New to forum, 96 Accord 41mpg

[drockshabac]

I've been reading some of the great ideas from this site off and on and its time to get contributing. I'm concerned with carbon emissions and dislike driving culture in general. I currently live in Atlanta where public transport is terrible, people leave cyclists meager space for survival and all places seem far apart.

I have owned a 96 Accord with a F22B2 gas engine for a while and when some repair needs came up, I began to wonder about making the car more efficient. Its not terrible to begin with, and is rated 22/29mpg stock (although this seems a little conservative).

Its a Canadian car and the exhaust rotted out, so I replaced it with 3" stainless steel pipe (with little resonating chambers, and one of those N1 "mufflers", but basically its a large, unrestricted pipe) from the catalytic converter back. The kit was on ebay, like many other "cat backs" and costs about $130 delivered (vs $350+ for a stock replacement). It took about 2 hours to change with hand tools and a little elbow grease. Its certainly louder now, and I keep a silencer on the tip, but on a recent drive from Georgia to Ontario I filled up the gas and realized i'd made 41mpg (I tend to do a lot of coasting and follow others when possible, but this was a steady 75mph even on heavy climbs). On a subsequent trip I was averaging 85mph for a couple hours and still achieved 38mpg.

I'm impressed with the new economy of this car, and want to stretch things farther.

I am interested in other refinements I can make which give it high efficiency at 'flow of traffic' highway speeds. I'm concerned that ram air and cold air intakes may increase fuel consumption, but I feel that a better aspirated engine could increase efficiency.

[Daox]

Welcome to the site.

I'm assuming your gallons are UK gallons, not US gallons? Those speeds are incredibly high. You could gain quite a bit just by slowing down. I'd recommend taking a look at our 100+ ecodriving tips and starting a mileage log here in the EM Garage.

[drockshabac]

US Gallons : 850kms (530mi), and a little over 13 gallons. i filled it until it overflowed, but still my my methods of measurement are only so good. could my odo be a little optimistic?

I coast whenever possible and draft whatever is around.

the other factor was it was through NC and WV with moderately high altitude driving. i'm running 185 width tires, 10w40 oil, and have recently redone valves, all belts and full tune up on a 180k engine. I'd use 5w oil but i seem to have to always top it up.

I usually drive 50/50 city/hwy and i'll see what numbers i get on the next tank.

[DifferentPointofView]

^ you might have an oil leak then. Does your car have an oil pressure gauge? if so, you might wanna look at it. If the pressure is in the lower half after driving it warm, you've got a leak somewhere. It might be at the valve cover, cause those gaskets only last so many thousand miles. Also, if you have an oil filter elbow, the o-rings can get hard and crusty and then you leak from there. I know honda's usually use a lighter weight oil. Something like 5w-20 or something? (might be the newer models though. Yours is a 96')

What RPM's are you running at the speed you usually cruise at? cause backpressure can be good if your car is geared really low (taller final drive). Back pressure increases low end torque, but chokes the car at high-rpms. While low back pressure has little low end, but the higher rpm's thrive. Normally hypermilers like to keep a slower speed and lower rpm at cruising speed, so back pressure is beneficial, while racers like large or no exhausts because they're almost never in the low-rpm's range. they're always up near redline, shift, redline. etc.

A 3" exhaust might be too big if you decide to slow down, especially from the smaller motor. You might want to downsize to a 2.5" exhaust if you can.

[Doofus McFancypants]

Welcome -
to the forum. glad to see more people from the ATL on the forum
and you are dead on about the ladk og public transportation.
It would take me 90 minutes to get from my house to work on Bus. and it is a whole 12 mile drive. 3 hours for 24 mile round trip? Not gonna happen.

If you see a Red Altima going the speed limit ( probably the only one in the state) that would be me.

Steve

[drockshabac]

Thanks for the ideas. The accord dosent drip a drop of oil, although i've had the valve cover off one too many times lately. Every few months it starts up with an impressive blue cloud so i think a valve seal is bad which could be the root of it all.
Its rated to use 5w just like our 92 civic vtech, but i should look into it because it even uses a bottle of 10w after a couple thousand miles.

Good ideas on back pressure. The silencer creates a a lot of back pressure and gives it some torque so i feel alright shifting into gears a little under 2000rpm. Funny until you mentioned it, i was unhappy about the back pressure but it makes sense.

I cruise around 2500-3000 i dont know how to calcuate gearing but its at 3000rpm at about 80mph so its comfortable going quick. In the city i try and keep it at 1900rpm but sometimes i worry about the bottom end of the engine.

I'm curious about the civic too. the exhaust fell to pieces (and to me eco modding is about spending as little as possible on gas as well as parts) so i opted for an ebay pipe set up the same. right now the 92 auto/1.6 vtech civic gets about 34-37 mpg. I'll see if there's a difference when we change it up

I appreciate the responses.

[DifferentPointofView]

How many cars do you have? and Welcome to EM!

[drockshabac]

2, a civic and an accord. Me and the girlfriend. Its temporary until we can move to a more pedestrian/ cycle / human friendly place.

[drockshabac]

30 mpg in the city in atl is impressive! I'm the blue accord with Canadian plates. see you at spaghetti junction.

[cfg83]

drockshabac -

Welcome to EM! I am really impressed with your MPG on the 1996 Accord. If you are not sure about your odometer, use a GPS to check it's accuracy. I needed to do that when I got my new tires, which I deliberately bought one size up from stock.

CarloSW2