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Discussion Starter #1 (Edited)
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This mod will only give the MPG performance boost in moderate temperatures. Too cold and MPG suffers in all cases. And like with all hyper MPG driving it cannot make up for a heavy right foot. It will in moderate temperatures and with hyper MPG driving techniques _help_ retain up to 10MPG that would otherwise be lost to the colder weather.

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The radiator block and MPG improvement has been discussed many times in here. I too have used the above block but removed it early this June with the onset of summer and temps in the high 80's - low 90's. Several other type radiator blocking schemes that have been presented in here appear much more complex, difficult to install and remove.

Now that outside temps have moderated to low and mid 80's I reinstalled it. On my well worn route home today - voilà +10MPG with ECT readings approaching 203F (still safe, fans auto on @ 205F).

Simply slide the above size piece of plain cardboard long length horizontally in between the radiator and AC condenser. AC users should not use this since it also decreases air flow across the condenser, increases compressor load and reduces AC efficiency. Insighters in warmer climates should delay this until daytime temps moderate to the mid 80's or if you frequently get into heavy stop & go traffic such that the auto stop function is "used up".

I would also recommend that unless you have the means to monitor your engines temp separate from the dash gauge (e.g. a scan tool) that you carefully consider the risk.

My summertime average for my afternoon ride home without the radiator block was in the upper 70's to low 80 MPG. Today's MPG (under ideal conditions of weather and traffic) was 90!

I'd like to hear other field test reports!

[Edit 2/17/07, Summarizing the design and cautionary considerations]

1) The amount of blockage can be varied according to the outside ambient air conditions. Just remember that the maximum needed unrestricted radiator area depends on both the _load_ (e.g. hill climbing) and speed. There is an interrelationship between the blockage size, load, and outside air temp. In -20F, -30C conditions and with a light throttle a near 100% block would likely be optimum, but have a _very_ narrow tolerance for change in temperature and engine load (e.g. speed).

Should you go for a weekend drive in the mountians or be late for work and decide to run with the big dogs in the fast lane, the size that has worked perfectly in the past may now cause a severe overheat and damage :!: And don't forget $$$$

The above is why monitoring the engine temperature with something more accurate than the stock engine temperature gauge is necessary. IMO once you establish the safe operatinge range, continuous independent monitoring is better, but redundant. Perhaps the easiest way to get this data is from a scan tool via the ECT (Engine Coolant Tempertaure sensor). There are many tools to choose from and it will also serve as a code reader for any future check engine light problems you might have. If you already have a Palm or Pocket PC then there are cables & software available for only a couple hundred dollars (google or the forum search feature is your friend). But a nice temperature gauge can probably be had for about 2/3 of that.

For your _maximum_ load (and speed) condition the cardboard block should not allow coolant temperature above 205F, 96C (the fans on point).

2) Running the Air Conditioner (AC, remember "Auto" is AC on) in warm weather with the block is just as bad. The restriction will also reduce airflow over the condenser (the outside AC coil). This _will_ cause higher AC pressure loads and could rapidly cause AC compressor failure :!: IMO and from my calculations (there are charts for AC pressure based on temperature and humidity) with a 50% blockage (6x17" ;) ) and "using" the AC in winter (60F, 16C and lower) as the "defogger" will be in the "safe range" and no additional compressor "wear" will result.

3) Positioning the cardboard so that the blockage is primairly horizontal is also a design consideration. The radiator cross flow tubes on the Insight are vertical. A horizontal piece of cardboard is effectively "cooling" the tubes in their normal direction of flow. Blocking a percentage of the radiator vertically will cause the entire length of a tube to be chilled, rather than the "normal" temperature drop from top to bottom across all tubes (which happens with or without the _horizontal_ cardboard). In theory _vertical_ cardboard can contribute to mineralization (internal flow blockage) in these cold tubes over the _long term_ and can ultimately require premature radiator replacement.

[end edit / addendum]
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Hi Insightful Trekker:

___I have been using my very thin summer based radiator block anytime it has been below 75 - 80 degrees with my almost all-highway commute. Given I use forced and or Autostop in heavy traffic exclusively, below 70 degrees F and I am ok. Above that, I just pull it before I start my commute or if traffic was incurred while under way above 70 degrees, I remove it while stopped on the road in the parking lot some of us call a normal commute ;)

___The following came 3 days ago on a mid 70’s - low 80’s day with the radiator block.



___The next one came 2 days ago on a low to mid 80’s day without …



___During the winter, I use a much more robust radiator block that isn’t nearly as breathable.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:3oe5cauy][email protected][/email:3oe5cauy]

 

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From reading the threads above, it seems that the extra MPG is due to a rise in engine operating temp only? At first I thought maybe you were talking aerodynamics from blocking the body opening, but you are talking about putting cardboard infront of the radiator, but still "inside" the body shell.

