Electric Heater

<div class='quotetop'>QUOTE(JimN @ Feb 10 2007, 09:13 PM) [snapback]388246[/snapback]</div>

No, although I have read several posts on grill blocking. This seems to me another extreme method to squeeze more mileage out of the system, but what negative effect does blocking up the grill, which is there for more than decoration, have on the engine? I'm not as interested in obtaining unrealistic mileage but simply trying to determine from PriusChat postings a median mileage that is a reasonable expectation given that the EPA ratings are established in a near-perfect environment. As a journalist, I would say the EPA data - and Toyota for heavily promoting it - is disingenuous and a classic example of when caveat emptor (buyer beware) ought to rule. But I would be interested in your analysis of grill blocking on engine mileage.

 

I don't consider blocking the cold air that robs the heat, extreme. Toyota should make this standard in the next gen Prius. It is just common sense! Why let the air cool down if you don't want to? In fact you need the heat in winter and it should be an engineering challenge to bring the car to the operating temperature as soon as possible. We have the thermal coolant storage bottle but the grills is wide open and cold air are coming in.

Storing hot coolant in the thermal bottle does help but it doesn't solve the problem completely. I wish Toyota takes one more step further by adding an "Electric Coolant Heater". Say, as soon as the SKS detect the driver, let it start heating up the Coolant (if need to) and when the power button is pressed, let the juice flow and heat up the engine block.

That combined with a controllable variable girll should be ideal.


Dennis

 

<div class='quotetop'>QUOTE(chuck kershner @ Feb 11 2007, 08:27 AM) [snapback]388434[/snapback]</div>

Toyota doesn't get to report anything but what the EPA say's the car gets on the Dyno in a closed room in perfect conditions, anything other will result in court action against Toyota. There are no downsides to blocking the grill in cold weather. That's been proven by lots here on PC over several winters of operation in warmer and colder climates than the one your operating in. Your poor mileage is the result of short trips and nothing else. One of the problems with short trips is the coolant thermos only saves the warmer of the two, ICE or the thermos so if your continually filling it with cool antifreeze from the ICE it is of little benifit. but the ICE still has to heat 2 times the normal amount of coolant that a car with the same size of ICE would. Think Yaris, same size ICE, no thermos. Running the ICE in the Yaris heats only the ICE in the Prius it heats both the ICE and the coolant in the thermos plus all the hoses associated with the coolant recovery system. A block heater and a grill blocker will help your situation a bit but it's your short trips that are bringing down you mileage. Sometimes the real world sucks.

 

<div class='quotetop'>QUOTE(Tom_06 @ Feb 5 2007, 07:18 PM) [snapback]385639[/snapback]</div>

Okay, it sounds like the US model is different to the European model then. The European wiring diagram shows 2 PTC Heaters, one with 2 sub-parts.

P14, "PTC Heater" contains two elements, switched through relays PTC HTR1 and PTR HTR2, with power coming through fuses 30A PTC HTR1 and 30A PTC HTR2.

P15, "PTC Heater" is switched through relay PS HTR and fuse 50A PS HTR.

The relays are in engine room relay box 2 - the one at the top centre; there are 5 relays in there; left-to-right: PS HTR, FR FOG, PTC HTR 1, PTC HTR2, RR FOG.

There's no obvious reason in the wiring diagram why P14 would be separately wired, as the two relays are switched by the same control signal (HTRO from the A/C Control Assembly). P15 is switched by a separate signal (HTR2).

However, looking at all the mechanical diagrams, it seems clear that 4-pin connector P14 is leading to the pair of footwell heaters - the wire harness splits and goes to two separate heater units.

P15, the single 50A-fused heater, looks like the heater core heater; this is actually two 165W strips in the core, but they're run from a single relay+fuse.

It sounds to me as though you actually have the footwell heaters, and not the core one. The footwell heaters are two separate boxes - quite large (about 25% the width of the core). In the picture above, the arrows are missing them - they're the things with the leads running to them below the lines.

 

<div class='quotetop'>QUOTE(chuck kershner @ Feb 11 2007, 10:27 AM) [snapback]388434[/snapback]</div>

Not nearly enough if you still have such negative comments.

<div class='quotetop'>QUOTE(chuck kershner @ Feb 11 2007, 10:27 AM) [snapback]388434[/snapback]</div>

Extreme? Hardly. It's incredibly simple. Squeeze more mileage? Definately. On average I'm regaining about 6MPG of my lost 12, and I could be doing a much better job of blocking than I am.

