View Full Version : Thermal management (Prius)
11-22-2006, 02:27 PM
So, I've got a prelim of the various heat-conservation tricks
I've been working on up at http://techno-fandom.org/~hobbit/cars/heatgames/
which I might add to after today's messing around with radiator-opening
blockoffs too. Comments welcome; I expect I'll do another round
of edits before I consider the pages finished.
___I have been waiting to hear about your WAI results for a while now ;) I hope to hear of its success or failure in the not to distant future. I believe Krousdb had one installed and it appeared very similar to what I have installed on Insight’s. With the radiator block, the engine bay temp may come up enough to help as well. I do not remember if the Prius’ intake horn came from in behind the radiator or in front down near a wheel well for example. Can you take a pic of that for me as well? I should just call Tony and take a quick look see …
___WRT pulling the upper and lower cowling, wiper connectors and assembly, are you sure this is needed to install the block heater? I believe Horacio is installing these for free for those Prius owners that want them in the parking lot at the Milwaukee Hybrid Group meets. I will have to contact him to get more details but there is a lot of work involved to install the heater from the pics and description you have posted.
11-22-2006, 03:04 PM
Nice writeup Hobbit.
I'm thinking of going another route. I think that a full grille block and a full belly pan will serve to keep the engine bay warmer, provide warmer air to the intake and keep the cat from cooling as quickly. I have a scanguage on the way to monitor intake air and coolant temps. I hope to see a difference. But first I need to wrestle the Prius back from my wife.
I will also be interested in your results from trying to get better highway FE. How did that end up?
11-22-2006, 03:48 PM
Ah, well part of the intent was to show how pulling the cowl is
*not* that much work after all. Horacio probably has it as hardwired
into his hands as I do by now, and it's great that he's helping
people out like that.
I expect I'll have a lot more data on the highway-mileage thing
after the haul to FL and back. Having just done all this *and*
put new tires on, I'm sort of restarting from zero as far as
data collection goes!
11-22-2006, 04:51 PM
Will you be stopping by for a visit? Im not for from I95.
How many watts is the Prius block heater? Could you give me an idea how much of an impact it makes temperature wise? I'm wondering about adding a heater to the thermos bottle?
11-22-2006, 08:03 PM
The block heater draws about 420 watts.
This is interesting stuff and something I'd be interested in, but frankly that degree of disassembly just makes me nervous...a lost screw, something put on wrong that breaks at the first use, etc.
So, I go for the cheap and easy fixes.
I bought a single strip of that black pipe insulator stuff. Cut properly it fits over the front upper grill and I used 3 zip ties to keep it on...nearly 100% blockage of the upper grill results.
I used the remainder of the piece (almost exactly the right length) and just pushed the upper split side into the top and the other side into the bottom and friction seems to hold it in place quite well. Now both upper and lower grills are completely blocked off.
I also purchased 2 small rolls of yellow fiberglass insulation...at Home Depot it was labled "for small jobs" and cost about $4. I crammed one entire roll around the top of the ICE into every nook and cranny I could get it to reach without it hitting the radiator fans or anything else important looking and avoiding the Inverter/MGs. I took an approximately 1 ft. square piece and applied it to the back (rear) side of the ICE where the manifold is, but not touching the manifold...there's a long screw sticking out of the ICE in this area and I kind of used it to support the piece while wedging the sides into any spot I could find that I thought would hold while not getting tangled in the belt or axle/steering mechanism.
I'm finding this is working very nicely to hold ICE temp once it's warmed up and allows the Engine Block Heater to achieve a slightly higher maximum starting temp (around 136 compared to 131 degrees F without the insulation). The ICE cools down much less quickly now when I stop to shop or pick up the kids staying above 150 for up to 30 minutes...in the past, even in cool weather, it would drop to 150 or less in just 10-15 minutes.
Now, today was quite warm with highs in the mid-60s and all this modification caused me to see ICE temps up to 193 degrees on the CAN-View...very unusual even for summer temps. So, I do not recommend anything this extreme unless you can monitor the ICE temp and definately don't do it when it's above mid-60s outside or you risk overheating.
In any case, my last tank with temps in the 40s-50s and I finished the tank at 59.3mpg with my usual commute. My lifetime average is only 53.3 right now and November is usually when I start struggling with mid-50s mpgs.
11-22-2006, 08:44 PM
My clamp-on ammeter only saw about 3 amps draw which later dropped
to 2.5, but maybe my old clamp-on has gotten inaccurate or the
extension cord itself was dissipating a bit. I'll have to drop
some known resistance in series and measure some voltages...
[btw, I bandied some figures around near the end of the second
page of that set, and I was hoping for a sanity-check on some
of that from y'all]
11-24-2006, 07:59 AM
Anyone in the Chicago area that wants their Prius block heater installed just let me know, already done about a half-dozen from "below". Total time maybe 30-40 minutes, hardest thing is to route the cord and zip-tie it.
Hobbit great write-up as always.
11-24-2006, 01:34 PM
Well, yesterday I hooked up the laptop and got a sustained temp-reading
test in on my way toward two tons of turkey. Unfortunately, the new
WAI doesn't seem to be working as well as I anticipated -- just
holding about 20 degF over ambient at highway speed, which is
worse than the old klunker. I think the problem is that the gap
behind the head is *too* small, and not letting enough hot air
up from the header. I will play with jacking the top of the heat
shield up on a couple of standoffs when time permits; I still
think the collection strategy is valid but I'm just running into
a couple of restrictions in the way things are put together back there.
Ken1784 responded over on Priuschat with the observation that the
Japanese hypermilers found more positive results from radiator
blocking rather than WAI hacking, so maybe dealing with the second
opening is also in the cards...
11-30-2006, 09:44 PM
I've been mostly updating the continuing saga of this on the
prius_technical_stuff group, but long story short is that after
raising the heat-shield slightly on a couple of standoffs and
substantially widening the collection aperture, and rigging up
a grille-blocker for the lower opening of the Prius schnoz,
I'm seeing IAT up around 120F. This is *very* healthy heat
recovery, enough to impress ken@japan who was always dubious.
Now, whether that will translate into better overall MPG still
remains to be seen, especially on the long steady-state haul.
___I hope to hear of good results but I have a few doubts … What I found many years ago is that RR goes up drastically with colder temps and I have the feeling this is one of the major impediments not really considered in the tech groups yet?
___I tried to get the Ranger to roll back (just filled her Conti’s to 55 #’s all-around from 48/49 the other day in 50 degree temps) and spin around before coasting out of the drive tonight. It is now 24 and her pressures were probably down to the 52.5 range all-around. She would not swing around but maybe 30 degrees. A few pushes and I got her headed down the drive. She would not make it past the second turn which again is a no-brainer in 50 + degree temps. Passing along info that I have experienced in Northern IL. winters that might lead you onto another path as far as reduced temps causing a loss of FE :(
Copyright 2006 Clean MPG, LLC. All Rights Reserved.
vBulletin® v3.6.7, Copyright ©2000-2013, Jelsoft Enterprises Ltd.