Tuesday, July 29, 2008

Octane Boosters

I occasionally get asked about the use of octane boosters in performance engines. While in some rare cases they are necessary, they are NOT in our builds if tuned properly...primarily because we make sure to put you into a build that fits your riding style and conditions. This issue came to me today from one of our dealers...their dyno tuner in fact, who is very capable, was kind enough to send me these pictures. As you can see, there is an extensive layer of iron and manganese deposits on the plug insulation and electrode as well as the oxygen sensor for the closed loop fuel system thus corrupting the vital control of the air to fuel ratio. This generally results in a rich bias, compromising both emissions and fuel economy.

The primary ingredient used in most octane boosters is a chemical called methyl cyclopenta dienyl manganese tricarbonyl, or MMT. In VERY controlled and minute quantities (.018 grams per liter...or a couple drops per gallon) it's not harmful however, even the slightest over mix can cause what you see here as well as increased valve and combustion chamber deposits.

General Motors (GM), and others have reported spark plug fouling with MMT. Reports indicate that spark plug failures are due to iron and manganese deposits on the plug insulation and electrode, resulting in:
• Increased hydrocarbon emissions from the incomplete combustion of fuel
• Premature component failure (e.g. plug and O2 sensor) at circa 10,000 km, where
normal life would be more than 100 000 km.

Despite what the packaging says on various octane boosters about being "safe for oxygen sensors", if they contain MMT or Ferrocene, I would highly recommend against using them....of course as better advice, I wouldn't recommend using any at all. Happy Motoring!

Kevin Baxter


George said...

and IF I recall correctly Kevin, (It's Been TOOOOO Many Years away from EFI for me) the way an O2 sensor is measuring, If You want to say it this way, is, It's Measuring a LACK of Oxygen, and when That happens, it can Compound the issue they May have been Trying to Cure with a Band aid approach. If the O2 sensor can Not measure the LACK of Oxygen Properly, it wants to cut the Fuel Back, resulting in an Even Leaner Mixture, resulting in a Poorer state of Tune, and with the Resulting Lean Mixture, shittier running Vehicle, MOST People are too Quick to Blame Something Else, than CURE the Problem to begin with, TUNE IT! Maybe after a Piston or two they Might get lucky and Find a Real Technician that Knows Why they are burning the Engine Up......
Edit it as you see fit Kevin, like I say, it's Been MANY Years away from Driveability/Emissions for me.



I agree Hogman...you haven't been away too long ;)

I've often seen an overly rich condition as well due to incomplete burn...seems to effect the spark plugs before it takes out an O2 sensor but it's so inconsistant, the O2 cant compensate but when it does...it's off too.

Anonymous said...

I am curious what I can add to my fuel if I'm on a trip and find myself in an area with lower octane ratings? I know my engine running 10.5:1 comp needs the 93.