idle warm-up experiment

[MetroMPG]

i realize this is probably preaching to the choir here...

<img src="http://www.ultralightnews.ca/westach/images/squarewatertemp.jpg" width="180" align="right">

we all know that it's better to drive a cold engine gently than to let it idle after a cold start. it's generally accepted that driving uses less total fuel than idling to warm up first. driving also warms the motor up faster than idling (not to mention the drivetrain, tires, bearings, etc., which idling alone doesn't help.)

but how much faster? i didn't really know. time to get me some data!

<b>the test:</b>

i did a really basic experiment: i timed how long my car took to reach operating temp (195 F) idling, from a cold start.

(have some fun... before you read any further, take a guess at how many minutes it took, from 19 F ambient...)

<b>the test conditions:</b>

- ambient: -7 C / 19 F
- NO electrical accessories on
- cold soak (hadn't driven it since the day before)
- WAI in place
- didn't touch the accelerator at all - left the ECU to do its thing

<b>the data:</b>

note: a couple of minutes into the test i dope-slapped myself because i realized this was also a perfect opportunity to monitor changing fuel enrichment as the engine warmed up. so you'll see those figures start part way down the table - "liters per hour" of fuel consumption.

the acronyms:

FWT: coolant (water) temp in degrees F
FIA: intake air temp in degrees F
Lph: fuel consumption in liters per hour

<TABLE CELLSPACING="0" BORDER="1" CELLPADDING="2"><TR><TD><B>time (min)</B></TD><TD><B>FWT</B></TD><TD><B>FIA</B></TD><TD><B>Lph</B></TD></TR><TR><TD>0</TD><TD>19</TD><TD>22</TD><TD><P></P></TD></TR><TR><TD><P></P></TD><TD>30</TD><TD>19</TD><TD><P></P></TD></TR><TR><TD>1</TD><TD>42</TD><TD>21</TD><TD><P></P></TD></TR><TR><TD><P></P></TD><TD>57</TD><TD>21</TD><TD><P></P></TD></TR><TR><TD>2</TD><TD>73</TD><TD>21</TD><TD><P></P></TD></TR><TR><TD><P></P></TD><TD>83</TD><TD>21</TD><TD><P></P></TD></TR><TR><TD>3</TD><TD>96</TD><TD>22</TD><TD>0.8</TD></TR><TR><TD><P></P></TD><TD>105</TD><TD>24</TD><TD>0.8</TD></TR><TR><TD>4</TD><TD>110</TD><TD>24</TD><TD>0.7</TD></TR><TR><TD><P></P></TD><TD>118</TD><TD>26</TD><TD>0.7</TD></TR><TR><TD>5</TD><TD>127</TD><TD>28</TD><TD>0.7</TD></TR><TR><TD><P></P></TD><TD>132</TD><TD>30</TD><TD>0.7</TD></TR><TR><TD>6</TD><TD>137</TD><TD>30</TD><TD>0.7</TD></TR><TR><TD><P></P></TD><TD>141</TD><TD>30</TD><TD>0.7</TD></TR><TR><TD>7</TD><TD>146</TD><TD>31</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>150</TD><TD>33</TD><TD>0.6</TD></TR><TR><TD>8</TD><TD>154</TD><TD>35</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>157</TD><TD>37</TD><TD>0.6</TD></TR><TR><TD>9</TD><TD>161</TD><TD>37</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>164</TD><TD>37</TD><TD>0.6</TD></TR><TR><TD>10</TD><TD>166</TD><TD>40</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>168</TD><TD>42</TD><TD>0.6</TD></TR><TR><TD>11</TD><TD>172</TD><TD>42</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>173</TD><TD>46</TD><TD>0.5</TD></TR><TR><TD>12</TD><TD>175</TD><TD>46</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>179</TD><TD>48</TD><TD>0.5</TD></TR><TR><TD>13</TD><TD>181</TD><TD>48</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>182</TD><TD>51</TD><TD>0.5</TD></TR><TR><TD>14</TD><TD>184</TD><TD>51</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>186</TD><TD>51</TD><TD>0.5</TD></TR><TR><TD>15</TD><TD>188</TD><TD>53</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>190</TD><TD>55</TD><TD>0.5</TD></TR><TR><TD>16</TD><TD>191</TD><TD>55</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>193</TD><TD>57</TD><TD>0.5</TD></TR><TR><TD>17</TD><TD>195</TD><TD>57</TD><TD>0.5</TD></TR></TABLE>
<img src="http://metrompg.com/offsite/warm-up-chart.gif">

<b>some observations:</b>

- how'd you do with your guess??

- it was shockingly slow to warm up, wasn't it. way off my guess. it only takes 3 or 4 minutes to reach operating temps when driven, though i'll have to wait until the ambient is the same and do a repeat test for a proper comparison.

- a larger engine might warm up quicker than my 993cc alumninum powerhouse, since it will be using more fuel (though it's also a larger heat sink...)

- since doing this, i have watched the Lph figure and have seen <b>2.0 Lph</b> (!!!) immediately after start-up. i'm curious to see how fast it tapers down to 0.8. the plot suggests Lph tapers faster in the beginning, which makes sense. it steps down relative to FWT at 110, 146, 172 F

[rh77]

The general public overwhelmingly believes in the "idle warm up", but as it's mentioned more that this is a bad idea, hopefully more folks will figure out that it's bad not only for the car, but for the environment. That's why I've decided to keep my engine block heater plugged-in all the time. I get to closed-loop almost immediately, and the overdrive kicks right in. Even after the car's parked for 5 hours, it's back down to cold start-up conditions, so the heater is needed even during the day. I'm sure it's sucking up some juice from the electrical grid, but the fuel savings has to even out the electrical use.

RH77

[Compaq888]

where can I get this engine block heater?
It takes my car 4.5-5 miles to reach operating temp and go into overdrive.

[SVOboy]

Nissan and ebay have them. Different types of course, check out the engine block heater threads, y0!

[Matt Timion]

For older cars I'd recommend getting the inline block heater. Hell, I'd recommend it for newer cars too. Much easier to install and you don't have to remove the frost plug, which might come in handy one day.

MetroMPG, awesome data. Your experiments put me to shame.

Soon I'll be testing again, once the weather clears up.

[MetroMPG]

the inline *circulating* heater is much more effective than the *non-circulating* kind.

the non-circ. one installed in the lower rad hose isn't very efficient at spreading the heat. i've read several accounts of people using the lower rad hose style - they can feel and hear the coolant boiling away in the hose, but it doesn't transfer past the (closed) thermostat very well.

my pick would be on the recirculating type that installs in the heater hose line.

[MetroMPG]

Originally Posted by rh77

That's why I've decided to keep my engine block heater plugged-in all the time.

literally all the time?

that may be overkill. 2 hours before driving is the most you should need to get the good effects (closed loop & o.d.). i aim for 1 - 1.5 hrs of plug-in time before i drive.

you know you can also get a block heater timer, eh? if you're on a regular schedule, they work great. and it saves some power & money in the long run.

[rh77]

Originally Posted by MetroMPG

literally all the time?

that may be overkill. 2 hours before driving is the most you should need to get the good effects (closed loop & o.d.). i aim for 1 - 1.5 hrs of plug-in time before i drive.

you know you can also get a block heater timer, eh? if you're on a regular schedule, they work great. and it saves some power & money in the long run.

Maybe a lack of planning on my part, but I don't really know when I'll be driving the car again during the day (I work from home and drive to the airport often, or to the post office). I could probably have it set up on a heavy-duty timer where it shuts-down at night, and comes on 1.5 hours before I leave in the morning for my daily routine (coffee run -- it's psychological -- I love driving, and I drive to the coffee shop before I start work in the morning to get into the work-flow mood).

By the way, I installed the OEM version that I ordered from my dealer. I've been accused of overpaying, but it came with helpful info for installation and it installed right into the drain plug (note: lots of coolant will drain -- get a sizable pan to collect it if you go that route, and follow proper technique for bleeding air from the cooling system).

RH77

[DaX]

RH77,

which coolant plug did it install into - the one on the front of the block? Does yours circulate?

[Compaq888]

rh77 how much did you pay and is yours AC or DC power?

[SVOboy]

By the way, I installed the OEM version that I ordered from my dealer. I've been accused of overpaying

I hope this wasn't me, I think it was a good deal actually, y0!

[rh77]

Originally Posted by SVOboy

I hope this wasn't me, I think it was a good deal actually, y0!

Hmmm, let me think back, I can't remember -- wait...

Originally Posted by SVOboy

;-)

Just bustin' your chops. I probably could've gotten one online cheaper, but I couldn't find one for my year specifically (even though I'm sure the B18B1 block is the same over the years). I went to the dealer, got the OEM version and the service guy was nice enough to print-out the mechanic's install diagrams with all of the bolt sizes and torque specs.

