[Delta Flyer]

I'm curious myself. A clueless new driver could get under 50 mpg, but could raise their lifetime mpg to 60-65 mpg using the advice from this forum. If you do a lot of stop-and-go commuting, 60 mpg is probably as good as it gets.

I'd have to concurr with meow77's implication: sustained 75+ mpg is possible only driving under 60 mph.

The only way I can imaging getting 80+ mpg on a trip is cruising on level land in moderate weather in light traffic that will allow me to go 50 mph. Back in 1988 I managed to get 76 mpg on a CRX HF under such conditions.

I'd be very interested to hear from the people getting very high mpg and see if I can use some of their tips for urban driving.

I have a 25-mile commute to work. About 85% of it is freeway. I have occasionally gotten 80+ mpg, but only crusing at 55 mph before 6:30 am on warm days.

 

[meow77]

City Driving

I also do quite a bit of city driving which also doesn't help; but the way I think is any car driven slowly gets better gas mileage..irrespective of the car... heck if I drive my supra at 55 mph .... I'll get way better gas mileage... . I'm just wondering if there are any modifications I can make on this car to get even better mileage.

I was hearing that some person put some mod to make the engine hotter I just don't remember what they did to get the better gas mileage by doing this....

 

[Delta Flyer]

I think you were refering to someone replacing a thermostat that had a higher cutoff point.

The 5-speed Insight is going into it's fifth year as the milage champ in the US. Whatever your milage is, it's better than driving something else.

I could make a long list of things to upgrade the milage of the 1974 Civic I had. It says a lot about Honda that they basically did everything possible to get great milage on the Insight so the driver would be limited to good maintanence and driving techniques.

If you read many posts, you get reported mpg ranging from 50 to 100. My 25-mile commute to work is about 85% freeway. Early some summer mornings in light traffic, I have gotten over 80 mpg cruising 50-55 mph. That's at least 15 mph under typical Dallas freeway traffic and near impossible to do during rush hour. I have also done about 50 mpg averaging 80 mph, keeping up with charging "men" with 5-litter engines. :twisted: Then three years ago when the roads were iced up, I did that commute off the freeway with extreme stop-and-go at 2-3 mph, getting 25 mpg.

You have to assume that there is a wide variation of both driving habits and traffic conditions. If someone talks about getting 85+ mpg on a tankful, I wonder if they were doing 50 mph on a quiet highway. The same person might be doing well to get 55 mpg in an urban area off the freeways during rush hour.

 

[Tim Maddux]

it IS possible

sustained 75+ mpg is possible only driving under 60 mph.

Naw. I used to consistently get sustained readouts of instantaneous highway mpg over 100 on flat roads at 65 mph on dry days in southern California (no sub-40 F temps). My driving style was simply to hold the instantaneous mpg readout at or above 75, including compensating for rich-burn purges. I would slow down on hills to 55mph at which point I would floor it to get maximum assist. I would see regular trip (average) mileages over 75mpg, with low mpg numbers at the start from gas burned in getting up to speed.

I have moved twice now and maintained the same driving style but with shorter driving distances I don't get the MPG I used to. My lifetime is still over 70mpg, however.

 

[Rick Reece]

I have a lmpg of 89.0 with over 77K miles driven. No you don't have to push your car or drive 25mph just try to keep the instant bar graph reading above 100 mpg. Unless the temp drops into the low 40's I can usually average over 90mpg on a tank of gas. I do have a few mods to help me but mainly I keep the RPM around 1900 while cruising which keeps the engine load low and therefore I tend to stay in lean burn.
- I draw the intake air off the catalytic converter so that it is preheated.
- I also block the radiator in the winter. (I block it enough to keep the oil temp in the 170 region.
- I have a small percentage of cold start driving to warmed up driving. (In other words I take long trips).
- I try to keep the engine vacuum at 5 in or more to stay in lean burn.
- I drive let my speed vary on the hills (slowing while climbing and speeding up while desending.

The 04 Prius uses a vacuum bottle to maintain engine heat for up to a couple of days. From what I have read this is mainly for improved emissions but I believe it helps the mpg as well. Have fun, Rick

 

[meow77]

Hmm..

Well I see some interesting things.. there ...

A. thermostat at a higher temperature rate is that to have the engine hotter for better fuel efficiency?

B. The air intake off the catalytic converter... how is this done?

C. Engine vacuum at 5 in how is this done??


Good info... but I would like to know how to do those things..


Also I was thinking earlier today... about the battery... its only
6hp... I really believe Honda could have made this a 15hp battery
and used lithium ion batteries instead... this would have saved
a lot more gas or what about a 2 stage battery one to assist on
1st gear for startups and a second for later assist .. there are
other things they could have done...

