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Discussion Starter #1
For the last 37000 miles I've have only been able to get an average of 53MPG. So I have tried to improve the engines ability to breath and exhale or intake and exhaust flow.

I was going to replace the factory muffler after inspecting the inside to find out how restrictive it is with a free flowing muffler. Problem is there are no lightweight small mufflers on the markets. Stock muffler is 8lbs. So I decided to keep the stock muffler and just modify it. On the backside of the muffler and above the outlet pipe I drilled a large hole. One more hole was drilled into the outlet pipe. I shaped and welded a 1 7/8" 90 degree elbow from the muffler to the outlet pipe. This allows the exhaust flow to bypass the most restrictive part of the muffler. Sound was hardly increased. Can't tell anything from inside the car. Total cost was 1.99 plus my time welding. Only one test drive showed little improvement in MPG. However the RPM's raised quicker and a slight power increase was felt. An alternative to the elbow and easy to do is just remove the muffler and run a straight pipe.

Next mod was on the intake side. If you look at the air intake you'll notice that its right behind the radiator and after the engine warms up the intake pipe warms up a lot. There is a resonator located in the drivers side fender with a pipe running from it to the intake pipe. I placed tape over the inlet and just disconnected the pipe from the resonator. It’s held in place with a squeeze clamp and requires no tools to remove. I just let the hose hang. Perhaps the better set up would be to extend the length of hose to get cooler air. I wanted to keep it so I can return to factory setup in minutes. Basicly a cheap CAI cold air intake!

After I performed this mod I drove 8 miles across town and got 70.5mpg!!!. I took a longer way home to look at some houses total miles was 21 and final MPG was 65.5 The car felt like didn't loose power up hills. MPG was increased on flat roads. The car increased speed quicker and with less pedal. I'm real impressed and pissed at the same time. I wish I had done this 37,000 miles ago :!: :idea:

I'm going to DYNO test the car before I get my Volk rims installed then once more after the rims so that I can have solid proof that I have improved the car.
 

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Could you send a picture? Yes, this is interesting!
 

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Discussion Starter #4
Pictures are not needed. I could take pictures not sure how good they come out. I try tomorrow

For the exhaust mod. Just take the car to a local exhaust shop and have them remove the muffler and weld up a straight pipe. Be sure and ask if the have the small pipe 35mm or I think 1 1/2". It should cost less than 45.00. This will also save 6lbs of weight..

For the intake mod.
1 raise the hood
2 look in the middle of the car and just between the engine and front of the car and you'll see the intake pipe
3 place tape over that pipe opening
4 follow the pipe around to the airbox the back up a few inches and look on the underside. You should see a flexible hose that goes to the drivers side fender area.
5 reach in with your right hand and trace the hose to a box. at this point feel around for a clamp.
6 Squeze the clamp and pull in back.
7 Pull the hose off the resonator.
8 Just must the hose in front of the resonator and leave it

That's it.


I'll taking a 50 mile trip tomorrow on the freeway and will post the results.
 
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Hi Cakely:

___A future Insight owner here possibly? Wouldn’t the intake mod cause a problem in colder temps when you actually want/need a bit of preheating for the intake? I guess you could simply reconnect the intake up to stock in the winter so it wouldn’t be that big of a deal ... As for bypassing the muffler, I would also guess the muffler’s back pressure has been calculated for in the engine management system. If you drop off that back pressure, I am not so sure the ECU can compensate. I hope so of course given your new found city mileage but I am wondering?

___I will be looking forward to your Dyno test and future MPG posts ... I have to ask why you were not receiving the 70 + with your 5 Spd. in the first place? Are you a fast driver in and around town only? What was your average Hwy mpg when you do in fact get the Insight into Lean burn at a steady 60 to 65 mph?

___Good Luck and thanks for pushing the envelope.

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1jxzl97r][email protected][/email:1jxzl97r]
 

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Discussion Starter #6
xcel said:
___ Wouldn’t the intake mod cause a problem in colder temps when you actually want/need a bit of preheating for the intake?
Never gets that cold in Georgia. This "preheating" ideal is for the books and not real life. When you drive on the road you need X amount of power. If you had a perfect road with a 5% decline the the engine could afford to make less power and then the preheating would be useful. I live in Georgia and need power to make it up hills.

xcel said:
I guess you could simply reconnect the intake up to stock in the winter so it wouldn’t be that big of a deal
Yes. Only takes a few minutes. Once winter hits us in the south I could if needed return to stock.
xcel said:
As for bypassing the muffler, I would also guess the muffler’s back pressure has been calculated for in the engine management system. If you drop off that back pressure, I am not so sure the ECU can compensate.
I hardly think that Honda thought about exhaust back pressure. I'm not talking about a Fully Open Exhaust set up. The car still has two cats and the small pipe running the length of the car. Beside I have yet to read anything about a pressure sensor for the exhaust in any car.


xcel said:
___I will be looking forward to your Dyno test and future MPG posts ... I have to ask why you were not receiving the 70 + with your 5 Spd. in the first place? Are you a fast driver in and around town only? What was your average Hwy mpg when you do in fact get the Insight into Lean burn at a steady 60 to 65 mph?
Most owners never get the 70+ MPG. Yes I am a fast driver but I do allow the speed to drop when climbing a hill and I watch redlights so I can time them. Lean Burn also = less power. I could never climb a hill in Georgia with the lean burn. If I tried I would drop down to 40ish MPH. I have made a few trips and kept the speed lower and got around 58-60. Normally I drive 85MPH on the freeway. Faster down hill and slower up hill. In town I drive around the speedlimit.