Curious: what is the normal operating temp of the insight? -all I have is the C ||| H gauge :( ) or what is the rating for the thermostat in the engine?

200-205F with the mod is not too bad, especially with Mobile 1 oil. My old vette did not kick on the fans 'till 220F and it would rise to 225-230F before the cooling started to take effect.

I wonder if there is a chance to find a higher temp thermostat? 180,190 and 200 degree thermostats are pretty common. That may keep you from having to get a daily weather forcast and futz with the cardboard accordingly.
 

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Discussion Starter #5
xcel:

I knew you used some type of radiator block. I'm "green" with envy over your MPG but wouldn't trade the hills of east Tennessee for the increase. :)

BTW WHY for sale!?? :(


Corey872:

I the thermostat according to the SM pg. 10-7 begins opening @ 187-194F and is fully open @ 212F. On pg. 10-27 the Radiator fan sw closes (fan on) @ 201-208 and re-opens (fan off) 5-15F lower.

Hmmm, strange interference overlap.


James:

My cardboard block from last fall lasted intact through early June of this year. THe plastic idea sounds better but I'd be wary of it melting and fusing to the radiator (no matter which politician's "promises" are emblazoned on it <VBG>).
 
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Hi Insightful Trekker:

___My commute will soon be dropping back to maybe 20 miles round trip from the current 180 + and the cost of the Corolla and Insight’s insurance can’t be made up with the Insight’s fuel economy with that few miles driven no matter the fuel economy differential :(

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1mya9a8g][email protected][/email:1mya9a8g]
 

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What I have done on my Insight, is blocking the lower opening, I can accomplish this since I own a Bra, I just put some rivets, made a cover, and it works just fine, it takes about a minute to put it in, and about 3 seconds to take it out, if I don't want to take it completely off, I just unsnap the edge on the drivers side, and tuck it in, and there is a small opening only on the side of the radiator, one of the benefits is the car is more aerodynamic, I have taken some pictures, e-mail me if you'd like to look at it.

And by the way, mileage goes up by about 10 MPG, I only use it in the morning, since temps here in the LA area are quite warm.
 

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I'm confused - my dad says that blocking the radiator shouldn't make any difference because there is no coolant flowing through the radiator unless the engine is too warm. Is this inaccurate? Or is the radiator block a "poor mans" alternative to installing a higher temp. thermostat?
 

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You are not the only one confused, and your father has a good point. First there is I believe a tiny hole in the thermostat that allows a trickle of coolant through even when the thermostat is closed. I don't think that this has a major impact though. Blocking the radiator does affect the air flow through the engine compartment and around the car. Whether this improves the aerodynamics is unclear. Certainly it prevents cool air from blowing directly onto the engine body, which is in itself a passive radiator. It also prevents cool air from entering the air intake. Note that part of the winter solution is to take air for the engine from around the catalytic convertor area, presumably a much warmer area. Lean burn seems to be largely dependant on having a warm air intake, perhaps because cool air and a lean mixture don't ignite effectively. The only way to prove what is really having the noticeable effect would be to separate the components and make accurate and repeatable tests. Honda knows the answer to all of this, but it cost them huge amounts of development capital to research, so they rightly keep this info to themselves. We can only speculate and try things for ourselves. However, another strong clue is how the mileage decreases in the rain. Presumably this is also due to the cooling effect as the radiator airflow is unchanged and the difference is unlikely due to tire resistance or slippage, or the impact of raindrops on the body alone.
 
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Hi Foxpaw:

___If you have seen your Insight’s coolant temperatures w/ an OBD-II scanner connected, 32 degree F ambient temps with around town hypermileage driving will result in a nice and cold 160 - 175 degree F coolant temperature. With a radiator block, you will see 205 + in around town and high 190’s out on the highway. It works and works even better as temperatures fall although there is still a huge fuel economy hit as external temps drop down into the 30’s and below :(

___B1shmu63, the hit during heavy rain is not the rain hitting the body but the tires pushing the water away. I have seen it too many times in very light and initial heavy w/ a very light sheen on the surface vs. after a hard rain with what appears to be ¼” of water standing on the pavement. The standing water drops my little beauties instantaneous by at least 25 mpg in the deep stuff.

