benjamachine Posted June 22, 2009 Share Posted June 22, 2009 greetings, friends! i have an '86 GL wagon with a normally aspirated, carbureted EA82, and am hoping someone can shed some light on a few facets of engine performance that might be tinkered with to get better mileage, and maybe even a little more power (don't worry, i have no delusions that this will ever be a speed demon of a car). the main thing is, as i am in california, i can't afford to do stuff that messes with the emissions controls, and don't want to anyway, as i've found that tinkering with hoses and isolating vacuum operated devices degrades fuel economy and makes me fail smog testing. it gets 30 mpg on the freeway, but it would be kind cool to get a couple more mpgs. 1. ignition advance: it's set at the factory-recommended 8-degrees BTDC. will advancing it a bit make fuel economy suffer? will it make the engine run too hot? 2. exhaust: my muffler fell off, and i think it sounds cool. as long as i warm it up before putting a heavy load on the engine, it doesn't backfire...too much. (hmmm...what IF i had a swappable exhaust - y'know, for smog - that somehow didn't include a cat, but did have a solid turbo muffler to maintain backpressure?) 3. intake: if i fashioned an open back and side scoops on the air box, would that improve performance at all, or just lean out the mixture? 4. any other little tweaks i could make? i want to stay conservative here so that i don't get into huge mods to balance improvements made. cheers, -b Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 22, 2009 Share Posted June 22, 2009 greetings, friends! i have an '86 GL wagon with a normally aspirated, carbureted EA82, and am hoping someone can shed some light on a few facets of engine performance that might be tinkered with to get better mileage, and maybe even a little more power (don't worry, i have no delusions that this will ever be a speed demon of a car). the main thing is, as i am in california, i can't afford to do stuff that messes with the emissions controls, and don't want to anyway, as i've found that tinkering with hoses and isolating vacuum operated devices degrades fuel economy and makes me fail smog testing. it gets 30 mpg on the freeway, but it would be kind cool to get a couple more mpgs. I commend your efforts. Sadly you won't see much better than 30 MPG in mileage and anything you do for performance is only going to use *more* fuel to get there. Your engine is an air pump - all it does is move air from the intake to the exhaust. It does this by mixing in a small amount of flammable vapor and then igniting the mixture to create a motive force on the pistons. To increase effeciency you have to move MORE air with LESS fuel. To increase power you have to get more motive force from each cylinder full of air - that means MORE fuel. Best mixture for economy is around 14.5:1 Best mixture for power is around 12:1 Those are general rules but as you can see your goals are very much at odds with one another. The more you increase the performance (and drive it like you stole it) the worse your effeciency will be. 1. ignition advance: it's set at the factory-recommended 8-degrees BTDC. will advancing it a bit make fuel economy suffer? will it make the engine run too hot? More advance is always better but you risk pinging if you go too far. Advance it till you get pinging then pull back a degree or two. 2. exhaust: my muffler fell off, and i think it sounds cool. as long as i warm it up before putting a heavy load on the engine, it doesn't backfire...too much. (hmmm...what IF i had a swappable exhaust - y'know, for smog - that somehow didn't include a cat, but did have a solid turbo muffler to maintain backpressure?) If you have backfireing it's due to holes in the y-pipe or a malfunctioning air injection system. Leave the y-pipe stock for best scavenging effect and run a 2" open system all the way out. A resonator and a cherry bomb will do nicely for a decent rumble without being obscenely loud. 3. intake: if i fashioned an open back and side scoops on the air box, would that improve performance at all, or just lean out the mixture? It would do precisely nothing. The stock airbox is more than sufficient for the demands of the engine. 4. any other little tweaks i could make? i want to stay conservative here so that i don't get into huge mods to balance improvements made. Being that you are unwilling to remove the carb and replace it with a Weber or fuel injection..... sadly the answer is no. If I were you I would take pictures, label everything, and remove the entire manifold. Install a used manifold with a Weber and then swap back when you need to pass smog. Or just swap the whole engine out. It's not really that difficult. If you were to get a used engine you could pull it and change back to your "smog" engine in a matter of hours. GD Quote Link to comment Share on other sites More sharing options...
Jerry DeMoss Posted June 22, 2009 Share Posted June 22, 2009 Well put. I totally agree. Quote Link to comment Share on other sites More sharing options...
Caramanos2000 Posted June 23, 2009 Share Posted June 23, 2009 I have gained quite a few mpg by doing the following: Swapped Auto to 5 spd Over inflated tires by 1-2psi 2" exhaust with cherry bomb use MMO in fuel and in oil replaced pcv replaced air filter Seafoamed the engine cleaned all the intake tubbing replaced o2 sensor Use ngk plugs or Autozone +4 plugs Installed MSD Blaster 2 coil Quote Link to comment Share on other sites More sharing options...
benjamachine Posted June 23, 2009 Author Share Posted June 23, 2009 thanks all very much for the responses! ok, so increasing power decreases economy. does that include advancing the timing and installing a weber? i read somewhere that despite a host of performance mods, you can only get about 100 horsepower out of these mills anyway. Quote Link to comment Share on other sites More sharing options...
Caramanos2000 Posted June 23, 2009 Share Posted June 23, 2009 100hp is being very generous :-\ Quote Link to comment Share on other sites More sharing options...
Numbchux Posted June 24, 2009 Share Posted June 24, 2009 100hp is being very generous :-\ I'd go as far as to say 100hp out of a carbed, cali-model N/A EA82 isn't possible. fuel economy is a mysterious lady. yes, an engine with more power to give CAN mean it doesn't work as hard to maintain speed. But, as GD said, usually not. Generally speaking, intake and exhaust restrictions can fit under this category, specifically speaking about your car, the intake is fine (as long as the filter is in good shape), but there is a bit to be gained from the exhaust. a weber carb would allow you to tune it more specifically, and make the engine much more efficient. which would probably yield better power AND mileage (once/if it's tuned correctly). but you'd risk smog failure. an SPFI swap might not though....but I don't know the specifics. all the vacuum solenoids and crap that are under the hood of that car are definitely not necessary for efficiency's sake. but you might be right in saying that messing them will risk failing smog. BUT, vacuum leaks will hurt everything. so depending on the condition of them, it might be a big help to go through there and replace a bunch of those hoses. as mentioned, 30mpg is awesome for your car. my '85 cali-spec carbed EA82 was lucky to see 20. that thing was the biggest POS subaru I've ever owned, and just because of all the cali-spec garbage. considering your situation, I'd say the only "modification" that might help is exhaust. free it up after the cats, and you might gain a bit. Then just tune-up stuff. plugs, wires, cap, rotor, filters, 02 sensor (my '85 had one.....), etc. Quote Link to comment Share on other sites More sharing options...
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