Hey

I have a 1985 IROC Z Camaro with the LB9 305 TPI engine. What kinda of gas should I be running. I usually use 87 Octane. What Octane grade should I be using....

http://camaroz28.cardomain.com/id/56424

 

Unless you're rich, I'd say to use the lowest possible octane you can while not having your car ping AT ALL. I imagine that 87 is about as low as you can go. Around these parts it's 85, 87, 91-- so you're using midgrade I guess.

 

I run my -85 tpi 95 ron octane gas in colder weather(below 15 degrees celcius) ,and 98ron at hotter summer days.

 

My LB9's have never seen anything other than 87, doesnt need it.

 

WTF 98 octain??!!!! unless you have ALOT of spark and high compressor WTF are you running that for? 87 is all stock needs....anymore wastes power because it burns slower.

 

Lower octane gasoline actually contains more energy than higher octane. You should use the lowest grade that your car will run on without producing knock retard (which totally kills both power and economy).

 

I'm really suprised that the available octane differs from region to region. Around here it's all 87, 89, 93.

 

Then why does my car run quicker when I mix 110 with my 93?

 

Probably because (1) 110 isn't pump gas; and (2) there's less knock retard; and (3) in most places, 93 is nothing more or less than 87 with some MTBE or methanol to slow down combustion and oxygenate the fuel, whereas 110 racing or av gas is actual unadulterated fuel. Run Diacom or something on it and check for knock counts.

 

the thing that causes spark knock is the short chain HC's in the gas. They burn faster than octane (detonate). They also contain less energy than octane.

 

What does GM state we should use? I always have used 93. Once I used 94 Ultra (kinda noticed less power to no diff). The gas choices here are 87, 89, 93, 94, 110.

 

110? dang the best I can get is 91 if I'm lucky most is 90 for like $1.50 a gallon. well besides race gas

 

yeah, my bro's friend has a license to sell 110, race gas, and stuff like that, haven't used it yet, but its good to know its there.

 

By the way,octaneratings here in europe are different than yours.I think your's method is ron+mon/2, european's method is ron rating.Typically our 98 octane unlead gas ron rating is 98 and ron 88.

 

watch out fot that 110 racing gas... make sure it isnt leaded. Some of those racing fuels still use lead to control knock.

 

To Mark305TBI, the octane levels available in different parts of the country differ because here in Colorado, for example, we are at a pretty high altitude compared to the coast. A car here doesn't need as high of an octane level because our air is much thinner (and our cars much slower thanks to that!).

 

where the heck in nj do u find 110 octane. the only place ive found that sells gas out of a garage is in jersey city. i useully run 94 from sunoco from up the street. it burns faster then like regular what ever octane it is. but i also heard that runnin a higher octane is good for an older engine? is this true or no?

 

This goes along with z 28 jari. He is correct. The US way of things is the ron+mon/2. Europe, due to the metric system, or b/c they are just weird,, use just the ron. The ron is research octane, and mon is motor octane. The research number is what science says it should be, and the motor number is what it actualy is in an engine. Now, this doesn't really answer the main question, but its good to know. We have 86, 87, 89, 91, 92, 93, 94 available. If we want to go to K-Motion, or Auto Tech, we can get 114 for about $5/gallon, or $179/55 gal drum.

 

I just wish I could find some 83-85 octane over here
the lowest they have is 87

 

I read a senior member here advise on using the highest octane you can afford because it has more cleaning agents in it to keep you valves and comb chamber cleaner.

Any comments on this?

 

higher octane doesn't have anything to do with how clean the gas burns or how many deposits it leaves behind. It has to do with the knock resistance of the gas (read higher flash point). The lower octane gas will burn faster and more readily which is a good thing so long as it does it when its supposed to.. High compression and a lot of timing can will cause more readily-burning low octane gas to combust before its supposed to ie knock. Thats when you need high octane gas to prevent this. As said above, you want to use the lowest octane gas you can without running into knock. If you're throwing 110 race gas in say a stock 8.6-1 compression Lg4 motor you will not only throw money out the door but power as well, with maybe a few exhaust valves here and there.........

 

I recently got a 10 degree timing chain which is supposed to bring back some power to my aging '82 CFI... They told me to use a higher octane gas, (I think 95 is about the highest I can get). Is this because the gas is being ignited sooner so I have to use a slower burning gas? And why would a 10 degree timing chain help with the power? I dont really understand how using a lower power fule and igniting it sooner really helps... I would have thought that a gas that would burn faster, and more powerfully and be ignited closer to dead center would be more advantages, but then again, i dont know too much about reciprecating engines, im a turbine man! thanks for any help.