ICE Radiant Heat Reflector for the Gen II

[Rokeby]

I've got a piece of "super insulation/radiant barrier," made up of heavy
duty aluminum foil bonded to both sides of 1/4 inch thick plastic foam.
The piece is about 36 in. by 48 in. I'm thinking about using it as a
radiant heat reflector/thermal blanket over the top of the ICE in my
Gen II. The goal is to help retain heat as the temps drop and help keep
FE/MPGs up. Here's a view of the engine bay:



I won't cover the electronics package on the right, as I don't
want/need it kept warm. By cutting the sheet in half, I can extend
the blanket about halfway down between the ICE and the radiator and
keep well away from the serpentine belt on the far passenger side of
the ICE. By feeling over the top and behind the ICE, I can cover it,
and maybe extend the insulation /barrier half way down the back side.
Here's a picture of the insulation/barrier in place:



I can work the two pieces of insulation around the various bits of
piping and wiring at the front of the ICE, and between the ICE and
electrical boxes going to the rear. Here is a view looking down
between the ICE and the radiator with the insulation in place:



As I'm not going to try to mold the insulation tightly to the
block/head, there will still be an airspace and some moving air
between the insulation/barrier and the block. I expect that the only
real contribution to heat retention will be to reflect radiant heat back
to the block when I'm stopped in traffic with the ICE off and block
temps plummet. I'm thinking the insulation/barrier will stay in place
due the many bends and curves created in working it into place.

I use grill blocking already. I'm using a ScanGaugeII, so I can monitor
ICE temps.

My questions are:
* Have any of my fellow Gen II Prianistas experimented with
something like this?
* If so, did you see any noticeable/measurable FE/MPG results?
* Did you encounter any problems, or incur any damage?

I welcome constructive comments, suggestions, concerns, etc.

(I know what you're thinking....
No, there isn't enough left over foil/foam/foil to make an insulated
aluminum foil hat. )

[PriusLewis]

If possible you might want to place this under the air cleaner box. Heating the intake air reduces thermal efficiency of the combustion process and, therefore, requires more gas to produce less HP. This is why performance engines use cold air intake (hood scoop or under bumper intake) - the cooler air is denser, producing better performance.

[a_gray_prius]

I imagine this would be an effective upgrade for Prius owners who live in cold climates, especially in cases where the engine runs simply to maintain heater temperature.

However, I have significant concerns about the effect of heat retention in places where temperatures exceed 100 degrees F. Fundamentally, my question is: At the top range of normal environmental temperatures, could this modification have negative consequences related to overheating?

[usbseawolf2000]

The hood already has a layer heat retaining material. You may be better off covering the bottom of the engine/transaxle block. They are openly exposed under the car.

I am thinking about heat shielding them as well as the cat converter with fiber glass insulation.

I wonder if it can handle the temp of the cat converter. I am also concern about the cat getting too hot and possibly causing damage. Anyone with knowledge about it? Is this a bad idea?

I am not concern about overheating the ICE and transaxle because they have active cooling with coolant through radiator.

[KJF]

I have been looking for some foil-backed foam material such as this for similar purposes. Where did you get this material?

[Rokeby]

Originally Posted by KJF

I have been looking for some foil-backed foam material such as this for
similar purposes. Where did you get this material?

KjF,

I got my scrap piece from a friend.
However, you can get it, or something like it, at Lowes:

Reflectix at Lowe's: 16" x 25' Double Reflective Foil Insulation

[Politburo]

Overheating a cat can damage it.

[drees]

Originally Posted by PriusLewis

If possible you might want to place this under the air cleaner box. Heating the intake air reduces thermal efficiency of the combustion process and, therefore, requires more gas to produce less HP. This is why performance engines use cold air intake (hood scoop or under bumper intake) - the cooler air is denser, producing better performance.

While cooler air can make more power, hotter, less dense air can actually improve fuel economy since being less dense, allows you to open your throttle body more (and the throttle body is a huge restriction).

So without actually testing it, I'd say don't worry about it.

[Rokeby]

Originally Posted by PriusLewis

If possible you might want to place this under the air cleaner box.
Heating the intake air reduces thermal efficiency of the
combustion process and, therefore, requires more gas to produce
less HP...

