Tuning stock engine for premium

[ryanprins13]

Hey, so probably a dumb question but i did a fair bit of reading on my phone this evening while trying to fix my computer (still waiting for it) and saw a few things. 1: ethanol fuel gives you less mpg 2: gas stations near here sell non ethanol fuel only in premium and they are a 'top tier' gas supposedly having lots of cleaning agents. 3: its $0.20/L more for premium. ( 59.9/L regular and 79.9/L premium (94octane i think)).
So just for fun would it be worth it to reset the ecu and run a couple tanks of premium to see what it does? My timing is currently set properly and running leaner would be ideal for better mpg so could i advance the timing a bunch with premium? Running non-ethanol is supposed to increase fuel milage 4%, would being able to advance the timing give me 5-10% or not? I realize it would not be enough to offset the cost of the premium gas, i would need a 33% increase for that, but it would be fun to see a 10% increase in the fuel milage numbers for a bit, then go back to regular. I got 43 us mpg last 2 tanks ( up from 41 avg after using seafoam!) and i would have to get 57.5 with premium for it to cost match so i dont expect that.
So my question is, is it possible just doing simple stuff to my stock 1993 B3 efi to optimize it for premium gas? Like changing the spark timing or something. Or would there be no point to trying this at all?
Thanks.


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[blkfordsedan]

Compression and chamber design is really what determines the need for higher octane. It will allow you to run more ignition timing, but that doesn't always mean more power or efficiency. It depends on the engine. That said, you will see an increase in MPG using non-ethanol fuel. You can bump your timing a few degrees if you want and see how it does, it may help, but you don't have to. You can burn Premium just fine on stock timing....and you could probably get by with a few degrees more timing even on regular fuel.

On my 97 F250 (5.8L), I would get 15mpg on stock timing (7*)and 89 octane E10 fuel. I could pull 17mpg on stock timing and 87 octane non-ethanol. I bumped the timing up to 10* and went back to 89 octane E10, and was able to pull 18mpg....but the truck ran MUCH better at 10* timing. E10 fuel was .10/gal cheaper, so that was the best of both worlds. Unfortunately, they re-blended local E10 and now it's only 87 octane. The truck wouldn't tolerate 10* of timing on 87 octane, so now I'm back down to 15mpg.

[bhearts]

Theoretically for fuel economy, the least timing the better. The less the piston has to fight against the fire the better your mpg. Which could mean that even 85 octane with less timing could net you the best economy.

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[ryanprins13]

So one says advance timing and another says retard it? :p Guess ill have to do more research on the topic before i try it. After thinking about it some more i will probably wait until summer anyway when my mpg numbers are up from the warmth. Thanks for the replies!


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[bhearts]

It's not about turning it down though. It's about maximizing the flame speed so you have to turn it down. Higher compression,

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