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 Octane Boosters: Any Downside?

 Created by: Rosebud
Orig. Posting Date User Name Edit Date
Apr 27, 2017 07:40AM Alex  
Apr 25, 2017 03:56AM elpez  
Apr 23, 2017 11:14AM Rosebud Edited: Apr 23, 2017 09:26PM 
Apr 23, 2017 03:31AM Richard1  
Apr 22, 2017 03:26PM Rosebud Edited: Apr 22, 2017 03:28PM 
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 Posted: Apr 27, 2017 07:40AM
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GB

My take on that statement from Honda is that the manganese is probably a catalyst poison rather than harmful to the engine internals.

When building an engine, one of the important factors I consider is the fuel it will be running on.  There's no point at all in building a balls-out high compression engine if the only fuel you can obtain won't run a chainsaw...

Suzy insisted that the engine in Tigger had to be capable of running 95 octane pump fuel, so the static and dynamic compressions were kept below a level that would cause an issue.  Running a higher comp and 98 octane would see it producing more than the 90bhp that it does, but at a cost in terms of fuel price and availability across Europe.
The very high compression engine in Gertie HAS to use 105 leaded racing fuel, at an eyewatering cost (somewhere in the region of £3.50 a litre from memory) but it is safe from any pinking or det.

Your 91 octane is, I think, somewhere between our 95 and 98, so even with a short duration cam and high dynamic compression ratio you ought to be fine.

Some engines just run on...

 Posted: Apr 25, 2017 03:56AM
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US
Mildly related to this, I will sometimes use ethanol free ron 90 gas in the Mini and 65 Mustang, boat gas.  Definitely feel an increase in power in both of them and they run great

 Posted: Apr 23, 2017 11:14AM
 Edited:  Apr 23, 2017 09:26PM
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US
Quote:
Originally Posted by Richard1
"Do not use gasoline containing MMT (Methylcyclopentadienyl Manganese Tricarbonyl). MMT is a gasoline additive that is used by some refiners to boost octane. It contains the metal manganese…
Thanks for your comments, Richard. Conversations about fuel additives can quickly get out of hand, especially on the internet. It's a complex subject and manufactures are purposely obtuse, preferring to use meaningless phrases like "increases power," etc. 

I'm sure most new car manufacturers discourage the use of octane boosters for a variety of reasons—unknown ingredients, lack of quality control, the damaging effects that MMT has on catalytic converters, and of course because they're mostly unnecessary as the ECU can adjust the ignition timing, change the fuel/air ratio and in some cases even change valve timing to accommodate a variety of fuel shortcomings. 

Knowing all this, I wanted to limit my question to the possibility of manganese oxide buildup on valves and valve seats. Spark plugs reach >5K degrees F, while valves, pistons, etc. don't get anywhere near as hot. So it's entirely possible the manganese simply passes through the cylinder head and out the exhaust like lead does/did. Just wondering if anyone has actually seen manganese oxide buildup on anything other than spark plugs.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Apr 23, 2017 03:31AM
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I am not a profesional engine builder. I've built three engines for myself (Corvair, Mini, Dauphine). But I am a professional Oil, filtration, and fuel consultant/teacher/etc.

First I will add this quote from Honda:
"Do not use gasoline containing MMT (Methylcyclopentadienyl Manganese Tricarbonyl). MMT is a gasoline additive that is used by some refiners to boost octane. It contains the metal manganese. This additive contaminates your engine components and exhaust emission control system, and can lead to a significant increase in emissions and a loss in performance and fuel economy. Damage caused by the use of fuels containing MMT may not be covered under warranty. Gasoline containing MMT is not common in the United States. It is prohibited in federal reformulated gasoline and in all California gasoline. However, MMT has been found in some fuels in the Southwest, mountain states, and the northwest area of New York State. MMT is more prevalent in gasoline sold in Canada"

That being said, The US (except California) allows up to 8.3 mg Mn/L and Canada about double that. I think Europe still allows up to about 10. It is a way to boost the octane that is cheaper and uses less energy than better processing of the gasoline. But it's benefit is also reduced as the concentrate increases. You can get some good results from one bottle, but about half of that increase with a second bottle. I would not go over the 8.3 mg limit for the reasons Honda (and other brands) says.

But before I would put an octane booster in a car, I would put Techron to clean up the heads and valves, cabs and inyectors. My first Grand Cherokee (1993, bought in 1999) pinged terribly and had run-on even if I could get premium gas. Our premium is 95 RON, regular 85 RON. Premium was only available in in one station in the city, and only every 4 to 6 weeks. And I spent most of my time in the mountains and country. I put in a bottle of Techron, and reduced the problem significantly, so put in a second. Problem eliminated. I was able to use regular gas (also half the price of premium).

Some brands of octane booster add a form of cleaner to their product to get both effects, and if used in each tank, they should maintain a clean system.

I have my own brand of fuel system cleaner that I formulate with the Oronite concentrate used in Techron, and am working on a MMT formula octane booster that would also use some of the Oronite to combine the effects.

Obviously the gov't limits are not to protect the engine, but to protect the environment. But if you are in a state where there is no MMT in the gas, a bottle should not cause any damage, but don't expect much boost if you buy a brand that already uses MMT to get the octane they sell. But I would use the Techron every 3000 miles to keep deposits down and maybe even eliminate the need for the MMT

An additional note: Timing: On my Corvair and Mini I set my timing by ear. Retarding the spark a touch will reduce or eliminate ping, and in come cases reduce the temperature enough to eliminate run-on. When I first tuned my Corvair in the city, I had it perfect. But leaving my home 600 ft lower in altitude, it pinged, so I had to reset it for that altitude. When I brought it to my other home, 4000 feet lower, I had to reset it again.

 Posted: Apr 22, 2017 03:26PM
 Edited:  Apr 22, 2017 03:28PM
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Overview: My motor is in tip-top tune. EZ starting, plenty of throttle response, excellent torque. Only problem is momentary run-on when I turn it off. My compression ratio is 10:1, so I naturally assumed that my 91 octane pump gas is a little on the low side, octane-wise. I'm not terribly concerned about the run-on (EZ fix; keep it in gear and release the clutch). What I AM concerned about is the potential that I may be experiencing a pre-detonation knock—or at least close to the edge. My car is loud; loud exhaust, rock hard suspension w/ lots of clanks & rattles. I'm certain I'd never hear a knock if indeed I had one.

So I began using an off-the-shelf octane booster. Run-on problem solved, and hopefully I'm well out of the pre-det range. After several tanks of octane boosted gas I checked my spark plugs. What were formerly a dry, light tan color were now an alarming shade of reddish-orange. I immediately turned to the internet and soon discovered that the reddish-orange color is associated with methylcyclopentadienylmanganesetricarbonyl (MMT) used in most of the common octane boosters. The red coating is very thin and it doesn't strike me as having any plug fouling potential. Still, I'm concerned that the red oxide might be building up on the valves and seats. My question is to the actual engine builders on this forum—not the armchair mechanics like myself (are you listening "Specialist"?). I taught advanced organic chemistry for 30 years, so I'm pretty clear on what octane is and how it works. I'm simply wondering about this red oxide thing.

Question: Has anyone rebuilt an engine that was known to use an octane booster? Any sign of red oxide build-up on the valves and seats?

I know that the old school method of increasing octane was to blend in benzine (and lead). There are formulas available for substituting reagent grade toluene and/or xylene to increase octane without the use of MMT. This is probably ideal, but obviously a PITA!

Thanks!

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports