Discussion
I have been using Shell optimax or V power as now known now for 6 years, but a couple of months ago i tried the BP high octain petrol and it seemed ok but thought i would leave my decision as to if it was any good or not until after a few tank fulls.
Anyway, a few months on now and i am converted, the car has never run so good in the 6 years i have had it, will even run at just under 30mph in 5th without problem, with Shell it always seemed on the edgey side causing a type of transmition shunt when in traffic, only down side with the BP is it doesn't seem to pop and bang on over run as much as the Shell.
Has anyone else noticed any difference between BP and Shell.
Oh and the engine is a SP6.
Anyway, a few months on now and i am converted, the car has never run so good in the 6 years i have had it, will even run at just under 30mph in 5th without problem, with Shell it always seemed on the edgey side causing a type of transmition shunt when in traffic, only down side with the BP is it doesn't seem to pop and bang on over run as much as the Shell.
Has anyone else noticed any difference between BP and Shell.
Oh and the engine is a SP6.
Opposite for me though I run a 4.0 RV8. Mine runs perfectly on V-Power and tescos 99 (pops and bangs more prominent on Tescos) but absolutely hates BP Ultimate. She feels very rough and doesn't idle at all well on it. Switch back to one of the others and all is fine once again.
I've never known an engine to be so sensitive to different fuels.
I've never known an engine to be so sensitive to different fuels.
zippee said:
Opposite for me though I run a 4.0 RV8. Mine runs perfectly on V-Power and tescos 99 (pops and bangs more prominent on Tescos) but absolutely hates BP Ultimate. She feels very rough and doesn't idle at all well on it. Switch back to one of the others and all is fine once again.
You're right. My V8S loves V-power but hardly runs on BP super. Idle speed fluctuates and will even die in stationary traffic occasionally. Texaco or Sainsbury's Super isn't a bad emergency option. Its not overly keen on the Tesco's stuff either. Then again that's normal unleaded topped up with something iffy from Brazil isn't it ?
zippee said:
I've never known an engine to be so sensitive to different fuels.
Its freaky isn't it....Still so long as Shell don't drop V-power we'll be OK. BP Ultimate at my local s/s, and my nearest Shell V Power s/s is 20 miles away.
So guess which is usually in the car?...Well that was until January's Interpro RR session when my car was pulled off the rollers mid run, and got a stern talking to by the guys for my choice of fuel, There comment was "we have hasd more cars pinking using BP than any other fuel". There recomendation was Shell V power followed by Tesco 99RON.
So i finished off the last of the BP and have been using solely Shell since and wow! what a difference.
So guess which is usually in the car?...Well that was until January's Interpro RR session when my car was pulled off the rollers mid run, and got a stern talking to by the guys for my choice of fuel, There comment was "we have hasd more cars pinking using BP than any other fuel". There recomendation was Shell V power followed by Tesco 99RON.
So i finished off the last of the BP and have been using solely Shell since and wow! what a difference.
Yes Tailslide it's a strange thing this petrol, who reallknows what goes in it, as it happens the BP garage is the nearest, so providing everything runs like it is at the moment then BP it is.
Could do with a few more SP6 replies to get a better feeling of which is the better for this engine.
Could do with a few more SP6 replies to get a better feeling of which is the better for this engine.
andyvdg said:
I think the most important thing is to use the same fuel for a while before getting the car serviced, so it's tuned up for what you normally use. I prefer V power. Used Tesco once (not smooth) and BP (less low down torques).
EVO mag did a test last year of many fuels with a GTi - with an ECU which adapted to the fuel - which showed fairly significant differences, putting Shell & BP at similar high levels of torque/bhp but Tesco firmly in front.
The TVR MBE ECU is not adaptive, so differences are minimal. We'd have to have a re-map to take full advantage, and then take a risk if we're ever stuck with lower standard fuel, as there's no knock-sensor.
It's shocking to see what Shell passes off as "V Power" here in Kanuckistan...
www.shell.ca/home/Framework?siteId=ca-en&FC2=/ca-en/html/iwgen/shell_for_motorists/zzz_lhn.html&FC3=/ca-en/html/iwgen/shell_for_motorists/fuels/gasoline/gas_gold.html
91 is their best grade.... disgusting.
