'89 Southwind Fuel

[wildtoad]

With the older big block engines such as the 454 in my old '88 Superchief the higher octane may reduce knocks and dieseling, but I don't think you will get any noticeable improvements in mpg.

Also for a list a pure gas stations try here: Ethanol-free gas stations in the U.S. and Canada

[Gary - K7GLD]

Originally Posted by TXiceman

Run the fuel that meets the octane rating requirement for the engine. You will not see any appreciable increase in fuel mileage with the premium fuel.

Ken

The so-called "Premium" fuel, at least in our area, is a paltry 92 octane - vs 89 for the standard regular - hardly an earth shaking increase!

I buy the Premium grade purely because it is the ONLY NON-ethanol grade gasoline locally available at the Pacific Pride pumps where we normally fuel up - and the lack of ethanol is what I'm after - the increased octane is purely a small side effect...

[RonS1985]

Unfortunately my state has a law that ethanol must be added. There is talk about repealing it - I hope it is! On my last long-distance trip I noticed an increase in mpg when I filled up at non-ethanol stations (in my van). When gas was at normal price ($1.20 gal) I used to experiment between the 89 and 93 octane. I did see a nominal increase in mpg but where I really noticed the difference was in power. I also noticed in older vehicles the higher octane would quiet any light pinging there might be. I don't know about anyone else but with my Southwind's 454 I don't have much power when climbing long inclines. Running the higher octane will probably help with that. That, and perhaps some Slick 50.

[BA-in-Mich]

I would be listening to Jim E. I had my distributor rebuilt and recurved about 2 months ago and I found a local mechanic to tweek the Qjet. i went from 7-7.5mpg to 8.75. I just got done advancing the base timing up another 4degrees and still have no engine knock. I am probably about 40 degrees advanced at 60-65mph and it runs like a top on 87 octane w/10% ethanol.

[JimElliott]

Originally Posted by BA-in-Mich

I would be listening to Jim E. I had my distributor rebuilt and recurved about 2 months ago and I found a local mechanic to tweek the Qjet. i went from 7-7.5mpg to 8.75. I just got done advancing the base timing up another 4degrees and still have no engine knock. I am probably about 40 degrees advanced at 60-65mph and it runs like a top on 87 octane w/10% ethanol.

, Brian...Your 60 MPH with the 3 speed spins your engine up to and around 3,000 RPM....Have you cut back the vacuum advance to 10*?
How is the vacuum advance hooked up?, Ported (carb) or full manifold advance?
Full manifold will (at idle) will increase the RPMs about 275-300 and you can trim back the idle speed by that much.
Maybe a 1/4 turn (IN) on the idle air mixture screws will cut back the fuel usage also.
With those small "dial-in's" I see a solid 9+ MPG in the future which ain't hard to take with todays gas prices......

Jim

[Wanabee FTer]

Originally Posted by RonS1985

. My next question is, would running a higher grade of fuel give me better fuel mileage? Would the mileage be worth the higher cost of the fuel? I'm just trying to get a bigger bang for my buck (no pun intended). Thanks again.

By higher grade do you mean a different brand of fuel or higher octane rating?

As mentioned by others, fuel companies/refineries use different additives and some use ethanol when blending their gasoline. Generally a fuel that has more oxygenates will burn hotter than a fuel watered down with ethanol, which may equate to better performance and improved gas mileage. The more oxygenates used, the more the fuel will cost to produce. Thus you will pay more at the pump for it.

There is also summer fuel and winter fuel. Winter fuel is cheaper to produce then summer fuel. The cost is lower in winter because the refineries produce the fuel by blending butane with the gasoline. Butane is cheap and plentiful.
But this fuel has a high evaporation point and will boil off in hot weather causing all sorts of drivability concerns, so in summer months the fuel must be processed differently.
Most refineries shut down in April to start producing summer fuel. At this point butane can no longer be used, so instead they have to blend the fuel with higher cost oxygenates and other additives to raise the boiling point of the gasoline.
Depending on how the gas company/refineries blend their fuel, it may burn hotter or cooler, produce more or less power, burn cleaner or dirtier, and so on.

Originally Posted by RonS1985

I don't know about anyone else but with my Southwind's 454 I don't have much power when climbing long inclines. Running the higher octane will probably help with that. That, and perhaps some Slick 50.