<div class='quotetop'>QUOTE(chuck kershner @ Feb 11 2007, 10:27 AM) [snapback]388434[/snapback]</div>

If done correctly, in cold climates, there is no negative effect. In fact, it helps the engine.

The engine is a lightweight aluminum block. Aluminum conducts heat better than steel. So in effect the engine block is to a small extent its own radiator. In freezing temperatures, even with the flow to the radiator cut off (which the Prius will do when it doesn't need the cooling effect of the radiator) the engine block itself still cools the engine too much to keep it at an optimal temperature during lowered activity. Because the whole point of a hybrid is to lower the ICE's activity, that's a bad combination. To keep it optimal it runs the ICE until it gets back up to temp ... which can mean it almost never uses the electrical side. And in very extreme cold the engine can't even warm up to an optimal temperature flat out.

What grill blocking helps is reduced the amount of cold air coming into the engine compartment, so the engine doesn't cool off at the drop of a hat (or the engagement of an EV). Thus the hybrid aspect can actually be used as often as it should be instead of hobbled to keep the engine warm. Grill blocking is a simple solution to overcome a design flaw in the over-cooling of the ICE.

Just remember to take the blocks out in warm weather or else your engine will overheat, your dummy light will come on, and you'll have to pull off the road and pull out the blocks then and there instead of in the convenience of your own garage. As long as you don't ignore that dummy light you won't be able to do any damage.

And don't block the electrical components. Unlike the engine, they actually need their cooling.

I really hope that the next verison of the Prius either has an automated shutter and protects the engine better from this, or just plain wraps the engine block in insulation and uses the radiator for all cooling.

 

as far as blocking the radiator being extreme, i am at a loss to understand why Toyota did not design this into their Prius. last year when i had CANVIEW on my 04, i tracked engine temps and found that on my morning commute if the temps were as high at 35ºF, i would never reach proper operating temperatures. frequently, my top temp would not exceed 155ºF for the entire commute. now THAT is extreme. so blocking the radiator is a no brainer. its not extreme in anyway.

besides better mileage, having heat within a few minutes of startup is a nice thing to have. something that i did not have a lot of especially when my commute never exceeds 35 mph.

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Feb 13 2007, 11:54 AM) [snapback]389654[/snapback]</div>

Also, maybe they (Toyota) consider it too much of an added expense, but loovers that open and close automatically to maintain the temperature in the engine compartment at an optimum value would certainly be doable.

Dave M.

 

<div class='quotetop'>QUOTE(dmckinstry @ Feb 13 2007, 06:24 PM) [snapback]389775[/snapback]</div>

The "shutter-stat" has been a common feature on heavy trucks operated in Canada for a long time. The shutters are usualy air powered and thermostatically controlled, with a "fail open" design. That way, if the sensor bulb acts up or if the air line to the louver freezes, the shutters stay open.

The shutter-stat works well at helping those large diesel motors warm up quickly and stay warm. Combined with an air operated fan, the engine is kept at an optimum temperature.

<div class='quotetop'>QUOTE(DaveinOlyWA @ Feb 13 2007, 03:54 PM) [snapback]389654[/snapback]</div>

Hmmm, now you know how I felt - or at least how my pointy bits felt - my first winter when the temp went down below -20 F the first time, without the grille blocked.

 

<div class='quotetop'>QUOTE(Frank Hudon @ Feb 11 2007, 01:50 PM) [snapback]388503[/snapback]</div>

Wow, didn't know Prius engine coolant capacity is 9.1 US qt. My previous Celica 1.8 liter used only 5.9 US qt. Learning new things everyday. B)

Why does Prius need so much coolant? Is it due to the thermo bottle? Since European Pri don't come with thermo, does it mean EU version use less coolant? Can anyone confirm it?

Dennis

 

<div class='quotetop'>QUOTE(usbseawolf2000 @ Feb 13 2007, 07:00 PM) [snapback]389944[/snapback]</div>

page 312 of the 2k4 owners manual states total capacity of the engine system as 8.6 liters, 9US quarts or 7.5 Imperial quarts.

Edit: Classic uses 4.9 liters, 5.2US quarts or 4.3 Imperial quarts.

 

<div class='quotetop'>QUOTE(usbseawolf2000 @ Feb 14 2007, 12:00 PM) [snapback]389944[/snapback]</div>

JP Prius engine coolant is 5.3 liters. US manual says 8.6 liters.

Ken@Japan