 

[Rick Reece]

In regard to the air intake all you need to do is extend the hose. I disconneted the exsisting piping and used a dryer duct hose (Aluminum) and ran it down to the catalytic converter. In regards to the engine vacuum you need to add a vacuum guage. If you see the vacuum falling let up on the gas slightly to stay in lean burn. Have fun, Rick

 

[meow77]

ok

Ok I get the cat... thing... but this vacum gage where does it go?

Also the the heated air on the cat... how does this improve fuel econ? In my sports car you want cold air for more power... so on our insights you want hot air?

 

[Delta Flyer]

The mention of vacuum gague got my attention. This is something I'd consider putting on my 1974 Civic, but figured would be redundant with the Insight's mpg computer.

 

[meow77]

ah..

Ah ok. a literal vacum gage... naw don't think I'll add that.... however the aluminum tubing down to the cat... is something I might consider ... however I am not fully understanding why this will improve fuel economy?

I have a toyota Supra as my other car and in that puppy the colder the better more power...... more cold air more power! So why would I want to put hot air into the insight's engine? Not getting that point...

 

[Rick]

Hot air is less dense and thus you get better mileage by having to mix less fuel with less air. So, in the winter when it's really cold the hot air from the cat would increase fuel economy. I think this also can help fool the car in to thinking the ambient air is warmer and will let the car enter auto stop durring colder weather conditions.

 

[meow77]

hmm. ok

So I guess now its just figuring out how to get the tubing down to the cat. wihout interferring with anythng...

 

[b1shmu63]

A recent post suggested going under the battery box. That is the route I will be trying. There are wires down there that could be damaged by heat so either the duct has to be clamped carefully or insulated somehow. Probably both would be a good idea. Perhaps the person that suggested the mod could send you some digital shots of their installation?

 

[Rick Reece]

I know very little about engine's but I believe the warmer air helps support combustion at a higher air to fuel ratio than cold air. The leaner the mixture the better the fuel economy. If you want HP then you want cold air and a rich mixture. In regards to the Vacuum guage you just tap into the vacuum line on the left side of the engine (a very small black hose. I sent Willie a picture and he showed me the place to tap in). This is then run to the sensor/guage. I used the Dakota Digital guage. Have fun, Rick

 

[meow77]

hmm

Well the vacumm gague is something I dont' think I'm going to do... my car is still under warranty... so not going to touch that... however

Still wondering how to effectively get the air from the cat to the engine air tube etc... Rick do you think you can send some picts on how you did it?

Also my question about the thermostat is still out there... higher temp thermostat for a hotter engine for better fuel efficiency? Is this so?

 

[Rick Reece]

Meow77,

Send me your email address ([email protected]) and I will take some pictures next weekend. It is really easy in that all you have to do is:
1. Remove the plastic piping that connects to the air filter box and runs along the front of the engine.
2. Go to Home Depot and pick up a rubber plumbing elbow pipe (Same diameter as the air filter box connection) and a aluminum dryer vent hose.
3. Connect the elbow on and tighten the hose clamp. Then snake the dryer vent behind the engine to run between the hose connection and the catalytic converter.

I have a temp guage inside the dryer vent and the intake temp is usually close to 35-40F above the outside air temp. I also block the radiator to reduce the cooling due to driving. For about a year I used a T connector and on the other end had a 700 watt (low setting) hair dryer that I could add some additional heat on really cold days. (I probably have a picture of that somewhere as well). I took it off sense I didn't use it that often but if I had a lot of cold weather starts with short trips I would probably put it back on. Its purpose as you might imagine was to preheat the air before entering the engine. Have fun, Rick

 

[meow77]

ok

thanks for your response Rick I'll email you ... looking forward to the info.

 

[Rick Reece]

Meow77,

I did receive your e-mail but seam to have deleted it (Busy couple of days). For my driving I would say the hot air intake provides perhaps a 1-2 mpg increase. Its not as b9ig an effect as increasing your tire pressure but still seams to help. It may help more where you have shorter trips and multiple warm up cycles but I don't know. Anyway if you look through the Archives on the old Yahoo Honda Insight group you will find opinions of several that experimented with this approach. Have fun, Rick (If you still want some pictures I will need you to send me another e-mail and I will send you some this weekend. (Hopefully I want delete this one).

 

[megaoptimus]

rick,

Can you send me pics of the cat mod as well? That is an excellent idea for winter driving when the weather is consistently below 40. I would say once it is warm again, remove the mod and do another that allows cold air intake. There is a simple mod mention on this board some where. it is easy. I shall send you an email as well if that is ok. thanks