race fuel - how much more hp

[16bit]

Just wondering if anyone has got there 5 tuned to 102 ron race fuel. If so do you have a before and after hp figure from say 98 ron pulp? I am going to get a second map for the track for race fuel and wondered what gains people may have got tuning for race fuel.

[Cal]

No figures, but I'd say you are wasting your money.

[irwin83r]

Just wondering if anyone has got there 5 tuned to 102 ron race fuel. If so do you have a before and after hp figure from say 98 ron pulp? I am going to get a second map for the track for race fuel and wondered what gains people may have got tuning for race fuel.

is it an FI setup?

[Boags]

The sound made by my arse "slamming shut" when 16bit floored the loud pedal while taking me for a drive confirms that the induction is forced. Very forced.

His sig also says "rotrexed and loving it".

Boags

[AJ]

The sound made by my arse "slamming shut" when 16bit floored the loud pedal while taking me for a drive confirms that the induction is forced. Very forced.

His sig also says "rotrexed and loving it".

Boags

I heard you squealed like a big girls blouse

[Boags]

I feel no shame in admitting I giggled like a girl. I can't remember any squealing though...

[irwin83r]

i heard a big bonous was the higher octane made it more tunable as far as advancing timing, leaning fuel and even winding in more boost goes.. anyone know more about this?? the guy i heard it from wasnt much of an petrol head just paid people to do things to his car and then claimed to know what he was on about

[bigdog]

Yes and no is the answer... and to explain it I did some searching for a concise technical explanation rather than rely on my second hand knowledge from hanging around good tuners... and found this:

Quoted from Carsales.com:
MYTH BUSTING: High Octane fuel will make a car faster (June 2008)

Looking for more power? It's as easy as filling up with some racing fuel... Isn't it?

Words: Alan Swanson

'High Octane' is a phrase that conjures up images of fast cars. It's also a phrase that is bandied around by nearly all of the petrol companies in advertising slogans, along with products described as 'ultimate', 'racing' and 'extreme'.

So, high-octane petrol must be the fuel of choice if I want my car to go faster... After all, petrol companies refer to 'improved performance and acceleration' and racecars use it -- it must have a performance advantage!

Not necessarily...

Let's have a look at what an octane rating is and what it does.

In Australia petrol uses an octane rating called RON (Research Octane Number). The RON number is achieved from the results of lab tests in which the fuel is run through a test engine which varies its compression ratio under controlled conditions.

The results of the test are compared to results for a mixture of iso-octane and n-heptane. For example, if a fuel is found to perform in a similar way to a mixture of 95 per cent iso-octane and 5 per cent n-heptane, it is given the rating of 95 RON.

When a fuel mixture is compressed there is a point at which the extreme heat and pressure will make the fuel explode, or spontaneously combust. This is the process that diesel engines rely on. However, in a petrol engine the point of combustion is controlled and the fuel mixture is ignited by the sparkplug.

Basically a high RON fuel will have a higher resistance to pre-ignition (also called knocking or pinking or pinging). This is because the higher octane rating means that the fuel has a high activation energy. In other words the fuel needs to be subjected to more extreme conditions before an explosion will occur, either by high levels of compression or high engine temperatures.

So will high octane fuel give a car better performance?

Let's look at the case of a normal road car. Most road cars have a recommended octane number of the fuel which should be used. The compression that takes place in the combustion chamber and the internal engine temperatures while running are suited to work efficiently with the recommended fuel rating.

If a lower octane fuel is used then it's possible that some problems may occur. Pre-ignition (also known by the terms noted above) can damage the engine internals in the worst cases.

If a higher octane fuel is used what happens? Well, nothing. The engine is already able to perform at its highest efficiency on the recommended fuel. The extra octane rating has no effect.

So why do high performance cars or racing cars use high octane fuels?

This is because their engines are designed to take advantage of the properties of high octane fuels. High-performance road cars tend to make their extra power from generating higher pressures in the combustion chambers of the engine, either by having high compression ratios or by using turbo or superchargers.

To avoid pre-ignition due to the high pressures, high octane fuels are used and, in the case of road cars, recommended by the manufacturers.

