Timing Advance for Best Mileage?

[JohnGunn]

What have you found to be the best timing advance for optimal fuel economy on your stock, fuel injected Festiva with 5-speed.

And by what process did you come to that number?

Your input will help me as I design my own experimentation.

Thanks in advance.

John Gunn
Coronado, CA

[TominMO]

Other than to say more is generally better, I don't know that anyone has done any definitive experimentation on this. When Kittystiva was stock, I could have tried this, but I never could find the timing marks on that timing belt cover. Maybe they weren't there anymore.

What I would have done is do the same mileage runs I did with other variables: I had a specific highway loop around the city I would use for every test, and run it at various speeds. I tried to keep air temp and wind variation at a minimum when testing. No reason you couldn't do something like this too, at a specific speed, with different timing settings.

My guess is that maximum timing, or close to it, would give the best results, because less pedal (gas) would then be needed. Of course you would want to use only the highest-octane gas for all tests, to eliminate the chance for detonation, and so the gas itself would not be a variable. Fill the tank to the max every time, try to have the left rear to be the highest point to help eliminate bubbles in the tank, and bounce the rear bumper for the same reason.

[eurotiva]

Premium gas will offset the savings of running the timing advanced. IMO. I used to run mine at 10* BTDC. But I used 93 octane gas and didn't care about mileage. As for Tom's blue car it's now at 2* BTDC, and will require good gas.

[TominMO]

Premium gas will offset the savings of running the timing advanced. IMO. I used to run mine at 10* BTDC. But I used 93 octane gas and didn't care about mileage. As for Tom's blue car it's now at 2* BTDC, and will require good gas.

True on cost, they will probably even out more or less. But you will also have a much peppier Festy in the bargain, so it's a win anyway.

Edit: I forgot to mention in the earlier post that I also opened up the lower airbox half for better high-RPM breathing. Costs nothing and doesn't affect mileage, if you just drive to get good mileage.

[ryanprins13]

hey, I realize this thread is old, but i am wondering if anyone has tested or played with this more. Timing will be slightly more retarded for turbo or high compression cars and more advanced for stock or worn engines, and since this thread was about stock engines and im interested in a worn B3... It looks to me from searching online that 12-14 degrees btdc would work well on a stock 1.3 with low compression. Here is a link to a page about setting the mazda 1.6 timing for more power http://www.miata.net/garage/KnowYourCar/S10_Timing.html
Do you guys agree? Any other thoughts or experiments done? Reading through the hundred other threads about ignition timing it seems to always be 'advance it till it knocks and then retard it a bit'. I'm just wondering if anyone has gotten fancier or more precise than that. I'm hoping to kind of set it close and leave it rather than playing with it every day and trying to figure it out in different temperatures, sun/rain and so on without having a good unpopulated area to really test it on my way to or from work.
Thanks.

[ryanprins13]

Well i went to set mine last night with a timing light and the timing marks were way off. As in like 3 or 4 inches towards the firewall from where they should have been. Tried all the other spark plug wires even though i knew i started with cylinder 1 but they were all out too. So after spending too much time trying to figure that out i marked the dist and tried moving it around each way and taking it for a rip each time. Advanced a bit from where it was seemed to work the best, however its hard to tell and the distributor is advanced almost all the way, so theres got to be something wrong. Runs perfect though. When i change my spark plugs next i will stick a dial indicator in there and mark my pulley, set the timing proper, then fine tune from there.


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[drddan]

Did you ground the STI when you checked timing? The STI must be grounded

[bhearts]

Theoretical best mileage would be as close to 0 as possible. The best ways to create more cylinder temps would be a warm air intake. High compression ratio.

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[ryanprins13]

Did you ground the STI when you checked timing? The STI must be grounded

I did, yes. Not much difference grounded to not grounded but did it grounded.

Theoretical best mileage would be as close to 0 as possible. The best ways to create more cylinder temps would be a warm air intake. High compression ratio.

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0 as in sparking at top dead centre? I dont know a ton about it but i would think that you would need super high compression, 2 spark plugs per cylinder and probably a shorter stroke for that to even work. On an engine like ours i cant see that working, would you mind explaining that a bit more to me?
Thanks.

[bhearts]

I did, yes. Not much difference grounded to not grounded but did it grounded.

0 as in sparking at top dead centre? I dont know a ton about it but i would think that you would need super high compression, 2 spark plugs per cylinder and probably a shorter stroke for that to even work. On an engine like ours i cant see that working, would you mind explaining that a bit more to me?
Thanks.

You don't want to just turn the spark timing down, you want to force your engine to have to run that low of timing advance

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[bhearts]

Other things, like trying to run with your throttle body all the way open, to minimize intake restriction. This could also be accomplished by running hot intake air, and or an air displacement, like steam.

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[bhearts]

If you could suck in 1-300 degree air, you could then flash boil water from a spray nozzle.

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[FestYboy]

But why would you want to flash boil the water mist before it gets into the chamber? Given the expansion rate of water to steam, that extra potential pressure would be more beneficial used as extra cylinder pressure (torque)

[bhearts]

But why would you want to flash boil the water mist before it gets into the chamber? Given the expansion rate of water to steam, that extra potential pressure would be more beneficial used as extra cylinder pressure (torque)

I think that could be true if you were in abundance of cylinder temp from the beginning. Like with a head mil. But you wouldn't want to take any more precious heat from the combustion chamber in cooler weather. These engines already fight to maintain equilibrium in the winter. So I'm implying that you use the waste exhaust heat to warm up your intake charge, to recycle some of that waste energy.

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[bhearts]

And spray the mister in where evs. Preferable closest to the vacuum source so it boils and doesn't have time to puddle.

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