___As for external temperature data, Honda has probably already performed these tests. Look at the Super Car project by GM, Ford, and Chrysler. I believe the Ford had an active front hood opening for coolant temperature and aerodynamics as exterior conditions change. All it would take is a straight up simulation of falling temps with a model of this colder airflow in and around the block as well as into the intake while on the Dyno with fuel pump readouts to see the results. How to cure our little beauties of this cold weather inefficiency would take a simple fuel heater w/ TCV bypass (some diesel’s have something similar already), a warm air intake using the waste heat of the CAT or after (better engineered then our current home made solutions), and an enclosed engine bay with some type of active opening(s) so as to keep the Insight’s variables at a close to optimum temperature. Take a look at an HCH sometime to see how tight those bays are. I was underneath one at the Milwaukee group meet earlier this year and talk about tight. Our Insight’s by comparison have more open holes then the Titanic!

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:3f9z2vop][email protected][/email:3f9z2vop]

 

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"I believe the Ford had an active front hood opening for coolant temperature..."

Deja vu all over again :) Had an old Volvo once (60-something, the one that looked like a '40s Ford), and it had an active radiator block. Or sort of active: it was like a little roller blind that was connected via a cable to a lever under the dash...
 
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Hi James:

___I wish I would have been around to see that as I believe it would be a very practical item for use on our hyper efficient little beauties today! Thanks for the “Insight” … No pun intended ;)

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:36j0z5pt][email protected][/email:36j0z5pt]

 

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Discussion Starter #14
xcel said:
<snip>

Take a look at an HCH sometime to see how tight those bays are. I was underneath one at the Milwaukee group meet earlier this year and talk about tight.

<snip>
Since you brought up the topic maybe this formula will work for you.

1 Insight + 1 Corolla = 1 HCH :)

<VBG>
 
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Hi Insightful Trekker:

1 Insight + 1 Corolla = 1 HCH :)

Is more like the following:

($10,000 @ 105/75 mpg) + ($10,000 @ 52/35 mpg) ≠ ($20,000 @ 63/53 mpg) w/ fuel ≤ $1.81 :(

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1xes9wtc][email protected][/email:1xes9wtc]

 

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Foxpaw, to answer you question, blocking the airflow prevents the cold air from taking away precious heat from the engine block, since it takes up to 2 hours to burn one gallon of fuel, you can see that it can make a big difference over a long period of time.

The thermostat controls the coolant temperature, but it cannot compensate for heat loss thru the engine block.

I block not the radiator itself, but the air dam opening, so the front of the car is more aerodynamic, that's another reason it helps the mileage as well.
 

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Discussion Starter #17
xcel said:
Is more like the following:

($10,000 @ 105/75 mpg) + ($10,000 @ 52/35 mpg) ? ($20,000 @ 63/53 mpg) w/ fuel ? $1.81 :(
Well my math works if you cancel out the MPG factors. And the MPG factors do eventually reduce the costs. Looks like no more dashboard video game for you.

$1.81 for how long? You are the optimist! :)

Its just I'll miss your contributions from behind the wheel in here. :(
 

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Insightful Trekker said:
Simply slide the above size piece of plain cardboard long length horizontally in between the radiator and AC condenser.
OK, I'm a newbie here, but this sounded like a pretty easy mod to try, and I was recycling some cardboard boxes anyway, so I tried it.

I slid my 6x17 cardboard piece in between the AC condenser and radiator, let go, and watched it slide out of reach...

So my question: did I do that right? I'm sure I could get it out if I tried, with some long skinny instrument, but I haven't seen anyone mention that it would slide away 6+ inches out of reach-- so it made me question whether I put the right sized piece in the right place in the right orientation. And with so many other people talking about taking out and putting in their radiator blocks within seconds, I wonder if this one is supposed to be so far in.

Anyone have any reassurance or any corrections for me?

Thanks.
 

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Discussion Starter #19
Sounds right to me. For rapid removal you'll need some type of pickup claw or loong needle nose pliers. Simply remove the 10mm hex bolt from the top radiator support and gently tilt the radiator back.

DO NOT try something like snagging it with a hooked end of a coat hanger. The radiator and condenser fins are very delicate and are easily damaged.

A vertical orientation would make removal easier. However, the radiator flow tubes are also vertically oriented and chilling 1/2 the radiator _may_ have some _long term_ undesirable consequences in regard to mineralization. Horizontally assures that all the flow tubes are more or less equal in temperature.

HTH!
 

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for easy removal, when you cut your cardboard, 6x17, cut it so there is a strip in the middle that goes to the top of rad, about 1 inch wide.
Or just attach a string to it!
What i actually did is, form a 8x18 inch cardboard, i cut it 6x17, with the remaining strip of 1x17, i stapled that piece vertically in the middle of the horizontal 6x17 board. voila.
 
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