___Good Luck and thanks for pushing the envelope.

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email protected][/email
 

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Discussion Starter #7
Made a longer trip today.

50.5 miles on I-75 air temp was 68 with a slight rain. Two people, two pistols, and 200 rds of .45 ammo for the range. Est weight to be 320lbs. I kept the speed around 80mph faster on the down slopes and slower on the up slopes. The car just has more power. I'm sure it's not much but any gain helps. MPG was 68.5

Drove around town and on backroads then came back. Had a slight headwind and I was driving faster. Total miles was 130 @ 63MPG.

I have notied that this surging problem others have including me is stronger with this set up.. My .02 is that the EGR system is used more to warm the air. Or because the engine makes more power I can feel the loss in power becuase of the lager drop.
 

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The Insight pre heats the intake air via the coolant lines that goes through the "throttle plate" body. This is done to decrease emissions and for economy. The black box you refer to is a "baffle box", (resonator) for the intake air to lessen the sound of the intake air being "sucked" into the engine. If you measured the area of the standard intake pipe opening versus the opening of the "hanging hose" you would see that the "hanging hose" is much larger. This allowes the engine to "pull" a higher volumn of air giving more power. You are also possibly getting warmer intake air as the area where you are receiving fresh air for the intake is one of the hotest spots in the engine bay. That's why I have my air cleaner for the turbo mounted where it is as that was the "coolest" area in the engine bay. You should be able to cruise at high speed with a lower percentage of throttle opening, and your acceleration should be "brisker". Better mileage could be contributed to the fact that you get to cruising speed quicker. (Fast acceleration vs slow acceleration)(That has been debated many times).........My opinion.
 

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Discussion Starter #9
Thanks for your input. The car does pick up speed with less throttle.

How do you feel about the use of Redline Water Wetter. I'm currently using it. I'm waiting for a infared laser to come in. I want to measure the surface temp on various parts on the engine. Then drain and refill without the Water Wetter and take measurements.
 
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cakley said:
Never gets that cold in Georgia. This "preheating" ideal is for the books and not real life. When you drive on the road you need X amount of power. If you had a perfect road with a 5% decline the the engine could afford to make less power and then the preheating would be useful. I live in Georgia and need power to make it up hills.
Well, I live in Indiana, and when the temperature dips into the single digits, my engine runs like crap until it is warm. Not to mention the much higher emissions when the engine is cold. That's real life.
 

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For the last 37000 miles I've have only been able to get an average of 53MPG. So I have tried to improve the engines ability to breath and exhale or intake and exhaust flow.

<snip>
From your description you have de-tuned the Insight to much a more aggressive driving style.

Better: as long as your style doesn't begin to take additional advantage of the increased performance.

Worse: if and when you decide to try and achieve the ultimate MPG performance the Insight is capable of.

The intake resonator is more than just a noise reducer. You can achieve mid single digit performance improvements if the intake is tuned to a specific resonant frequency. To peak engine torque and HP at streetable RPM's a correctly restricted exhaust systems has similar benefits.

Colder intake air temps (IAT sensor reading) below a rather warm 120ish appears to narrow the lean burn window.

With the Insight the peak MPG performance point is rather narrow. Consistently drive outside the envelope and you'll see correspondingly poor performance. Make the envelope bigger (as you apparently have) and you reduce the upper MPG potential.

Not a criticism. Just an FYI for others looking to get ultimate MPG.

John K. Bullock
aka. Insightful Trekker

03 5spd
78.8 best tank avg.
94+ best one way commute
87+ best round trip commute
 

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hey cakley,

Decent suggestions you have there. I'm going to attempt the intake MOD as soon as the temperature here in PA increases a little. It is a bit colder then usual around here. Since I am no welder by any stretch of the imagination, I'm going to either have a straight pipe installed as you suggest or perhaps describe your muffler MOD and have some one with more skill in that area make the MOD. I just bought my'03 insight about a month ago. Life time MPG thus far is 58.6. I would like to see a means of increasing the threshold at which the IMA kicks in, I was also thinking of some sort of manual means of engaging the assist. Of course, all that requires some sort of technical/engineering prowess that I simply do not have when it comes to cars. Just a thought.

