Interesting Take on Octane and Fuel Additives

[X Ring]

http://vettenet.org/octane.html

Marty

[Former BMW Guy]

My experience has always been the higher the octane the more efficient detonation resulting in better MPG.
I have recently started using 91 octane non-ethanol fuel and have been getting between 39 and 41 MPG.
Your results may vary.

JP

[donaldcc]

Interesting article, thanks.   

[Patrick]

The article really didn't say much about what most folks are concerned with,, fuel mileage and detonation.. I did like what he had to say about additives as it does appear that some additives work better than others..
Simple put,, low octane fuel burns faster than high octane fuel.. Therefore low octane produces more BTUs than high.. Higher octane reduces the speed of the flame front thru the combustion chamber which sometimes is necessary to reduce the chance of detonation[spark knock]..
Detonation is an uneven flame front which produces the knock/pinging sound.. Pre-ignition is an altogether different animal..

[Madmike]

thanks for teh read....

[X Ring]

The article really didn't say much about what most folks are concerned with,, fuel mileage and detonation.. I did like what he had to say about additives as it does appear that some additives work better than others..
Simple put,, low octane fuel burns faster than high octane fuel.. Therefore low octane produces more BTUs than high.. Higher octane reduces the speed of the flame front thru the combustion chamber which sometimes is necessary to reduce the chance of detonation[spark knock]..
Detonation is an uneven flame front which produces the knock/pinging sound.. Pre-ignition is an altogether different animal..

It was written for a Corvette group.  Mileage probably wasn't a big consideration; although, the comments about deposit buildup due to brand additives would effect efficiency and efficiency does effect fuel mileage.

Marty

[MarkT]

I just changed the oil in my generator, after several years.  The generator is used only about 3 times / yr, usually for up to about 8 hours.  It is always run up to operating temp and run for several hours.  The fuel it uses is always regular grade, with a preservative strength of SeaFoam in it - 1oz per gallon. Because actual use time is so low, and it's always run for several hours at a time, I wasn't concerned with the time factor, but more with the hours on the oil.

Anyway, the oil drained was runny like water.  I had run it for 10 minutes first, to warm it up before draining.  I don't know what brand it was, it was the original oil.  I replaced it with Mobil1 10-30.

Now I'm wondering if I was seeing the SeaFoam having contaminated the oil.

[Jess from VA]

Sorry for the drift, but you started it.

My big 4600 Coleman Vantage generator is 14yo, but probably only 20 hours on it.  New plug, air cleaner, fresh gas with seafoam added, started on first pull after a year (gas drained, carb bowl cleaned, every time it's used).  But for the first 6-8 hours would cut off after 15-20 minutes.... usually fairly easily restarted (but what a big PITA).  It also has a low oil shutoff, and the oil was topped off, but also needs changed.  When it gets down to below 100 every day, I am going to change it.  Seems to me a stationary air cooled generator should take straight 30 wt, not 10-30.  I will be looking for a synthetic 30 wt.  I have the manual around here somewhere.  LOL

Went to my good small engine repair guy, and he said it's probably the carb, though easy starting was not consistent with that.  He also said running premium was a better idea, because with ethanol only available in our area, premium is always cleaner fuel.

[Disco]

Thanks, Marty!

[Ricky-D]

Simple put,, low octane fuel burns faster than high octane fuel.. Therefore low octane produces more BTUs than high

I do not subscribe to this statement regarding BTU's

BTU and Octane are only peripherally related and one is not dependent upon the other as you declare.

***

[sugerbear]

Simple put,, low octane fuel burns faster than high octane fuel.. Therefore low octane produces more BTUs than high

I do not subscribe to this statement regarding BTU's

BTU and Octane are only peripherally related and one is not dependent upon the other as you declare.

***

i think it should say more USEABLE btu's. the higher the octane, the more goes out the exhaust. provided the motor isn't designed to use higher octane.

[sergbutton]

Switching Brands?

Well I might give it a try.

I usually just buy Sunoco or Exxon Gas. Occasionally I get my gas at the grocier store that offers 10 cents off for every $100 you spend.

The nice thing about that is the Gas is usually used up quickly (put it in the RV before I head out). Also my local station is only a year old and runs a lot of gas through the station.

For by bikes, I actually run 89 in all of them. It is simply a seat of the pants feeling that I use.

The bike feels like it makes "smoother" power with 89 and no difference between 89 and 93.

I only try to buy from name brands. Exxon and Shell are my favorites. 

[The Anvil]

You're supposed to replace the factory oil in something like a generator after the first 20 or 30 hours, depending on manufacturer. It's break-in oil and not meant for long-term use.

As for octane and how it relates to engines, some people here need to do some more reading.

[Patrick]

As far as the octane fuel and its additives.. I've never put much stock in what the makers said of their additives,, but,, I've pretty much changed my opinion..
Here at home for the 3 seasons in the north Sunoco is pretty much the only fuel available and my truck will have a light throttle hesitation after about 6 months.. I would find a carbon ring on the throttle plate/bore and clean it.. During the winter the closest gas stations to us are/is Shell.. I've found that if left alone and not cleaned before the trip south,, the hesitation will disappear in about a month and when checked the throttle plate has been cleaned.. Those 2 local Shell stations also sell marine gas cheaper than the marinas.. Therefore I kinda like Shell..

This pretty much also refers to octane ratings.. Hard starting in the cold,, GM was the first [ others followed] to issue a TSB to inform owners to use 87 octane fuel during the winter to improve starting..