Octane V's RON ratings
Discussion
Higher is better 
What exactly are you trying to compare? British vs. American petrol?
http://en.wikipedia.org/wiki/Octane_r
What exactly are you trying to compare? British vs. American petrol? http://en.wikipedia.org/wiki/Octane_r
Hi,
Yes, I was aware they used the other measurement in the US.
My reason for asking is two fold.
1. I'm looking into what compression ratio's are being used in street engines on their Regular (or is it Super)petrol. I think it's around 93 octane. The engine I'm looking at is the 5.8 litre 351ci Ford Cleveland.
2. I've also read on more than one site that when one switches from iron to ali heads one can jump a poinmt or two up in compression ratio.
I'm in the very early stages of an engine build and I'd like to run a fairly high comp ratio (within reason) to gain max benefit.
Finding the original fuel data allows me to at least talk the same language.
Phil
79 de Tomaso Longchamp GTS
Yes, I was aware they used the other measurement in the US.
My reason for asking is two fold.
1. I'm looking into what compression ratio's are being used in street engines on their Regular (or is it Super)petrol. I think it's around 93 octane. The engine I'm looking at is the 5.8 litre 351ci Ford Cleveland.
2. I've also read on more than one site that when one switches from iron to ali heads one can jump a poinmt or two up in compression ratio.
I'm in the very early stages of an engine build and I'd like to run a fairly high comp ratio (within reason) to gain max benefit.
Finding the original fuel data allows me to at least talk the same language.
Phil
79 de Tomaso Longchamp GTS
Transmitter Man said:
Hi,
Yes, I was aware they used the other measurement in the US.
My reason for asking is two fold.
1. I'm looking into what compression ratio's are being used in street engines on their Regular (or is it Super)petrol. I think it's around 93 octane. The engine I'm looking at is the 5.8 litre 351ci Ford Cleveland.
2. I've also read on more than one site that when one switches from iron to ali heads one can jump a poinmt or two up in compression ratio.
I'm in the very early stages of an engine build and I'd like to run a fairly high comp ratio (within reason) to gain max benefit.
Finding the original fuel data allows me to at least talk the same language.
Phil
79 de Tomaso Longchamp GTS
Yes, I was aware they used the other measurement in the US.
My reason for asking is two fold.
1. I'm looking into what compression ratio's are being used in street engines on their Regular (or is it Super)petrol. I think it's around 93 octane. The engine I'm looking at is the 5.8 litre 351ci Ford Cleveland.
2. I've also read on more than one site that when one switches from iron to ali heads one can jump a poinmt or two up in compression ratio.
I'm in the very early stages of an engine build and I'd like to run a fairly high comp ratio (within reason) to gain max benefit.
Finding the original fuel data allows me to at least talk the same language.
Phil
79 de Tomaso Longchamp GTS
IIRC They have regular, premium and super, 89, 91 and 93 PON respectively. PON = (RON + MON)/2. I think their premium and super should be comparible to our premium and super.
Compression ratio is just a geometric thing, an ali head won't make any difference to CR if it's the same shape, but it conducts heat away much faster than iron, so with a switch to an ali head it's best to go up by around 1 CR IIRC.
Hi Mathew,
Yes, I wrote it wrong!
It was the fact that switching to ali heads allowed one to run a higher compression ration.
OK, two more questions.
What is the equivalent RON to BP's 102?
What would you consider the maximum CR one could get away with in the UK with said fuel and optimised ignition/fuel supply?
11:1 or maybe more on the street?
Phil
Yes, I wrote it wrong!
It was the fact that switching to ali heads allowed one to run a higher compression ration.
OK, two more questions.
What is the equivalent RON to BP's 102?
What would you consider the maximum CR one could get away with in the UK with said fuel and optimised ignition/fuel supply?
11:1 or maybe more on the street?
Phil
Transmitter Man said:
Hi Mathew,
Yes, I wrote it wrong!
It was the fact that switching to ali heads allowed one to run a higher compression ration.
OK, two more questions.
What is the equivalent RON to BP's 102?
What would you consider the maximum CR one could get away with in the UK with said fuel and optimised ignition/fuel supply?
11:1 or maybe more on the street?
Phil
Yes, I wrote it wrong!
It was the fact that switching to ali heads allowed one to run a higher compression ration.
OK, two more questions.
What is the equivalent RON to BP's 102?
What would you consider the maximum CR one could get away with in the UK with said fuel and optimised ignition/fuel supply?
11:1 or maybe more on the street?
Phil
BP's Ultimate 102 has 102 RON, 90 MON and so the PON would be (102+90)/2=96
As for CR I wouldn't like to say, I have very little experience of any other engines than a 1.4L Ford CVH, I'm just an engineering student who enjoys reading about technical stuff in my spare time. I've a feeling I've read that a few stations in the US sell potent stuff for road use, so I would suggest finding out the sort of CRs people are using for road engines similar to yours using 96PON petrol. Hope that helps.
Mathew,
Good luck with your studies.
I'm trying to keep my classic on the road as much as possible which is the reason I searched for a rebuildable engine, the heads that came with the 'two' engines I purchased are of the low compression variety (unlike the better factory heads on the car). For this and other reasons they are only good as door stops!
I'm therefor looking to import some new ali heads with matching inlet manifold and have to decide what CR I want to run:
www.chiheads.com/
Got to try and keep up with the rest of you guys somehow.
Phil
79 de Tomaso Longchamp GTS
Good luck with your studies.
I'm trying to keep my classic on the road as much as possible which is the reason I searched for a rebuildable engine, the heads that came with the 'two' engines I purchased are of the low compression variety (unlike the better factory heads on the car). For this and other reasons they are only good as door stops!
I'm therefor looking to import some new ali heads with matching inlet manifold and have to decide what CR I want to run:
www.chiheads.com/
Got to try and keep up with the rest of you guys somehow.
Phil
79 de Tomaso Longchamp GTS
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