Random - how can you improve gas mileage on a civic?

[Hobie]

Thinking about buying another old civic for a beater. The last one was a 00 5spd 2 door that I converted to manual steering, ran 165s (oem was 185) on all 4 corners, had a cold air intake, and an external coil conversion with MSD coil and decent wires/plugs.

It got 54mpg on highway trips to Austin @ 80mph for the most part.

What else could be done? They make thicker head gaskets for boosted cars. Would decreasing compression improve mileage? What about valve springs, with the Honda aftermarket what it is I'm sure you could buy a variety of springs, but I doubt any would have softer rates than stock.

I know a complete aftermarket exhaust would help, but I would rather the car not sound different than stock.

Timing is adjustable and they make adjustable cam gears. I've always thought in terms of power, but what timing adjustments increase efficiency?

Anything else that can be done in the valvetrain to reduce drag?

I'm sure ceramic wheel bearings would help too, but that might be cost prohibitive.

Just spitballing and wondering what else can be done. How far away can 60+mpg be???

[Grape]

as much compression as possible, which is what you get when you move the cam centers around. Just have to be careful when getting the intake number down under 104 that the valves don't touch, but i doubt those piles are set up that close.

[95ragtop]

54mpg at 80mph is down right impressive. Not sure how far you are wanting to go, but some used light weight wheels or dropping some weight. I'm pretty sure ricers have gotten those things down to 2000lbs. I've always heard added compression helps mileage, because the engine is more efficient. How about aero, if you aren't opposed to having some holes in the hood. Could look into a tranny swap with a taller 5/6th gear.

[46Tbird]

Definitely run as much compression as you can get away with. That is squeezing extra power from the same fuel. If you've got an MSD box, you could put a rev limiter on the engine to keep you from inadvertently exceeding your target RPM.

There are some pretty simple aero tricks you could do. Try building a pan under the engine compartment and rear axle. You could lower it. Run some Moon discs, lol.

[Hobie]

as much compression as possible, which is what you get when you move the cam centers around. Just have to be careful when getting the intake number down under 104 that the valves don't touch, but i doubt those piles are set up that close.

Well shit, my logic was certainly flawed and I was going the wrong way. lol

54mpg at 80mph is down right impressive. Not sure how far you are wanting to go, but some used light weight wheels or dropping some weight. I'm pretty sure ricers have gotten those things down to 2000lbs. I've always heard added compression helps mileage, because the engine is more efficient. How about aero, if you aren't opposed to having some holes in the hood. Could look into a tranny swap with a taller 5/6th gear.

It's been awhile since I googled but there was a transmission in the civic hatches that was designed for better mpg. The hatches are lighter and more aerodynamic, but it's hard to find one that hasn't been butchered by a ricer.

I just wanted to get as much mpg out of the car as is financially reasonable. I don't want to buy carbon parts and high dollar race seats just to drop a few lbs.

I did think about making a splitter out of wood, but didn't want the car to wind up looking too ridiculous.

[Hobie]

Definitely run as much compression as you can get away with. That is squeezing extra power from the same fuel. If you've got an MSD box, you could put a rev limiter on the engine to keep you from inadvertently exceeding your target RPM.

There are some pretty simple aero tricks you could do. Try building a pan under the engine compartment and rear axle. You could lower it. Run some Moon discs, lol.

That was seriously the next thing up on the previous car. LOL

[BttleFedC10]

Wish i could do all that to my fusion to achieve 30mpg. ITs only getting 25mpg average witht he 2.5L in it. It weighs around 3500lbs too.. Lol

[Vertnut]

I'm thinking at 65mph, you will see your 60mpg. You need to decide if speed > mileage.

[95ragtop]

Quick search:
For a B series-tranny code s80, 94+ LS/GS, 5th is 0.714, and final is 4.266
D series in 88-91 HF, tranny code L3 with cable clutch-5th is 0.694 and final is 3.88
D series in 92-95 civic cx/vx, tranny code P20/A000, hydraulic clutch-5th is 0.702 and final is 3.250
96-00 D16Y5 and D16Y7 hatches, hydraulic clutch-5th is 0.702 and final is 3.722

What about tires with a larger sidewall?

[Grape]

taking gear out will hurt until you are making enough power to pull in that rev range with less throttle angle input........

[dsrtuckteezy]

i'm knocking down 35-40 mpg in a 98 ex 1.6L 5spd with no 5th gear! i saw the same mileage before 5th gear and reverse took a shit.

i dont see how you were getting 54...guess maybe from the manual steering and no a/c? pretty good either way

[95ragtop]

taking gear out will hurt until you are making enough power to pull in that rev range with less throttle angle input........

Well looks like that idea is off the list.

[shumpertdavid]

Smaller diameter tires will make the odometer add more miles than you are actually driving, thus giving the appearance of better fuel mileage. Going for from the 185 to a 165 assuming the aspect ratio is the same (ex 185-75r14 to 165-75r14) will give you a narrower thread, but also a shorter sideway.

[shumpertdavid]

i'm knocking down 35-40 mpg in a 98 ex 1.6L 5spd with no 5th gear! i saw the same mileage before 5th gear and reverse took a shit.

i dont see how you were getting 54...guess maybe from the manual steering and no a/c? pretty good either way

From what I remember 5th and reverse (at least in the older trans that I messed with) can be changed without removing the trans. The one I messed with was in a small housing on the very back side of the transmission. They are usually damaged from being run low on oil.

[Hobie]

D series in 92-95 civic cx/vx, tranny code P20/A000, hydraulic clutch-5th is 0.702 and final is 3.250

I think that was the one people said to find.

i'm knocking down 35-40 mpg in a 98 ex 1.6L 5spd with no 5th gear! i saw the same mileage before 5th gear and reverse took a shit.

i dont see how you were getting 54...guess maybe from the manual steering and no a/c? pretty good either way

I got around 40 iirc totally stock with mixed driving. Seemed like it got high 48ish on Austin trips stock. Still had A/C, can't do without that!

I might've posted on the old board about the 92 I had before that. Same mileage, no a/c, no power steering on that one. No a/c was murder! I didn't keep that one very long. lol

Smaller diameter tires will make the odometer add more miles than you are actually driving, thus giving the appearance of better fuel mileage. Going for from the 185 to a 165 assuming the aspect ratio is the same (ex 185-75r14 to 165-75r14) will give you a narrower thread, but also a shorter sideway.

Don't remember what aspect ratio they were. Got them off the wal-mart website.