Saxo Engine/Performance If you're interested in tuning Saxo engines, or if you need to know something which is engine related... this is the place for you. |
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5th June 2006, 17:47
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#1
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Established Member
Join Date: Feb 2005
Location: Truro United Kingdom (England)
Posts: 1,229
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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.
Let’s 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.
That’s the fundamental point, here’s the fundamental problem:
Less than 30% of the fuel (assuming it’s 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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The Following 6 Users Say Thank You to oilman For This Useful Post:
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5th June 2006, 17:50
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#2
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Saxperience Hardcore!
Join Date: May 2004
Location: Hull (England)
Posts: 18,709
Car(s): 1.6 vtr
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very intresting
you know your shit dont you
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5th June 2006, 20:27
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#3
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Saxperience Post Whore
Join Date: Dec 2005
Location: MaDchester
Posts: 8,432
Car(s): Vts
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hmm, this was posted on my local cruise site..
he must be posting it on all of the forums like these
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5th June 2006, 20:55
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#4
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Established Member
Join Date: Feb 2005
Location: Truro United Kingdom (England)
Posts: 1,229
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Yes it has been posted on some Cruise Forums, the ones we have relationships with.
Cheers
Simon
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5th June 2006, 21:02
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#5
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Administrator
Join Date: Dec 2002
Location: Glasgow United Kingdom (Scotland)
Posts: 26,097
Car(s): Chelski Traktor
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Quote:
Originally Posted by b0t13
hmm, this was posted on my local cruise site..
he must be posting it on all of the forums like these
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and? Hes offering us a discount and fantastic advice, whats the problem?
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5th June 2006, 21:15
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#6
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Established Member
Join Date: Feb 2005
Location: Truro United Kingdom (England)
Posts: 1,229
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mmmm discounts............nice
Cheers
Simon
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5th June 2006, 23:08
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#7
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Established Member
Join Date: Jan 2006
Location: pikie central
Posts: 1,790
Car(s): Ram raiders roller, cosser init
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Good post though and well worth a read.
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30th January 2009, 21:21
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#8
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Established Member
Join Date: Jun 2004
Location: Worcester United Kingdom (England)
Posts: 2,209
Car(s): Saxo VTR MK2
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Thats a good read! Very useful, cheers!
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31st January 2009, 00:55
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#9
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Established Member
Join Date: Sep 2007
Location: Plymouth
Posts: 1,951
Car(s): Ibiza FR Tdi
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Good useful read, Thank you
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Warning: The above post may be random, abusive and/or off topic
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