SOooo, your idea seems to work well in theory, in the sense that it can help to decrease the amount of "pedal pressure" required to accelerate and maintain cruising speed. What troubles do you (or anyone else here) foresee if I were to do the intake MOD now given the cold climate? Temperature this morning was near freezing. Ya know, that seemingly slight "oomph" you get when you first drive a car on a cold morning? Is that something like what you are seeing with the MODs you made? I would love to reproduce that little extra "oomph" on a regular basis if possible. I notice that my insight accelerates much easier/quicker with less pressure to the pedal on a cold morning then it does on a mild or hot day. So what are the pros and cons of allowing cold air to intake to the engine at all times, even during near freezing temps? Thanks for all your ideas and posts:)
 

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Surely that 'oomph' you are feeling on a cold morning, is the automatic choke? The engine is running on a richer mixture until it warms up. However this reduces MPG - not what you want to reproduce?
 
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I have inproved mt LMPG too, by driving carefully.

It's gone up from 60 when I got the car to 80.
 

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megaoptimus,
If you only bought your car one month ago you have alot to learn to drive more efficiently.
I suggest you wait a year before you start playing with mods like this.
By then you would have stablelized your driving habits (good and bad) and any performance changes would likely be attributed to the mods or a placebo affect. (well that's reality).
 

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Discussion Starter #17
megaoptimus said:
hey cakley,



So what are the pros and cons of allowing cold air to intake to the engine at all times, even during near freezing temps? Thanks for all your ideas and posts:)
Might be too cold up north for the air intake mod during the winter months.. It will be great in the summer time. So far in georgia I've noticed that it takes my car slightly longer to warm up in the morning. Thus my MPG is about the same as before just slightly higher. Vice the drive home in the afternoon I can tell and see the difference.
If you have a heated garage or take long trips then save the intake mod till summer time.

For the exhaust. My MOD was long way to go about. Any muffler shop can cut the muffler off and weld up a straight pipe for less than 40.00

If you want better MPG. Get lighter weight rims ie VOLK ce28n 14x5.5. Keep a close track on the tire air pressure.
 

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Dumb questions

When I was looking at doing this mod, I realized that the entire intake could be disconnected at the airbox. Wouldn't this be more efficient at getting fresh air in than through the front heated air and the disconnected pipe that used to go down to the resonator?

Then it would basically have about 2 inches of pipe, go through the air filter (I have a K&N installed), then about 18" through the mass airflow sensor and into the intake manifold.

Granted that the cavitation from the rough pipe going down to the resonator could potentially do good things for the intake, though I think it is too far 'upwind' to do much good. Another use for the long intake is to keep water and other similar stuff out of the engine, but if the water gets that high in the car it is pretty much ready to be converted to beer cans.

Alternatively, would it be useful to run a hose that would be the same size as the intake to the airbox, and have it go down to the front of the car with some sheet metal formed ram air scoop? I'm guessing that this would be serious overkill of effort for minimal gain.

Also, with the muffler mod, would it be better just to open the muffler, cut out the baffling, button it up, and reinstall it? That way cops can't harrass you for having a straight pipe, but can still have a monster garage style "muffler". Even with straight pipes it couldn't be any louder than a 350 engine with a flowmaster setup, and I suspect it would be a lot quieter. Plus straight pipes or a "muffler" would have to sound better than one of those coffee can exhausts. Granted it may weigh an extra couple pounds, but I wouldn't think that would matter much.
 

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Discussion Starter #19
Re: Dumb questions

ScottH said:
When I was looking at doing this mod, I realized that the entire intake could be disconnected at the airbox. Wouldn't this be more efficient at getting fresh air in than through the front heated air and the disconnected pipe that used to go down to the resonator?

Then it would basically have about 2 inches of pipe, go through the air filter (I have a K&N installed), then about 18" through the mass airflow sensor and into the intake manifold.
I had allready tried what you said. Didn't see any improvement.

Cops and mufflers.... I rode a Harley for 3 years with straight pipes. I also had a Buell S1W 105+hp 1203 cc engine with 2 1/2 headers dumping into a 3" straightpipe. It was so loud that I had to wear ear plugs. I never once got questioned by the cops.

On the Insight. Its only 1.0L engine and has to flow through 2 cats. The cats kill most all of the sound. My muffler MOD just slightly increased the sound. A straight pipe would be only slightly louder. It would still be one of the quitest cars on the road.
 

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megaoptimus said:
Might be too cold up north for the air intake mod during the winter months.. It will be great in the summer time. So far in georgia I've noticed that it takes my car slightly longer to warm up in the morning. Thus my MPG is about the same as before just slightly higher. Vice the drive home in the afternoon I can tell and see the difference.
If you have a heated garage or take long trips then save the intake mod till summer time.

For the exhaust. My MOD was long way to go about. Any muffler shop can cut the muffler off and weld up a straight pipe for less than 40.00

If you want better MPG. Get lighter weight rims ie VOLK ce28n 14x5.5. Keep a close track on the tire air pressure.
Agreed. I hope we have one more warmer day up here before it gets too cold. I will try it then and see if I notice any difference. Other then that, I will have to wait until temps are warm again as I do not have a heated garage. Thanks for the info about the rims as well. I might look into that. I keep tire pressure at 46 all around. I figure that is a nice "hard" number while keeping a slight margin of saftey. I try to check it at least once a week. One of these I'll take it to 50 and see what 8) happens :shock:
 
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