Gas question

[silverstang2001]

I usually use 87 octane but filled up yesterday with 93.... since then it feels like my car is a little more sluggish and doesn't have as much "pop" off the line. Is it me? Has anyone had this problem?

[nowon805]

ya i got the same thing, i thought i was crazy but myn acts sluggish too when i fill the tank and i got a 99

[spike_africa]

93 octance burns slower and i have heard makes some stock or lightly modded cars feel slower. You dont need to run that octane until you are either tuned or pushing boost, nitrous etc.... its a waste of money otherwise.

[WaterDR]

Correct. The higher octane, the slower the burn. You can actually loose hp by going too high on octane.

Originally Posted by MT's#1Customer!

Correct. The higher octane, the slower the burn. You can actually loose hp by going too high on octane.

yep a roo pal...

also... running too high octane can be bad for some cars... it usually tells ya what octane to run... sometimes ya can ignore, sometimes ya shouldn't

[Milos]

well continous use of a high octane.. they say you should once every year use full tanks of a high octane three times in a row (three full tanks of 93) to clean out something in your engine or fuel injectors I don't know.. I forget I saw it in a video.

I run 87, but it doesn't hurt to run 93 every now and then.

[r3dn3ck]

Edumacation time.

You have noticed the fact of high octane. It sucks, that's the fact of it. here's how it works:

The higher the octane number the harder it is to light. Gasoline is a mixture of octane, nonane, pentane, cetane, decane and a number of other yucky substances. Each burns at a different rate but we've decided to use octane as the measuring stick for all the others as far as burn rate goes because a substance with 50% octane would burn at a very predictable rate. Y'all still with me?

So, if octane isn't a good thing why use more of it? Simple, when cars first came with gas engines octane was at like 20-30 at the pump. Gas was all the time detonating. As engines improved so did gasolines. Eventually we got really good at tagging the bar every time. So, we now have engines that like 87 which is a pretty unstable fuel and generates huge amounts of energy because it's so unstable. 91-93 Octane and high octane race gas is quite stable comparitively speaking and so is harder to light and burns less hot and generates less energy per gram of fuel than 87. The reason we need 93 at all is to handle big compression like hot rods usually use without detonating. You see if you squeeze 87 and 93 simultaneously, then 87 will go bang before 93 beause it's less vulnerable to the rigors of compression. Advancing your timing also creates conditions where higher octane is recommended.

If you look on diesel improver bottles, you'll see that it's usuall a cetane improver. Cetane is very unstable which is good for diesels which operate on detonation and deliver quick brute force but bad for gas engines which operate off of more time hungry reactions which deliver power in smoother longer bands.

So, if you dyno your car with the same tune and 87 in one tank and 93 in the other, the 93 will produce less power in the same engine and 87 may lead to detonation if your setup needs more octane or less timing. If you can't get high octane and you need it, try backing the timing off a couple degrees. That usually helps.

And lastly, if you use 93 constantly instead of 87 and you don't need 93 your car will eventually learn to love 93 and will run kinda poorly on 87. Periodic use is great to help clean injectors and remove valve deposits. There are a zillion little detail reasons that cars learn a fuel but suffice it to say that you should ALWAYS use the lowest octane you can safely run for best performance.

I'll go now and take my V8 with me, which I feed 87 octane just like the owners manual says. When I get it tuned again, I'll go back to 89 or 91. They don't have 93 out here because we don't know how to love cars in california or some junk.

[Justin99gtconv]

93 octane wont clean any better than 87 its not the octane it is the amount of detergent in the gas

Originally Posted by r3dn3ck

Edumacation time.

You have noticed the fact of high octane. It sucks, that's the fact of it. here's how it works:

The higher the octane number the harder it is to light. Gasoline is a mixture of octane, nonane, pentane, cetane, decane and a number of other yucky substances. Each burns at a different rate but we've decided to use octane as the measuring stick for all the others as far as burn rate goes because a substance with 50% octane would burn at a very predictable rate. Y'all still with me?

So, if octane isn't a good thing why use more of it? Simple, when cars first came with gas engines octane was at like 20-30 at the pump. Gas was all the time detonating. As engines improved so did gasolines. Eventually we got really good at tagging the bar every time. So, we now have engines that like 87 which is a pretty unstable fuel and generates huge amounts of energy because it's so unstable. 91-93 Octane and high octane race gas is quite stable comparitively speaking and so is harder to light and burns less hot and generates less energy per gram of fuel than 87. The reason we need 93 at all is to handle big compression like hot rods usually use without detonating. You see if you squeeze 87 and 93 simultaneously, then 87 will go bang before 93 beause it's less vulnerable to the rigors of compression. Advancing your timing also creates conditions where higher octane is recommended.

If you look on diesel improver bottles, you'll see that it's usuall a cetane improver. Cetane is very unstable which is good for diesels which operate on detonation and deliver quick brute force but bad for gas engines which operate off of more time hungry reactions which deliver power in smoother longer bands.

So, if you dyno your car with the same tune and 87 in one tank and 93 in the other, the 93 will produce less power in the same engine but may lead to detonation.

And lastly, if you use 93 constantly instead of 87 and you don't need 93 your car will eventually learn to love 93 and will run kinda poorly on 87. Periodic use is great to help clean injectors and remove valve deposits.

