HIgh octane make a diff for old cars?

[GQNammer]

My buddy and I were having a discussion about this. Basically, he drives an 86 corolla and he pumps 92 octane into it. Can you feel the difference (speed wise) if you were to pump higher octane into older vehicles?

[^SkylinE^]

HIgher octane = burns slower = higher tolerance for heat and presure= more stable

REally i don't think that i will make a difference in an old car unless it a high performance motor! ie. high compression or SC or turboed?

Just use plan jane 87 octane hes wasteing his money.

[sxtasy]

lots of talk about this before, try a search:thumbsup:

[rice_eater]

Originally posted by sxtasy
lots of talk about this before, try a search:thumbsup:

not really man...we beat it to death about new cars but we never talked about old cars. The same points probably apply here too but you never know with those crazy carbs and "old school engine design" :nut:

[rage2]

In some cases, yes.

For example, if you have an old car where the rings are worn, oil will get into the combustion chamber. Oil basically lowers the octane limit of fuel when introduced in the combustion process. So your 87 octane fuel all of a sudden effectively becomes 85 octane... you might need higher octane fuel.

Fairly rare in Calgary, since we're so high up in elevation, we usually require quite a bit less in octane rating than the manufacturer suggests.

[Akagi Redsuns]

Oil blow by can also accelerate carbon buildup which can lead to the combusition chamber to be smaller, essentially raising the compression ratio of the engine. Higher octane would cure knocking problems if it was occuring in the old worn engine.

[noid1234blueya]

i have a 454 ss (7.4 litre) with 280000 miles on it! i run 87 octane all the time and she runs like a champ!:D

[Ben]

My car is an 87 (92 motor) and I run 92 or 94 cause its high compression.

[szw]

Originally posted by Ben
My car is an 87 (92 motor) and I run 92 or 94 cause its high compression.

:clap: good for you!

[Maxt]

How old of car are we talking?.. If its anything before 1970, even the 92 is barely livable in these engines...Consider something like a 64 or 65 max wedge RB engine, with 12.5:1 compression off the showroom floor, 92 isn't gonna cut it...
Old large bore engines are very detonation prone due to the large combustion pocket and sometimes overly large quench area due to inconsistent casting and machining..
If you are talking about 1972 and up grocery getter machines, unless its a forced induction car, 92 oct is a complete waste of money..Maxt

[GQNammer]

Basically I was implying to cars in the 80s. I have an 88 rex and I pump 87 octane all the time. My buddy tells me i should pump 92 but i say no since I only run like 107 bhp.

[88CRX]

Originally posted by GQNammer
Basically I was implying to cars in the 80s. I have an 88 rex and I pump 87 octane all the time. My buddy tells me i should pump 92 but i say no since I only run like 107 bhp.

i've been pumping 87 on the crx since i bought it, but next time i have to fill up i think i may give 91 or 92 whatever it is a try


ill let you know what happens

[Ben]

Originally posted by 88CRX


i've been pumping 87 on the crx since i bought it, but next time i have to fill up i think i may give 91 or 92 whatever it is a try


ill let you know what happens


I'm willing to wager you wont notice any difference, psychologicly you'll be hoping you do and might think you are but unless its high comp (more than like 10.5:1 or so) or FI, it doesn't really make a difference.

[djfob]

I pump 92 in my civic mainly cuz i noticed that i get more gas mileage.

[Ben]

Originally posted by GQNammer
Basically I was implying to cars in the 80s. I have an 88 rex and I pump 87 octane all the time. My buddy tells me i should pump 92 but i say no since I only run like 107 bhp.

Dont bother, thats 10c a liter you're throwing away.

[4wheeldrift]

Unless the car is detonating for one reason or another, its just wasting cash. That said, going to a higher octane fuel fixed some problems we were having with detonation and dieseling in our '87 tempo, but that car had nearly 250k kms on it and the motor wasn't terribly healthy.

[88CRX]

Originally posted by Ben



I'm willing to wager you wont notice any difference, psychologicly you'll be hoping you do and might think you are but unless its high comp (more than like 10.5:1 or so) or FI, it doesn't really make a difference.

ya man... im hoping for that extra 3 whp.;)


actually i was told it may run smoother with it, so im going to give it a try.... why not.

[GQNammer]

Well, my last 2 gas tanks were pumped with 92 octane. i don't know if it's a mental thing but I feel a difference. But I personallly think it's just a mental thing =)

[Khyron]

Doesn't all the cleaners/additives the stations put in their high end gas make a diff tho? The octane difference might be insignificant, but the other stuff? (Like that gas cleaner/injector cleaner you can buy?)

Khyron

[GQNammer]

All i got is fuel injector cleaner =

[GTS Jeff]

my car (1985) has an engine (1991)

and i use 94 cuz its knocks if i dont.

[gpomp]

Originally posted by GTS Jeff
my car (1985) has an engine (1991)

and i use 94 cuz its knocks if i dont.
:werd: My engine makes weird sounds on anything less than 94. But unless yours does the same thing, 87 should be ok.

[^SkylinE^]

What kind of weird noises?

[gpomp]

Detonation.

[three.eighteen.]

it makes a difference, even on shitty cars, the gas pedal feels minutely meatier in my car with premium

[James]

I use to run 91 on my MR2 cause it was a BC car and had never seen anything lower eventhough it only needed 87-89, didnt bother me to spend the little extra.....im sure it would be a complete waste to run anything over 87 on my jetta, it has 270,000km on it, so im pretty sure its doing just fine ;)