Discussion
Er, chaps, dumb question. What Octane rating does the Ford 2.9 V6 have. Have just realised that while I run mine on Optimax, this is probably pointless as the car runs a bog standard Cologne that will probably rumble along happily on 95RON - 98 will give no benefits.
Will changing the timing lead to benefits from 98 RON? And how do I check whether such a change has already been made?
I don't understand timing/octane ratings, by the way...can you tell? :hehe:
Will changing the timing lead to benefits from 98 RON? And how do I check whether such a change has already been made?
I don't understand timing/octane ratings, by the way...can you tell? :hehe:
Harry Flashman said:
Er, chaps, dumb question. What Octane rating does the Ford 2.9 V6 have. Have just realised that while I run mine on Optimax, this is probably pointless as the car runs a bog standard Cologne that will probably rumble along happily on 95RON - 98 will give no benefits.
Will changing the timing lead to benefits from 98 RON? And how do I check whether such a change has already been made?
I don't understand timing/octane ratings, by the way...can you tell?
Hello Harry,
Octane ratings are just a way of expressing the degree of advance achievable on a test rig engine with out knock for a given fuel.
Fuels burn at different speeds, fast burners have a low octane rating and slow have a high rating. So, with a higher octane rating you need to run more advance, otherwise the all the fuel in the cylinder will not have time to combust before the exhaust valve opens.
If you are using optimax In you car and if it is set to run on normal unleaded, chances are that some of your fuel may remain unburnt at the end of combustion. This is not good for emissions / economy.
You can check the advance your car is running using a strobe, or get a mechanic to check for you. Some of the other guys should know the recommended advance for your engine using optimax.
If you are able to run a few more degrees of advance you will increase the engines efficiency and should see a little more power and better economy.
That’s the basics, if you want to read some more have a look for the calorific values of different fuels and how these compare to octane ratings. There must be a load of info on the net for those with an inquisitive mind.
Z
So if youir car is running rich and you are using Optimax are you saying that it may run better on normal unleaded... if that is what it is set to?
I put Optimax in mine but only cos I thought that is what it would want but if I can run it on 95 octane and possibly stop it running rich that would be a double win...
I put Optimax in mine but only cos I thought that is what it would want but if I can run it on 95 octane and possibly stop it running rich that would be a double win...
mmm,
the short answer is just as the poser of the question thought: the S3C has a 95 octane engine, and 98 octane will not damage it. But will not do any good.
The, or a, long answer is here: www.faqs.org/faqs/autos/gasoline-faq/
mvg Boudewijn
the short answer is just as the poser of the question thought: the S3C has a 95 octane engine, and 98 octane will not damage it. But will not do any good.
The, or a, long answer is here: www.faqs.org/faqs/autos/gasoline-faq/
mvg Boudewijn
GreenV8S said:
What does octane mean?
A very good website...I can now astound people with lots of new found petrol facts....thank you....Paul.
After reading this I put some cheap waitrsose fuel in it to see how it went!
Its probably my mind trying to justify the extra costs of opitmax but it didnt seem as responsive on the throttle.
But I was amazed I almost did the entire week without a re-fill. Normally Im back at Shell Wednesday night or Thursday morning.
Thats an extra 30 or so miles out of the tank!!!!
Its probably my mind trying to justify the extra costs of opitmax but it didnt seem as responsive on the throttle.
But I was amazed I almost did the entire week without a re-fill. Normally Im back at Shell Wednesday night or Thursday morning.
Thats an extra 30 or so miles out of the tank!!!!
doddze said:
So if youir car is running rich and you are using Optimax are you saying that it may run better on normal unleaded... if that is what it is set to?
No, running rich has nothing to do with the octane rating. Runnng rich means that there is too much fuel in the fuel to air mixture. A higher octane means that you can run more ignition advance with out the risk of knocking, it also means you can run a higher compression ratio. The highest you can go with 95 RON is around 10:1.
More ignition advance and higher compression ratios equate to more performance and better part throttle economey/performance.
Wildfire said:
The highest you can go with 95 RON is around 10:1.
I'm not sure it is *quite* as clearcut as that. Your comment seems to be implying that the 10:1 compression is almost enough to ignite the mixture spontaneously. It isn't anywhere close to that. The pressure rise that occurs as the mixture starts to burn is what causes the detonation. This would be avoided by retarding the ignition slightly, this reduces the power output slightly.
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