more octane gas

[themetalman]

i have been putting lower octane gas in my motorhome since i bought it,the last couple trips i filled the gas tank with 92 octane gas and it ran alot better it seens like it had more power. do you think putting the more octane gas in the motorhome, and paying 20 cent more per gallon is worth it in the long run...

 

[BernieD]

The general rule is to put in the lowest octane which doesn't cause pinging. Higher octane's benefits are usually strictly the ability to handle higher compression engines. So if your engine doesn't ping with low octane, save the 20?.

 

[Gary RV_Wizard]

the last couple trips i filled the gas tank with 92 octane gas and it ran alot better it seens like it had more power.

Sorry to be so blunt, but you are deluding yourself.  A engine designed for 87 octane regular gas won't run one bit better on 92 octane. No more power.  No better fuel economy. All you achieve with 92 octane is a higher fuel bill.

If your engine pings on regular fuel, get it repaired/adjusted so that it does not and then buy regular grade fuel for it.  That will give you the best perfromance and most cost effective results.

 

[Lowell]

Some of the newer vehicles adjust for the octane of the gasoline being consumed.  For example, my 2005 Dodge 5.7 Hemi recommends 89 octane but the manual states that using 87  octane is acceptable.  So I use 87 octane for day-to-day running around but go to 89 octane when ever I do any towing.

 

[Gary RV_Wizard]

You can only get more power from higher octane by increasing the compression ratio of the engine.

 

[King]

Not true, The new engines with computer controlled advance will make the best use of the available fuel.  I doubt that the improvement will be worth the extra cost.  You could try recording gas milage to see if it improves enough to merit the expense.
Art

 

[Gasser]

You can only get more power from higher octane by increasing the compression ratio of the engine.

Don't forget about timing advance.  There is more to  it than just compression.  In general I agree with most of the above.  Its all about tuning and using the lowest rating you can.  Actually the lower octain fuel contains more energy but tends to burn more quickly and easily.  By going to a higher octaine fuel when not needed then you are loosing power.

Higher rated fuel will hide or prevent knocking from dirty valvs, hot spots in worn engines so it may prevent the engine from destructing itself until you get it either rebuilt or repaired.  Knock ( premature ignition) is bad for the motor so if you are knocking, use a higher grade of fuel until you can get it repaired unless you want to throw a rod on the side of the road.

Jeff

 

[dave95.1]

Don't forget about timing advance.? There is more to? it than just compression.? In general I agree with most of the above.? Its all about tuning and using the lowest rating you can.? Actually the lower octain fuel contains more energy but tends to burn more quickly and easily.? By going to a higher octaine fuel when not needed then you are loosing power.

Agreed.  With fuel injection the computer can advance timing more without the detonation when running higher octane fuel.  You just have to figure your mileage both ways and see if the fuel milage gain offsets the price per gallon.  When towing with my pickup, it actually comes out a little better with premium because of the fuel mileage gain, but when not towing it costs more.