How to tune for best gas MPG
#31
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pick away
first I would say though that if you are looking at it from an economic standpoint it would not be beneficial to do the 120 mile RT.
However, from a performance standpoint that is a totally different story. I used to drive 45 miles to get it for my s/c car b/c it absolutely needed it.
first I would say though that if you are looking at it from an economic standpoint it would not be beneficial to do the 120 mile RT.
However, from a performance standpoint that is a totally different story. I used to drive 45 miles to get it for my s/c car b/c it absolutely needed it.
#32
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Here's a quote from Jim, one of the megasquirt gurus that may be able to shed some light on things for you. He seems to think that adding 2 degrees of advance for every point of leaning the AFR beyond 13:1 does the trick. I think the best way to really do a good job is to get some mustang dyno time and really dial in the maximum power in the cruise and low load zones by leaning and advancing the timing until power starts coming down. Obviously don't do this in high load zones or you'll pop the engine in a hurry.
The EGTs "may" go up if you don't have enough advance for the
particular mixture you are running ,
they won't go up for instance if you go from 13 to 15 AFR ,
but the ignition advance needed to produce
peak pressure at 14 degrees ATDC will change by ~5 degrees or so .
If Peak Pressure is late things get too hot ,
If Peak Pressure is too early you get into detonation ,
13 to 1 AFR burns fastest ,
all mixtures above and below 13 require more advance because they burn slower .
"Slowing the burn down" by running rich is
the old skool way of backing off the ignition advance when
you have no other means of adjusting the timing for boost .
particular mixture you are running ,
they won't go up for instance if you go from 13 to 15 AFR ,
but the ignition advance needed to produce
peak pressure at 14 degrees ATDC will change by ~5 degrees or so .
If Peak Pressure is late things get too hot ,
If Peak Pressure is too early you get into detonation ,
13 to 1 AFR burns fastest ,
all mixtures above and below 13 require more advance because they burn slower .
"Slowing the burn down" by running rich is
the old skool way of backing off the ignition advance when
you have no other means of adjusting the timing for boost .
#33
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st: i would love any help to reach my goal, thanks ![Cheers](https://rennlist.com/forums/images/smilies/beerchug.gif)
re: e-85
Jeez.. there are only a couple of e-85 stations in NY, the nearest is 60 miles away from me.. but it's only $2.90/ga.
for me locally :
87 octane is @ 4.01 9/10
89 is @ 4.12
92 is @ 4.22!
So the savings would be $1.32/gallon. X23 gallons (irrc) = $30.36 per tank.
Say it would be ~4.3 gallons to go 120miles @ 28 mpg = $12.47 cost
That makes a savings $17.89/tank, even though I have to travel 120 miles round trip to get e-85.
I think I'm going to have both a 92 octane and e-85 tune..
blown_944/rouge ant, mind if I pick your brains about tuning w/ e-85?
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re: e-85
Jeez.. there are only a couple of e-85 stations in NY, the nearest is 60 miles away from me.. but it's only $2.90/ga.
for me locally :
87 octane is @ 4.01 9/10
89 is @ 4.12
92 is @ 4.22!
So the savings would be $1.32/gallon. X23 gallons (irrc) = $30.36 per tank.
Say it would be ~4.3 gallons to go 120miles @ 28 mpg = $12.47 cost
That makes a savings $17.89/tank, even though I have to travel 120 miles round trip to get e-85.
I think I'm going to have both a 92 octane and e-85 tune..
blown_944/rouge ant, mind if I pick your brains about tuning w/ e-85?
What is your average mileage today with the car?
#34
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Was that with e85 or normal fuel... if the latter, what octane?
Good thread btw... especially the e85 stuff - some great info. thanks Rogue and Sid.
#35
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Rouge thanks for the info!
blown 944 thanks for your previous pm info! Your guys thoughts and numbers are pretty close. I have everything I need and I will be E85 ready in 2 weeks
blown 944 thanks for your previous pm info! Your guys thoughts and numbers are pretty close. I have everything I need and I will be E85 ready in 2 weeks
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#38
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That was with 91octane gas. I doubt I will be able to get that good with E85... I really haven't tried yet because I can't keep my foot out of it
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Nize, no need to be patronizing. I really don't want to debate the point, besides I don't see anyone else posting about 30+mpg..
Your vehicle requires MUCH less fuel to lightly accelerate downhill then to maintain speed uphill. So by doing this you increase speed downhill and shed speed going uphill. Think rollercoaster.
I would suggest you try some of the things discussed in this thread, especially since you have a stand-alone to play with.
-Rogue
Your vehicle requires MUCH less fuel to lightly accelerate downhill then to maintain speed uphill. So by doing this you increase speed downhill and shed speed going uphill. Think rollercoaster.
I would suggest you try some of the things discussed in this thread, especially since you have a stand-alone to play with.
-Rogue
#43
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Instead of posting a new thread on the other board, it would probably be easier here. There's a new place serving e85 near where I commute weekly, is it worth getting some? Or would it be a bad idea from erroding my fuel system or whatever? (I drive a late '87 by the way)
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I suggest replacing the rubber lines before going to E85. Also, unless you have a way to tune the car, and a WBO2 then stick with Gas.
-Rogue
-Rogue
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Nize, no need to be patronizing. I really don't want to debate the point, besides I don't see anyone else posting about 30+mpg..
Your vehicle requires MUCH less fuel to lightly accelerate downhill then to maintain speed uphill. So by doing this you increase speed downhill and shed speed going uphill. Think rollercoaster.
I would suggest you try some of the things discussed in this thread, especially since you have a stand-alone to play with.
-Rogue
Your vehicle requires MUCH less fuel to lightly accelerate downhill then to maintain speed uphill. So by doing this you increase speed downhill and shed speed going uphill. Think rollercoaster.
I would suggest you try some of the things discussed in this thread, especially since you have a stand-alone to play with.
-Rogue
the advantage to using cruise control, which surprisingly nobody here has pointed out yet, is that it's much more consistently smoother than any human operating the gas for long periods of time. smooth = gas economy.
also, as you have pointed out, my ems has a 'autopilot' mode where if certain conditions are met (minimum tps movement, minimum engine load, rpm change, low boost, etc.), it will automatically run in closed-loop mode and try to maintain whatever AFR has been pre-set (in my case, 16:1). the easiest way to activate this is to turn the cruise control on.
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it's too boring to drive this way so i haven't fully tested it yet, but i have some long (400+mile) drives coming up this summer so i'll try it out and report back.