BHP gain from different fuels

[Jammy-R6]

Saw a programme on TV a while back about different fuels tested on a Impreza, with some giving a big BHP increase! Anyone know of any write up on the net about it or know which fuel gives the most improvement (Shell Optimax etc. not ethanol ) Even if it is just the placebo affect, if it feels faster and smoother it IS faster and smoother, so I want it

[McGee]

Not sure but I can feel the difference in my bike here as the normal petty is 84 octane medium is 87 and super is 90 Plus I occasionally by the octane booster as the fuel here sucks.

If I put any thing lower than super my bike idels funny and smells awful (like burning plastic). Also it feels slower than when I use good petty. The garage where she gets serviced (full I do most my own work) Will always fill the tank up for you. So thats the only time she gets cheap fuel.

Maybe it does increase hp, thats why it feels different, but I dont use nothing but super in my bikes anyways.
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Its pronounced Jixxer!

[brooky]

My brother in law told me that Shell Optimax was a pretty good fuel and that bikes like it although I would be very suprised if it actually made any BHP gain especially a significant one.

I would of thought it would make the bike more responsive if anything but hey what do I know

Im watching this thread to see what others(more experienced) riders have to say
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Suzuki GSX-R 750 K6.

[lllN30lll]

i remember seeing that program too, if i remember rightly all the different fuels had no effect on standard cars, but on Performance vehicles shell Optimax had a 3-5 bhp difference, wouldn't mind watching it again
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Turbo R1
CRF450R

[Jammy-R6]

[Jammy-R6]

[lllN30lll]

yeh i can't remember the BHP exactly mate, have a look here about Shell Optimax

https://www.shell2004.com/2004%20Documents/sundaytimes/sunday_timesoptimax3oct04.htm

*edit* found what after in that link i posted

"The results surprised us all. The torque and power graphs produced for all three fuels as the car accelerated from low through to high engine revs were virtually identical. Maximum torque was the same for the three fuels, and horsepower was almost equal throughout the acceleration range, except at very maximum revs where Optimax and Ultimate managed just one extra bhp. But even this 1bhp is not significant because at other points in the rev range the standard unleaded petrol gave marginally more horsepower anyway."
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Turbo R1
CRF450R

[MarJay]

I think it all turned out to be because the impreza has a knock sensor that retards the ignition when using lower quality fuels.

The Optimax simply allowed the car to run on full ignition advance.

It won't help on a bike which has a standard igniton afaik.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[0ddball]

What Marjay says is spot on. In fact if you use higher octane fuel in an engine without a knock sensor you can lose power.

[lilredmachine]

Evo or top gear did a test on this with a golf GTI and a Beamer m5. The new tesco 99 octane fuel gave similar horsepower (212, at the front wheels!) to Optimax, but less peak torque. The base cheap stuff was about 204 HP. The tests were performed many times and averaged out afterwards.
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Bikes: too many, too much for one man to maintain anyway.

[Deano]

Heres the fuel characteristics table from the Graham Bell 4 stroke tuning book. As marjay says a knock sensor is used on cars to help ride on areas of the rev range where early ignition happens. But for race bikes you always chase for the redline so for motorbike its only advised for racebikes where you ride through the bad areas quickly.

fuel: - ron - fuel/air ratio - heat energy
(lb/lb) - (btu/lb)
Acetone - - 1:10.5 - 12,500
avgas 100/130
"green" - 105-110 - 1:12.9
"blue" - 105-110 - 1:12.7
benzol - 105-110 - 1:11.5 - 17,300
ethanol - 108-115 - 1:6.5 - 12,500
ether(diethyl 15,000
methanol - 105-115 - 1:4.5 - 9,800
nitromethane - 1:2 - 5,000
nitropropane 6,700
petrol
premium unleaded - *96 - 1.12 - 19,000
premium leaded - 96 - 1:12.5 - 19,000
racing unleaded 100 - 100 - 1:13
propylene oxide 14,000
toluol (menthyl benzine) - 120-124 - 1:9.8
triptane - 110-112
xylene - 117-118



My choice would be ethanol from those stats but if I were to run pure ethanol i think there would be big fuel consumption problems. espacially for a 20 lap race.

[Deano]

soz if the table isnt clear i tried to format it best as I could but the site wont have it.

[Kickstart]

[Deano]

yep Im still learning all about that. its very long wounded. the racers I know of use 70/ 30% mix of petrol and methanol. Only drag racers run on pure meth.

theirs also the swirling effect in the ports to be considered if you dont have enough of that then the air and fuel wont mix properly enough and lead to a crap burn. thats on carbbed bikes i think fuel injection is alot better for this.

[Kickstart]

Hi

One problem with methanol is that you use such a rich mixture of it that a missfire or 2 on a cylinder can result in a fluid lock, and a bent con rod.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[dansuresh]

I use BP ultimate because of the cleaning additives in it more then the claimed performance/economy.

That program did say that if you use it regularly then it does make a difference to the health of the engine rather than using normal petrol and then putting the higher octane one in every now and then.

It only makes abt a £1 diff to my fuel costs anyway.

Thanks
Dan
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'S' Derbi GPR50R ------> 'Y' Aprilia RS125 -------> '04' SV650S K4 -------> 'Y' Honda CBR600 F Sport

[mrchips]

For 7p a litre, I think I'd risk being down 3bhp.
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Northern Irish? www.nibikers.com

[Chriss]

This what you looking for?

https://fifthgear.five.tv/jsp/5gmain.jsp?lnk=601&featureid=143
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TheShaggyDA: I've got 3 or 4 pairs that predate my wife, so at least 11.5 years old.