To answer all the questions:

*It was $42 + Tax
*The heater element goes into the coolant drain (frost) plug of the engine block (which is a buggah to get off, by the way).
*It doesn't circulate the coolant, but it heats the coolant in the jacket and the block itself. Basically, I imagine the heated coolant to flow immediately at startup and homogenize to get everything up to temp rapidly.
*The heating element is 110-Volts AC. Basically, the element is like a stovetop coil on the end, and has a heavy-duty rubber boot where the wiring harness plugs into. The harness then routes to the air dam where it can be plugged into a wall-socket via extension cord.
*All of the zip-ties, harness tubing, even a rubber pad for the harness to rest on a coolant return line was included. Also, it has a little cap to cover the plug so it doesn't get corroded. Surprisingly, it's hardly noticeable.
*I'm also taking comfort in the fact that warm fluids are available on cold-starts to reduce friction in the first 5 minutes of operation (since I don't warm-up, that would include the auto-trans and oil delivery system).

RH77

[Compaq888]

I think this mod and 2 more psi in the tires might push me to 30mpg average mixed. I hate the fact that in the morning my car is cold.

Is there any DC power Engine block heaters? My car is parked away far from the house.

[rh77]

I park at the airport for extended periods with no AC plug, so I looked into the same thing. Unfortunatley, to generate the heat required would take a LOT of DC Voltage, something that a car battery or solar panels wouldn't provide. There's a device on the market that like a little generator that runs on gasoline, but it's like $1600 -- It seems like a counter-productive luxury item for toasty starts.

I've struggled with the same problem, and I don't really have a solution. The only thing I can thing of is to get a small AC generator, and have it start via a servo via a cell-phone call (like some remote start systems), and use the traditional EBH. But those have substantial weight, and could also be counter-productive.

RH77

[Matt Timion]

THis thread has inspired me to get an inline circulating block heater for my wife. She drives to work every day at 5:40am and never gets the full effect of the heater (if any effect at all).

Her having hot air AND wasting less gas is way worth it IMHO.

[MetroMPG]

Her having hot air AND wasting less gas is way worth it IMHO.

i've always said that even if my block heater was a "net zero gain" as far as energy use (consuming electricity to save gasoline) OR for saving money, i'd still use it for the comfort factor and also because it reduces wear from starting a (very) cold engine.

[rh77]

Originally Posted by MetroMPG

i've always said that even if my block heater was a "net zero gain" as far as energy use (consuming electricity to save gasoline) OR for saving money, i'd still use it for the comfort factor and also because it reduces wear from starting a (very) cold engine.

I echo that sentiment. It's just worked out for the better in so many ways.

RH77

[JanGeo]

Hey guys what is the wattage of these block heaters. If in the couple of hundred watts then a simple inverter could do the trick off the battery or a spare battery - which you would charge off solar cells or the car alternator when decellerating or going down hill when excess voltage is present even run it off the brake lights with a relay because loading the alternator when stopping or stopped makes better use of the gas you are burning anyway. Next you setup a smart timer for those long airport parking intervals and have it turn on an hour before you return even if it is a week away or the next morning. There are also 12 volt remote control relays available for parked outside the house use.

[MetroMPG]

mine's a 300 watt deal.

so if you wanted to use it for 1.5 hrs on a 12v source you'd need 300w / 12v * 1.5 hrs = 37.5 amp hours.

is my math right?

that's running it straight off the battery though. if you used an inverter, it would take even more power due to conversion losses.

my deep cycle boat battery is rated at 75 amp hours capacity, so, yes i guess you could use up half the battery's capacity to preheat the engine.

[JanGeo]

Yup the math is correct and the inverter is going to add some losses You should look at the temperature rise as a function of time like the idle test you did to see what gives the most increase per watt hour of energy by the heater. This will give you the rate of heat loss of the engine. Maybe you could run a bunch of smaller 12 volt batteries in series instead of the inverter and get a little less voltage and watts into the heater but still have it help. Now you are starting to see the power of gasoline vs electricity. Anyone for an engine blanket??? Maybe a fully insulated engine compartment. Another idea would be an insulated tank with extra coolant that you heat up while driving then with a valve seal off from the motor. When you get back in the car you dump the still hot water back into the motor an poof instant heat. No extra energy used and if you want use the block heater on the insulated tank. Man what a great idea huh? Only would take a few gallons of storage - a small hot water heater would work.