What clouds the issue is some of the 'smarter' engine management systems used by car manufacturers today. As well as being able to measure when pre-ignition occurs and alter the ignition timing, boost (in turbocharged cars) and other factors to stop it, these engines can also 'tune' themselves up to take advantage of the extra octane rating and potentially make more power.

One example of this is Saab's BioPower turbo fours. By taking advantage of the higher octane number of ethanol rich fuels such as E85 (85 per cent ethanol, 15 per cent petrol), the turbocharged 2.0-litre engine offered in the 9-3 Sport Sedan increases its turbo-boost and tweaks ignition timing automatically to increase its claimed output from 129kW/265Nm on normal fuel to 147kW/300Nm on E85.

Okay, but if the octane rating typically doesn't improve performance, why do premium fuels claim better power and acceleration? Well, such improvements are possible, not because of the octane rating, but because the chemical composition of the fuel may be capable of producing more power.

It's a matter of how much 'bang' each drop of fuel contains. Looking at the chemistry of the fuels in question, Carbon-to-Carbon bonds actually contain more energy than Carbon-to-Hydrogen bonds. Therefore a fuel which contains more Carbon-to-Carbon bonds will give more power, regardless of the octane rating.

It's more likely that a premium brand fuel will contain more Carbon-to-Carbon bonds and boast a high octane rating.

So yes... Premium fuel with an octane rating higher than recommended by the car manufacturer may well be able to improve the performance of your car, but it's not necessarily because of the high octane rating...

The myth 'High Octane fuel will make a car faster' is therefore -- Busted.

Published : Friday, 6 June 2008

[16bit]

i was talking about tuning for 110ron race fuel - not bp 98. I know it works I was just looking for figures people have got with a 5. This stuff has much more energy in it and up to 3% oxygen content.

[Steampunk]

Just to put a simple illustration to what bigdog posted:

It's all about tuning your car to JUST on the verge of detonation.

Higher octane fuels allow cars to run more compression/boost/timing because the detonation threshold is increased.
Take the example of a turbo/supercharged car:
The easiest power increase in a car is to increase the boost in a forced induction car. If you use, say 95RON premium, you can only increase boost up to, say for example from 10psi to 15psi until detonation occurs.
If you use 98RON then you'll be able to increase boost to 18psi; 110RON 25psi and so on.

Higher RON fuels are actually harder/takes more effort to combust (I stand corrected if I'm wrong), thus allowing greater cylinder pressures to occur prior to the combustion/power event.

[timk]

I just want to add; peak torque isn't always just before detonation.

[16bit]

flash point is dependent on what is actually used in the fuels to create the knock protection. Things like toluene and xylene and other hydrocarbons which have really high knock protection also have a very high flash point. This is due to a very complex or long chain chemical makeup that takes a little bit to get the ignition happening - especially under high pressure environments. In the 80s the turbo f1 cars used 85% toluene and 15% iso octane. The fuel tanks had to be heated so the mixture would actually combust. This fuel would allow them to run up to 4 bar boost. But alcohols have a lower flash point but still offer high knock protection - their downside is the lower amount of energy that they contain. Which is why the afr has to be so high or low whichever way you look at it to get the horsepower out of it. Which is why they don't use them for anything but drag racing because you would have to pit every few laps - that and they have ƒü¢k all lubricating properties in pure forms. I am fully aware of knock protection and the increase of either timing advance, compression and or boost to make power. I know you have to tune to get the power out of it, all I was after was how the bp motor performs with race fuel.

[Hellmun]

I've only seen the Toyota Crown(he runs AVGAS) at the super sprints run anything but Pump 98 fuel. I'd have to look it up to be sure but I believe all the 2F/2B regs keep you on normal 98 octane pump fuel so doubt most of the racers have used the ridiculous stuff for their cars.

[16bit]

bollocks. i may to consult some of the drag racers in the states.

[FMS01]

I've only seen the Toyota Crown(he runs AVGAS) at the super sprints run anything but Pump 98 fuel. I'd have to look it up to be sure but I believe all the 2F/2B regs keep you on normal 98 octane pump fuel so doubt most of the racers have used the ridiculous stuff for their cars.

A couple of the 2B and also 2F cars in Qld run 102, doesn't seem to help em enough to make it worth the extra cost...having said that maybe they haven't forked out as much in initial engine build costs as the people they are keeping up with

Cheers,
Julian