Brand of 98 octane fuel?

[750hp]

I've been hearing so many contradictory stories about what brand of 98 octane fuel is the best, I'm confused.

Some have said all along that Shell's Optimax is the original and best.

Some say that Optimax tankers are corroding inside (bullsh..?)

Other say the BP Ultimate is the only one to use...

Does anyone have any inside knowedge here? I don't want to go and blow a head gasket for the sake of putting some bad fuel in the tank.

Maybe I should just stick with Avgas, it certainly smells better....

[ToyCollector]

You aussies really know how to do it BIG. Anything more than 93 octane from all the states I have been in here in the U.S. are served at a racetrack or airport. If an O2 sensor is not a concern, here in the states, AVGAS is the way to go for bang for the buck, but I have been told for max limit situation the blends are different and can creat issues.

[Bryan Wilson]

Craig,
I have tried all the high octane fuels and found that my car seems to run the best on Mobil Synergy 8000.
Used to use leaded Super before they stopped making it.
My car runs like a dog on that LRP sh!t.
Regards,
Bryan

[750hp]

TC - we are pretty spoilt as far as fuel goes, and it's roughly what you guys are paying for your lower octane stuff! I ran Avgas in my car for a little while, but the government has really increased the fines if you get caught using leaded fuel on the street. Queensland is now $1,000 PER CYLINDER if you get caught!!!! As such, I think I'll stick with the 98, at least until the 102 is introduced within the next 12 months...

Bryan, I agree about that LRP dish water junk. My 460 Falcon looks like the spark plugs have done 200000 k's with a bad tune-up, when in fact they've been in the motor for less than a month. Terrible stuff, and I wonder how the piston crowns look after a few months of the stuff.... Mobil??? Good on you - I hadn't even considered that one! Now I have another one that I'll have to think about!

[347]

750.....I have used all three 98octane fuels and cant honestly say I have noticed any difference

I do use methyl benzine(toluene) with 98octane fuels when I go to the dyno or track

It doesnt give me a major increase in power(as compression ratio doesnt require it)but the throttle response is much much sharper and over all engine smoothness is better

Its estimated that for every 5% toluene you use you will get 1 point octane increase(as per bp email I received)

Tell me more about this 102 fuel you refered in your initial post....

The table below is from my email from bp.......


Fuel RONtypical MONtypical Air/fuel ratioby massstoichio- metric Air/fuel ratioby massmaximum power # Latent heat of vapour- isation MJ/kg Highestusefulcompression ratio *
BP Lead Replacement Petrol 96 85 14.4 12.0 0.34 9-9.5
BP Premium Unleaded 96 85 14.4 12.0 0.34 9 - 9.5
BP Regular Unleaded 91 82 14.7 12.5 0.34 8.5 - 9
BP Ultimate 98 87 14.4 12.0 0.34 9.5-10
BP 100 Racing Fuel 110 100 15.0 12.9 0.36 11.5 - 13
BP Methanol Racing Fuel 115 91 6.5 4.5 1.17 15 - 17
Toluene 124 112 11.5 9.8 0.41 13 - 15

[ac andy]

Craig, I run Mobil Synergy in my XR8 and also in my Statesman and find it much smoother than standard unleaded and better than Optimax in my opinion.

Andy.

[Adrian S]

Hi Craig,
I worked for BP for 4 years and have now worked at Shell for about the same time. I'm only an IT techhead so know little about fuel (shameful I know!). So I asked the Shell product manager your question and have posted the reply below. It contains a lot of marketing B.S. but the main differences in fuel brands seem to center around additives and fuel density. The higher the density - the better the fuel economy. The additives prevent carbon deposits etc etc. Personally, I like either Mobil Synergy or Shell Optimax - mainly because I know both products are superior quality as compared to other brands. Whatever you do, don't buy fuel from an independant outlet - these guys import the refined (and I use the term loosely) fuel from Singapore. This fuel is cheaper for the wholesaler as the refining costs are less - which results in poorer quality.
Anyway, enough rambling from me. Here is the Shell response...
Cheers,
Adrian.
Check out www.shell.com.au/optimax for more info.

------------------------------------------------------------
To list but a few of Optimax's main benefits:

- Optimax is manufactured from components that are unique to Shell Geelong Refinery. These components are blended together to ensure that the fuel performs in an optimal way in an engine.

- Optimax has a high octane (minimum 98.00, this will mean that an engine is less likely to experience knock due the octane requirement of the engine being greater than the octane of the fuel.

- Optimax has a special volatility profile. This means that the fuel is delivered to the engine in such a way that the engine will respond smoothly and quickly, because the Optimax will burn smoothly in the engine combustion chamber.

