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Comment by simonsquiff | Hacker News Reader

One similar anecdote I really like is what happened with diesel cars. You used to have to wait when starting the engine for it to ‘warm up’ and drivers obviously didn’t like that. Now you don’t have the wait. They actually hadn’t reduced the warm up time. What happens now is the warm up starts when you unlock the door, not when you try to start the engine! So by the time you go to start the engine it’s already done – to the driver there is no warmup time.

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That sounds a lot like how Instagram starts uploading pictures when you select the photo, rather than when you hit upload!

http://news.ycombinator.com/item?id=3913919

On a similar note, the image sharing site min.us[1] will display your local copy of the image you wish to upload in place of the uploaded image as it is uploading. Gives it a feeling that it uploads absolutely instantaneously, even though it also gives a real progress bar.

[1] http://minus.com/

That story reminds me of something I did for a classical music e-commerce site I was working on. I needed to update the ID3 tags on MP3s and FLACs when the user downloaded an album (I couldn't do it in advance as a batch - arcane nonsensical licensing rules w/ storing digital content).

The problem was that it took too long to modify the files when the user clicked "download" after completing their purchase - they had to wait as the ID3 modifier chugged away doing its thing. So instead of waiting for the user to fill out their CC data and complete the sale, I started updating the ID3 tags as soon as the user put the MP3s into his/her shopping cart and cached the result. It didn't really matter much if the cart got abandoned, but the files were all ready for the customer once they got done checking out if they made the purchase.

Hum, I call BS. Direct injection reduces greatly the need for warming up, and almost all modern diesel engines come with direct injection.

I'm not saying this is the only reason for the lack of warm up (especially today), but it was a significant part of the perceived reduction from old diesels. It's also why if you put petrol in the car by mistake, you can still ruin the engine even before you've turned the ignition (as opening the door starts the warm up and fuel pumps etc)

Modern car aren't actually completely on or off when you turn the key, sure. However I've put petrol by mistake in a diesel car twice and didn't ruin anything (but lost some money cleaning the mess up).

By warm up he's talking about the pre-heat system that helps diesels start when they are cold. Diesel engines ignite fuel by compression heat alone, there are no spark plugs. When it's cold, they can be harder to start. Two approaches, one is to heat the intake air with a heating element in the intake, the other is to have a glow plug (heating element) in each cylinder. Once the engine is running those pre-heating devices shut off.

With a diesel car, it's better to not let them "warm up" after starting... diesels don't warm up very quickly if they are not under load and they will accumulate carbon and parts will wear more if you let them "warm up" at idle after starting.

I think all diesel engines need glow plugs.

There were some low pressure direct injection diesel engines without them. However this is extremely uncommon.

Not for a while. From my VW service manual (model years 1999-2005), p. 28b-3:

"Preglowing is not linked to operation of the driver's door as in some earlier VW diesel systems."

In my experience, it's got to be pretty cold (well below freezing) for the warm-up time to be over 1 second.

My gas VW Golf primes the fuel pump once I open the driver's door. It's just a smart way to do things.

My last 3 cars were diesel and I'd forgotten that you had to wait for them to warm up (having learned how to drive in diesel cars).

Thanks for reminding me.

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