I'll go now and take my V8 with me, which I feed 87 octane just like the owners manual says.

i go back n forth myself... i notice an improvement running 93... gas lasts longer and she runs just a tit nicer...

yet...

my neighbor has a 1969 plymouth road runner with a 440 under the hood ... and he puts 87 in that beast...

[Milos]

Originally Posted by Justin99gtconv

93 octane wont clean any better than 87 its not the octane it is the amount of detergent in the gas

are you saying that the video ****ing lied? is that what you're saying? I was lied to. Son of a bitch.

[silverstang2001]

thanks for the info, ya'll, preciate et.... no, really, thanks

[herndy_1]

So does it make a difference between the sixers v v8's?

[silverstang2001]

you know, its weird, today my car felt like it had a lot more power. who know's. i checked the manual and it says to use 87 octane, so next fill up i'm switchen back

[spike_africa]

Originally Posted by herndy_1

So does it make a difference between the sixers v v8's?

nope, basicly if your car is on the stock tune you dont need 93 and should 87 because you dont need 93 and its a waste of money.

[Grimmz]

Originally Posted by spike_africa

nope, basicly if your car is on the stock tune you dont need 93 and should 87 because you dont need 93 and its a waste of money.

Yup!...Mmmmm XCAL2!!! XCAL2!!! LoL... I need one of those...

[herndy_1]

So, say you get a Xcal 2, get a tune made for a higher octane, and then use that higher octane....what would it do for you?

[WaterDR]

The tune will advance your timing to take advantage of higher octane fuel.

[xpaeanx]

I forget exactly what it says in the manual, but it leaves the impression that it's actually bad to use higher octane than what is recommened for ur car.

Then again it also tells u to shift like a granny. "5mph 2nd gear, 15 miles per hour 3rd gear, 20 miles per hour 4th gear, 30 miles per hour 5th gear... wow we're driving fast today! 35 miles per hour... i really feel like a speed demon, I hope I don't get pulled over! hmmm... maybe I should slow down..." OMG.... grrrrrrrrrrr those people get under my skin.... There's SOOOOOO many of them where I live... and half of them drive around in ferrari's at like 10mph through town, and then come to a complete stop before any unevenness(is that even a word? well i guess it is now) in the road. It's like watching a pack of 100 yr old ladies with walkers...

[Milos]

Originally Posted by xpaeanx

I forget exactly what it says in the manual, but it leaves the impression that it's actually bad to use higher octane than what is recommened for ur car.

Then again it also tells u to shift like a granny. "5mph 2nd gear, 15 miles per hour 3rd gear, 20 miles per hour 4th gear, 30 miles per hour 5th gear... wow we're driving fast today! 35 miles per hour... i really feel like a speed demon, I hope I don't get pulled over! hmmm... maybe I should slow down..." OMG.... grrrrrrrrrrr those people get under my skin.... There's SOOOOOO many of them where I live... and half of them drive around in ferrari's at like 10mph through town, and then come to a complete stop before any unevenness(is that even a word? well i guess it is now) in the road. It's like watching a pack of 100 yr old ladies with walkers...

You don't always have to fly... people look more when you're doing 35 instead of 70.

[xpaeanx]

Originally Posted by Milos

You don't always have to fly... people look more when you're doing 35 instead of 70.

yeah but it pisses off those behind them(me) who have no patience and just want to where we're going.... norm work, which i'm running at least 15 min late to already....

[Milos]

Originally Posted by xpaeanx

yeah but it pisses off those behind them(me) who have no patience and just want to where we're going.... norm work, which i'm running at least 15 min late to already....

So? **** them, tell them to leave earlier :banana:

[xpaeanx]

Originally Posted by Milos

So? **** them, tell them to leave earlier :banana:

well, if it happened once in while I wouldn't mind, but I work in southampton which must be said with that i have way to much money than's good for me tone, and they ALL only drive on weekends 2-3 months out of the year... which means they can't! so I'm either stuck behind mr.slow*** in the ferrari, or mr. let me swirve all over the road and almost hit u about 50 million times before cutting across 3 lanes to make a left and almost causing a 5 car pile up. Which is actually why I drive so fast... I want to get away from ASAP. Though I suppose out of the 2 the slow guy posses less of a threat.

[Grimmz]

Originally Posted by xpaeanx

well, if it happened once in while I wouldn't mind, but I work in southampton which must be said with that i have way to much money than's good for me tone, and they ALL only drive on weekends 2-3 months out of the year... which means they can't! so I'm either stuck behind mr.slow*** in the ferrari, or mr. let me swirve all over the road and almost hit u about 50 million times before cutting across 3 lanes to make a left and almost causing a 5 car pile up. Which is actually why I drive so fast... I want to get away from ASAP. Though I suppose out of the 2 the slow guy posses less of a threat.

It's called offensive driving, ur gut reaction when something happens on the high way is to hit the breaks...however, whether you have ABS or 4 wheel breaks, breaking is guna put you in a unstable possition. Instead you have to be read to hit the gas and go for things, when your on the throttle in a straight line your car is guna be more stable, think of it like how a bike is stable when fast and wobbly when slow...

sometimes hitting the gas is safer then hitting the brake...