Octane ratings seem to be one of the most miss-understood terms to describe the amount of power contained within the fuel. Actually the octane rating has nothing to do with power, it has to do with how quickly the air/fuel mixture ignites. Gasoline with a low octane rating will ignite prematurely on a performance engine with high compression. The fast flame rate kicks back down on the piston during the compression stroke and produces an audible ping. The higher octane fuel burns slower and should not cause pre-ignition (ping). Most engines nowadays are produced with a low enough compression ratio to run on regular unleaded without pinging.

If the engine is equipped with OBDII emissions (roughly 1999 and newer, give or take) the computer and sensors will allow the engine to advance or retard the ignition timing to maximize power and fuel mileage. This computer system can be vary reactive to different grades and octane ratings of fuel. There are also various after market companies that can modify computer chips to fine tune the timing to the engine to make even more power. If you can still find a good distributor man, similar power gains may be obtained with older HEI distributor engines.

[JiminJersey]

Originally Posted by RonS1985

I don't know about anyone else but with my Southwind's 454 I don't have much power when climbing long inclines. Running the higher octane will probably help with that. That, and perhaps some Slick 50.

Slick 50 is snake oil - save your money. The 454 ain't exactly a high-tech computer controlled engine, but if it's in tune, good plugs and wires, correct timing and such, you've probably done about all you can do without major $$$.

Higher octane helps with pinging and such - it does not add power or MPG. Anecdotal evidence has never been backed up by scientific proof.

Balance the proven higher cost of premium vs the "imagined" better fuel economy. At 30 to 40 cents more per gallon, you'd need to get at least that percentage back in increased MPG, over and over, to make it worthwhile.

Remember, a lot of your MPG is based on weight, driving style, and other "non-engine" factors. Keep a light foot, watch the vacuum gauge, and make sure the engine doesn't lug, and you'd be surprised how much difference you might see with everything else being the same.

[RonS1985]

Well, my plug wires were bad so I replaced them. I did a test run around the block and it made a huge difference. I guess I'm just expecting miracles. On a side note, I can't believe how long this fuel thread has gotten.

[whem2fish]

now im towing close to #6000 4 door chevy pick uo truck but do thr dist mod and you will see it
jim im gone to the coast ill send pics

[BA-in-Mich]

Originally Posted by JimElliott

, Brian...Your 60 MPH with the 3 speed spins your engine up to and around 3,000 RPM....Have you cut back the vacuum advance to 10*?
How is the vacuum advance hooked up?, Ported (carb) or full manifold advance?
Full manifold will (at idle) will increase the RPMs about 275-300 and you can trim back the idle speed by that much.
Maybe a 1/4 turn (IN) on the idle air mixture screws will cut back the fuel usage also.
With those small "dial-in's" I see a solid 9+ MPG in the future which ain't hard to take with todays gas prices......

Jim

Jim I'll have to get back with you on those questions. I believe the Vacuum advance is 15* and now the base is up to 12-15* not quite sure.

[RonS1985]

You guys are talking about stuff that's way out of my league. I know about vacuum advance but I have no clue where it is. A "dist mod?" I assume that is distributor modification. I'm lost there!

[Wanabee FTer]

The ignition timing advance is controlled with centrifugal weights and a vacuum advance. The vacuum advance unit is mounted in/on the distributor. You can check the vacuum advance to make sure it is working by using a vacuum pump/gauge or even a piece of vacuum hose, suck on it and see if it holds vacuum. If it does and the distributor base plate moves it's OK.
The centrifugal weights are preset from the factory to apply additional spark advance at a certain RPM. Back in the good old days it was easy to find a good distributor man that could modify the centrifugal advance to get more power. Now a days not sure if I would attempt this modification.

[RonS1985]

Originally Posted by Wanabee FTer

The ignition timing advance is controlled with centrifugal weights and a vacuum advance. The vacuum advance unit is mounted in/on the distributor. You can check the vacuum advance to make sure it is working by using a vacuum pump/gauge or even a piece of vacuum hose, suck on it and see if it holds vacuum. If it does and the distributor base plate moves it's OK.
The centrifugal weights are preset from the factory to apply additional spark advance at a certain RPM. Back in the good old days it was easy to find a good distributor man that could modify the centrifugal advance to get more power. Now a days not sure if I would attempt this modification.

Thanks. I'll look into that in the AM.

[whem2fish]

search a post her by jimelliot he gave a great write up on this mod i did it maybe 20,000 miles ago now that being said i have a heavy toad (2007 chevy 4 door truck) if i cruise 67 to 69 i averaged 8.1 mpg now when i move with traffic it drops if he doesnt chime in ill e-mail him