High Octane gas/timing?
Logistics Pro
Joined: Feb 2011
Posts: 3,522
Likes: 11
From: Townsend, MT
My 416 is around 9.5:1 and will "ping" on regular (my timing is at 12*). I therefore run premium so I don't have to back my timing off (less power) and I don't like ethanol and I do like cheap corn.
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
I say if anyone notices a smoother running engine with higher brand x gas run it.
It seems most guys have run their timing up to 12*btc which can cause pinging at times when the conditions are just right, like in the warmer weather when running the lower octanes gas.
Plus if you look at your operator's manual that comes with every new vehicle,
oh you don't have one. Find them on ebay.
you'll see that all like all 1971 240,300,302,360,390 grade of fuel recommended
(91)octane with factory adjustment setting..
I use 91 octane when it's under $3.25
Also less carbon built up.
Orich
It seems most guys have run their timing up to 12*btc which can cause pinging at times when the conditions are just right, like in the warmer weather when running the lower octanes gas.
Plus if you look at your operator's manual that comes with every new vehicle,
oh you don't have one. Find them on ebay.
you'll see that all like all 1971 240,300,302,360,390 grade of fuel recommended
(91)octane with factory adjustment setting..
I use 91 octane when it's under $3.25
Also less carbon built up.
Orich
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
I'm not old enough to know, but I doubt they'd change the rating. For what purpose would they do that? I do know however that ethanol is used in most fuels today, which has about 10% less energy per gallon. E85 is said to have 27% less than gasoline. Potentially unrelated, but I know for sure that my 13.5:1 compression dirt bike runs a lot better on non-ethanol 94 octane than it does on 10% ethanol 91.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Without regard to ethanol. Or not? Has to do with oxygenates and pollution. There are different measurement standards, one was called RON for research octane number. Probably the same outfit that publishes inflation numbers.
I think the high test stuff was better back then. Better mileage, at least. Ethanol complicates things as well. Could be wrong, often am.
I think the high test stuff was better back then. Better mileage, at least. Ethanol complicates things as well. Could be wrong, often am.
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
I'm not old enough to know, but I doubt they'd change the rating. For what purpose would they do that? I do know however that ethanol is used in most fuels today, which has about 10% less energy per gallon. E85 is said to have 27% less than gasoline. Potentially unrelated, but I know for sure that my 13.5:1 compression dirt bike runs a lot better on non-ethanol 94 octane than it does on 10% ethanol 91.
This fuel I made up really put the Tiger in your tank.
Back then a few gas station had pumps the you could select to octane rating you wanted from like 91up to 105 and think Standard/Chevron had the highest octane grade then.
I could buy MEK fairly cheap from where, I worked for like $4. bucks a gallon in the mid 60'. I was running close to 13.5 to1 in 55 car with 1961 HP 390 bored 1/8" .060 milled off the heads with the steel head gaskets.
Orich
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
Will our old engines run on E85? I know if you pump it into a new vehicle that isn't made for it it can destroy the engine in a hurry.
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Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
So that's why alcohol isn't used for racing.
Wait, what? It's my understanding that alcohol needs a lot richer fuel mixture and more advance to be used efficiently. There isn't anything "wrong" with it, except when ran in an engine designed for gasoline. I expect an engine tuned for alcohol would not run well fed on a diet of pure hydrocarbon, either. Gasoline is a blend of different distillates and fractions, as a WAG the octane rating is technically there, but the "go farther" component isn't quite what it used to be?
Wait, what? It's my understanding that alcohol needs a lot richer fuel mixture and more advance to be used efficiently. There isn't anything "wrong" with it, except when ran in an engine designed for gasoline. I expect an engine tuned for alcohol would not run well fed on a diet of pure hydrocarbon, either. Gasoline is a blend of different distillates and fractions, as a WAG the octane rating is technically there, but the "go farther" component isn't quite what it used to be?
Post Fiend
Joined: Jun 2003
Posts: 8,209
Likes: 12
From: Black Hills of SD
I wouldn't. IDK if it would "destroy" the engine but it will almost surely degrade any rubber not designed for alcohol. My old 69 390 hated even the 10% stuff and wouldn't idle if I tried to use it.
Fleet Mechanic
Joined: May 2001
Posts: 1,396
Likes: 4
From: Cupertino
Ted, engines do run powerfully on alcohol. Back in the day there was the TAD dragster class which changed to Federal Mogul and was then terminated for reasons that I do not know.
E-85 eats up old motors because fuel lines, carb soft parts, stuff like that slowly dissolves in alcohol solvent.
Orich?
E-85 eats up old motors because fuel lines, carb soft parts, stuff like that slowly dissolves in alcohol solvent.
Orich?
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Pretty sure the jet sizes need to be ramped up a couple clicks and the timing advanced, and higher compression with E85. "Flex-Fuel" engines have provision to sense % of ethanol and make adjustments, except for compression ratio. My experience is that E85 will run in a flex-fuel vehicle but not real well, and rumours at least that auto techs advise against it. Gasoline is not oil as such but has some lubricity, it may be that high ethanol % tears up injectors? Maybe that kind of thing is being addressed but it's not good to be the guinea pig.
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
And aftermarket intake manifold, carb jetting and air filter.
An it's very possible in many give engine builds the higher octane could be
a more enhancement of mileage.
Mythbusting is almost like saying all women are the same. And can get by on the same amount of a home weekly $$$
Just to many differences engines & where we all live, plus how we drive..
Orich
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
Since we don't all have the same engine specs. With most not stock compression aftermarket dizzy's, exhaust system, with pushed up timing.
And aftermarket intake manifold, carb jetting and air filter.
An it's very possible in many give engine builds the higher octane could be
a more enhancement of mileage.
Mythbusting is almost like saying all women are the same. And can get by on the same amount of a home weekly $$$
Just to many differences engines & where we all live, plus how we drive..
Orich
And aftermarket intake manifold, carb jetting and air filter.
An it's very possible in many give engine builds the higher octane could be
a more enhancement of mileage.
Mythbusting is almost like saying all women are the same. And can get by on the same amount of a home weekly $$$
Just to many differences engines & where we all live, plus how we drive..
Orich
Advancing/retarding the cam or advancing/retarding the distributor doesn't change the compression ratio of the engine. It only alters the timing event of when the air/fuel mixture is ignited.
The only way to increase the compression ratio of the engine is to change/mill the heads, install thinner head gaskets, install flat top or pop up pistons or, any combination of these.
If my '03 Mach 1 didn't have a high compression ratio, I wouldn't pay to put high octane fuel in it. The 240 in my '69 F-100 definitely doesn't get high octane, since it's a low compression engine and high octane fuel would just be an extra expense for no advantage in it.
But, if someone feels like high octane fuel in their low compression engine is doing wonders for it, put that more expensive magic motion lotion over in it.