I thought of that, but it's against the "easy-in, easy-out" nature of
this project as initially conceived. That said, on a 30 mi. trip
earlier today, I monitored both OAT (Outside Air Temp) on the
MFD, and IAT (Inlet Air Temp) on the ScanGauge for the first time.
Outside air was 55 defF, Inlet Air varied beteen 62 and 88 degF.,
with a peak of 92 when stopped with the ICE off. The SG booklet
says that IAT will be "a few degrees" above OAT. That seems like
more than a "few," but since I've got no base line to compare
against, I'm going to have to do some data gathering on this.

I'm also going to check and see how easily the air box is to
remove/replace. If it's quick and easy, I may try this. Thanks.

Originally Posted by a_gray_prius

I imagine this would be an effective upgrade for Prius owners who
live in cold climates, especially in cases where the engine runs
simply to maintain heater temperature.

However, I have significant concerns about the effect of heat
retention in places where temperatures exceed 100 degrees F.
Fundamentally, my question is: At the top range of normal
environmental temperatures, could this modification have
negative consequences related to overheating?

Sorry. My OP is less than perfect; I didn't make it clear that I am
considering this only for cold weather use this coming winter.

Originally Posted by usbseawolf2000

The hood already has a layer of heat retaining material.

I pulled and poked at that when I opened the hood. I didn't see any
obvious stuff to suggest that it would act as a radiant heat
reflector. I toyed with the idea of putting the stuff I got behind it,
but decided it was too far from the block itself.

You may be better off covering the bottom of the engine/transaxle
block. They are openly exposed under the car.

As I drove around today watching various temps on the SG, I
thought about this as well. The oil sump is pretty much hanging
out in the breeze under there. Wrapping it would seem to be a good
idea, although I'm not in a position to get under there easily, if at
all. You would also probably need a thin gauge, well attached
aluminum shield to protect from rocks, pebbles, small road debris,
etc. Keeping the shield in place in heavy snow/slush would
be problematic.

For those interested in further reading, here is a thread I found
over at EcoModder:
Insulated Engine? - Fuel Economy, Hypermiling - EcoModder.com

Buried in that thread is this jewel of a link:
Randall's Insight - MIMA Honda Insight Modified Integrated Motor Assist

Holy Cow! a permanent, zippered closure, multi-layered ICE Cozy
sewed of some unnamed fabric/foil/insulation laminate. Hot stuff!

[Rokeby]

I've made two out and back trips of about 30 miles with the radiant
heat reflector/barrier in place. It is too early to quantify any benefit it
may provide. It appears that initial ICE warm up is hastened, WT cools
more slowly at ICE-off stops and no-arrows glide, and steady-state
running block temps are somewhat higher. I'm holding off putting
numbers to these conditions as I collect more data over a longer
period of time, maybe a week or so.

Some casual observations:

For the first time, I've been simultaneously monitoring three temps:
Outside Air Temp (OAT) on the MSD,
ICE cooling Water Temp (WT),
and Inlet Air Temp (IAT)
on my ScanGaugeII. Fascinating stuff. In the discussion that follows,
OAT is between 55-57 degF.

Inlet air Temp is a strange beast. I don't know where it is measured,
but it is subject to great variability:
* it appears to be located close to or in the engine block, head, or
intake manifold because after turing the car off, over a period of ~30
min. temps rise dramatically up to 110 deg in one case. As the car
sits, WT slowly falls, IAT slowly rises. When the two roughly match,
they then fall roughly together. The same thing happens when you sit
ICE-off at a light or in a long, no-arrows glide.
* it appears to react to large volumes of air passing it because with
the ICE running over 2 or 3 minutes, the temp begins to drop.

In general driving around, IAT runs from 5 to 55 degF above OAT. The
higher differentials are reached as the car fully warms up, this is well
beyond the Stage 4 warm up period, at least 20 minutes from start up.
Also, higher differentials occur in roughly steady state driving at
freeway speeds.

I haven't puzzled out what meaningful information I can learn from
further observation of IAT. However, I do wonder how to make head
or tail about the earlier postings about high IA temp with lower
density air and conversely low IA temps and higher density air. With
the 55 degF swings that i've see in very gentle driving in moderate
OATs, there must be a whole lot of computer based compensation
going on in real time. I suppose this is one reason why computer
controlled fuel injection is so vastly superior to a carburetor.