Hi all,

So with the drastic drop in gas prices, I've gone ahead and filled up with a high octane gas a couple of tanks in the last month. The high stuff is cheaper than the cheap stuff was a month ago. I have noticed a difference in how the truck idles, accelerates, and gets about...with the higher octane it's like I just had a Diet Coke. It's much better.
Can I adjust the timing or do anything so it runs on the cheap 87 octane like it does on the high octane?

Thanks

 

Huh, I've never ran 91 but a couple times in mine. I've got a filling coming up in a day or two. Maybe I'll put in premium and see what it does.

 

Octane is a the measure of resistance to pre-ignition. High octane is needed or required with high compression engines so the air/fuel mixture is lit off only when the spark plug fires.

Save your money cuz unless your engine is running over 10.25:1 all you're doing is wasting dollars for no benefit.

Whatever ya felt musta been all psychological.... or ya got toms of carbon build up that has raised the compression as to warrant some degree of detonation prevention.

 

Right, that's why it makes a difference on newer cars that can automatically raise timing without detonating.

 

Plus they have O2 sensors to maintain air/fuel mixtures and knock sensors and an ignition computer to dial back timing at any hint of detonation.

 

It's possibly a psychological placebo that the high octane fuel is causing the engine to seemingly run better. --unless your engine has been modified with high compression pistons/heads and has previously been run on low octane fuel, up until just recently.

High octane fuel doesn't have a higher combustion capacity than low octane fuel. High octane fuel is designed to have a slower burn rate than low octane fuel because high octane gas is designed to be run in high compression engines.

An engine with a high compression ratio is more subject to detonation, due to pre-ignition, than an engine with a low compression ratio. Low octane fuel being burned in a high compression engine is subject to igniting the low octane fuel mixture BEFORE the piston can make it to the top of its stroke --the heat generated by the high compression of the piston sets the low octane mixture off --much like a diesel ignites it's fuel mixture without spark plugs but ignites it through high compression.

Detonation is heard a 'ping', a rattle or sounds like ball bearings bouncing around inside a metal coffee can.

In this situation, the destructive detonation can crack piston rings, blow holes through the top of the pistons or, scatter the connecting rods through the oil pan or through the side of the block.

If the high octane fuel is currently cheaper than the low octane stuff, it won't hurt a low compression engine to run it, but the rest of the time you'er paying a higher price for a fuel that isn't designed for a low compression engine or any advantage to running the higher octane fuel in a low compression engine.

 

You must have been typing when I was but you posted before I did.

Looks like our answers pretty much were the same.

 

Your response is much more eloquent... I was being very conservative with my words cuz typing on a lil tablet is a pain in the azz.

.... dang typos are more frequent too... the m and n keys on my screen need to be futher apart!!!! LOL.

 

A TABLET!? That's HUGE compared to what I'm working off of!

Most all my replies, pictures, etc. are done from my iphone.

 

If you've ever heard the old advertisements they were always touting the advantage of Signal Oil Company "go farther" gasoline, even how Police departments used only Rio Grande "cracked" high octane gasoline, claiming better performance, better mileage, quicker starting, better acceleration.

 

....Some of the brake fluid manufactures have more recently started putting the word 'Synthetic' on the labels. DOT 3, & 4 brake fluid didn't recently become synthetic. It has always been synthetic from the very beginning.

I guess it gives an excuse to charge more for something that it's always been, since most people are probably unaware of this.

... gotta have a good gimmick I suppose.

People naturally associate a high octane number (and probably higher per gallon price) that somehow the higher number means it's a high performance gas and will make any engine racier if you pony up the extra money for it.

I run high octane in my '03 Mach 1 because I have to but, the mighty 240 in the '69 F-100 gets the cheap stuff.

 

I still use a flip phome, have fingers like Fred Flintstome, ... I'm a keyboardist by training.

Btw, I wish more guys on I-phones used proper sentence structure and punctuation as you do. Usually we get mega run-on sentences.

 

Higher octanes burn slightly colder with each step, but as far as smoother idle you might be noticing something that doesn't exist. Your brain might be saying, "I just changed something, so I want to notice something." However, with that being said, around here 91 at Shell and 94 at Chevron have no ethanol in them which will cause a difference.

I still think you Yanks don't pay enough for gas. Yeesh.

 

$2.73/ gallon for 91 octane here.

 

I went to a small country school, growing up in Arkansas but, they did teach reading, writing, vocabulary, spelling and punctuation in class.

My spelling isn't always the best but, it tends to be better than others I've read.

Long replies that are typed into one big block are usually hard for me to follow. It's much easier to read and follow what's being said if the sentences are grouped and divided up into paragraphs.