Important Breakthru In Fuel Efficiency!

[bronsin]

I have installed a block heater in my yaris and am currently experimenting with it. My drive to work is 6.7 miles so about a mile or three of that the engine is not up to temp. I get 32-34 mpg in summer but less than 30 in winter. So Im hoping the block heater will make things better.

So Ive had frost on the window and have to run the defrost at full blast. The cool light isnt going off for a mile or more in spite of the heater.

Im thinking "that fan is cooling the coolant and defeating the heater"

So I put plastic over the window last night so I wouldnt need the defroster.

This morning the cool lite went out after a block!

So you really dont want to use the cars heater to keep the coolant from cooling down and the engine from burning more gas.

At least on sub 10 mile trips.

[Captain Slow]

not worth it. these cars get fantastic fuel mileage as they are, I'll keep driving with a lead foot (and modding) and still enjoy way better mileage than my last 5 cars, lol.

thanks for the info though, I'm sure some will really use it.

[bronsin]

You never know if it might come in handy. then again it might all be for nothing.

Oh.

I could not, when inserting the heater, get the clip on the end of it to engage the bump over the hole to hold it in place.

But it doesnt seem to be moving.

[CTScott]

I have installed a block heater in my yaris and am currently experimenting with it. My drive to work is 6.7 miles so about a mile or three of that the engine is not up to temp. I get 32-34 mpg in summer but less than 30 in winter. So Im hoping the block heater will make things better.

So Ive had frost on the window and have to run the defrost at full blast. The cool light isnt going off for a mile or more in spite of the heater.

Im thinking "that fan is cooling the coolant and defeating the heater"

So I put plastic over the window last night so I wouldnt need the defroster.

This morning the cool lite went out after a block!

So you really dont want to use the cars heater to keep the coolant from cooling down and the engine from burning more gas.

At least on sub 10 mile trips.


When you go into defroster mode the AC compressor automatically runs, and when that runs the radiator fan automatically runs, so you are definitely correct that defrosting delays getting the engine warmed up.

If you do the mod to unlink the automatic AC with defroster, you will still be able to use the heat to clear the windshield, without causing the radiator fan to run.

[Captain Slow]

either way, to achieve ultimate fuel efficiency would mean running absolutely no accesories. that means no defrost, no radio, no blower, even try to lay off of the turn signals, lol.

in my opinion it's not worth it, I tried hypermiling in my BMW and got tired of it, so I bought a Yaris and drive it like I want to :burnrubber:

[bronsin]

When you go into defroster mode the AC compressor automatically runs, and when that runs the radiator fan automatically runs, so you are definitely correct that defrosting delays getting the engine warmed up.

If you do the mod to unlink the automatic AC with defroster, you will still be able to use the heat to clear the windshield, without causing the radiator fan to run.

I figure even running the heater cools the coolant in the heater core and prevents as quick a warmup. Of course once warmed up it would not hurt anything to run the heater...

My case is special cause my 6 mile trip is 2 or three miles at non warmed up temperature. What would be saved if you could cut that to a mile at non warmed up temp. I dont know.

Wheres that defrost mode without AC mod? :bow:

[CTScott]

I figure even running the heater cools the coolant in the heater core and prevents as quick a warmup. Of course once warmed up it would not hurt anything to run the heater...

My case is special cause my 6 mile trip is 2 or three miles at non warmed up temperature. What would be saved if you could cut that to a mile at non warmed up temp. I dont know.

Wheres that defrost mode without AC mod? :bow:

http://www.yarisworld.com/forums/showthread.php?t=10888

[jpmck03]

not worth it. these cars get fantastic fuel mileage as they are...

... in my opinion it's not worth it, I tried hypermiling in my BMW and got tired of it, so I bought a Yaris and drive it like I want to...

OK, we get it, you don't think it's worth it. Quit being a Debbie Downer and move along.

bronsin, interesting discovery. Who would have thought a little sheet of plastic would have made much difference! Makes a lot of sense though.

CTScott, good tip on the automatic A/C mod. I remember reading about that a long while ago, and promptly forgot until right now...

[bronsin]

OK, we get it, you don't think it's worth it. Quit being a Debbie Downer and move along.

bronsin, interesting discovery. Who would have thought a little sheet of plastic would have made much difference! Makes a lot of sense though.

CTScott, good tip on the automatic A/C mod. I remember reading about that a long while ago, and promptly forgot until right now...

Well yeah plastic sheet = no need to defrost.

But block heater + not turning on the heat = cool light out in one block instead of one mile.

Thats a summertime or better warm up.

For short trips (5 mile) that might be huge for mpg.

And Im wondering if using the bh makes sense even in summer for more mpg?