[Compaq888]

Originally Posted by JanGeo

Yup the math is correct and the inverter is going to add some losses You should look at the temperature rise as a function of time like the idle test you did to see what gives the most increase per watt hour of energy by the heater. This will give you the rate of heat loss of the engine. Maybe you could run a bunch of smaller 12 volt batteries in series instead of the inverter and get a little less voltage and watts into the heater but still have it help. Now you are starting to see the power of gasoline vs electricity. Anyone for an engine blanket??? Maybe a fully insulated engine compartment. Another idea would be an insulated tank with extra coolant that you heat up while driving then with a valve seal off from the motor. When you get back in the car you dump the still hot water back into the motor an poof instant heat. No extra energy used and if you want use the block heater on the insulated tank. Man what a great idea huh? Only would take a few gallons of storage - a small hot water heater would work.

The prius already has this system in use. It keeps the coolant warm up to 3 days.

[MetroMPG]

since initially doing the idle warm-up experiment, i kicked myself for not recording the fuel consumption data in the few first minutes.

<a href="http://www.gassavers.org/forum_topic/idle.html">sludgy's thread</a> today about his idle gallon-per-hour observations (he got a scangauge - new toy!) inspired me to complete the test.

as it turned out, tonight was the same temperature as the original test, so i only reproduced the first 3 minutes, and have added that data to complete the table and chart.

<b>the finished table:</b>

<TABLE CELLSPACING="0" BORDER="1" CELLPADDING="2"><TR><TD><B>time (min)</B></TD><TD><B>FWT</B></TD><TD><B>FIA</B></TD><TD><B>Lph</B></TD></TR><TR><TD>0</TD><TD>19</TD><TD>22</TD><TD>1.5</TD></TR><TR><TD><P></P></TD><TD>30</TD><TD>19</TD><TD>1.3</TD></TR><TR><TD>1</TD><TD>42</TD><TD>21</TD><TD>1.1</TD></TR><TR><TD><P></P></TD><TD>57</TD><TD>21</TD><TD>1.0</TD></TR><TR><TD>2</TD><TD>73</TD><TD>21</TD><TD>1.0</TD></TR><TR><TD><P></P></TD><TD>83</TD><TD>21</TD><TD>0.9</TD></TR><TR><TD>3</TD><TD>96</TD><TD>22</TD><TD>0.8</TD></TR><TR><TD><P></P></TD><TD>105</TD><TD>24</TD><TD>0.8</TD></TR><TR><TD>4</TD><TD>110</TD><TD>24</TD><TD>0.7</TD></TR><TR><TD><P></P></TD><TD>118</TD><TD>26</TD><TD>0.7</TD></TR><TR><TD>5</TD><TD>127</TD><TD>28</TD><TD>0.7</TD></TR><TR><TD><P></P></TD><TD>132</TD><TD>30</TD><TD>0.7</TD></TR><TR><TD>6</TD><TD>137</TD><TD>30</TD><TD>0.7</TD></TR><TR><TD><P></P></TD><TD>141</TD><TD>30</TD><TD>0.7</TD></TR><TR><TD>7</TD><TD>146</TD><TD>31</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>150</TD><TD>33</TD><TD>0.6</TD></TR><TR><TD>8</TD><TD>154</TD><TD>35</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>157</TD><TD>37</TD><TD>0.6</TD></TR><TR><TD>9</TD><TD>161</TD><TD>37</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>164</TD><TD>37</TD><TD>0.6</TD></TR><TR><TD>10</TD><TD>166</TD><TD>40</TD><TD>0.6</TD></TR><TR><TD><P></P></TD><TD>168</TD><TD>42</TD><TD>0.6</TD></TR><TR><TD>11</TD><TD>172</TD><TD>42</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>173</TD><TD>46</TD><TD>0.5</TD></TR><TR><TD>12</TD><TD>175</TD><TD>46</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>179</TD><TD>48</TD><TD>0.5</TD></TR><TR><TD>13</TD><TD>181</TD><TD>48</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>182</TD><TD>51</TD><TD>0.5</TD></TR><TR><TD>14</TD><TD>184</TD><TD>51</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>186</TD><TD>51</TD><TD>0.5</TD></TR><TR><TD>15</TD><TD>188</TD><TD>53</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>190</TD><TD>55</TD><TD>0.5</TD></TR><TR><TD>16</TD><TD>191</TD><TD>55</TD><TD>0.5</TD></TR><TR><TD><P></P></TD><TD>193</TD><TD>57</TD><TD>0.5</TD></TR><TR><TD>17</TD><TD>195</TD><TD>57</TD><TD>0.5</TD></TR></TABLE>

<b>the finished chart:</b>

<img src="http://metrompg.com/offsite/warm-up-chart-complete.gif">

<b>the verdict:</b>

man, i hate doing these fuel-wasting experiments! :\

[Matt Timion]

Just for reference:

FWT: coolant (water) temp in degrees F
FIA: intake air temp in degrees F
Lph: fuel consumption in liters per hour

[krousdb]

Evidently I missed this thread. Great info, let me add some more. My OEM EBH cost was $42. It installs in the fromt engine block drain plug and yeah, its a PITA to get out. It is marked 400W, but my kill-o-watt mater says 375W.

