Fuel question

[Rich 89 Gr. Wag]

This week when pumping gas, I screwed up and pressed the hi-test button and proceeded getting 20.05 gallons (20 gallon tank, right?) at $1.75/gallon. $35 later I drove off.

Here's the quesion...it seems like my engine is warming up much faster with the higher octane gas. Is that just my imagination? It's colder than a witch's tit up in the Northeast. 2 degrees this morning, just kinda shrivels your balls.

[Va-Rob]

Your engine is desgined to run 87 octane. filling it once with 97 won't hurt it but I would not do it again.

Rob

[crispyboy]

you could burn hi-octane all the time. this fuel provides a much more even burn across the top of the cylinder. you'll find less knocking and pinging. motor should also get another one or two mpg's. I usually burn 89 octane, vehicle runs better.

[Smooshy]

Vehicle needs to be tuned to take advantage of high octane, other wise just waisting money and burning valves a little too.

[turtlejoe]

Smooshy - when you say tuning, what do you mean? Adjust richer or leaner, advance or retard timing, hotter or colder plugs ... I'm interested.

[Don S]

..
... Using ‘high test’ every so often is a very good idea and should not need retuning of the engine for one or two tank fulls.

... Part of the increased price of the high test in most brands is cleaners that they don’t put in regular gasoline. Crudy fuel injectors on modern cars will usually be cleaned and run much better with a dose of high test.

Good Luck and CUL ;) … ds..
- - - - - - - - - - - - - - - - - - - - - -
1976 Wagoneer 406 MC4300 TH400 QT TruTrac 2" lift 31x10.50s duel Optimas
It’s taken us over 261 Colorado Mountain Passes since 1985-
link> 2003 OURAY FSJ Invasion Info and High Altitude Tips (http://groups.msn.com/ATexasOklahomaJeepClub/ouraycotopic.msnw)
link> Acronym and Abbreviations for 4X4 Gearheads (http://groups.msn.com/NISSAN4X4TRAILS/acronymlist.msnw)

[turtlejoe]

Don, the way I always understood it too was that the octane number was a measure of the fuels resistance to preignition, meaning you could advance your timing a bit and pick up a little power.

The extra cleaners are nice too, but since I started using the two stroke oil as you suggested everything seems to be much cleaner anyway.

KT

[kkeithnyc]

I was told by the PO to run "high test" because of the rebuild on the 401 and the Edelbrock carb. PO said it would eliminate pinging. Does that sound correct?

[Va-Rob]

this topic has been so beat to death I wish someone would kill it :eek:

Rob

If you like wasting money fill your rig with 97 every time. While your at it lower the rear window and fill the back up then throw in a match ;)

[Don S]

Originally posted by kkeithnyc:
I was told by the PO to run "high test" because of the rebuild on the 401 and the Edelbrock carb. PO said it would eliminate pinging. Does that sound correct?..
kkeithnyc:...
... Yup !!! Basically true but reducing the timing by a degree or two (if it was pinging) might
be less expensive.
… Another sometimes helpful thing (if you read Turttlejoes post) is in the link below.

link> CARBON & FUEL ADDITIVES (http://groups.msn.com/JEEPTECH101/jeeptech.msnw)

Because Carbon contributes to pinging. :mad:

Good Luck and CUL ;) … ds..
- - - - - - - - - - - - - - - - - - - - - -
1976 Wagoneer 406 MC4300 TH400 QT TruTrac 2" lift 31x10.50s duel Optimas
It’s taken us over 261 Colorado Mountain Passes since 1985-
link> 2003 OURAY FSJ Invasion Info and High Altitude Tips (http://groups.msn.com/ATexasOklahomaJeepClub/ouraycotopic.msnw)
link> Acronym and Abbreviations for 4X4 Gearheads (http://groups.msn.com/NISSAN4X4TRAILS/acronymlist.msnw)

[kkeithnyc]

Don,
thanks for the info.

[Smooshy]

Before I say anything I want to be sure to give my credentials in this area of my expertise, (think electrical post): I am a dumb guy that likes to tinker on jeeps, I have no idea what I am talking about other than what I have read.

