyno operator!
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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