Alright... I have a question about gas . I have the car down in my sig. Around here 93 is the most common premium gas, and 91 is kinda hard to find, so I always get 93. Now I'm wondering about it though. I know in the manual it says 91 or above. I don't really remember what the car was like before the mods, but I know now it feels kinda the power stalls high up in the rpms(I mean, its still pulling, but not like it sounds like it pulls up there for other guys. More what I would imagine an LT1 feeling like I guess), and I know that seems weird considering LS1s are known for the opposite. Also when its up there it has some little ticking noises from the engine. I'm just wondering if it could be caused by the 93 gas? I know they burn at different speeds and I'm still on the stock tune so I'm just wondering if it could make a difference, since it hasn't been tuned on 93 or for some other reason. Should I use 91, or is there not any difference really? What could cause that acceleration alowing feeling up high too? Maybe it's normal, I don't know, this is the only one of these I've been in. (my car shifts at 5500rpm too, I've heard that isn't normal, is it?)

 

if you find 91, use 91. the reason is your car will not run any better on 93 than it does on 91, and if 91 is available, buying 93 is just throwing money away. the way our cars are tuned is if we run LESS THAN 91, the computer reduces timing to combat engine knock. therefore, putting 89 or 87 will hurt your power and fuel economy since the engine isn't running optimally. however, putting MORE octane than 91 will not do a damn thing since the car runs at its maximum at 91. contrary to popular belief, adding more octane WILL NOT make you faster and WILL NOT give you better fuel economy. octane slows combustion, it's not a power adder.

so to paraphrase, less than 91 is bad for your power and fuel economy, more than 91 will not make you run any better. where i live, my local sunoco stations offer 91 and 93. i always buy 91 since it is 4 cents a gallon cheaper. anything else is throwing money away. i've been paying ~$2.15/gal for 91 octane around south jersey, plus i get a 5% discount through my credit card company. another few weeks and with my discount i'll be paying under $2/gal for premium

 

Certain tunes will dictate 93 octane or higher. It does make a difference in some cases.

 

we're talking about a stock tune, though. aftermarket tunes are irrelevant as he can dictate what octane he wants to run if the time ever comes. stock tunes can't tell the difference between 91 and 93 octane. all it knows is that there is enough octane.

 

As with ChocoTaco369 said higher octane slows combustion. So the lower the rateing you can get away with the better the performance you can get. But I would not go lower than 91

 

Ok, so would 91 actually perform a little better than 93 for me then? Or just the same and no difference? Cause around here they really cost the same, so if it's just the same and I wouldn't gain any from 91 I'm not going to try finding it anywhere. I was just wondering if maybe it could cause the slight ticking I notice up top or the slowness feeling.

Its funny though. Every once in a while my car isn't too impressive to me, like when I have that slowness feeling up top, but other times it is. Like just a minute ago. I was coming back and turned off the little highway that our road is on, onto our road which is probably about a 45* aangle, maybe a little more, I was going about 40 and hit it. The back tires slipped, something was banging in the back (hopefully just exhaust pipes hitting something and not something worse :/) and the traction control had to come on and push my foot back to stop them from spinning. Those are the times that it impresses me . hehe

Anyway, like I asked before I went rambling on about that, will I actually gain any power, or at least maybe make that ticking go away if I use 91? Or will it basically be just the same as 93? Thanks.

 

But his mods will definitely require the highest octane he can afford. It might be a stock tune, but it's not a stock car. The car should be tuned with all the mods that have been done so the car can run properly on the gas that is used.

 

the problem isn't the gas, its you getting used to your car. My car feels sluggish too..till I borrow my moms subie forrester to go to the store. Then I realize my car is quicker than my brain is telling me. Go drive a much slower for a car for a day..then get back in your car and try not to **** your pants.

ps...octane isn't a power adder...but with higher octane..you can run more boost(if tuned properly) and more timing(if tuned properly), but neither of those make a difference since your on stock tune. use 91 or 93..which ever is cheaper or closer.

 

Also, weather conditions (density altitude, barometer, temp., humidity) will effect just how "punchy" your car feels day to day.

 

i live in houston and on hot, humid days, the car feels sluggish as all hell... but in the evenings when it's cool, it seems like a damn rocket.

and i agree with BrandonDrecksage... my car feels slow, but then i drive my fiancee's sunfire around (learning to drive a stick lol) and then get back in my car... night and day. Also, if you actually look at your speedo when you punch it, say from 30, it feels like 1 second and you are already at 60. Doesn't feel as fast anymore, but when you do the math, it's fast. ;p

 

Well, I agree that could be the problem. But for me I don't fit those things. I drove a '00 Silverado with the 5.3L in it, and that actually wasn't too bad. Then I got my car and now my dad has the truck to drive. Even when I very first got my car i wasn't overly impressed with it after the truck. I have no idea why. Now I drive a 93 Mazda Navajo around (the dd about 1/2 the time now) and other than in 1st gear that thing really is slow. My foot to the floor in that thing is about 1/4 of the way down in my car. 1/4 is usually enough to accelerate faster than all the other traffic at stoplights in my car, but with the mazda i have to go about 3/4 of the way down to keep up with everyone else. So I have no shortage of a slow car to feel . I think maybe it's just because I expect more because of how highly everyone talks about them. It was like hype to me, I was expecting something and it wasn't quite what I was expecting. Don't get me wrong, I love the car and there are times it feels really fast, but there are those other times... I don't know.

One weird thing is, after I drive my dad's car it feels really fast to me. He has a CTS and talks about how peppy and fast it is(which is weird cause he had a 97 z28). Anyway, when I drive it and I feel what is in his opinion fast, then i drive mine I go wow... this thing is fast.... So I guess going from driving a slow car to a fast car doesn't do much for me, but then going from "fast" car to mine makes it feel really fast cause mine is so much faster. I don't know.... I'm just weird Ok, I'm done now. lol

 

lol his mods don't require the highest octane rating at all. he has no engine internal work done so his compression ratio is the same as stock. he has no head work done to the motor. he can run 91 day in, day out, even tuned, unless he has the timing advanced to run 93 octane. unless he goes and gets an aftermarket tune requiring 93 octane, he can run 91 day in, day out. as Hot94Z28 has said, octane slows combustion, so technically he may actually see a tad more power running 91. you want as little octane as you can get away with. don't run less than 91, and running more than 91 will simply combust slower. that's a negative in my book.