1. High octane does not "clean" better - all gasolines are required to have cleaning detergents. - Fed Trade Commission, and a billion other sources

2. High octane does resist preignition - detonation is a fast incomplete burn of fuel and is very bad for your engine, the octane rating for gas is its resitance to detonation. - Fed. Trade Commission

3. High octane burns longer and colder - FTC
so to answer the timing question, yes, advance your timing and run the stuff (unless your running a charger or turbo, thats a waaay different story). - personal experience and Hot Rod Mag.

And from the mouth of a friend of mine who is an instructor for engine mechanics at a local college- High octane will hurt an engine not tuned to run it, the gasoline will still be burning as it leaves the combustion chamber and cause your valves to get hot and build up carbon.

The cam also plays a large roll, tuning is only part of it. I am not aware of why the mixture must change with dif grades, although I have been told by many that it matters.

Disclaimer - I am not an expert and dont really know what I am talking about but I am really good at doing research so please correct me or ask me a question smile.gif

[Smooshy]

Oh and kkeithnyc, you may very well need to run high octane, a higher compression motor with a longer duration and larger lift cam needs it. If your motor knocks i can do some interesting damage to you piston. Although I have not seen many motors built for off road need high octane, seems like that would mean you have too much cam for off road stuff.

[kkeithnyc]

Thanks Smooshy!
I'm really new at all this, so I try to do as much research and ask the right questions to learn and take care of this nice rebuilt egine (401). The cam is Wolverine (Crane) & the info from the rebuild states 204º x 214º @ .050 and .448" x .472". And I honestly don't know how to read that. Have not noticed any knocking or ping, but have not driven her much.
Thanks

[Smooshy]

It sounds like you can run regular, that is not an aggresive cam (great for offroad). Crane will make recommendations on fuel if you can give them details about the motor, they are a great company.

[kkeithnyc]

Thanks again Smooshy!
I'll give them a shout. The more I can save on gas, the more I can spend on fixin' her up.

[Peter Matusov]

FWIW,

my '79 Chero with a 73 motor will take any gas, and ping only lightly under heavy load.

my '68 definitely prefers 92 to 87 - i never hear any pinging with the 92-octane gasoline. I also have to keep adding lead substitute, but... what can i do short of rebuilding the heads...

peter

[Don S]

Smooshy:...
... Are you implying that I don’t know what I am talking about when I advise someone that…
.
.. Part of the increased price of the high test in most brands is cleaners that they don’t put in regular gasoline. Crudy fuel injectors on modern cars will usually be cleaned and run much better with a dose of high test. .
The little clip below should explain the difference in a minimum regular requirement and a quality premium fuel mix.

For Refinery and Branded Retail Gasoline
 OGA Compliance Additive Packages: Formulated to meet minimum regulatory requirements, such as those in the U.S.A. and Thailand.
 OGA Enhanced Additive Packages: Provide higher levels of performance and additional performance attributes. These packages offer inexpensive solutions for gasoline marketers wanting to differentiate their products from mere compliance gasolines to generate enhanced image, revenue, and profits.

And furthermore

 Gasoline additive for preventing carburetor deposits starting in 1954
 Deposit control additive (Polybutene Amine) in 1970
 Full deposit control additive (Polyether Amine) designed specifically for unleaded gasoline in 1980
 Full deposit control aftermarket additive (Polyether Amine) capable of cleaning up the entire intake system and the combustion chamber, introduced in 1982

Additives cost more than the gasoline THERE FOR…

.. Part of the increased price of the high test in most brands is cleaners that they don’t put in regular gasoline. Crudy fuel injectors on modern cars will usually be cleaned and run much better with a dose of high test. Originally posted by Smooshy:
Before I say anything I want to be sure to give my credentials in this area of my expertise, (think electrical post): I am a dumb guy that likes to tinker on jeeps, I have no idea what I am talking about other than what I have read.

1. High octane does not "clean" better - all gasolines are required to have cleaning detergents. - Fed Trade Commission, and a billion other sources

Disclaimer - I am not an expert and dont really know what I am talking about but I am really good at doing research so please correct me or ask me a question smile.gif You, of course were just joking weren't you http://www.nagca.com/forum/images/smiles/1wink.gif http://www.nagca.com/forum/images/smiles/1wink.gif :D