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Discussion Starter · #1 ·
Just wondering if people living where there is only 91 octane fuel use a quality octane booster (ex Torco) to bring it up to 93 octane. If so, what do you use?

What are the advantages to bringing it from 91 to 93 in higer altitude regions?

I have been using 91 since getting the car due to the lack of 93 in my region but wondering if it will be be good to start boosting it up to 93. Would one get a performance increase under WOT?

Thanks!
 

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I can't speak for the Cayman but the BMW 335 guys were having to replace their plugs fairly frequently when using torco (it turned them orange), and the O2 sensors did not like frequent use of octane boosters.

The practice is to mix in some race gas those times when you want to increase octane. Although, I noticed some of the guys are now running meth injection to compensate for lower octane (especially the California folks) which allows them to run higher boost.

Other than torco, most "octane boosters" don't really increase octane much and can do more harm than good. Again, this is coming from someone more familiar with BMW engines.

Dave
 

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+1 on what Dave said.

Those "octane boost in a bottle" products contain chemicals like MTBE, which can foul your plugs and leave deposits in the combustion chamber.

I found this reference:

The main drawback to MTBE is that it creates major carbon deposits on the valves and fuel injectors. MTBE, being the most widely used fuel additive, requires the constant use of fuel system cleaners to maintain throttle response and power. This is a slow building process and sometimes the performance loss isn't apparent until hesitations, misfires, hard starting and rough iding manifest themselves. Regular use of Chevron' Techron or LubroMoly's Jectron and Ventil Sauber products will prevent these problems. In addition, those Porsche dealers and independent repair facilities that employ the MotorVac fuel system cleaning process, can restore full power and drivability.
(The above quote is from here: Welcome to Rennsport Systems, Porsche Performance Products for the 21st Century )

Also, some of these products claim they increase octane by 5 points or 7 points or whatever. They lead you to believe it will increase your octane from 91 to 96. However, that is not the case. The "points" they refer to are decimal points. This means it will increase your octane from 91.0 to 91.5.

Also note that some of the commonly available racing fuels, like VP Racing fuel, uses MTBE. Check out the second to last product on this site:

VP Drag Racing Fuels

Notice it says "can be used in all 50 states, including those that restrict the use of MTBE in fuels." To me, this means that unless the product has this disclaimer, it uses MTBE.
 

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Discussion Starter · #5 ·
thanks for the replies....I have also been reading up on other car forums and I have concluded that it is not worth the risk and besides the car runs fine under at these altitudes.

What about using race fuel with 100 octane (unleaded) and mixing it with 91 octane at a certain ratio to get 93 octane for use when required like at a track?
 

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What blueone says is correct, the loss of performance at altitude is due to a lack of oxygen, not octane (which is why forced induction engines suffer less at altitude).

Secondly, IIRC (Scott S. at Softronic once mentioned something about this), the performance gain (HP) going from 91--> 93 octane in a non-FI motor, even at sea level, is pretty small - probably less than 3-4 BHP, if that much. However, you might get a placebo effect. ;)
 

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Discussion Starter · #7 ·
nothing wrong with the placebo effect....many companies rely on it...lol!

Does higher octane fuel keep the engine cleaner with less deposits? I heard this before but can't get a confirmation if this is true or not.
 

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. . . What about using race fuel with 100 octane (unleaded) and mixing it with 91 octane at a certain ratio to get 93 octane for use when required like at a track?
I do that, because I figure on the track, every little bit helps (see previous post). ;)

Actually, I mix with 104 octane race gas to get closer to 100 oct; my Softronic flash is supposed to be able to take advantage of up to 100 octane, but as I pointed out above, Scott at Softronic said that is still only good for a few more HP.

. . . Does higher octane fuel keep the engine cleaner with less deposits? I heard this before but can't get a confirmation if this is true or not.
I don't know if that is true or not, though I suspect that it probably doesn't make a big difference.
 
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