[Captain Slow]

Fine, I'll be helpful :w00t:

wheel & tire package that weighs less than stock (Honda CRX HF wheels for instance)
remove spare and tools
remove hatch floor
remove rear seats if not needed
moon disc hubcaps
micro image's underbody cover
keep less than 1/2 tank of gas in car at all times
block off grille (only if you don't live in really hot area)
remove any roof racks or mud flaps
replace side mirrors with smaller/more aerodynamic ones
remove radio antenna
remove windshield wiper arms completely (could be very dangerous)
block any/all holes in front bumper
lower your car (closer to road means less air underneath)
use lowest viscosity oil recommended (synthetic preferably)
air tires to maximum rating
run open-element air filter (warmer air helps save gas)
remove any accessories you don't use (power steering, A/C, etc...)
lube axle hubs with synthetic grease


of course driving with as little as possible electrical devices running also helps, make sure to stay in gear and coast to use the DFCO feature, don't keep extra junk in your car.

I really would like to see someone try all of this and get a 50+mpg Yaris, hehe.

[eTiMaGo]

Captain, you need to look up BailOut's posts :)

[jpmck03]

... For short trips (5 mile) that might be huge for mpg...

Yeah, short trips in the winter are a drag on your mileage... But your method might get you a couple extra MPGs... which comes out to maybe an extra 20-30 miles to a tank. So, you save a couple of bucks each fill up (because you went further than you would have) and over the course of the winter that can add up! :biggrin:

... And Im wondering if using the bh makes sense even in summer for more mpg?

Hmmm... I'm thinking that the gains would be minimal, like "without the block heater I get 33.5 mpg, and with the block heater I get 33.7 mpg!" minimal gains department. Which might just barely offset the cost of the electricity spent on the block heater? :iono:

[Yaristeve]

When you go into defroster mode the AC compressor automatically runs,

I've had my Yaris for over a year and I just noticed this "feature" this week, LOL. :bonk:

[matthewai]

My drive to work is 6.7 miles so about a mile or three of that the engine is not up to temp.


get a remote start boom car warmed before you get in

[jpmck03]

get a remote start boom car warmed before you get in

Yeah, but then he'd be getting 0 mpg while he was in the house waiting for it to warm up. We're trying to save gas here, not use more! :wink:

[bronsin]

Hmmm... I'm thinking that the gains would be minimal, like "without the block heater I get 33.5 mpg, and with the block heater I get 33.7 mpg!" minimal gains department. Which might just barely offset the cost of the electricity spent on the block heater? :iono:


As I understand it the Prius has a thermos flask the coolant goes into upon shutdown. So at startup the engine has a headstart to get warm faster = better mileage.

That works during summer as well as winter so maybe....its worth it?

[krolos]

I have installed a block heater in my yaris and am currently experimenting with it. My drive to work is 6.7 miles so about a mile or three of that the engine is not up to temp. I get 32-34 mpg in summer but less than 30 in winter. So Im hoping the block heater will make things better.

So Ive had frost on the window and have to run the defrost at full blast. The cool light isnt going off for a mile or more in spite of the heater.

Im thinking "that fan is cooling the coolant and defeating the heater"

So I put plastic over the window last night so I wouldnt need the defroster.

This morning the cool lite went out after a block!

So you really dont want to use the cars heater to keep the coolant from cooling down and the engine from burning more gas.

At least on sub 10 mile trips.

sounds like your getting about average mpg, dont believe all the posters
with their lofty prius like mpg claims.

[bronsin]

Im on my first tank of gas during this experiment. Not every drive to work was done after using the block heater. Its been far warmer this winter at night so far than last winter. (35 vs 17)

But drawing on previous posts, the block heater makes the cool engine light go out after .5 mile or a little less. Others experience as well as mine. Without it at 30 degrees the CEL takes at least 1 mile. And using bh AND turning on the defrost with hot selected on the temp dial also causes CEL to take a mile or more to go out. So we are getting useful data here.

Remember this car is ONLY driven 6.7 miles to work. Almost never any different. How much difference ~ half a miles makes in reaching CEL out I dont know. Ceertainly the people who designed the Prius that thought it did or they wouldnt have gone to the extraordinary lenths of equiping the car with a thermos flask for the coolant to keep it hot.

But whatever happens I will report truthfully the results.

[10 Francis]

The reason the A/C runs when you turn the defrost on is to dehydrate the air you're blasting at the inside of the windshield. It makes the defroster more effective.
The reason the Prius engineers went to the lengths of putting the thermos bottle in was because the engine doesn't run all the time, and running the PTC (Positive Temperature Coefficient) heater (an electric coil like on a space heater) uses quite a bit of current, and in that car, that reduces the electric-only driving range.

[bronsin]

Huh interesting.

Seeing this thread come up reminded me I havnt posted my findings.

Normally the cool engine light goes out on a typical winter morning after about a mile. With the block heater on for about 1 1/2 hours the light goes out after 4 tenths of a mile. Lower temps result in longer CEL outages and higher temps result in shorter one.

I figure on an average night in NJ using the block heater results in a 2 mpg gain. Thats for my situation which involves a short drive of ~6.5 miles. Longer drives the result would probably be less....