ea82 carb gas mileage driving?

[RichLo65]

hey, i am new to subies, and have been on this forum for a little while. but i do have 1 question.... i have 29" tires, 87 wagon ea82 carb, 5-speed DR, and i have heard that many people very rarely put it in 5th because the gas mileage goes down or something? i have also done all of the normal gas mileage stuff. i am acustomed to the 2500RPM rule, and i have been doing that with my wagon, but i have been getting 17MPG or so, i was wondering how others with simalar setups drive? and what is there gas mileage? i have heard people making like 28mpg thanks, please help! lol

[Snowman]

When I had my EA82 engine, I almost never used 5th gear. The engine would always lug in that gear unless I was going downhill at like 70mph.

 

17 is a little low. Are you sure you're calculating the tire size difference correctly? Regardless, it sounds like a full tuneup is in order, because most people I've talked to get somewhere between 20 and 25 mpg in their lifted rigs on the highway.

 

After trying the stock hitachi carb and a Weber, I finally gave up and converted to fuel injection. At least for my primary car, I'll never go back.

[DirtyMech]

My 1985 Subaru DL 2wd with an EA82 engine gets pretty good highway mileage, and I've never heard of not using 5th gear when applicable. 5th gear is overdrive, and should always produce better mileage than 4th gear at the proper speed. Personally I don't use 5th gear until I get past 60 mph. At below 55 mph on level ground in 5th my engine will start to chug from the strain, but past that its fine. Never had a problem, and as long as the engine is steady everything should be working fine.

 

On the highway I usually get between 35 and 45 mpg, and have gotten as high as 47 before. But in crowded city streets with moderate traffic I only get about 17, just like you stated before. 28 mpg sounds like a good average of both driving conditions, if that is where you got the number from.

 

As far as the 5th gear thing goes, well I don't know much beyond that its there for a reason, and that reason is to save gas, so I don't see why it wouldn't. If you're having problems with it past 60 mph, there might be something wrong with the engine or fuel delivery. Have you had problems with 5th gear, or are you just stating what you've heard about it?

[RichLo65]

I am having problems in 5th. i could put a brick on the pedal and i wouldnt pass 65 (on the guage, maby 75 actual) when i am in 5th, and thats at like 3000rpm. as far a tune ups, i have new plugs, wires, tires inflated, fuel filter, put sea foam in tank, umm and a few more little things like that. and 17mpg is my average.... i get 15-18mpg. i drive alot of hiway miles to.

 

i do not know the conversian rate for 29" tires, what is the stock diam tires?? and also the rate if you have it, thanks

[DirtyMech]

Hmmm...strange problem. Does your car hesitate or hiccup when trying to go up a hill? Because then its your fuel pump, which would explain the low speed in fifth gear. If not then it might be something else.

 

If it feels like something is wrong with that gear and that gear only, then the problem is likely inside your transmission. Got any more detail you could add? 65 mph is your max with the pedal to the floor? Can you go faster in 4th?

 

Dunno about the tire question, sorry.

[Snowman]

My 27's result in a 15% increase in speed/distance. I can't remember what the stock diameter is.

 

About the 5th gear thing....with larger tires, using 5th lowers the revs below where the EA82 likes to run, so it's always struggling...hence the decrease in fuel economy. Hypothetically, if you're using 80% throttle to maintain 60 mph in 5th gear, you will burn more gas than if you are using 40% throttle to maintain 60 in 4th gear, even if your revs are much higher. With small motors, fuel economy is all about throttle position, not RPMs.

[Tom63050]

I am having problems in 5th. i could put a brick on the pedal and i wouldnt pass 65 (on the guage, maby 75 actual) when i am in 5th, and thats at like 3000rpm. as far a tune ups, i have new plugs, wires, tires inflated, fuel filter, put sea foam in tank, umm and a few more little things like that. and 17mpg is my average.... i get 15-18mpg. i drive alot of hiway miles to.

 

i do not know the conversian rate for 29" tires, what is the stock diam tires?? and also the rate if you have it, thanks

 

I wonder if your ignition timing is off. Since the driver-side timing belt also drives the ignition, if the belt hasn't been adjusted recently your ignition timing might well be a little retarded, which will affect power and gas mileage. I adjust my timing belts every 10K miles and can notice a difference.

 

Also, one of the belts might have slipped a tooth due to looseness (since the adjusters aren't automatic) or been installed off a tooth originally, giving wrong valve timing & less power.

 

To check your odometer, notice the reading (including tenths) when you pass a highway mileage marker. See how many miles more it reads when you pass the marker ten miles down the road. If your odometer reads 8.5 miles more than when you started, for example, your odometer is reading 15% slow because of the taller tires. The speedometer will of course be off by a similar amount.

[RichLo65]

the car doesnt hiccup (exept when its cold blooded). and as for going faster in 4th, ya, the way i drive now i put it in 5th for strait steady speeds (flooring it the whole time), then when i see a hill coming up i downshift into 4th and floor it (maby get 2MPH faster) then it holds that speed kinna well depending on the hill, but if id be in 5th on that same hill id loose 5-8 MPH. i think thats just an underpowered engine with big tires.

