ive always been pumping 91 , but then i heard from someone that 87 is better for an LS because it burns quicker and u get better performance. and does 91 burn slower so you would get a loss in performance?

 

yeah i heard that too i use 87 and i noticed better milege and its way cheaper then the 91 octane espically that now gas price is sooo expensive

 

You don't need 91 until you do the FULL ITR conversion...including the motor!

 

so with ls motor, 87 is good , no point in getting 91? damn ive been wasting gas money for like a hot one.. lol and i live in san diego where its like +$3 per gal.. lol

 

the ls engine can run on 86...so yea get 87

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vietblood129 &raquo;</TD></TR><TR><TD CLASS="quote">so with ls motor, 87 is good , no point in getting 91? damn ive been wasting gas money for like a hot one.. lol and i live in san diego where its like +$3 per gal.. lol</TD></TR></TABLE>

DEWD!!!

 

wow thats new to me. I've been using at least 89 octane. Mayb i should try 87.

 

I love my car too much to drop to 87...

 

I get best gas mileage with 87

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bLaCK_GsR &raquo;</TD></TR><TR><TD CLASS="quote">I love my car too much to drop to 87... </TD></TR></TABLE>

I guess what they say is true "Love comes with a price"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MugenDC4 &raquo;</TD></TR><TR><TD CLASS="quote">

I guess what they say is true "Love comes with a price" </TD></TR></TABLE> haha.. thats funny...

 

The octane rating of a gasoline tells you how much the fuel can be compressed before it spontaneously ignites...this is so because you don't always have octane in your fuel, there are other additives which burns faster...87 octane means you have 87 octane and the rest of the "stuff" can be heptane or some other additive. Heptane is a seven carbon chain which ignites waaaaay more quickly (almost instantly) than octane, the 8 carbon chain. So having more of this "8 carbon chain" (like 89 octane or 91 octane or even 100) will allow you to compress more fuel in your chamber before igniting. However, the thing is, we don't know what other additives each gas company puts in other than the given octane ratings (87, 91, etc)

But to sum it up, the octane rating is basically an anti-knocking index which tells you its knocking ability (think: having more heptane and less octane which causes the combustion process to ignite instantly from a small compression before the spark plugs can even fire)

So the POWER LOSS occurs in untuned vehicles running higher octane ratings because during the combustion process, you have unfinished burning fuel that's dumped out to your exhaust due to a slower burn rate.

Therefore, the advantage of having a higher octane gives you more of a safety net to modify your vehicile. By this, I mean it allows you to safely increase your timing or compression, run a forced induction vehicle, etc because the likelihood for detonation or pre-ignition will not occur as much in the combustion chamber.

In a nutshell, you want to run the LOWEST octane rating you can WITHOUT detonation. However, things change when you modify your car i.e. cams, forced induction applications...which means you need to put in higher octane (how much higher? trial and error or do scientific calculations) and TUNE it so you can get the most out of that octane rating without detonation or pre-ignition.

For all you stock b18b'ers out there (by this, I mean stock compression, timing, etc), if you're running anything higher than 87 octane, you're paying more to go slower.

 

How about a 98 GSR? Would it be okay to go 89/91? Premium is kind of pricey these days.

 

there no reason for a ls to be running anything higher than 87, unless you have a serious all motor set up or fi.

 

wait i got a 93 ls, so 87 is better? will it preform better or just get better gas mileage?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by XyKo &raquo;</TD></TR><TR><TD CLASS="quote">How about a 98 GSR? Would it be okay to go 89/91? Premium is kind of pricey these days.</TD></TR></TABLE>

your speedometer has the answer to that

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18btegra &raquo;</TD></TR><TR><TD CLASS="quote">wait i got a 93 ls, so 87 is better? will it preform better or just get better gas mileage?</TD></TR></TABLE>

technically both.

 

i just swapped the ls motor out of my integra into a del sol. the del sol with b18b get over 32mpg on 87 and runs great

 

i have noticed with my 91 ls that using the lowest octane my car feels more like it just wants to see red line, so if you do add cams uping the number is better? sorry if its a noob question but beyound i\h\e i got alot more to learn. better to ask a question then learn by blowing a motor

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bLaCK_GsR &raquo;</TD></TR><TR><TD CLASS="quote">I love my car too much to drop to 87... </TD></TR></TABLE>

me too... plus when i use 87 in the morning during cold starts its a little more pingy and ive found that 89 is better than 87 i get a little better mileage with the 89 too but id never use 91 or 93 or 97 like some of you's its only an ls but dont rape the motor with cheap *** 87


but your saying that the 89 is making me go slower??? if anything the type of gas you use is irrelevant to performance when your stock so i dont see how using 87 to 89 will retard performance its nothing noticeable

 

look when i use the higher numbered gas, the car does feel sluggish, when i use the cheap gas, its more peppier id say, im not in no way trying to say that oh its big gain cuz its not. its just the feel it feels

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allmotor dc4 &raquo;</TD></TR><TR><TD CLASS="quote">

me too... plus when i use 87 in the morning during cold starts its a little more pingy and ive found that 89 is better than 87 i get a little better mileage with the 89 too but id never use 91 or 93 or 97 like some of you's its only an ls but dont rape the motor with cheap *** 87


but your saying that the 89 is making me go slower??? if anything the type of gas you use is irrelevant to performance when your stock so i dont see how using 87 to 89 will retard performance its nothing noticeable</TD></TR></TABLE>


Having a higher octane slows the burn rate in order to obtain a more complete burn. If for some reason your car is misfiring or knocking or whatever, higher octane would be better. The reason for not wanting a higher octane is because if the burn is TOO SLOW (slower than normal combustion) your thermodynamic efficiency would decrease because the burn rate is not ideal.

For a GSR, yes, you need premium, because 91 octane is the standard burn rate for GSR's and has the best thermodynamic efficiency. If you go any lower, you would probably knock, and going any higher isn't producting an optimal burn rate. Of course, for every car it'll probably be different because we are running different settings (compression, timing...i.e. modified engines)

 

i know how the whole octane thing works im just saying it doesnt feel different i just noticed the valves arent so loud when you use 89 instead of 87 i dont really notice any difference though

 

Now see I usually run 93/94 in mine always. I rarely run 89 unless I'm near broke. It seems to run alot better on the higher octance and I dont know it just seems better.

Or I could just be losing it

 

87 octane

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97tegGS &raquo;</TD></TR><TR><TD CLASS="quote">Now see I usually run 93/94 in mine always. I rarely run 89 unless I'm near broke. It seems to run alot better on the higher octance and I dont know it just seems better.

Or I could just be losing it</TD></TR></TABLE>

You are losing it, use 87 and save your money for something else. You will not be doing a disservice to your LS by putting 87 in it.