octane

Cobain03 · Apr 5, 2005

m always running off of the cheap stuff when i fill up. But a bud of mine runs the highest stuff in his 66 with pretty much exact same setup as me.. is there any advantages/disadvantages for running the good stuff in ani old engine like ours?

thehueypilot · Apr 5, 2005

It depends on your compression ratio and/or how much your timing is advanced. Higher octane resists detonation (spark knock) better then lower octane fuels.

65fastback2+2 · Apr 5, 2005

taylor4g63 · Apr 5, 2005

thehueypilot said:
It depends on your compression ratio and/or how much your timing is advanced. Higher octane resists detonation (spark knock) better then lower octane fuels.

Yep thats pretty much it. If you have high compression (i'd say higher than 9.5:1 with iron heads), you're gonna have to run 93 or whatever the highest available is. With higher octane you can also advance the timing a bit thus producing more power. If your motor runs fine on the cheap stuff then i'd stick with that unless u mess with the timing.

67coupe351w · Apr 5, 2005

taylor4g63 said:
the cheap stuff

WHERE do I find some of that?

65fastback2+2 · Apr 5, 2005

67coupe351w said:
WHERE do I find some of that?

look at the bottom of the gas list it'll say $2.50, now look up at the top, it'll say $2.20, $2.20 is cheaper than $2.50 thus making that the cheap stuff

meanroy · Apr 5, 2005

You must be joking.

65fastback2+2 said:
look at the bottom of the gas list it'll say $2.50, now look up at the top, it'll say $2.20, $2.20 is cheaper than $2.50 thus making that the cheap stuff

2.73 here today.

And low octane to boot.

Huh!

65fastback2+2 · Apr 5, 2005

meanroy said:
2.73 here today.

And low octane to boot.

Huh!

hehe, im lucky to live in texas

meanroy · Apr 5, 2005

Yo.

65fastback2+2 said:
hehe, im lucky to live in texas

Carefully refraining from comment.

heHeh heh Well not really.

Roy.
=============

Hey whats up?
Have you guys screwed up our avatars trying to restore stuff?
I mean - heres mine. View attachment 518052It'sa a graphic crash helmet desighn done by Dutch.

This is a post crash change.

Roy.

65ShelbyClone · Apr 6, 2005

65fastback2+2 said:
$2.20 is cheaper than $2.50 thus making that the cheap stuff

No, $2.20 is less expensive than $2.50. None of it is cheap.

Anyway, if you're not pinging on 87 the be happy it works for you. I had a 289 with factory heads and flat top pistons and I ran 87. Higher octane in and of iteself does not make more power. Heck, if you dont need it you might even lose a small amount.

limey66 · Apr 6, 2005

Hey guys, stop bitching about the price of your cheap gas - we pay the equivalent of seven bucks a gallon over here...

Edbert · Apr 6, 2005

Another consideration of the modern fuels in a vintage engine is the lack of lead and your valves. If you have factory heads you are going to need hardened seat-inserts and modernized guides. You either need them now or you will when your heads are being rebuilt becuase you waited.

I filled up for $2.03/gallon in my 21mpg 2005 GT this morning

Max Power · Apr 6, 2005

Premium fuels actually burn slower than regular 87 octane. Unless you have detonation issues, it is not only a waste of money, it is probably providing less performance than the "cheap stuff.

65fastback2+2 · Apr 6, 2005

limey66 said:
Hey guys, stop bitching about the price of your cheap gas - we pay the equivalent of seven bucks a gallon over here...

and this is where i kindly say, sucks to be you.

edbert said:
I filled up for $2.03/gallon in my 21mpg 2005 GT this morning

wow, so what was 87 octane??? like $1.90??? cuz i know you didnt put 87 in that car since it requires premium 93

Edbert · Apr 6, 2005

65fastback2+2 said:
wow, so what was 87 octane??? like $1.90??? cuz i know you didnt put 87 in that car since it requires premium 93

Yes, it was 87, and no the 2005 GTs do NOT require 93. My 97 Cobra did but this 2005 is only down 5hp to my old Cobra (but it has 15 more ft/lbs) and it takes the cheap...errr...less expensive...gasoline.

krash kendall · Apr 6, 2005

I'm running 89 in mine. The 87 makes it run like crap and burn more fuel, so what I save at the pump I lose in mpg. Running 91 gives me the same result as the 89 so I save my money and go with the less expensive of the two.

I live 5 minutes north of Washington state and gas is the equivalent of $4.93 / gallon here.

Edbert · Apr 6, 2005

The engine requireds 87, the owner's manual clearly states so. I don't think 91 would cuase you any trouble but I've heard horror stories of guys who put 93 in them and burned up stuff. Of course if you get the chip reprogrammed...

brianj5600 · Apr 6, 2005

Max Power said:
Premium fuels actually burn slower than regular 87 octane.

At the same heat and pressure. The resistance to pre-ignition allows more heat and pressure w/o pinging, and more cylinder pressure, and more power.

Max Power · Apr 6, 2005

brianj5600 said:
At the same heat and pressure. The resistance to pre-ignition allows more heat and pressure w/o pinging, and more cylinder pressure, and more power.

Yup, but ya gotta engineer the motor for that. Cam selection, pistons, heads and head material, etc.

Bout all you can do with a stocker is mess with timing and advance.

octane

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