 

anyway when i posted this i was just wondering how others drove around town, and on the highway that could help with gas mileage a bit.

 

thx snowman for the 15% that gave me a better idea of how fast i was really going 65=75, 55= 63.5, and 17mpg=19.5mpg aprox. so 19.5 is still pretty low, but not as bad, lol.

 

and snowman, so if Throttle position is more than rpms, what is the limit on that?? aka if i was in 3rd with 10% throttle would i be better than 4th with 40-50%? i kinna doubt this, but i would like to know where my peak shift points are.

 

i am sorry for sounding like a newb on these questions, but i got to used to my 13.9 sec summer daily driver, lol, where 2-2.5k meant best mileage (on an engine that reved to 7.5k, lol) thanks for all the help guys!

[RichLo65]

also i just read post before mine (tom63050) posted while i was writing, and my timing is advanced 5 deg, and the timing belt has just been replaced like 10k miles ago. thx for the advice on the markers on the road, ill try that next time im on the interstate.

[zyewdall]

47mpg? I wish I was even close to that. I've never gotten more than about 33 highway in my EA82s (carbed or SPFI about the same) 4wd. I've also never gotten less than 21 city or offroad. Most of the time it never varies more than 2 or 3 mpg for a tank, right around 27mpg. I must mix my driving together pretty uniformly on a typical tank. 5th gear on the carbed one wasn't used much, unless already up to speed on the flat or downhill. On the SPFI it's got a little more power and can actually go up slight hills in 5th. But I have stock tires, so I can see 4th being the highest gear that you can use in the lifted ones. These engines just don't have much umph below 2,800 rpm.

 

 

 

My 1985 Subaru DL 2wd with an EA82 engine gets pretty good highway mileage, and I've never heard of not using 5th gear when applicable. 5th gear is overdrive, and should always produce better mileage than 4th gear at the proper speed. Personally I don't use 5th gear until I get past 60 mph. At below 55 mph on level ground in 5th my engine will start to chug from the strain, but past that its fine. Never had a problem, and as long as the engine is steady everything should be working fine.

 

On the highway I usually get between 35 and 45 mpg, and have gotten as high as 47 before. But in crowded city streets with moderate traffic I only get about 17, just like you stated before. 28 mpg sounds like a good average of both driving conditions, if that is where you got the number from.

 

As far as the 5th gear thing goes, well I don't know much beyond that its there for a reason, and that reason is to save gas, so I don't see why it wouldn't. If you're having problems with it past 60 mph, there might be something wrong with the engine or fuel delivery. Have you had problems with 5th gear, or are you just stating what you've heard about it?

[Snowman]

Yeah, of course there's a limit to the "throttle position trumps RPM" theory. I never like to cruise on flat ground above 3500 rpm unless I'm in the top gear. A lot of it is trial and error as well, and depends on your individual setup. Most of the time though, you'd probably be better off running in 4th on the highway.

[Tcat55371]

The wagon got around 28mpg with stock tires. I think they were 175 70 13's

 

Chux's would know, he got the old rims and tires. You can try this link for different sizes and speeds:

http://www.miata.net/garage/tirecalc.html

 

Also when the 29's wereput on it got around 20mpg driving back and forth to work and thats 40 miles each way and mostly highway

[robm]

Your car's crummy fuel consumption and gutless behaviour on hills sounds a lot like a timing belt problem. The passenger side cam sprocket could be one tooth off and it will behave like this. I drove mine for >1000 km before I figured it out. Just for fun, what happens if you put the stock tires back on?

[jacobs]

Try removing your exhaust pipe to see if you have more power. My catalatic converter disassembled itself and jammed tight into the exhaust pipe behind the cat. I had to cut the exhaust pipe in half in order to remove the plug and then weld it back together again - what a difference.

[fbh]

My EA82 gives me about 12km/liter, which is about 28mpg, this is completely stock standard, no mods whatsoever (yet ;-) )

 

EDIT: At highway speeds (100kmh, or about 60mph) it cruises along in 5th quite nicely, and can climb a hill without losing speed, but not a steep one. If I downshift to 4th, it can pick up speed on level road, and it can climb more serious hills without losing speed.

[Subarian]

My carbed 86 gets about 27 average combined. I'm running stock tires, but running 4th with your tires should be comparable to running overdrive with the stock. 17 sounds way too low. Your ignition timing is retarded a little- it should be 8 BTDC for the carbed engine, and you can advance it a couple of degrees for more power. I would do a compression test. If both cylinders on the passenger side are low but the driver's side is good, that's a good indication of a timing belt problem.

[84gl]

whats with your rigs my 3door with a mildy moded ea82 (heads shaved .040 delta 240 cams slightly bigger valves and port&polished) does fine on hills pulls good in 5th from 40mph to 105 (as fast as i've had it) and gets anywhere from 29 to 36 mpg in my driving.

 

sorry maybe this is for wagons well then i think my wagon gets 21-26 mpg but it is a real slug and hasn't seen 70 for years burns oil has 90 pounds of comp. per cly. but, hay what do you think a car of its milage would run like but it still runs and thats the main thing (when driving it you have to have the state of mind i'll get there advently)