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Discussion Starter #1
Hi, I haven't had my insight too long, but have had some experience getting good mileage on my Civic HX. I have been averaging 72 mpg on my current tank of gas, but have a question. I can tell when I get into lean burn mode, but is it better to cruise in lean burn in 4th gear or lower the rpm and cruise in 5th. Seems like at 40-45 mph or when accending a slight grade I can maintain lean burn in 4th gear, but not in 5th unleass I'm going faster or I'm on the flats. At 50 mph + I can cruise efficiently in 5th. So should I stay in 4th and stay in the lean burn mode as long as I can. From the readout, it seems like 4th gear is more efficient, contrary to what I've always believed. Also, is it better at times to use some IMA in a lower gear early to pick up speed when going up a grade and then ease off and upshift as you hit the crest. I can see why the guys with MIMA can take advantage of this. I rarely see my battery level go down more that a couple of bars. I don't push down on the throttle much. In my HX, I've always used my Scanguage, keeping an eye on the GPH and lose speed going up a grade til I hit the crest.
 

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Lean burn in 3rd gear produces better MPG than not being in lean burn even in 5th gear.

Generally try to maximize your time in lean burn... Secondary to lean burn is staying in the highest gear you can while staying in lean burn.

The exception of course is the pulse and glide method... but that is another can of worms all together.

And of course watching the road carefully and managing your momentum is yet another powerful technique.
 

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Hi met-head; Iamian is correct, but there's more to the story. First, you need to maximize the envelope at which lean burn can occur. The main way to do this is to make sure you have lots of air in your tires. I run 55 lbs. And hopefully you have the stock Bridgestone Potenza 165-65-14 rubber.

By far, cruising in 5th gear is the most efficient. But to keep it in lean burn you may need to slow down to 58 mph or less, depending on the wind, the grade, and the tires, etc. A steady speed of about 38 mph is ultimately going to yield the very best mpg, but who has the time or patience to linger there very long? Therefore, everything else is but a compromise. But surely, accelerating slowly & gently, and staying OUT of electric assist yields the best MPG.
 

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I have a dashdyno that I set the alarms to light green when AFR/voltage
is reading lean burn and red when not. Its not as distracting as looking
down to see the fcd. When cruising its surprising how easy it is to
go in and out of lean burn with small hills.

From some trial runs I have increased the mpg about 10mpg by
using this device. With addition of MIMA I could keep that green
light on all the time and boost mpg a lot more. That might be the
next project after finishing the seat install.
 

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Discussion Starter #6
Thanks for the response. I run 40 psi in my tires, may try to add a little. One other thing I notice on my freeway commute to work, is that I can get up to 60-65 mph, and then get into lean burn and stay there, but my speed will gradually decrease to 50 mph over the course of about a mile or so. So then, I'll get a little assist and get back up to 60+ and do it again. This seem to be more efficient than keeping a constant speed. Also, I've been building speed before slight hills and let the momentum carry me over. One more thing, is it better to try and stay out of assist, using light throttle to maintain speed, or use it to pulse and coast. I am averaging 70-72 mpg
 

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Hi Met, If you add 5 more pounds to each tire, that is a total of 20 lbs. That will make a substantial difference in your rolling resistance. Your lean burn envelope will increase, and you will glide farther.

Yes, it is generally best to stay out of the pack (electric assist). Pulse and glide is excellent at lower speeds, (0-35 mph) and when there is little or no traffic. Also, you will likely find a 4-10 % increase in mpg this summer when temps are hot.
 

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Discussion Starter #8
I still have a lot to learn. On my commute to work, I was taking it easy and getting low -mid 70's. The other day, I did a lot of pulse and glide, and coasting and not using any regen and got 83 mpg going to work, but my SOC got down below 1/2. On the trip home it was hard to cruise without regen until the SOC got up to about 3/4. On the way home I only got 69 mpg, so I guess not letting the SOC drop below about 3/4 is the best compromise. Does this sound right? What happens if the SOC gets too low? Let's say, I'm going over the Cajon pass (10 mile grade up to 4000 ft getting steeper as you approch the summit) If I run out of assist, do I just downshift, or do I need to plan my attack speed so I just run out of assist as I clear the summit, and then regen? What's harder on the IMA battery, keeping it nearly fully charged, or a healthy discharge and then charge. I figure a lot of discharge or charge generates heat which is bad, I guess.
 

