What's a safe fuel/air ratio for open track - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 9 Old 09-23-2009, 02:50 PM Thread Starter
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What's a safe fuel/air ratio for open track

Going to get my new motor tuned and need to make sure that it is set up for a good safe fuel/air ratio for open track. This is a dedicated track car so I'm not concerned with any type of street driving ability. I would think that the type of on the gas/off the gas driving it will see that it needs to be set up just a shade on the rich side. Am I on the right track? (no pun intended)


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post #2 of 9 Old 09-23-2009, 05:11 PM
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I shoot for 12.9 - 13.0 at WOT. Also a track only car. Plugs, everything else looks fine after 40 hours on the Watts.

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post #3 of 9 Old 09-23-2009, 05:22 PM
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It's naturally aspirated, right?
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post #4 of 9 Old 09-23-2009, 06:58 PM
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I see 12.9 to 13.5 on my LC-1 on my WOT spurts. This is a fairly stock ModMotor car, not sure if relates to your application. 93 octane, 260-ish whp
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post #5 of 9 Old 09-23-2009, 09:53 PM
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Fueling is important and can help to control engine temps. Too hot? Try adding some fuel. Many say that 12.5:1 is pretty close to ideal for power production, and is a little "safer" than a 13:1 ratio in terms of controlling combustion temps and therefore avoiding burned pistons.

The other key to a safe tune is ignition timing. Don't get greedy with timing. Find your timing for power then back off a couple degrees. Leaving a few HP behind is cheap compared to what can happen if you get greedy and get detonation.

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post #6 of 9 Old 09-24-2009, 07:22 AM Thread Starter
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Quote:
Originally Posted by mlanoux View Post
It's naturally aspirated, right?
That's correct. Dart347, TW205's, 75mmTB, 90mmMAF, 42#injectors

Larry95
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post #7 of 9 Old 09-24-2009, 11:06 PM
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Quote:
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That's correct. Dart347, TW205's, 75mmTB, 90mmMAF, 42#injectors
If you don't get about 450 HP and 450 lb/ft torque out of that, you're doing it wrong. What kind of cam, intake and exhaust?

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Last edited by a79coupe; 09-25-2009 at 05:54 AM. Reason: speeelin
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post #8 of 9 Old 09-25-2009, 09:21 AM
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This is one of my tunes back in 2004, where I was running out of MAF cpacity, and started to run "lean" (at 12.0+)...
Yeah, running this rich hurts power... but after 10 years and 37K miles on ORIGINAL shortblock, still doing fine.
I re-tuned and get pig-rich like 10.8 (opposite of this graph), dumping fuel at 5800+ for a "soft-touch" rev limiter...

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post #9 of 9 Old 09-28-2009, 05:33 PM
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What is the compression ratio on the motor, and what type of fuel are you running?

General rule of thumb for my track cars: 9.0:1 - 10.0:1 93 octane be conservative on the timing side and look for a 12.0-12.3 under wot.

Anything over 10.0:1 I would run 100 in it between 12.2-12.5.

There are a whole lot more variables than this, but, here is what I start with. I have about 5000 miles on my track car motor with no issues
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