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dann_04 07-10-2008 09:35 AM

Ep3/k20a3 drivers give me tips please
Hi, i drive an 03 civic si(ep3) with the k20a3 5 speed manual. Right now i'm getting around 34mpg. I want to do better, and on my old metro it was easy, shift a 2k and you get good gas mileage. This car isn't the same, it lugs under 1.5k and if you shift at 2100 rpms(before vtec) it gets worse mpg than shifting at 3000 rpms. So i was wondering also, when i'm cruising is it better to do 40 mph at 2100 on 3 valves, or is it better to cruise at 45mph at 2300 rpm's on 4 valves? Anyone have a scangauge that can check on this for me? Also is it better to shift at 2500, 3000, or 3500 for in city mpg? It's really confusing for me because i'm so used to keeping speed and rpms low, but now i have the whole vtec thing with 3 and 4 valves thrown in. Just trying to figure out what's more eficient with this dangfangled technology lol. But so far it's been pretty good to me and only has 12.5% parasitic loss to the wheels. I am eventually going to install the 6th gear from a tsx, but that comes after the warranty is up. Any help is appreciated.

MetroMPG 07-10-2008 04:03 PM

You really need to get yourself a SG or make an MPGuino. If you're serious about saving gas, it'll pay for itself in no time, and if cost is really an issue, you could easily re-sell one after a few months for close to what you paid for it.

greenwar 07-10-2008 04:22 PM

I drive an ep3 and have a scangauge. Staying below 2200 rpm gives me zero advantage in terms of fuel savings. It shows 22-25mpg if I am shifting below 2200rpm. If I am shifting around 2800-3000 rpm SG shows me I am getting 22-30mpg. With this car, the trick is to get upto speed with moderate accelaration and then maintain the speed with pulse and glide (I don't turn my engine off). Car has fairly good aerodynamics and coasts fairly well. I usually drive around 60-65mph which shows best mpg on SG.

Don't lug the engine on the K20A3. It gives no fuel advantage. Like wise staying below 2200rpm gives me no advantage.

dann_04 07-10-2008 04:37 PM

Any chance you could see what your gauge reads at 40mph in 5th gear cruising and 45mph in 5th gear cruising? Thanks.

greenwar 07-10-2008 04:42 PM

I will keep an eye tonight to see what SG says at 40mph and 45mph. Feel free to pm me if you got other questions as well.

EP3 07-10-2008 04:53 PM

Yeah I don't have one ethier any help with that would be great. Trying to buy a house no extra money right now. What is the best speed for mpg in 5th gear that you find. I always wondered about shifting real low. Seems to shift at 3000 for best results? and low accelaration to 3000? Oh BTW 45ish psi on my tires Greenwar and just a little rougher feeling when driving through city. On highways it seems to be more senstive to any kind of inpute from me... Reminds me of when I use to have low profile tires on another car.

dann_04 07-10-2008 05:48 PM

I have found with my archaic gas mileage tracking device(calculator after fill up) that i get the best city mpg shifting at 3k with rather unspirited acceleration. I haven't tried honda's recommended shift points because they seem way too high, but who knows maybe they work. I do alot of coasting down hills, to stop signs/lights, and sometimes shift 1235 to cruise in town. I might start turning off the ignition at longer lights and on a particularily good hill.

Also, i have heard alot of talk about it being more efficient to use the a/c with the windows up on the highway than to cruise with windows open. But is that only full open? Because i normally open them like 2 inches on the highway, is that better or is closed with a/c better? I'm sure optimal is closed with fan on, but that's not always possible. Also anyone know how much fuel our car uses at idle?

rsx2002 07-12-2008 06:57 AM

I drive mine in 5th gear going forty when im on a very flat road and will get 49-52 mpgs. But those spots are rare here in WV and if you got any slopes, even small inclines/declines, your better off driving 45 or 50 or the engine will start to lug.

greenwar 07-19-2008 11:54 PM


Originally Posted by rsx2002 (Post 43345)
I drive mine in 5th gear going forty when im on a very flat road and will get 49-52 mpgs. But those spots are rare here in WV and if you got any slopes, even small inclines/declines, your better off driving 45 or 50 or the engine will start to lug.

Sorry for the delayed response. I finally managed to go for a relatively longer drive to check for mpg through SG.

All at 5th gear no ac but sunroof open (has a sunroof visor so drag isn't as bad)

At 50mph with LOD at 38-44 SG shows 37-39 MPG
At 55mph with LOD at 40-45 SG shows 35-36 MPG

At 70mph with LOD (can't remember) shows 29-30mpg
At 80mph with LOD (can't remember) shows 28-29mpg

Total 64miles driven with an avg of 34.2mpg. I forgot to check what it shows at 40-45mph on 5th. I would guess it would be around 38-40mpg. My tires are at 31 psi (cold).

There were some faster acceleration in between that I can't go into details. :)

Edit: I did a 40mph on 5th and 45mph on 5th today:

at 40mph on 5th with LOD 43 SG showed 37-38 mpg
at 45mph on 5th with LOD 38-40 SG showed 38-39mpg

dann_04 07-21-2008 10:24 AM

Hey, i appreciate the time and input helping out us slackers with no sg lol. I think i may get one soon...But i am pretty proud my last tank i milked 35.6 mpg's out of my ep3 so i'm hoping to break 40 mpg on at least one tank some day(probably after i get a sg and do some eoc). Have any of you thought about a pan on the underside like some people are doing? my back bumper looks like a parachute lol. Also any one know the drag coefficient of our car? I can't find it.

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