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I have seen a few different attempts at making the Insight get better MPG by increasing the temp. My question is: The temp of what? Some people block radiators, some people put a hair dryer down the air intake. Is it the fact that the intake air is warm which aids mileage? Or, is it just a warm engine in general? Is it both? If you do run the engine at an "artificially" warm temp, is that bad for the engine? I would really like to make some type of simple temp altering mod. Please let me know if you have anwers to any of my questions. Also, any links to sites with examples of mods would be great. Thanks.
 
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Hi Brpeterson:

___You want to increase both the temperature of the coolant (radiator block) and the temperature of the air into the air intake manifold (warm air intake mod). Both have there purpose in an Insight.

___The Coolant temperature is the one that rises and falls as you run through Autostop, Fuel Cut, or simply stays low when traveling highway speeds in colder temperatures. This turns your lubricating oil into syrup … That was an extreme exaggeration of course but viscosity increases with lowering temperatures thus causing anything lubricated to run with a bit more friction thus reducing fuel economy. That is just one theory …

___The Air intake is the one that will keep you from lean burn in real cold weather or shrink the lean burn window to the point you don’t see much of it below 40 degrees F. It is not just lean burn window that shrinks but the ability for the fuel/air mixture to mix properly up to the point of ignition in the cylinder. I have read that some of the fuel in the fuel/air mixture can actually pool (condense?) when cold or when injected into colder surfaces and this pooling against a cylinder wall leads to unburned or at best uncontrolled flame fronts leading to a further reduction in fuel economy and performance. This second effect hurts the CVT’ers as well so it is recommended that they use this mod in colder temperatures also.

___Once you are above lets say 75 degrees F, the warm air intake isn’t really needed as you usually have a 95 - 100 degree F AIT which gives close to maximum fuel economy IIRC. The coolant temperature however is dependant on the thermostat and the Insight’s ability to create and maintain the heat in the block. If you are a hyper miler, you are only burning lets say 1.5 to 2 oz. of fuel a minute. At that rate, I am sure you can understand that the fuels energy not only warms all the rotating parts involved but also propels the Insight down the road at 50 - 55 mph. Take a thimble of gas and light it off. Now consider how small the amount of heat generated is when burning it efficiently across a minute of time. This tells you how little energy the Insight actually uses to do all the things it does and why coolant temperatures can vary so much when the ICE stops or Fuel cuts for any length of time. A 70 # chunk of aluminum heated by < 2 oz. of fuel a minute (remember that 30 - 35% of that 1.5 - 2.0 oz. goes to propel the Insight through the air) can cool off pretty darn fast with any amount of air flow moving across it.

___If anyone has a better or more straightforward explanation, I would certainly be glad to include it in any future posts on the Warm Air Intake/Radiator block mod subject’s myself.

___The real solution is to warm the incoming fuel and air intake to ~ 90 degrees as well as sealing off the entire block assembly from any external temperatures effects. I have looked under the Insight and it would take a hell of a specialized plate to cover all the exposed openings as well as a specialized contraption to warm the fuel before it hits the injectors as well. Someone will eventually do it if they haven’t already but I haven’t seen it done by anyone for our little beauties just yet. Another benefit of a full cover plate is our Insight’s Cd would probably fall another 1 or 2/100 of a point given the front underside of our Insight’s is relatively rough with the openings even with the aero shields/plates already installed from the factory.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:3s7y5j9y][email protected][/email:3s7y5j9y]
 

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I have some mods at:

http://fungiart.com/insight

I will be posting more on the warm air intake mod I have done.

It is funny that you can be driving with the cabin too hot (because of sun) and the poor little engine with the air running over it isn't hot enough at all because it doesn't burn enough gas to make it hot!
 

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Great explanation xcel! :)

Maybe the simplest explanation of why warmer intake air (up to a limit) improves MPG is better fuel vaporization and the more complete combustion that is enabled by the Insight's lean burn design.

