If you advance the timing to the point an 8.3:1 CR pings on 87 octane, it's advanced beyond the point of improving power or economy.

A couple of caveats:

- "87 octane" does not mean "absolutely 87 octane". The sticker on the pump says "(R + M)/2" - that means the posted octane rating is an average of the "Research" octane testing method and the "Motor" octane testing method. The "Motor" method is more real-world, and why the oil companies didn't want to be tied to it. By tweaking the blend they can get the average to come out to "87", but you may be on the edge because they relied on a high "Research" number to get there. But, an 8.3:1 CR engine still shouldn't have any problems regardless.

- An improperly operating EGR system (note I said "system" and not "valve") can cause pinging because advance curves are tailored to increase the advance when the EGR system is active. If the exhaust gases aren't getting into the intake charge like they should be, which cools the combustion temp, the "extra" advance in the curve can cause pinging. This happens particularly at mid-throttle load conditions, like going up a good-sized hill at a steady 40 MPH.

 

not to sound like an *** but get used to it there is NO RISK in using 87 vs. 93 just put it in and don't worry about it. Call it done and then go and use your spare money on white castle

 

I didn't read all the way...
But if you look in your owners manual...it will say USE REGULAR UNLEADED GASOLINE.

Just sayin. You're paranoid as hell.

 

On the topic of higher octane being better or not... Aside from performance and what it NEEDS or doesnt need, would higher octane prolong the life of the engine, no matter the compression ratio or other specs?

 

no. Just wasting money.
There's nothing extra in the gas that makes it any better for the engine (unless otherwise specified by the station...and even then...).
Take care of your engine, and it'll last longer.

 

Why the judgmental name-calling bud?
You already said you didn't read "all the way" so,
you really don't know what you're talking about now do ya?

I'm presuming you have right there in front of you the Owner's Manual for the '83 Sport Coupe with the page turned to my engine specs where it says "For optimum performance, using the highest-octane fuel in this engine is recommended."...
oh wait..if you did you'd see just how wrong you are and you could have saved yourself embarrassment by not posting such baseless drivel.

And, you replied to this thread.......because?

More than 50 replies and over 400 views tells me this question raises a bit more interest then might be expected from those who have perhaps been wondering the same thing as the price of fuel reaches levels that dictate many car owners investigate alternatives.

 

That's not judgemental, nor is it name calling.
I read the first page (didn't realize the second page was only 2 replies). Anyway, what has been covered very simply in this ENTIRE thread, is that regular gasoline will work fine. And, if it doesn't, then fine...you found out and you go back to premium.

I do not have the exact manual for his car, no...but I asked my friend to look in his for his camaro with a 350 and it said regular unleaded...so I guess they changed it, if you are actually telling me the truth.

No need to fight...I'm just mentioning the paranoia because so many people run regular without problems, and the OP is reluctant to try.

 

Lots of back and forth here about you get your 8to1 slugs running on junk fuel. How about some high performance solutions?
So what about water injection:
http://www.motherearthnews.com/Green...-Wizardry.aspx
It's been around about sixty years.
I've noticed some success after clearing out carbon deposits with Techron.
Tom

 

Well, this thread isn't about cooling fluids ( water/alcohol injection ) but it is true that you can run some REALLY high boost and get some REAL big increases in power for a very short term without damage, as in climb-out with old radial engine aircraft, where it was pretty much invented.
Water or alcohol injection is merely to prevent end gas overheating before the flame front arrives due to an effective BIG increase in compression due to the boost, and overstressing "too much" an engine being run well beyond its ratings for a short period. It's well known that it doesn't work anywhere near as well as simply running an appropriate high octane fuel, which didn't exist at the time water injection was found to work.
The claims in that article about 20% increases in economy from 5% water injection alone are pure bunk, proven time and time again, as well as running against science.
The improvement in performance comes strictly from the increase in thermodynamic efficiency due to the increased compression. Water injection is merely a band-aid to allow high compression on inferior fuel. Water alone will do almost exactly the same thing as oxygenated fuel. ( ethanol )
Poorer performance, poorer milage when blended to the same octane as gasoline, but can be run in the same engine. If blended to higher octane, can be run in a higher compression engine, with poorer performance compared to that same engine on an appropriate fuel, but with better performance when compared to a lower compression engine, as we'd all expect.
Water does displace air, and fuel, with something that doesn't contribute anything to the reaction, so of itself not only adds nothing, but actually takes away, just like ethanol.

 

Are ya' telling me then we'd be better off at 8-1 on regular than with 12-1 and water injection in terms of performance and economy?
A quick Google shows there's a bunch of these water injection systems out there a heck of a lot more sophisticated than the pressurized can driven off the air pump the Mother Jones article shows. I'm paying twenty to thirty cents per gallon to jump up to the midgrade gas my old Corvette needs. It seems like a rip to me for what I suspect is a few cents worth of additives. The cost of water injection might be amortized within a couple of years. Anybody had some experience with long term use of these?

Tom

 

Anyone remember the Edelbrock water injection system they marketed back in the early '80s? Back then they were trying to sell to the muscle car guys that could no longer get leaded regular. Don't remember it going over very well.

 

If the cost of premium gas is killing you with your high compression old school muscle car, convert it to E85. Hopefully it's available in your area.

 

you just answered your own question right there. "for optimum performance.." is the key, now if it said "in order to prevent engine damage..." then i would worry. it will run perfectly fine on regular gas all day, you may get better performance running premium but i doubt you would notice. actually if you look at the newer 98+ camaros it says right on the gas cap premium recommended. doesnt mean you have to run premium, just that it will perform better, though i didnt notice one single bit of difference. In computer controlled vehicles there are actually tables in the computer that change the timing based on which octane fuel you run. The only time you need to run premium is if the manual and car says premuim unleaded only, cars that have this usually display it on the instrument cluster and gas cap. these are usually luxury cars or cars that run turbos/superchargers from the factory.

 

In may be wrong but isn't some of the increased cost of mid grade and high grade gasoline cleaning additives also? I know I add a container of injector cleaner occasionally. I haven't bothered to figure that into fuel costs. Maybe I should. Of course, I didn't start doing this until my Camaro became my DD last January. I got an immediate MPG increase.

 

with the price difference, you can go 10 more miles per tank if you avg 20mpg by using regular octane. If that matters to you fine. If not, good for you. But the point's been beaten to death over where the necessity of higher octane comes into play.

 

Grumpy.
He was running some sort of boost fluid on his GN, long term. The details are on this site somewhere.
If you can rig it to only inject when you actually need the boost in octane, I suspect it'll amortize rather quickly at today's gas prices.
----------
Perhaps with some brands, but not where I get fuel.

 

I love it....snotty 350 owners always hating on the 305's....we can win our share of races too....

 

The reason, obvious to anyone who has ever participated in any kind of track, street, stock, or a "starting still from a red light" impromptu race against another car of the same class is simple: when you come right down to the nuts and bolts, it's not the size of the engine that wins races nor even the extent of modification to increase that engine's power beyond factory limits but, it's the size of the heart, the size of the skills and most importantly, the unbeatable size of the daring and boldness of one of those drivers who refuses to relinquish control until his victory is assured and he is first to the finish line, that wins races.

The "finish line"...which could be a pre-arranged end point OR when one driver backs off in concession and yields to his opponent which is the case in many impromptus that are raced on Main Street USA...where the victorious 305 has just simply outmaneuvered his 350 challenger in all the categories mentioned. All of this could be condensed into one simple word which is the one, single and most definitive aspect of all that is behind victory:
"nerve".