Regular or premium?
Pro
Joined: Jun 2007
Posts: 634
Likes: 0
From: Hastings MN
Boy has this become a discussion!!!!!!
My original question was "what octane gas was the 1977 L48 engine designed to run on?"
If I was running 93 octane fuel and changed to 87 octane fuel would other adjustments be required?
The motor is strictly stock....NO COMPUTER!!!!!! The car is a daily driver
The responses have been interesting....from what I've read there would be very little difference in engine performance but I could save .40-.50 cents a gallon.
12 gallons = $6.00 at each fill. Not bad, eh?
My original question was "what octane gas was the 1977 L48 engine designed to run on?"
If I was running 93 octane fuel and changed to 87 octane fuel would other adjustments be required?
The motor is strictly stock....NO COMPUTER!!!!!! The car is a daily driver
The responses have been interesting....from what I've read there would be very little difference in engine performance but I could save .40-.50 cents a gallon.
12 gallons = $6.00 at each fill. Not bad, eh?
You don't need to change anything to run 87, because that's what the car was designed to run on. 93 octane (or 110) won't give you any advantage in your engine, because it is designed to run on 87 octane.
Now, if you had a newer engine that was designed for 91 octane, and is computer controlled, its a different story. It will run best on 91 octane, but it will still run at 87 octane because the computer will retard the timing. The changing of timing will affect the combustion (and ultimately your sfc, or the mpg you get.)
Summary: 87 for the win
Burning Brakes
Joined: Oct 2006
Posts: 1,089
Likes: 43
From: Native Californian CALIFORNIA
Army
No.
With the assumption of increased fuel cost and improved mileage from running premium rather than regular you pickup $.0031/ gallon. On 15 gallons that is $.05 per tank.
I agree that running premium will not help your stock engine. I would also run my own fuel comparisons, however in the end, if the assumptions are correct it is a wash.
With the assumption of increased fuel cost and improved mileage from running premium rather than regular you pickup $.0031/ gallon. On 15 gallons that is $.05 per tank.
I agree that running premium will not help your stock engine. I would also run my own fuel comparisons, however in the end, if the assumptions are correct it is a wash.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
I actually tried something in my truck at the beginning of the summer and recommend everyone try it at least once.
I typically get 17.4 mpg on regular, but ran the tank down and filled it with premium (20 cents more per gallon). At the next fill up, I had clocked an extra 1.5 mpg.
Now thats a heavily regulated by computer fuel system in my 08 ranger, compared to the weaker than an Atari 2600 in an '81... So considering we're all dealing with 30+ year old technologies, I would recommend testing a few tank fulls. It's obviously a better grade than the homogenized stuff you're "saving money with" pumping regular.
saving money.... 20 cents / 10 gallons .. 2 bucks.
wow....
I typically get 17.4 mpg on regular, but ran the tank down and filled it with premium (20 cents more per gallon). At the next fill up, I had clocked an extra 1.5 mpg.
Now thats a heavily regulated by computer fuel system in my 08 ranger, compared to the weaker than an Atari 2600 in an '81... So considering we're all dealing with 30+ year old technologies, I would recommend testing a few tank fulls. It's obviously a better grade than the homogenized stuff you're "saving money with" pumping regular.
saving money.... 20 cents / 10 gallons .. 2 bucks.
wow....
Thread Starter
Racer
Joined: May 2007
Posts: 370
Likes: 0
From: Cherry Hill N.J.
Regular or Premium
I never said mileage went up! When I computed the cost of a fill-up,not counting the actual miles driven, it was strictly on 12 gallons of fuel @ a savings of .50 per gallon ($6.00).
If anyone else is like me they spend as much time with engine running, and not driving......How else can you adjust,fix,or play with your engine.
I really never tried to check MPG because I would cry.....
I enjoy trying to improve a basket case I bought 7 years ago to work on because I like working on cars!!!
If anyone else is like me they spend as much time with engine running, and not driving......How else can you adjust,fix,or play with your engine.
I really never tried to check MPG because I would cry.....
I enjoy trying to improve a basket case I bought 7 years ago to work on because I like working on cars!!!
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
I realise that, I was asking how pbcanney did it. Not trying to hijack your post.
I'm glad you've seen through the mist and realised that there's nothing to be gained (and dollars to be saved) by using the correct fuel, 87 octane in your case.
I'm glad you've seen through the mist and realised that there's nothing to be gained (and dollars to be saved) by using the correct fuel, 87 octane in your case.
Racer
Joined: May 2008
Posts: 353
Likes: 0
From: boulogne buenos aires
Hi there, back in argentina we have a lot of difference between regular (85 octanes), super around 95 and premium 98+ even 100 octane on regular gas station. I always used my car on super fuel, its a 1973 l-82 stock. I Always wondered if it will run ok with regular even if its 85 octanes here? prices though are in a 50cents difference between each type of fuel.