I did some testing to determine how long I should set the timer prior to leaving in the morning. After about 8 hours, the ECT was 60F above ambient. But it only takes one hour to get 35F and two hours to get 45F over ambient. In the winter my garage is usually 45F so 80F is my usual staring temp. The extra 10F wasn't worth another 3.75 cents IMO. I am impressed with the performance and am glad I installed it.

I have tried two other types of EBH. The magnetic oil pan heater is rated at 200W, actual 180W. I would use this to heat the engine oil but it is thermostatically controlled and it shuts down only after a minute or two. Not sure if it is a malfunction or not, but it has little effect on the temperature of the oil pan as reported by my IR thermometer.

The second type is the recirculating EBH, 850W rated, 750W actual. For these to function correctly you need to have a hose that comes from the bottom of the EB and into the top of the EB. I don't have such an arrangement so I installed it in my heater hose line, the only place available. In that configuration it did nothing but heat the water in the hose, no circulation. Be aware that there isn't a pump in these, they rely on convective flow which reguires the hose configuration previously mentioned. If you dont have that config, IMO you are better off with the drain plug type.

[Compaq888]

What about having something like the prius. It has a system where you shut off the car and the fluid goes into a special container and stays warm in there up to 3 days. I already mentioned this and nobody payed attention.

[krousdb]

Originally Posted by Compaq888

What about having something like the prius. It has a system where you shut off the car and the fluid goes into a special container and stays warm in there up to 3 days. I already mentioned this and nobody payed attention.

There would be a great deal of expense involved with a system like that. Sure you could find one in the junk yard but where will you put it and how will you connect to the coolant system? How will you activate it? I don't have room under my hood for the thermos and no room in the wheel well either.

As far as keeping warm for 3 days, well I guess warm is a relative term. The next morning, depending on the temperature of the garage, when first powering up, the coolant temp is 110 - 130F. But drops down to 90-110F very shortly as the aluminum block and head pull warmth from the coolant. So what you end up with after about 12 hours parked in the garage is about 100F on average or in my case, 55F above ambient. I can be at 100F after 2.5 hours with the OEM EBH at a cost of under 10 cents. For 3 cents I can be at 80F. I doubt that there would be significant fuel savings between 80F and 100F starting temps.

The same would apply to non garage kept vehicles except the amb ient temp would be lower so the thermos protected coolant would be cooler, the block and head would be cooler, which would lower the ECT further.

IMHO, the OEM EBH is cheaper, easier to install, easier to maintain and nearly as effective as a Prius type thermos.

[MetroMPG]

Originally Posted by krousdb

For 3 cents I can be at 80F. I doubt that there would be significant fuel savings between 80F and 100F starting temps.

good EBH info, krousdb.

should i take your comment to mean you won't be plugging in year-round?

[MetroMPG]

Originally Posted by Compaq888

I already mentioned this and nobody payed attention.

i don't think anyone was ignoring your comment. fyi, the coolant thermos topic was in this thread too:

http://www.gassavers.org/forum_topic/engine_block_heater_success.html

[Matt Timion]

Originally Posted by MetroMPG

i don't think anyone was ignoring your comment. fyi, the coolant thermos topic was in this thread too:

http://www.gassavers.org/forum_topic/engine_block_heater_success.html

THis is why no one responded to you Compaq888. It was previously mentioned that exact same day by someone else. When you mentioned it I was unsure if you had not read the other thread or not.

[krousdb]

Originally Posted by MetroMPG

good EBH info, krousdb.

should i take your comment to mean you won't be plugging in year-round?

For 3 cents a day I can raise the ECT 35F over ambient. So in the summer, when my garage is 80F overnight, I will be at 115F for 3 cents. And that doesn't take into account the smaller delta between ECT temp at shutdown and garage temp in the summer. The ECT will go down much slower overnight so it may be above the garage temp the next morning. So yes, I think it will be worth it to plug in year round.


What I meant to say is that it didn't make sense (cents) to spend twice as much on electricity for only 10F higher on the ECT because of the diminishing return.