How to keep an efficient engine warm?

[Isaac Zackary]

So I have a 1985 VW diesel. So far I've been getting upper 50's (mpg US) on the highway. But the problem I've been having is warmth. Even during the summer our town is so small that if I drive to the store, work, anywhere in town, it's so close that the engine does not warm up to running temps in that distance. To make matters worse winter temperatures here are constantly below freezing and can reach well below zero Farenheit for most of January sometimes reaching as low as -40° F. This not only makes me a bit unconfortable (ya, I wear long johns, sweater, coat, hat scarf, gloves, boots, the works!) but it also worries me for the engine's sake. I'm sure that it's not good for fuel efficiency nor the enviroment when I'm billowing out huge clowds of white and black smoke as it warms up. I've got it adjusted so that it hardly smokes at all at full throttle when warm (only when at high RPM and full throttle). But all that smoke when the engine is cold indicates that much of my fuel is not burning completely or at all!

I think part of the reason is that my engine is a bit too efficent. With a 23:1 compression ratio I think it converts too much fuel into power instead of heat. I've tried new thermostats, different temperatures, grill block offs, and a block heater. My current block heater is a 1,600 circulating tank heater that does a very good job, if I'm where I can plug it in. But when I leave the car at work and other places it cools down fast. Now what?

So instead of using 0W-20 to keep my oil pressure from blowing my oil filter, wouldn't it be nice to have a way to warm and keep warm my engine? I'm throwing a couple of ideas out there. Any other ideas would be welcome!

Passive solar block heater
So I've been thinking of plating below and around the whole engine. I'd leave a space in the back where air from the radiator can exit. Also I'd like to keep the radiator blocked off, at least during winter. Automated louvres would be nice! Besides that I was thinking of cuting a large part out of the hood and placing a piece of glass in it. I might coat the whole inside with aluminum foil. With the black engine all that light should reflect on it and keep it warm, at least during the day.

Exhaust coolant heater
I was also thinking of using exhaust heat somehow to heat the coolant. There are few ideas to this. One would be to just place one piece of tubing along the exhaust down pipe and re-route the heater hose through it so that it doesn't overwhelm the cooling system during summer use. Another idea would be to have the exhaust pass through a heat exchanger, maybe a modern TDI EGR cooler, and have an exhaust valving system that bypasses the heat exchanger once operating temperatures are reached.

Also there are two coolant sources on my engine for this. One is the cabin heater coolant circuit, which passes back near the exhaust system. This is constantly flowing, although probably not as much as the cold bypass circuit does when open. The cold bypass coolant circuit is on the front of the engine and it circulates coolant until the thermostat opens the radiator circuit completely, at which point it shuts off this circuit. This could be routed to the back of the engine.

Of the two each has their pros and cons. The heater does not have an air recirculating feature, so the coolant running through the heater is obviously going to be cooled quite a bit. So it makes sense to reheat this coolant as much as possible. On the other hand it is constant whereas the cold bypass circuit shuts off when hot. Yep, if I did have an overheat situation, this would generate steam at the heat exchanger. But as long as the thermostat is working, at least it would not continue to circulate coolant through the heat exchanger.

I kind of like both ideas. But maybe someone else has a better idea. What's your thoughts?

[cptsideways]

Bodge an EGR circuit into the heater/water system job done

[Isaac Zackary]

So it's winter again. My pet peeve about owning a car with an internal combustion engine is that every time I go to start it, the engine is cold. Now I'm missing my Nissan Leaf with it's cabin preheat system.

There are a few things that can be done to and ICE car, but overall nothing seems to be a perfect solution. And now that I'm driving a new car, a 2013 Toyota Avalon Hybrid, I'm tasked with figuring out what I'm going to do to heat the engine.

Right now I have a stock block heater I installed. But the thing only outputs like 200W. I read these only keep the engine about 20°F warmer than ambient. Right now it's about 10°F outside. That means the engine is like 30°F plugged in. I wonder what it'll do when it's -40°F. So I guess my first line of priority is a better block heater. Perhaps a 1,000W or 1,500W circulating tank heater. But of course I got to figure out what water goes where and how to plumb it in.

But on the other hand only when I'm home can I be sure I'll be able to plug in my car. I just got off work with no place to plug in there. I don't have a long drive from this last place I work at and I hate warming up the engine before driving. So I had to drive home in a cold car. By the time I got home the temp gauge had only reached the C. In other words the engine never got warm, the gauge had only moved like 1/16 of an inch by the time I shut off the car. I have a few drives a day like this where the car sits for a few hours, then I have to move the car only a mile or two. Ironically, when I do my 70 mile one way commute I start at my house where I can plug in. But on my short drives during the middle of the night and early morning (janitorial work), where I would benefit most from a pre-heated engine, is where I don't have any place to plug in.

So should I just start the car and idle it anyway to warm it up like three or four times a night? I really would hate to do that! But I hate not driving far enough to get the engine warm either. Plus there's the problem of frost on and inside the windshield not wanting to cooperate.

Another thing I can do is block the radiator. But on my 70 mile drive I have to climb some 6,000ftduring the day. So the question is if I'm going to risk overheating.

The idea of a Thermos system, like on the gen 2 Prius, keeps intriguing me. Maybe I should do something like that.

[euromodder]

How about a solar radiator system (with a fairly small reservoir) filled with engine coolant , being run trough the engine using quick-disconnect couplings ?

[Daox]

You basically have 3 options.

1) Recover more heat from the engine.

2) Retain more heat from the engine.

3) Add external heat from another source.


#1 isn't very common as far as DIY mods go. But you can use exhaust heat to warm up your coolant faster. This could be an inline heat exchanger, additional EGR cooler type setup, or brazing/welding tubing to your exhaust manifold and running coolant through it.

#2 means insulation basically. Grill block, block insulation, coolant thermos. They all fall into this category of not letting as much heat be lost to the atmosphere.

#3 we're all quite familiar with due to block heaters which are a fairly easy item to add.

Hopefully that helps some creative juices flowing.

[oil pan 4]

Get a block heater or 2.
That is the fastest easiest way to do it.

[redpoint5]

I personally wouldn't idle to warm up.

Get a temperature gauge so you know what coolant temperatures are doing, and set an alarm for some upper limit, like 215 F. Then grill block in a way that you can quickly add/remove it. I use foam pipe insulation wedged in the grill slats.

Can you put a higher wattage block heater in? An oil heater would help too.

You could add insulation to the engine, like a blanket or something, to retain more heat.

[oil pan 4]

I put a little space heater in my cars.
In my leaf it deices the car and makes the ride bare able with no heat.

[Ecky]

My Insight suffers from this as well. The engine even has exhaust heat recovery - there's a water jacket over the exhaust. When it's below freezing and I turn on cabin heat, I start losing coolant temperature, nevermind when it's 20 below zero. Cabin air recirculation helps but then my windows fog up. A 100% grille block helps, but isn't enough. Pre-warming the engine helps, but doesn't stop it from cooling back off after I'm driving.

And before you ask, my thermostat is fine, it's only when running heat.

[ThermionicScott]

Assuming we're talking about the Avalon and not the VW, get a Scangauge/Ultragauge/Torque app or whatever so you can watch the coolant temp, and block the crap out of your grille!