But then I'd be leaving out all the other good aspects you included! <g>

Brpeterson, if you want to see one type of hot intake air system see the link in my signature. :)

HTH! :)
 

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I have done some mods on my Insight, I started with placing six thermocouples in several places in engine, the first one is for outside air temp, second is for air intake temp, third is for coolant return to the engine, the fourth is for coolant coming out of engine, the fifth is for oil temp, the sixth is for exaust temp.

This is what I found so far, DO NOT block the radiator directly with cardboard, as temperature will rise to about 235 F with the outside temperature being around 60 F, the coolant return was about 217 F
air intake temp was about 75, the fan turned on but the temp will take a long time to go down. I immediately stopped the car, removed the cardboard and took off, in less than 1/4 of a mile the temp was back down to normal, Even at 235 F :oops: , I didn't see the stock temp gauge climb significantly, it only moved about 2 bars.

What I found it works best to leave some space between the radiator and the cardboard, so here is what I did. I bought a bra for my car, I decided to modify it as well as make it more aerodynamic, I covered the lower air intake, and the results are as follows:

Outside temp 60 F. Incoming air temp 75 F, Coolant returning to the engine 140 F, Coolant from the engine to radiator, 190 F.
I have not done the Hot air intake mod yet, I will keep you posted what the temperature reading is, but I noticed that when you run the AC the intake temp. goes up about 20 - 25 F.
I took some pictures with the bra cover, I will try to post them soon. :wink:
 

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So did you find that these mods had a significant impact on mpg down there in "frosty" Northridge? 8)
 
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Hi Calpod:

___You can watch the Coolant temperature via the OBD-II. If you are traveling in the city w/ stop and go, at 32 degrees, you will see in the low 200 - 210 degree F range. On the highway even up to 70 degrees F ambient, you will see ~ 200 degrees F so no; you do not have to pull the radiator block if you are a highway driver almost exclusively. If you see 8 bars on the temp gauge, it is time to pull, otherwise, leave it fully covered for maximum fuel economy until 70 - 75 + degrees F. The AIT is also available via OBD-II as well.

___SeanW, it depends in what temperatures you are driving in. I haven’t had a tank < EPA highway estimates w/ the warm air mods installed since I owned her and that includes one cold SOB tank with an average of ~ 10 degrees F! I have pulled the radiator block ~ 10 X so far this year for afternoon commutes home when it is > 75 but other then that, everything stays as is and I reinstall the radiator block for my commute to work in the morning (usually 45 - 55 degrees F) when I am on days.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:18e7f1bx][email protected][/email:18e7f1bx]
 

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Very funny. :!:
I lived in Georgia and the it would be below freezing sometimes, and I noticed my mileage would drop like a rock, I started taping the air dam about 3 years ago. but I noticed even here in California it helps getting the engine warmed-up, I get auto-stop about 2 blocks from my house in the morning, and I have had the front covered in temperatures as high as 80 F and the coolant going to the radiator does not change much, it only gets to temp much quicker, I am setting up some pictures in Cardomain.com, so you'll be able to see the pics, and also the data, I may drive the car back to Georgia when the weather starts getting cold, so I can see the temp in cold weather, as I did not install the thermocouples until I was here in California.
 

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How about warming the fuel line, thus incresing the fuel temp for better vaporization.
 

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You could warm the fuel lines - that's the opposite of what many drag racers do. Cooler fuel means you get a denser air/fuel charge inside the cylinder - which is good for power. Warmer fuel would result in a less dense air/fuel charge, which would likely improve mileage, but reduce power. It would be similar to having a slightly smaller displacement engine.
 

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Warming the fuel lines sounds like a good idea until you think it through.

Get it too hot and it will burn the car to the ground.

Get it too warm and it will begin to boil causing the wrong volume of fuel to be metered to the engine.

Let it stay too warm after shutdown and all kinds of gunk will build up in the heated area.

A much more difficult task than warming the intake air.

HTH! :)
 

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The gas probably gets quite hot when the car is parked in the sun on the asphault in the south. Since the fuel injection system is running at a positive pressure vapour lock shouldn't be a problem. I knew a fellow 25 years back who had tried a system of heating it using the engine coolant and he insisted it worked wonders. Heating the air sounds safer and easier though.
 

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One of the problems with heating the fuel is that excess fuel pressure is relieved by venting fuel back to the tank. So if you heat the fuel going to the engine, you are going to end up with a tank full of hot gasoline. Not a good thing.

Any system will require a thermostat (i.e. be closed loop), since too much temp will result in vapor lock. Also the amount heat needed will vary greatly depending on ambient conditions.

Anyone remeber if the honda uses a fuel temp sensor? Hot fuel is less dense and if not corrected, will make your engine run lean when it should not. That may mean better MPG but at the cost of increased emissions and prehaps reduced drivability.
 
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Hi All:

___I think some are taking the warmed fuel discussion beyond the temperature range it is needed in? Those of us that drive in colder temperatures would only need this in lets say 50 degrees F and below. Just a slight warming is all. When its 0 degrees F, the warm air mod might get us to ~ 30 - 40 degrees AIT at best. The problem is that the fuel from the tank and all the way to the point of mixing w/ the air stream in the fuel injection system is still 0 degrees F. This is a shattering blow to ones fuel economy in the winter. In the summer months, it wouldn’t be needed so all this talk about vapor lock and such is great discussion for a year around mod but like the warm air intake or radiator block, it is really only needed below a certain temperature that either the driver sees fit to control or controlled via a thermostat. I would love to have a 90 degree fuel and air intake at all times and the only way to get it is by using the waste heat of the ICE in some fashion to get both the AIT (via warm air mod) and fuel intake temperatures (via a thermostatically controlled internal block passage and bypass TCV) to keep them there. Maybe an external electric fuel line heater would do the trick as well but I don’t know of such a device or how it would be integrated without burning my little beauty to the ground :(

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:uvagbdh6][email protected][/email:uvagbdh6]
 

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How about a water intercooler running a coolant in it? And a heated fuel filter. Then have a solenoid activated by a thermostat. Completely automatic, summer to winter!
 

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I might try running the heated fuel filter that I bought to go on my old diesel and see what happens and just make a cheap hot air intake until next winter. Don't want to put too much money into this car right away since I put 30k miles a year for work.
 

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The theory behind raising intake air temperature is partly that it improves combustion, but also that it makes the air less dense, allowing a more open throttle and thereby less restriction and pumping losses. If you fly aircraft, you know how pulling the carb heat lever requires an increase in manifold air pressure to maintain the same power output. Best efficiency is achieved when MAP is close to the outside air pressure.

The theory behind raising coolant temperature is to reduce heat loss to the cylinder walls. As the piston strokes down, the combusted charge has already begun to lose heat to the cylinder walls, lowering pressure. An ideal engine would have perfectly insulated cylinder walls, keeping all the energy in the burned mixture. I suppose that doesn't exist because the walls would melt? Instead, engine manufacturers have been raising coolant temperatures over the years. My 1988 MR2 used to run 82 C, the Insight is like 96 C, a 2008 Civic runs around 92 C. I see no harm in pushing the Insight up to 100 - 102 C as long as you have an Ultragauge that will sound an alarm if it gets over 105 or something.
 

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This is your second "Technical" post. Do you have an INSIGHT?

Willie
 

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I run adjustable rad block and adjustable warm air inlet all year (and have for almost 3 years), and lower grill block from now through April. Allows keeping ect above 200 F, preferably 205-212, and IAT anywhere from 20 to 100+ deg F over ambient preferably around 110-115 deg F IAT. Minimizes effects of at least one variable in weather. Allows for quicker warm up in cold weather.

After installing my lower grill block last night, and comparing commute runs from the day before with today (almost identical weather and road conditions at 35 deg F), I had a 7% gain on my mpg (58.9 mpg vs 63.4 'to work commute' in the cvt). Still losing due to seasonal change, but minimizing the hit.
 
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