- Optimax is a high density fuel. This means that for a given volume of petrol injected into the engine cylinder, more weight of fuel will be present. This generally translates to more kilometres travelled per tank full. The percentage increase can vary due to variables in engine maintenance, vehicle operating and driving conditions but many of our customers have reported up to 5% improvement in fuel economy. However, independent reports (RACV) have shown fuel economy benefits of 6.5% when using Optimax.

- Optimax also contains a high performance additive. This high performance additive can not only keep the fuel and engine inlet system clean but can also remove any deposits already present on the fuel and engine inlet system. This allows the engine to perform more efficiently, and respond better over the long term by keeping the inlet valves and ports clean.

When comparing Optimax to Bp Ultimate, I am not able to provide actual comparative data as Shell are not party to the product specifications of our competitor products (and vice versa) so I am unable to answer that question for you except to say that Shell Optimax was designed specifically for the Australian market using unique components only available from Shell's Geelong Refinery in Victoria. We believe that Optimax provides some specific benefits that are not available from other fuels, based on its high octane, high density formulation, along with its volatility profile and performance additive. Its profile allows delivery of fuel to the engine in a way which results in smooth, efficient operation, while providing added benefits of cleaning your engine while you drive - both the fuel system and the engine inlet system and valves.

My product knowledge of the competitors fuels , suggests neither are as dense, and the density means the fuels burns slower and therefore gives Fuel economy. Both are of the same octane as Optimax, with Mobil's Synergy probably being the most similar in that it has some performance related benefits although it is not a as dense, whereas BP's Ultimate product is more of a green, environmental type fuel.

Regarding the Optimax tankers corroding inside, this is a new one to me! Shell has some very strict quality standards and I believe there is legislation and regulations that would not allow this to happen.
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[750hp]

347 - that toluene surely is good stuff, but I like the idea of being able to just pull up at a servo, and fill up. At the track, I think I'll keep using Avgas because it was tuned on the dyno in this configuration. All the engine builders up here are talking about a 102 fuel that's coming. I know that there's a company that will sell you 114 octane unleaded, but it's around $7- per litre.... The 102 is suppsoed to be available at the pumps ?!?

Andy, I haven't tried Mobil. I might give it a go, for a laugh! How's the XR8 going? I suppsoe the new addition means the Vortech might be a little way off

Adrian, very interesting - thanks a lot! "BP is more of a green, environmental type fuel".... ****, I've been using that for the last month, and I want to save my pistons and head gaskets from detonation before I want to save the environment! I just don't know how to separate the sales BS from tech comments..... A special volatility profile means the fuel burns more smoothly in the combustion chamber... Is that not how "octane" ratings are calculated? Going to other extremes, Nitromethane effectively explodes in the combustion chamber, and is highly volatile. This makes the power. Wouldn't a lower volatility therefore make less power?

Sorry, just me overanalysing things again....

[ac andy]

Craig, XR8 is going well. Prefer to get Cobra finished before the Vortech goes on. Heard on the grapevine that Ford in Doncaster sold an XR6 turbo ute to a 19 year old, and with some extensive mods he has 340kw at the back wheels! Not bad out of a straight six!

Andy.

[vettestr]

Jumpin in on your Octane thread for a little input from you all. My engine requires at least 108 octane to run right, lower pings and knocks with poor throttle response and developps a miss.
I talked to my fuel distributor who I respect but admit he may be a little biased. He ststes Tolulene works great but tends to evaporate out of mix if allowed to sit for a while( 1 week) with a vented tank. Also claims it is very corrosive on all aluminium parts like tank/cell and fittings etc.. I am soaking a hose end in tolulene right now to check corrosive claim, 1 day so far.
Anybody know different or have first hand experience with these claims?

[347]

I have no first hand experience with toluene corroding things , the only thing I noticed is it makes my rubber lines go hard very quickly
I have spoken to the other people who say they believe it is responsible for destroying there o2 sensors

[750hp]

Jeff - you must have massive compression, or a really tight camshaft!!! I friend of mine has a 13:1 compression, 509 cube BBC in his 65 SS Impala, and it runs fine on Avgas... .700" lift, 260 degrees duration, 35 degrees total ignition timing, 1150 dominator with 98 and 102 jets.

That's interesting about the corrosion. I know that methanol gives the rubber and alloy a bit of a workout, but hadn't heard the same about toluene.

Andy, there's a guy up here http://www.redcliffedyno.com making a little over 360KW at the wheels with his XR6T. Here's a photo of it last wednesday at a Test and Tune. It's in the 12s, but it's mph points towards a high 10 in the next month or two....