Effect of fuel on power output

[RobT350C]

Just wondering with American fuel being quite low octane in general, does putting higher octane fuel in make any difference in power output? e.g. Is it just designed to make its power on low octane?

Local shell closed tonight so had to fill with ultimate instead of vpower, 97 versus 99 ron. Expect any difference?

I'm talking about a standard, except for exhaust, 5.0l

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[Charlie Brown]

I spoke to Mike at Modurstang about this and it’s just a waste of money filling with fancy fuel so I just use supermarket fuel (the money saved goes into regular oil/filter changes) and had no problems at all and don’t believe the view that the higher octagon fuel will cause an automatic increase in the ignition timing and hence power on the standard tune - not true at all

 

[RobT350C]

Thanks, thought as much with US fuel being low octane in general.

 

[Manders Mustang]

There's actual performance gains, but also longevity and engine maintenance gains from running the three top tier fuels (Shell, momentum and Costco(Shells fuels)) stations.

Will a stock car produce more power? marginally. Will you notice it, probably not on a v8 (you do on the EBM, it's worth a good 20 or so horses and has been dyno proven). The ECU's in these cars are smart and unlike ECU's of old so they have maximum targets to hit; and they can only hit them with the right amounts of fuel and air. (worse fuel, less likely to hit the targets).

Also rumoured to get better MPG on 99 fuels, but this is unproven.

In short, take what you like; but if you ever plan on doing power mods/tuning i'd recommend using only premium trims.

 

[Charlie Brown]

I think regular oil & filter changes are more important than using “designer fuel” and the ECU is measuring air mass flow through the throttle body and metering the fuel from that so I don’t see how the fuel brand can affect this. Also the ECU has a fixed wide open throttle map across the RPM range and is only backed off if the knock sensor detects detonation - it does not advance the ignition based on using higher octane fuel. Of course if you have a tune with advanced ignition settings then yes use the higher octane fuel. Personally I have tried the expensive fuel on my GT and it makes zero difference on performance or fuel economy, but it costs about £7 more on a tank fill.

 

[Manders Mustang]

I think regular oil & filter changes are more important than using “designer fuel” and the ECU is measuring air mass flow through the throttle body and metering the fuel from that so I don’t see how the fuel brand can affect this. Also the ECU has a fixed wide open throttle map across the RPM range and is only backed off if the knock sensor detects detonation - it does not advance the ignition based on using higher octane fuel. Of course if you have a tune with advanced ignition settings then yes use the higher octane fuel. Personally I have tried the expensive fuel on my GT and it makes zero difference on performance or fuel economy, but it costs about £7 more on a tank fill.

worse fuel = more change of knock.
also the ecu is tuned to have an OAR so will adjust power basted on octane rating.

 

[Charlie Brown]

worse fuel = more change of knock.
also the ecu is tuned to have an OAR so will adjust power basted on octane rating.

Fair point but the V8 is designed to run on the lower octane so knock should not occur particularly with the knock sensor and I would honestly not notice say a 5 or even 10hp increase on my V8 unless I was being timed at the track which I won’t be

 

[wack]

I've always used 99 ron fuel in my cars , it may or may not do anything but given it's only a few pennies a litre more in costco I'm prepared to waste that money if that's what I'm doing , I have seen it 15ppl more, i'd draw the line at 6-7p though

 

[GR11M]

My Lund map is tuned to v-power

 

[Manders Mustang]

Fair point but the V8 is designed to run on the lower octane so knock should not occur particularly with the knock sensor and I would honestly not notice say a 5 or even 10hp increase on my V8 unless I was being timed at the track which I won’t be

Yeah hence this point i made above:
"Will a stock car produce more power? marginally. Will you notice it, probably not on a v8 (you do on the EBM, it's worth a good 20 or so horses and has been dyno proven). "

 

[Little John]

From a post on MOCGB forum:

UK std unleaded "95"octane = is what they call 90/91 octane in the USA

UK "super" "97/99"octane = is what they call 92 /93 octane in the USA

Just in case anyone else was thinking 93 octane sounded pretty weak...

 

[Leeroy]

My 5.0 seems to run smoother and less lumpy on super unleaded so have mainly used this...

 

[tooley]

Bone stock car - 45000 miles in 2 years, cruising and abusing. Used fancy fuel and standard (though not supermarket) no difference at all in the real world . Don't believe the hype

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