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All energy for propulsion in an Insight comes from burning fuel. The IMA system can only recover a relatively small percentage that would otherwise be lost without using regenerative brakeing or downhill coasting in gear.

The specifics for _best_ MPG on any given route vary, and are different based on the 4 T's. Temperature (weather in general too), Traffic, Terrain and Time on trip.

If you misjudge IMA SoC consumption, coast too much, fail to recover or use too much SoC, you'll fall into a forced charge and MPG will suffer.

You'll need to employ the 3 P's too, and let your MPG meter be your guide.
(Practice, practice, practice) ;)

See:
http://www.insightcentral.net/forums/modifications-technical-issues/7728-recals-forced-charge-ima-battery-thermal-mgmt-long.html?

for more than you probably want to know about the IMA system. ;)

HTH! :)
 

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Discussion Starter #10
Thanks for the reply. I think I was just trying too hard. My wife uses the car to go to work on occasion (to take advantage of the carpool sticker). She says all the dashboard lights just confuse her. So I tell her to drive it like a normal car and don't worry. Her commute is 100 miles round trip and she gets 60-62 mpg, so I can't complain. I can get 70-72 driving easy, keeping the the SOC almost full. When I try to get much more than that, I start losing SOC. Of course, at 50 mph on level ground, I can get nearly 90. My big test will be next month when we make our semi annual Vegas run. We run 60-65 mph to see what kind of mpg we can get. We usually take my Civic HX and have gotten a best 48 mpg. Last time we took our 5 speed PT cruiser with the rear seats taken out, tires at 40 psi, and got 35.0. I'm looking forward to see what the insight can do.
 

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My big test will be next month when we make our semi annual Vegas run. We run 60-65 mph to see what kind of mpg we can get. We usually take my Civic HX and have gotten a best 48 mpg. Last time we took our 5 speed PT cruiser with the rear seats taken out, tires at 40 psi, and got 35.0. I'm looking forward to see what the insight can do.
At 60 mph you should be able to expect 80 - 85 mpg if your car is running good.
 

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Lean burn in 3rd gear produces better MPG than not being in lean burn even in 5th gear.

Generally try to maximize your time in lean burn... Secondary to lean burn is staying in the highest gear you can while staying in lean burn.
I'm a little confused here. I'm a pretty new Insighter. I just programmed the Lean Burn Gauge into my Scangauge. Yesterday was the warmest day (and my best mileage) in months and the first driving of any distance with the LBN gauge. On slower roads going ~ 30 mph (48 kph), according to the FCD, I could get 75 mpg and 0 LBN in 4th or ~100mpg and >0 LBN in 5 th gear. I don't remember the LBN number in 5th, I think it was ~ 80.

Do I trust the LBN on Scangauge? Could it really be better when the FCD is showing a lower number?

Thanks,
-Mike
 

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Discussion Starter #13
With no assist, I don't think I could drive my Insight at 30 mph in 5th gear. That would have to be like 1100 rpm and I think would be lugging the poor engine. In fact, I won't put it in 5th unless I'm going at least 40+ mph. I have a scangauge II hooked up in my Civic HX. I will try it out in the Insight as soon as I figure out a good place to mount it. I got a two day work trip the Palm Springs area tomorrow, and will be the longest trip I've taken in my little red tadpole since I got it. Be interesting to see what kind of mileage I can get.
 

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With no assist, I don't think I could drive my Insight at 30 mph in 5th gear. That would have to be like 1100 rpm and I think would be lugging the poor engine. In fact, I won't put it in 5th unless I'm going at least 40+ mph.
Yes, it's turning about 1000 rpm. But it was flat ground and I certainly wasn't speeding up at all :)
I just looked at the weather history and I probably had a 17+ mph tailwind at the time too!
I believe IMA charging is not allowed at that rpm, so there's less load on the engine from that.

-Mike
 

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With no assist, I don't think I could drive my Insight at 30 mph in 5th gear. That would have to be like 1100 rpm and I think would be lugging the poor engine. In fact, I won't put it in 5th unless I'm going at least 40+ mph.
I run down to 30mph in 5th all the time, and in fact a bit lower that sometimes. 35mph in 5th is routine. As long as you are very soft on the throttle you won't lug the engine down to 1000rpm. If you stomp on it though yes it will lug down there.
 

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Lean burn in 3rd gear produces better MPG than not being in lean burn even in 5th gear.
There are cases when 4th gear might be a better choice than 5th. 3rd gear is for acceleration, steep hill climbing, or cruising at ~20mph. No way 3rd gear is a good choice for cruising over 30mph.

