Premium Unleaded Fuel VS Premium Leaded In A Fully Decatted MY00
22 January 2003, 06:52 PM
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Does any one know whether there are any ill effects with running Premium Fuel as opposed to Premium Unleaded in a fully decatted UK spec MY00. Is unleaded really necessary if there are no cats in the system?
23 January 2003, 06:45 AM
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For the Lambda sensor just get a lead compatible one. I hear you can use one from a VW Golf VR6.
What does lead do to the valve seats?
I have heard it can effect some engine coatings but havent seen or heard of any problems.
Most of our 12 JDM STiVIs run 102RON leaded and a few JDM STiIVs. Also most people with STiVIIs (about 50) run 102RON leaded as well. The only change they make is to the lambda sensors and decat of course. This fuels lead content is < 0.5 grams/litre AFAIK.
What does lead do to the valve seats?
I have heard it can effect some engine coatings but havent seen or heard of any problems.Most of our 12 JDM STiVIs run 102RON leaded and a few JDM STiIVs. Also most people with STiVIIs (about 50) run 102RON leaded as well. The only change they make is to the lambda sensors and decat of course. This fuels lead content is < 0.5 grams/litre AFAIK.
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23 January 2003, 01:13 PM
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Thanks for the replies but I am confused about a few things. Lead in gasoline is not a naturally occuring substance and has to be added in the form of Tetraethyl lead during the refining process to increase the octane rating.
In 1922, an American called Thomas Midgely (who also invented CFCs) found that if tetraethyl lead, Pb(CH2CH3)4, was put into petrol, particles of lead and lead oxide PbO are formed on combustion. This helps the petrol to burn more slowly and smoothly, preventing knocking and giving higher Octane ratings. 1,2-dibromoethane is also added to the petrol to remove the lead from the cylinder as PbBr2, which is a vapour and removed from the engine. (This is how lead is released into the environment from leaded fuels). Using higher-Octane leaded petrol meant that more powerful high-compression engines could be built.
How then does leaded fuel negatively affect the internals of the engine?
In 1922, an American called Thomas Midgely (who also invented CFCs) found that if tetraethyl lead, Pb(CH2CH3)4, was put into petrol, particles of lead and lead oxide PbO are formed on combustion. This helps the petrol to burn more slowly and smoothly, preventing knocking and giving higher Octane ratings. 1,2-dibromoethane is also added to the petrol to remove the lead from the cylinder as PbBr2, which is a vapour and removed from the engine. (This is how lead is released into the environment from leaded fuels). Using higher-Octane leaded petrol meant that more powerful high-compression engines could be built.
How then does leaded fuel negatively affect the internals of the engine?
23 January 2003, 01:23 PM
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Lead can block the standard pass through type Lambda sensors and result in bad readings. Lead compatible Lambdas are pass over AFAIK.
A technician from NGK says that the lead fouls the insulator on the plugs after about 25000km.
You can see the grey coloured Lead based substance on the exhaust tail pipe.
I dont know about the engine internals though.
A technician from NGK says that the lead fouls the insulator on the plugs after about 25000km.
You can see the grey coloured Lead based substance on the exhaust tail pipe.
I dont know about the engine internals though.
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