Will this affect the engine?
Will this affect the engine?
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
The octane rating system might be different in Argentina than it is in North Americae. I know that Europe has a different system than us.
In any case, you should always use the use the lowest octane rating fuel possible that does not allow knocking or pinging to occur.
Your '73 was built to run on low octane unleaded fuel.
In any case, you should always use the use the lowest octane rating fuel possible that does not allow knocking or pinging to occur.
Your '73 was built to run on low octane unleaded fuel.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Advanced
Joined: Jul 2007
Posts: 75
Likes: 0
From: texas
a few points to ponder in this discussion is the formulation differences coming from the refineries from 1977 to present, ie. the absence of lead (which your car was maybe designed to run on((i don't know)), the blend differences for different regions of the U.S. (87 oct. is not the same as 87 oct. in s. Florida, etc...) I can buy regular pump gas and run fine all day long here in s. texas but sluggish. But, i can also go buy a tank of 100+ VP racing fuel and there is a night and day difference. There are several detailed discussions on the subject posted in the past. I'm no expert, but there is definately is a difference as I think the original poster experienced.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Well here we go again with 'myths' taken precedence over science and fact.
No Corvette built after 1971 needs lead in the gas. Even those built before this date will not suffer the dreaded valve recession that was a big fear in the 70s.
Regarding 'cleaning out the engine', all grades of gas contain sufficient cleaners to do the job. Very few carburated engines ever get dirty enough to need any cleaner, but that's another story.
And once again, high octane or 'racing gas' contains less energy (fewer BTUs per unit) than regular. So if you guys want to throw your money away, please throw it my way instead.
At least I'll say thanks.
No Corvette built after 1971 needs lead in the gas. Even those built before this date will not suffer the dreaded valve recession that was a big fear in the 70s.
Regarding 'cleaning out the engine', all grades of gas contain sufficient cleaners to do the job. Very few carburated engines ever get dirty enough to need any cleaner, but that's another story.
And once again, high octane or 'racing gas' contains less energy (fewer BTUs per unit) than regular. So if you guys want to throw your money away, please throw it my way instead.
At least I'll say thanks.
Thread Starter
Racer
Joined: May 2007
Posts: 370
Likes: 0
From: Cherry Hill N.J.
Regular or Premium
Let me sum up the responses so far........NO problem using 87 octane fuel in my stock 1977 L48.......Higher octane fuel will not make an engine run better if engine was NOT designed to run on it........There if no need to make adjustments to timing as long as engine does not knock...........
I should get less MPG with 87 octane.........I could save $ by changing to 87 octane fuel(added benefit)......
THERE ARE MANY PROS AND CONS TO THE CHANGE, THERE ARE MANY OPINIONS, some factual,some mythological....all input is appreciated.
This forum is so helpful as a tool to help form a persons opinion!!!
I should get less MPG with 87 octane.........I could save $ by changing to 87 octane fuel(added benefit)......
THERE ARE MANY PROS AND CONS TO THE CHANGE, THERE ARE MANY OPINIONS, some factual,some mythological....all input is appreciated.
This forum is so helpful as a tool to help form a persons opinion!!!
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Let me sum up the responses so far........NO problem using 87 octane fuel in my stock 1977 L48.......Higher octane fuel will not make an engine run better if engine was NOT designed to run on it........There if no need to make adjustments to timing as long as engine does not knock...........
I should get less MPG with 87 octane.........I could save $ by changing to 87 octane fuel(added benefit)......
THERE ARE MANY PROS AND CONS TO THE CHANGE, THERE ARE MANY OPINIONS, some factual,some mythological....all input is appreciated.
This forum is so helpful as a tool to help form a persons opinion!!!
I should get less MPG with 87 octane.........I could save $ by changing to 87 octane fuel(added benefit)......
THERE ARE MANY PROS AND CONS TO THE CHANGE, THERE ARE MANY OPINIONS, some factual,some mythological....all input is appreciated.
This forum is so helpful as a tool to help form a persons opinion!!!
All correct except :
'I should get less MPG with 87 octane'
You will not decrease mileage with low octane, conversely not increase it with high octane.
There no pros to using the incorrect fuel (unless you like wasting money)
Thread Starter
Racer
Joined: May 2007
Posts: 370
Likes: 0
From: Cherry Hill N.J.
Regular or Premium
DWnchs. Sorry you had a lot to assume.
I did say I had a stock 1977 L48 motor.
It has nothing tweaked other than boosting vac advance to 12 degrees before TDC. This done with can disconnected.
I will try 87 octane and adjust as necessary
I did say I had a stock 1977 L48 motor.
It has nothing tweaked other than boosting vac advance to 12 degrees before TDC. This done with can disconnected.
I will try 87 octane and adjust as necessary
