Gas question
 

Alright, Got a couple quick questions. Alright, all different 3 types of octanes offered in my area. What advantage does the 93 have over the rest? Also, how big of a difference does it make if I have a 1/4 vs a full tank drag /or street racing?

What's your timing at?

Right now it's at the stock timing, which I believe is 10*, But i'm gonna jump that up to 13* when it get's a little warmer out.

Difference between having a full tank and a 1/4 tank is weight. Obviously having a 1/4 tank is alot less weight. If there is any other reasons I'm not sure but that's just what I know.

Run 93 or 94 when you're at 13* of timing.


Excellent idea to wait until the warmer weather and the less volatile fuel.

i ran 14-15* on 91octane with no problems at all.

But that's F-ed up Canadian fuel. ;)


I'm kidding.

135 @ 4800 in 4th with 2.73's is almost exactly right if you're running close to 26" tires.

The difference between full and 1/4 tank of gas is about 70 lbs. (10 gal.X7lbs=70lbs). Depends on how your car hooks as to how this affects et's. Of course, every bit you can reduce your race wt. will help if traction stays the same. Taking 70 lbs. off the rear part of the car could hurt traction and make you actually run a slower time if you spun too much. If you could still launch just as well, the less you weigh the better.

Presonally, I always take my spare and all tools out of the trunk and try to keep just enough gas to get home. This won't make a huge difference, but every little bit helps. You do have to launch well without too much spinning to get your best times though.

Rev

Jeesh, I really never knew gas had that much of a difference in weight. :) Yeah, I was just wondering about all that stuff. Ahh...Also I've been running 89 octane and I think it's just gotten all out of my system. Figured I'd let it run down before I stuck 93 in, oh yeah, running out of gas is a great way to get rid of it too :D I dunno, maybe it's just me though, but the car seems to be even a little snappier with the 93 now. Maybe it's just me, or just that my car is running good today. Oh well. Thanks alot guys

It's not a lot of HP that you would gain with 100 lbs. (or 70) of wt. loss, it's only proportional.

If you had a 3000lb. car with 300 HP, then for each 100 lbs. you might lose, it would be like gaining 10 HP (more or less) at that same 3000 lb. weight . It is significant though.

Rev

Actually, octane makes fuel burn slower. Technically, if your car will run on 87 octane fuel without detonation, then it will make more power on 87 than 93. Or 104, or 110, and so on.
So, once you bump your timing, try running 89 first, and if it doesn't ping when you run it hard, you might even try running 87.
Just as an example, i had a friend with a '96 GT, and he put 93 octane gas in it with a bottle of 104 octane booster, and the car ran "like a pig" (his words). So, on the next tankfull, he put in 87, and he said that it ran like a raped ape. He suffered from the same misconception that a lot of people have that more octane equals more power, which i think usually stems from seeing wild drag cars running 114 octane gas and such, and thinking that that has something to do with making more power, when in reality they use such high octane to prevent detonation and engine damage due the high boost/compression/nitrous or whatever.
So anyway, bottom line, running more octane than you need to makes less power. Running less can cause detonation and damage. The key is to find out how much your car needs with the mods you have and run it.

Later,
Eric

Motorhead is right . You shouldn't run more octane than you need.

If, on the other hand, you only need 89 octane, then you need more mods for your engine. For the street, you need the compression and timing that would require 92 octane if you expect to run well.

Rev

As mentioned the higher the octane you run the more timing you need to burn it. Higher octanes are slower burning but when you advance your timing it burns longer leading to a more complete burn. With correct timing there are less byproducts and more power available. If you don't advance your timing it won't burn as completely and will leave gas in the cylinders that will help wash down the cylinders, dilute the oil and cause sludge build up in the engine. It won't affect your car immediately but 80k down the line you'll have lots of gunk and crusties in your engine.
If you want flat out performance run the octane you can afford and adjust your timing up until it pings or you can feel that you're losing power and back off a degree or two. Just my opinion.