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Lubricating a modded or track car, some advice
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Old 05 Jun 2006, 03:35 PM   #1 (permalink)
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Lubricating a modded or track car, some advice

If you are "modding" your car and adding BHP or using it on track then consider your oil choice carefully as the stock manufacturers recommended oil will not give you the protection that your engine requires.

A standard oil will not be thermally stable enough to cope with higher temperatures without "shearing" meaning that the oil will not give the same protection after a couple of thousand miles as it it when it was new.

Letís start with the fundamentals. An engine is a device for converting fuel into motive power. Car enthusiasts get so deep into the details they lose sight of this!

To get more power, an engine must be modified such that it converts more fuel per minute into power than it did in standard form. To produce 6.6 million foot-pounds per minute of power (ie 200 BHP) a modern engine will burn about 0.5 litres of fuel per minute.(Equivalent to 18mpg at 120mph). So, to increase this output to 300BHP or 9.9 million foot-pounds per minute it must be modified to burn (in theory) 0.75 litres.
However, fuel efficiency often goes out of the window when power is the only consideration, so the true fuel burn will be rather more than 0.75 litres/min.

Thatís the fundamental point, hereís the fundamental problem:

Less than 30% of the fuel (assuming itís petrol) is converted to all those foot-pounds. The rest is thrown away as waste heat. True, most of it goes down the exhaust, but over 10% has to be eliminated from the engine internals, and the first line of defence is the oil.

More power means a bigger heat elimination problem. Every component runs hotter; For instance, piston crowns and rings will be running at 280-300C instead of a more normal 240-260C, so it is essential that the oil films on cylinder walls provide an efficient heat path to the block casting, and finally to the coolant.

Any breakdown or carbonisation of the oil will restrict the heat transfer area, leading to serious overheating.

A modern synthetic lubricant based on true temperature-resistant synthetics is essential for long-term reliability. At 250C+, a mineral or hydrocracked mineral oil, particularly a 5W/X or 10W/X grade, is surprisingly volatile, and an oil film around this temperature will be severely depleted by evaporation loss.

Back in the 1970s the solution was to use a thick oil, typically 20W/50; in the late 1980s even 10W/60 grades were used. But in modern very high RPM engines with efficient high-delivery oil pumps thick oils waste power, and impede heat transfer in some situations.

A light viscosity good synthetic formulated for severe competition use is the logical and intelligent choice for the 21st century.

Cheers
Simon
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Old 05 Jun 2006, 03:51 PM   #2 (permalink)
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Thanks for the info = Great read all the best
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Old 05 Jun 2006, 08:52 PM   #3 (permalink)
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That was great Simon So I better get the more expensive oil then
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Old 05 Jun 2006, 09:08 PM   #4 (permalink)
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Hmm Bideford, memories! Went to school there.

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Old 05 Jun 2006, 09:10 PM   #5 (permalink)
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Funny thing mate, so did I!! East-The-Water Primary and Bideford College 1991 to 1996
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Old 08 Jun 2006, 10:45 AM   #6 (permalink)
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Grenville College for me as I was considered to be dyslexic in my youth, it turned out to be a combination of word blindness and laziness!

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Old 08 Jun 2006, 04:26 PM   #7 (permalink)
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I wasnt posh enough to go there mate!!

Where you too now?
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Old 08 Jun 2006, 04:28 PM   #8 (permalink)
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Work, Redruth - Home, Truro.

Nice part of the world

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Old 08 Jun 2006, 04:29 PM   #9 (permalink)
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My grampy lives in Roche, near St Austall I visit him every now and again Turbo I dont think, is all that far from Roche...
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