loading the engine early to warm up faster?

[mik13ST]

Hello guys,
I plan to install an alternator kill switch and the one thing unclear about ICEs is: do ICEs benefit from being warm early or is it better to load them when they are at their peak efficiency (when warm)?
Will the consumption benefit from forcing the alternator off when the engine is cold? It's not just the alternator, it might as well be early steep hill climb vs. later milder hill climb kind of thing.

The one idea here is, the earlier and higher load will be given to the engine, the faster it will reach optimal temperature, thus spending more time being efficient.
The other idea is just loading the engine after reaching the optimal temperature and better efficiency.

My intuition cannot answer any of these questions.
Can anybody clear this up?

[cRiPpLe_rOoStEr]

I'd be quite cautious about it, but at least in Diesels it has worked quite well.

[redpoint5]

Automatics seem to run higher RPM while in the warmup phase, not just at idle, but delaying upshifts too. I'm not quite sure why this is. I would think higher load is fine when cold, with higher RPM being less desirable, but that's exactly opposite of how cars are designed.

[jcp123]

The idea behind faster idles and delayed shifting is to light off the cat and oxygen sensors earlier, I guess it reduces cold emissions. Most of the cryptic things modern engines do make more sense when you take it as a rule of thumb that ECU strategies favor lowering emissions.

I don't know that I'd go too far in loading a cold engine, but definitely better to start and drive than idle. I don't have a choice when leaving the house, I have a nice little uphill at the end of the block. I say just get in and drive, settle into your hypermiling as you go.

[Frank Lee]

WRT alternator switch, I'd have it on at start-up; light load at start-up is good and the battery should get it's charge back right away.

[ksa8907]

Speaking to the engine temperature and load, it depends on how cold and how much load. Low RPM(sub 2000) and relatively high load(under 60%) with 80F coolant I would think is relatively safe, be cautious.

Below freezing, 3k RPM, 80% relative load might be asking for problems.

Use a block heater and you'll see benefits in longevity and fuel economy.

[mik13ST]

I think I was a bit misunderstood.
This has nothing to do with engine damage (I keep it in recommended RPMs all the time), nor with idling (I never idle to warm up the engine).
The thing I am trying to optimize is the time when I (would) turn the alternator on to recharge the battery after starting the engine. One situation could be recharging the battery when the engine is still cold to help it heat up faster. The other is recharging the battery after getting the engine heated up by driving.

I know the savings could be negligible, but having the answer to this question gives me answer to other more important questions about hypermiling (e.g. route selection).

[cRiPpLe_rOoStEr]

Originally Posted by mik13ST

One situation could be recharging the battery when the engine is still cold to help it heat up faster. The other is recharging the battery after getting the engine heated up by driving.

1st option seems to be what you're looking for.