When I do manage to get a wedge over here it will bloody well cost me more in octane boosting additives than it will in fuel.
www.shell.ca/home/Framework?siteId=ca-en&FC2=/ca-en/html/iwgen/shell_for_motorists/zzz_lhn.html&FC3=/ca-en/html/iwgen/shell_for_motorists/fuels/gasoline/gas_gold.html
91 is their best grade.... disgusting.
When I do manage to get a wedge over here it will bloody well cost me more in octane boosting additives than it will in fuel.
brap_brap said:
It's shocking to see what Shell passes off as "V Power" here in Kanuckistan...
www.shell.ca/home/Framework?siteId=ca-en&FC2=/ca-en/html/iwgen/shell_for_motorists/zzz_lhn.html&FC3=/ca-en/html/iwgen/shell_for_motorists/fuels/gasoline/gas_gold.html
91 is their best grade.... disgusting.
When I do manage to get a wedge over here it will bloody well cost me more in octane boosting additives than it will in fuel.
www.shell.ca/home/Framework?siteId=ca-en&FC2=/ca-en/html/iwgen/shell_for_motorists/zzz_lhn.html&FC3=/ca-en/html/iwgen/shell_for_motorists/fuels/gasoline/gas_gold.html
91 is their best grade.... disgusting.
When I do manage to get a wedge over here it will bloody well cost me more in octane boosting additives than it will in fuel.
Adapt it to run on Av-Gas (aviation fuel! About 102RON I think)
Aparently the way octane is computed is different on either side of the pond.
According to Shell Kanaduh...
[quote="www.shell.ca/home/Framework?siteId=ca-en&FC2=/ca-en/html/iwgen/shell_for_motorists/carcare/about_fuels/zzz_lhn.html&FC3=/ca-en/html/iwgen/shell_for_motorists/carcare/about_fuels/encyclo_gasoline_octane.html"]
Technically there are three different "octane numbers" associated with every gasoline. The Research Octane Number, or RON, is measured under fairly easy test conditions. The Motor Octane Number, or MON, is a tougher test measured at higher engine speed and temperature.
The value that relates most closely to actual driving conditions is the average of these two values: Road Octane Number = (RON + MON)/2. This Road Octane value is the one referred to in Shell stations: Shell Bronze gasoline has an octane rating of 87, Shell Silver is 89 and Shell V-Power is 91.
Occasionally, less scrupulous Canadian gasoline outlets will use the confusion of these different octane measurements to exaggerate their octane rating claims, by advertising their fuel's Research Octane Number - which will be higher than the Road Octane Number. It is also a common practice in many European countries to advertise the Research Octane Number on their pumps, so you may see unexpectedly high octane values when travelling abroad. In Canada, motorists should always be sure that the octane number a vendor advertises is its Road Octane value, not its RON.[/qoute]
I'll buy the best and dump in a 1/2 bottle of octane boost to be sure. If it knocks I'll add more... or just go to the local VP racing fuels and buy a 100 MON (not RON) www.vpracingfuels.com/vp_01_fuels.html#unleaded
According to Shell Kanaduh...
[quote="www.shell.ca/home/Framework?siteId=ca-en&FC2=/ca-en/html/iwgen/shell_for_motorists/carcare/about_fuels/zzz_lhn.html&FC3=/ca-en/html/iwgen/shell_for_motorists/carcare/about_fuels/encyclo_gasoline_octane.html"]
Technically there are three different "octane numbers" associated with every gasoline. The Research Octane Number, or RON, is measured under fairly easy test conditions. The Motor Octane Number, or MON, is a tougher test measured at higher engine speed and temperature.
The value that relates most closely to actual driving conditions is the average of these two values: Road Octane Number = (RON + MON)/2. This Road Octane value is the one referred to in Shell stations: Shell Bronze gasoline has an octane rating of 87, Shell Silver is 89 and Shell V-Power is 91.
