I've had a hard time finding a good resource that explains the best shifting points for highest fuel economy using this engine under various loads, so here is a hypothetical set of test conditions (substitute your own specs if you have some relevant numbers): Load: '05 Accord LX, 5M (unloaded vehicle weight: 3177lbs) <= 5,000 miles on odometer. Configuration: Windows up, vents & fan open & running, AC and other accessories off. Altitude: Sea Level Temperature: 72F Rel. Humidity: 50% Grade: Flat Fuel: Regular, no ethanol / seasonal additives From: 0 - 25: Best time / RPM shift points from %gear% -> %gear% 0 - 35: " 0 - 45: " 0 - 55: " If you know of any resource where this kind of info is posted, great! If you've done some experimenting on your own: Love to hear it. +-----------------------------------------+ | Charles Lasitter | Mailing/Shipping | | 401/728-1987 | 14 Cooke St | | cl+at+ncdm+dot+com | Pawtucket RI 02860 | +-----------------------------------------+
Good fuel economy and performance on a Honda are mostly about throttle control. You don't want to "lug" the engine. The classic way to do this is to push hard on the throttle from a low rpm. The car shudders as it picks up speed. You want the engine to gain RPM quickly and smoothly. If not, you probably need to downshift. Practise revving out the engine with the least amount of throttle. Honda's are built to rev. You don't need to be this extreme is daily driving, but you'll get the idea. Lighter throttle = good gas mileage = happy engine.
Hmm. The trouble is that your own vehicle is unique in many respects. What you're wanting is a way to drive the car, but surely, part of the appeal of a relatively new car to you is that economy discovery. It's possible to get pretty close to the best you'll return in a short space of time. [snip] You'll find generic consumption pointers on my website, but I can't be so specific - even if I owned that particular car. What I have found is short-shifting helps. My UK specification machine has a very different engine to yours so my experience will be academic and maybe interesting, if not entirely accurate or relevant. But in general terms, I follow the fifty / fifty technique. Up to fifty percent throttle and up to fifty percent maximum permitted engine speed. That makes for a maximum engine speed of 3,150 rpm for my own Accord. This Accord uses a SOHC VTEC 1.85 litre donk with Honda's two stage VTEC system. Maximum power is 134 bhp at 6,000 rpm. Peak torque is quoted as 129 foot pounds at 4,800 rpm, but as with all VTEC systems, the figures only tell you half of the story. The donk has two separate power bands. One from 2,500 rpm to 4,500 rpm, on the ordinary camshaft profile. The other, 4,500 rpm to the limiter, 6,700 rpm. It's hard to tell when it shifts camshaft, it's lovely and smooth, so essentially it feels up and at it from 2,500 rpm... Using the above that gives me from 2,500 rpm to 3,150 rpm for hill climbing, but she's perfectly happy from 2,000 rpm on the flat. Unhappy under this in fourth and fifth. Consumption figures have varied from a 32 to a 38 miles per (UK) gallon, equivalent to around 25 to 30 in US terms. Not wonderful by any stretch, this is mostly highway driving (my commute to and from work is 30 miles, 3 in cities, 27 on motorways).
I thought this condition would increase "pumping losses", and speed induced friction? http://tinyurl.com/j4g5w I was thinking that your best Brake Specific Fuel Consumption (BSFC) occurred with a more open throttle at a point in the RPM range closer to where the engine makes peak torque. That's around 4500 RPM for this engine. http://en.wikipedia.org/wiki/Honda_K_engine I wish I knew more about the theory so I'd know how to use this information. +-----------------------------------------+ | Charles Lasitter | Mailing/Shipping | | 401/728-1987 | 14 Cooke St | | cl+at+ncdm+dot+com | Pawtucket RI 02860 | +-----------------------------------------+
I want to start by offering a heartfelt thanks for actually addressing my question. All too often some people will heap ridicule on you for wanting to know something. It is. I regret that this car does not have a economy performance meter. The ones that can really tell you how you're doing have to look at all sorts of really specific data from things like injectors and so it's generally cost prohibitive to retrofit that capability onto a car that didn't have it as an option. Oh goody! I'm impressed by what the Datasheet 3.7 has to offer ... This page ... http://tinyurl.com/qctmj Had some useful info for K20 and K24 series motors. It sounds like this provides for relatively brisk acceleration. I'm still looking for the specific torque curve for the engine, but the previously mentioned link offered this: "This motor has no Vtec mechanism on the exhaust cam and runs on 12 valves before 2200rpm with the other 4 slightly opening." This seems to suggest that you are about right in terms of the sweet spot in the low range. Many thanks for your thoughts on the subject. +-----------------------------------------+ | Charles Lasitter | Mailing/Shipping | | 401/728-1987 | 14 Cooke St | | cl+at+ncdm+dot+com | Pawtucket RI 02860 | +-----------------------------------------+
throttled engines perform best at wide open throttle. So, for best economy you accelerate hard and shift early in each gear. Stick to the speed limit or close to it and always use cruise control.
How about this, use of a vacuum gauge- http://www.heraldargus.com/archives/ha/view_features.cgi?prcss=display&id=282242 The vacuum gauge was featured on a recent MotorWeek TV show (PBS and Speed Channel). How are those Pirelli tires working out?
I've been thinking about some of the "least obnoxious" places to put one. I was thinking about the front console storage bin with the flipup cover. I love them. They seem to ride about as well as the OEM 205/65-15s but I suspect they cost me something like one MPG for being wider. I've pumped them up to 44psi and either the ride is still good or I've adjusted to it. Either way, I'm now wondering which of the suspension kits offered by TireRack I sould be considering, since the car leans a good bit more on hard cornering than I'd like. The 225/55 was not "officially" recommended by the TireRack computer, but Cy said that they should fit fine and they did. I was all set to have the rear fenders rolled and it wasn't necessary. +-----------------------------------------+ | Charles Lasitter | Mailing/Shipping | | 401/728-1987 | 14 Cooke St | | cl+at+ncdm+dot+com | Pawtucket RI 02860 | +-----------------------------------------+
Alternatively, the gauge could be a temporary install. Once you learn the pattern, you probably will have little use for the gauge on a routine basis. Uh, oh. Maybe you should take that new Civic Si for a spin. Find out what a LSD and 500 lb. less weight can do for cornering dynamics.
197hp and 17" summer tires? Wow. Don't know if I could stand the premium unleaded though, and it might not haul three Golden Retrievers very well ... +-----------------------------------------+ | Charles Lasitter | Mailing/Shipping | | 401/728-1987 | 14 Cooke St | | cl+at+ncdm+dot+com | Pawtucket RI 02860 | +-----------------------------------------+
Kids, eh? The whole reason why my website is what it is because I enjoy finding stuff out... You mean like my OBD-II dongle? www.dervman.com/obdii That can do some of it. If only I could find the Accord's OBD-II port (rather, if it weren't so cold out...). I'm working on 4.001 at the moment, I've added another 50% vehicles, but I've had to reformat the data because this poor notebook has been struggling. Cool!
