Don't Warm It Up!

[jbowman1993]

Don't warm it up

Bangkok Post

Friday, February 17, 2006

A close friend called me up one day and asked about the pros and cons of the morning ritual of engine warm-up.

After a shoddy explanation, he proceeded on to ask me whether I had ever written on this subject, and if I did, requested a photocopy asap so that he could mail it to his next-door neighbours who never failed to warm up their automobiles _ 10 minutes every morning _ so that my friend and his family could smell the awful exhaust.

Warming up the engine is what we call running the engine without subjecting it to a load. During this phase, the engine is cold as long as the operating temperature of the coolants are below 90-98 degrees Celsius. Normal operating temperatures can reach 110 degrees during steep terrain.

During the cold period of the engine which is about 25-30 degrees (as in Thailand) there exists a host of phenomenon, so to speak, that will already contribute to the deterioration of the engine in general.

Engine oil that hasn't reached its operating temperature will be sticky and will be a tad hard to be transformed into spray particles as it is fed into the cylinder walls.

Meanwhile the fuel spray being injected from the injectors meet with air that isn't hot enough resulting in incomplete vapourisation. The residue that does not vapourise remains and gets in the way of the intake valves and cylinder walls.

And the fuel spray that was vapourised and mixed with air that comes in contact with cold cylinder walls will result in condensation. End result is that the blob will collect on the piston rings and cylinder walls after mixing with the lubricants. Lubricating capacity is lost by a great deal.

The only reason why the engine operates normally is that the engineer has already thought of this problem. A special programme has been incorporated to distribute additional fuel. However, there is no programme to make up for the deterioration experienced while the engine is not ''warm'' enough.

The primary issue here is that engines that run without load or what is conventionally called as idling take a very long time to warm up.

Terefore, warming up the engine for over 10 minutes will still not be enough for it to reach operating temperature. Engines running with a load usually take about 3-4 minutes to warm up properly.

Most engines running on the streets today have a life of about 300,000-400,000 kilometres based on the average deterioration or engine wear with ''cold'' and ''normal'' operating modes.

If an engine is used continuously without subjecting it to cold-starts at all, you could prolong the engine's lifecycle by 2-3 times the expected lifecycle of the engine.

I'd like to wrap things up by saying that you don't have to warm up the engine at all. Start the ignition, buckle up, check your fuel level, adjust seating position _ which should take about 15 seconds _ and drive off.

The stereotype on engine warm-up was born from the carburettor era a few decades ago. If you didn't warm up your engine, chances are it could stall after start.

Of course, the engine isn't a human athlete. These are the extreme ends of the spectrum and are very different. Of course, before competitions it is necessary to warm up the engine.

But you'd still be required to warm it up at intervals in order to achieve a virtual load and not rely on warming it up at idle as many people still do.

Jessada Tandhasettee is former department head of automotive engineering studies at Rangsit University and is currently a technical consultant. He holds a master's degree in automotive engineering from Technical University, Berlin, Germany.