Occasionally, less scrupulous Canadian gasoline outlets will use the confusion of these different octane measurements to exaggerate their octane rating claims, by advertising their fuel's Research Octane Number - which will be higher than the Road Octane Number. It is also a common practice in many European countries to advertise the Research Octane Number on their pumps, so you may see unexpectedly high octane values when travelling abroad. In Canada, motorists should always be sure that the octane number a vendor advertises is its Road Octane value, not its RON.[/qoute]
I'll buy the best and dump in a 1/2 bottle of octane boost to be sure. If it knocks I'll add more... or just go to the local VP racing fuels and buy a 100 MON (not RON) www.vpracingfuels.com/vp_01_fuels.html#unleaded
Edited by brap_brap on Sunday 25th February 19:06
Okay, lets figure a few things out here.
The "octane" rating is do do with the consituent makeup of the fuel. Petrol is a combination of Octane and Heptane. Both are carbon-chains of different lengths. Heptane is closer to butane and propane and hence is a lighter and more volatile substance. As a result, in a high compression engine, or in one that runs hot it is more likely to self-detonate before the piston reaches top-dead-centre, which is where the spark is set so that all of the explosive power is sent into a down-stroke, rather than trying to force the piston the way it just came due to pre-detonation before the stroke reaches TDC as petrol engines feed before detonation is desired - This results in "knocking" or "pinging" - Often referred to (for some bizarre reason) as "pinking". Fuels with a greater octane constituent are more stable, hence why high performance engines or tuned engines with greater cam lift, resulting in increased compression ratios MUST seek out higher octane fuels. THEY ARE NO MORE EXPLOSIVE, just more stable and hence why you may see better running on these.
You will see greater pop, crackle and bang on higher octane fuels due to the fact that they are more stable and will survive the inlet stroke in order to use the valve overrun and head down into your exhaust - which being hot will ignite them there.
This is also how diesels work - The compression on a Cerbera is considered high at 10:1, but a common diesel value is 18:1. The compressing of the air causes huge friction and heat. hence the diesel is injected AT TDC and self-ignites purely based on the heat inside the piston. Petrols feed before TDC, which is why, if you have a high compression or hot-running engine you should pick a fuel which is stable enough for the application.
BTW - diesel is also non-explosive, so a spark wouldn't ignite it anyway. Also - Did you know that Asphalt - yep the stuff they coat the roads with is EXACTLY the same in make up as the fuel you stick in you car? Just a few more carbon molecules in the chain to make it a whole lot heavier a substance. It's the crap they're left over with after refining crude oil into petrol and such like.
The "octane" rating is do do with the consituent makeup of the fuel. Petrol is a combination of Octane and Heptane. Both are carbon-chains of different lengths. Heptane is closer to butane and propane and hence is a lighter and more volatile substance. As a result, in a high compression engine, or in one that runs hot it is more likely to self-detonate before the piston reaches top-dead-centre, which is where the spark is set so that all of the explosive power is sent into a down-stroke, rather than trying to force the piston the way it just came due to pre-detonation before the stroke reaches TDC as petrol engines feed before detonation is desired - This results in "knocking" or "pinging" - Often referred to (for some bizarre reason) as "pinking". Fuels with a greater octane constituent are more stable, hence why high performance engines or tuned engines with greater cam lift, resulting in increased compression ratios MUST seek out higher octane fuels. THEY ARE NO MORE EXPLOSIVE, just more stable and hence why you may see better running on these.
You will see greater pop, crackle and bang on higher octane fuels due to the fact that they are more stable and will survive the inlet stroke in order to use the valve overrun and head down into your exhaust - which being hot will ignite them there.
This is also how diesels work - The compression on a Cerbera is considered high at 10:1, but a common diesel value is 18:1. The compressing of the air causes huge friction and heat. hence the diesel is injected AT TDC and self-ignites purely based on the heat inside the piston. Petrols feed before TDC, which is why, if you have a high compression or hot-running engine you should pick a fuel which is stable enough for the application.
BTW - diesel is also non-explosive, so a spark wouldn't ignite it anyway. Also - Did you know that Asphalt - yep the stuff they coat the roads with is EXACTLY the same in make up as the fuel you stick in you car? Just a few more carbon molecules in the chain to make it a whole lot heavier a substance. It's the crap they're left over with after refining crude oil into petrol and such like.
Edited by V8Cerbera on Monday 26th February 01:11
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