Hey everyone,
What kind of fuel do you think is best to use for a 86 transam GTA in terms of octane??
I live in Australia. The car sais "Unleaded fuel only". And weve got the standard 91 octane unleaded.
Then theres the 95 octane Premium Unleaded, and also the good stuff which is the 98 Octane Shell Optimax etc
What do you recommend??
Any help would be great.
Cheers

 

any of those will work most premium here is 93 so you have good octane there, dont run any leaded fuel it will harm the cat and o2's


what are the prices you pay for those grades there? by the gal or litere?

 

I'm running 87 octane on my '91 Z28 with no knocking. As long as you aren't running with high compression or boost get the cheapest octane rating available (87 or above of course).

 

98 octane out of the pump? wow...i cant find anything over 91 here...

 

With no timing advance, I run my car on 87 octane with no problems. Now that the price of gas has dropped substantially though, I might just advance the timing again and run 93. =D

 

thanks guys...
At the moment in Australia we are paying about AUD$1.15/litre of regular unleaded petrol (91 octane). Add another 15c for the 98 octane top stuff fuel.
Cheers,
Dave.

 

heres the question

is the octane rating measured the same over there?

 

I dont believe Australian octane ratings are the same as US octane ratings. When I lived in AU, I thought that every pump was selling race gas at first. Then I wised up and discovered that the british units were different than the American units of octane measurement. You'll need to do the research because it's been so long that I have forgotten the details.

Also, you need to specify what kind of engine you have in your '86. They didnt make a GTA in 1986. Do you have the tuned port or the carbuerated engine? If carb, is it a 305 H.O. or an LG4?

The 305 H.O. (with its 9.5:1 compression ratio) will require the mid-grade or premium due to its agressive timing table , the TPI ( 9.5:1 compression ratio) will be happiest with mid-grade, and the LG4 (I think its 9.5:1 compression ratio but with much less engine timing) can run any old gasoline just so long as it pours down the fillter neck without chunks.

 

Simply run the lowest octane fuel which allows no detonation. You do not make more Hp with higher octane fuel. You only make more Hp with higher octane fuel if that octane prevents detonation.

 

I thought of jokingly saying "use gasoline" but figured I'd get a dope slap.

My IROC uses 87 just fine.

 

Hi mate,
Yeah Ive got the TPI engine, not the carby. I believe its the LB9 engine which is what I decoded with the VIN number.
Cheers
Dave

 

well first off if you have an 86 trand am its NOT a GTA. 87 is the first year for the GTA.

secdonly you can run the midrange of fuel on the car and it shouldnt cause any ill effects. but i can tell ya right now that i ran 100 (american rating) octane in my 87 GTA 350 and it did absolutely NOTHING. i ran the exactly same times as i did with 93 in the car.

 

HEHE here in South Carolina we can get 105 Octane at the pump, for about the price as midgrade...Lucky Us!!!