MikeUK

Should we now move on to the environmental benefits of pluging in…

iaink

You have an over vivid imagination.

The heater in my sube is 400W, (I read somewhere 150W per liter is a rule of thumb for heater ratings) Maybe a kW would be necessary for 5.7l Vortec, but if you drive one of those then Im guessing savings in fuel economy and electricity usage are not a top priority anyway.

MikeUK

have you ever worked on a Engine ?

do you understand anything about viscosity, fuel vaporization, thermal conductivity...??

oceanMDX

I hope that means that you will stick to topics you actually know something about.

Actually, it's 900-1000 watts - more than double what you are suggesting.

oceanMDX

You might want to read the articles first before you use them to back up an argument. This is what it says:

"Use a block heater in winter when the temperature drops to -20 deg C (-4 deg F) or below. A block heater keeps your engine oil and coolant warm, which makes the vehicle easier to start and can increase winter fuel economy by as much as 10 per cent. Use a timer to switch on the block heater one or two hours before you plan to drive. "

This agrees with what I have been saying and contradicts what you have said - so thanks!

iaink

I do and I will. I wish you would do the same. Or is Jim Kerr talking out his arse too?

No, its 400W, 2 hours =0.8kWh a day
http://www.allsubaru.com/faq.html#heater

BTW, -10 was what the Subaru tech told me. What do your Honda and Toyota techs recommend? Sorry, I cant hear you? What was that?

Its easy to pick and choose quotes, its not big or clever, I could pick from "Generally, you should start using a block heater when the temperature drops to -12°C, and it is imperative to use it anywhere from -15°C to -18°C", or "When should the engine block heater be used? The heater can be used whenever the outside temperature is below freezing"

The governent environmentalists say 0 °C, the Subaru parts site says "below freezing", my trusted mechanic says -10, a PhD in wear and lubrication says -12. Generally speaking i would rather plug in too soon than too late.
Here is a quote from JK, master mechanic, teacher and member of the AJSC

"Keeping the engine warm by using a block heater also helps starting, but another major benefit is reduced engine wear. Warm parts allow engine oil to flow easier into critical areas. Most engine wear occurs in the first couple minutes after a cold start. Rich fuel mixtures wash lubrication from the cylinder walls. Thick oil doesn't spray onto moving parts as easily, so using a winter grade oil will help reduce engine wear.

When the engine is first started, the oil pump forces oil into the oil passages and through the oil filter. The pleated filter element may restrict thick oil too much, so a bypass valve is designed into either the oil filter or the engine itself so the thick oil can bypass the filter. Oil may bypass the filter for only a few seconds or for nearly a minute if temperatures are cold and the oil viscosity is high. During this time, unfiltered oil flows to the engine, which is better than no oil, but it still allows dirt particles to flow to moving parts."

I leave it to the OP to decide. Thats my last word.

MikeUK

block heaters are between 400 and 500w on average

and given that you can get about 34M joules for 1l of fuel

and a block heater at 500w for 2 hrs uses about 3.6M joules

Just burning the fuel to heat the engine block is twice as expensive and that doesn’t allow for any losses in the drive chain, efficiency due to oil viscosity, or the increase in pollution it would cause
(that’s based on a direct no loss energy conversion, the difference in real life will be much bigger)

Based on elec at 5c / kw.h and gas at 79c /l

oceanMDX

Actually, the auto manufacturers all do - oil grades are very important with respect to cold weather operation.

Good question, I checked both my manuals for my 1988 Toyota 4-Runner and my 2001 Acura MDX, and both of them don't say a thing about the engine block heater! I checked both indexes, and paged through the Acura manual to find some info on the subject. It's not referred to anywhere - not even with respect to cold weather starting! This surprises me somewhat, but it indicates that both Toyota and Honda don't think the engine block heater is very important. Both manufactures make a big deal about oil grades and frequent oil changes however.

oceanMDX

Excellent idea, but the block heater is on all the time during that 2 hours even if it only takes 1 hour to warm up the engine sufficiently. So getting the duration of operation right for any given temperature makes things more complex.

Steve_P

When you say electricity based on 5c/kWh what is the actual cost of the electricity after all the delivery charges, administration fees etc?

According to Energyshop we in Calgary (Enmax) are paying 5.97c / kWh plus 1.67c /kWh delivery charge for a total of 7.64c /kWh. This would be the regulated rate.

Cheers
Steve

oceanMDX

The block heater uses more than double the power you suggest, and you can use whatever fictitious numbers you want to support your argument, but it just won't sell. You get so few days when the temp. is -20C or lower where your are that the cost advantage (if there even is one) is insignificant.

Lets be honest here, the advantage of using a block heater is to make the car start easier and let the cabin warm up faster for the benefit of the passengers in very cold weather and not for any financial advantage.

MikeUK

so based on that figure 7.64c /kw.h as it was a rough calculation

a block heater is still about 25% cheaper than just ‘burning’ gasoline to heat an engine up

and that’s ignoring all the loses you get due to the mechanics of an engine

oceanMDX

Toyotas are run in at the factory. I agree that the experiences of only 2 posters on this thread are merely anecdotal, but they are still highly significant nonetheless. This is because if what you have been saying is true, then both of us should have had engine wear issues long before now because we seldom used the block heater - like we should according to you. When in fact, neither of us has any engine wear issues! In science that, would be enough to cast doubt upon - if not disprove - your proposition.

Steve_P

I wasn't questioning your calculations, I'm curious as to what you actually pay for electicity.

oceanMDX

From Internet references it looks like 900 to 1000 watts is more the norm for a block heater, but engine size would be a factor.