IMHO "Lean Burn" is highly over rated given the amount of pollution it causes.

Looking at the gen 1 Civic w MT:

Lean Burn (HEV LB): Model 1 Vehicle Characteristics

Non Lean Burn (HEV): Model 1 Vehicle Characteristics

The "California" (non Lean Burn) HCH gets 37/45 mpg and has a pollution score of 9/10 with 10 being the best.

The Lean Burn model gets 38/45 (almost the same) but the pollution score is only 2/10!
 

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I agree Lean burn is more about engine and fuel efficiency MPG potential instead of emissions.

The example of the two cars with and without lean burn is not showing the difference in lean burn it is showing differences in the models of car.... which includes a variety of other things as well... and does not address the potential the Insight's lean burn offers.

Here is the facts:

Lean burn is more efficient at converting fuel into usable energy.

Lean burn produces emissions that are more harmful per gram.

The CVT without Lean burn produces more emissions per mile, they are just less harmful per gram.

It is a question of more of less harmful ... or less of more harmful... how you fall between those two choice usually depends on allot of issues.

.......

I would also say... anybody that only averages out 38 to 45 MPG out of a MT Honda Insight... has a major flaw in their driving... either the terrain itself is horrible ... or the driver behind the wheel is horrible... or both.

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Lastly I would add... the emissions from lean burn can be cleaned up more with additional after treat systems.... but additional ICE efficiency above what the MT Lean burn Insight is able to do ~48% (Tests published by EPA in March 2004 Document #EPA420-D-04-002)... is extremely difficult ... even automotive diesel engines are almost never able to get that efficient.... it is an incredible achievement for Honda ... I would have liked more after treatment... but the ICE is still to this day ... in a league of it own.

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if it is about MPG... it is about lean burn.

if it is about emissions ... it is about driving your car as little as possible.... or get an EV.
 

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Scan gauge 2 mounting

Leo came up with an awesome magnetic mounting system for the scan gauge. Search for it, I used it and it is great. I have mine set: left top LOD, left bottom lean burn, right top MPG, right bottom engine temp. Temp is critical because I use radiator blocks (I have 2) to warm up faster, and I have found that MPG, although it does not match your FCD, will show you when you are getting the best possible MPG and also shows fuel shut-off (as 99999)
 

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Here is the facts:
Lean burn is more efficient at converting fuel into usable energy.
Lean burn produces emissions that are more harmful per gram.

The CVT without Lean burn produces more emissions per mile, they are just less harmful per gram.
Sorry Ian but I'm pretty sure you are wrong about that last statement. I know that there have been discussions about this in the past and I thought you eventually agreed with me (as well as the EPA) that these rankings are measured in grams per mile and nothing to do with miles per gallon. Take a look at the following link: Air Pollution (rating.htm)

Air pollution scores for the MT and CVT Insight:
Non CA and non New England states: MT Insight - 2, CVT Insight - 6
California and New England: MT Insight - 3, CVT Insight - 9

These are pretty wide margins. Now look at the 2 vs 6 and 3 vs 9 in the link that I provided.

You will notice that these stanards / rankings are based on grams per mile no matter what the vehicles miles per gallon rating is. It boils down to, no matter how many times we do the test, if you drive your MT Insight 60 miles and I drive my CVT 60 miles, I will always have better emissions during the entire trip (even if you disable lean burn somehow).

The CVT has lower compression and two catalytic converters, the MT model also has two cats but one of them (bottom of car) is specially designed to capture and purge the higher NOx that the MT produces during lean burn. So the MT has one less cat to scrub the other emissions and can only do an ULEV acceptable job at scrubbing NOx.

If Honda wanted to, they could have only put one catalytic converter on the CVT and still end up with a slightly better overall Air pollution score. In order to get a much higher ranking (SULEV), they placed another cat inline to scrub even more pollutants. That is what earned the CVT an SULEV rating.

Lean burn does have its drawbacks by design but it does boost that MPG level.

JoeCVT = Just your average CVT owner
 

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if it is about MPG... it is about lean burn.
if it is about emissions ... it is about driving your car as little as possible.... or get an EV.
????? Why can't it be about both?

I can drive my CVT and get second best MPG and at the same time, produce waaaaaaay less emissions during that drive :)

JoeCVT = Just your average CVT owner
 
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