Premium gas

[mattpiotr]

i just have a simple question gas is getting pretty cheap and i wasnt to sure if i can use it but on my 86 gmc with the 350 motor and edelbrock 600 carburator would i be safe if i filled up with Premium gas?

[85burb]

It wont hurt a thing. The guys at ls1tech sware they get better milage out of it. Not sure if you will notice any differance with an old school motor. Sure wont hurt.

[andrewmp6]

If it runs fine on 87 there is no need to change octanes.A ls1 is kinda designed to run premium gas is why it runs better then 87 in one.

[RandyP]

Originally Posted by mattpiotr

gas is getting pretty cheap

When gas gets under $1 a gallon it'll be pretty cheap. I stopped and put 20 gallons in my Yukon this morning and even with my discount card (local grocery store thing) it was almost $57. I'm not that old and I remember being able to do the same thing and only paying maybe $25.

Short version, your truck will run fine on 87 so why pay more for something that won't do a lot for you?

[tucsonjwt]

X2. My 83 454 runs no better on premium gas. Why waste the $$?

[Weasel Diesel]

Originally Posted by RandyP

I'm not that old and I remember being able to do the same thing and only paying maybe $25.

Ah, the good ole days... Take yer gal to a movie and smooch a bit, take her out for a burger, and put 10.00 worth of gas in yer ride and cruise Broad Street all night all on 25.00 total.... Then again,... my net pay after taxes back then was 127.70 for 40 hrs. I made a whopping 4.00 an hr working on cars at the Kmart auto center.

[Rich84]

Use the lowest grade you can without pinging...Anything else is a waste of money.

[Billett]

^that

[Firebirdjones]

Actually, my 79 454 1 ton still has a factory air cleaner sticker on it that recommends nothing less than 91 octane.

I run the highest octane I can put in for several reasons. For starters I have it tuned on the edge for most power. It's also hot in Arizona which promotes detonation. To top that off, I tow 10,000 lbs. with the truck on occasions (among other things) and with an expensive 502 in there now, I prefer all the octane I can find to keep that engine happy.

In the other cars (both classics and the cars with LS engines), I also run the highest octane I can find. Again though, I have the cars tuned for best performance and in turn I pick up about 2-3 mpg as a result. Simply filling the tank with cheap 87 now causes pinging issues, I'd have to completely revamp the tune ups, knock timing out, probably add some fuel, etc...all of which will knock my gas mileage figures down a tad. So really it works out, the mileage I have gained easily pays for the difference in the cost of the higher octane.

Now if you have a car that runs fine on 87 now, and you simply just pump in 91 or 93 without changing anything else, then you will see no real benefit. The guys with LS engines (me included) are seeing gains in mpg because the computers have 2 timing tables (high and low octane) and when knock is sensed, it reverts to the low timing table. This resets at every fillup. Running better octane will allow the engine to run the higher timing table, and in turn you pick up HP and MPG. I've tuned my LS engines to run the high octane table all the time for more consistent performance and consistent MPG. That's why mine get 30 mpg in my wifes 2000 SS camaro and I get 22 mpg out of the 6.0 LS installed in my 72 blazer 4x4. Just have to make sure to keep good gas in it. The knock sensors are still there doing their job for a little protection just in case.

Not a big deal to dial in the cars on the better octane. The difference in price is only 10-20 cents over the cheaper stuff. That's not going to break the bank. Cut out one cheese burger a week and it's covered, and you'll live healthier too

[HotRodScottsdale]

I run low oct all the time but once and awhile I used to add 91 but noticed my truck runs a bit ruff with it so I stopped
Posted via Mobile Device

[Number21]

Originally Posted by Rich84

Use the lowest grade you can without pinging...Anything else is a waste of money.

Agreed. Anything else is money down the toilet. My 350 requires premium to stop pinging, but most don't.

[BigBlocksRule]

Firebird, you're one of the exceptions to the rules. Your engines are built with more compression and run at a heavier load than most of us.
Octane rating is a fuel's resistance to detonation. Higher compression and/or heavy loading will cause detonation. There's a need for higher octane fuel there.
The fuel/air mixture burns, it doesn't explode as a lot of folks think it does. When it explodes, that's detonation. Anyway, the stuff burns and it's burn rate is relative to octane rating. Higher octane fuel burns SLOWER than lower octane, not the other way around. That's why if you put high test in an 8:1 engine, it won't pick up any power - might actually lose a bit.
If your engine isn't pinging (double check the plugs, too), it won't do you any good to spend the extra money for higher octane fuel.

[Firebirdjones]

Just throwing all the variables out there as to why I need/use it since it seems alot of people think they need to run it for no other apparent reason. I figure with more information they can make a better decision.

We dyno'd classic engines with 89 octane that made 600+ hp but actually run the engines in the cars with 91 or 93 (what ever is available) for the added safety since an engine in the car will see much more extreme conditions in a car rather than on a dyno (heat, DA conditions change, loads etc...) These engines use aluminum heads with modern combustion chambers. Modern cylinder heads (modern combustion chambers more specifically) that don't require so much ignition lead to make power. Much easier to get away with less octane on these engines.

Most of your dinosour heads with 40 year old combustion chambers make best power at 36-40 degrees of total timing. 87 octane won't support that.