Celica Forums General Discussion Exterior 87 or 91 octane GAS test and result on a 5-spd GT!

I own a 2002 GT 5-spd and fill it with 91 octane.I did some test switching to 87 octane. (tryed this 5 times)

On a trip of 350km (215miles) that i do every weekend, I noticed that I use the same ammount of gas if I keep a speed of 120kph (75mph)...

so the 91 only cost me more...

But everytime i did the test, I noticed a little lost in performance.

1. Worst acceleration on lower rpm.

2. Harder to keep my speed to 120kph (75mph). It seams like I have to play more with the pedal to keep this speed, and this sucks on a long trip without the cruise control...

3. Less power when trying to reach the top of high hill.

4. Overall acceleration seams to leak something... not alot, just a little. But you know, it's like if I always ask myself "whats is going on, something is missing"

I'll try the octane addon in the next weeks and will give you my impression.

I always use the midle one ... so it's usually 89 octane.

Here's another topic about gas
https://celicahobby.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=001300

you lost power with 87 or 91 (think I'm missing something), I use 91 all the time, and have never had a problem, much smoother than 87. I have use octane boosters like outlaw and that does make difference, small boost in power.

i said i lost power when i drive with 87

I've got 93 octane here in Houston. Never put anything less in my car.

yep same here i never put anything less then 93 in my integra

91 octane for me

i've been told higher octane is harder on the exhaust...any truth to that?

this topic has been covered so many times, here we go again.

Octane rating only indicates how much a fuel can be compressed before spontaneously combusting without the spark from a spark plug, NOTHING ELSE. the higher the octane number the higher the compression the fuel can take before spontaneously combusting w/o the spark from the spark plug. HIGHER OCTANE DOES NOT ADD POWER. if you think you notice a difference it is all in your head.

i experience awkward thinking also. when i wash my car, i think my car is so happy, it runs better.

dude wtf are you talkin about, so i guess all the NASAR drivers out there spend the extra money to put 100+ octane in their car just so they can say they have it? there might be a little difference but to say that there is no difference at all is just bullshit.

THERE IS NO ADDED POWER. NASCAR engines have a higher compression ratio thus need a higher octane fuel because like i said octane rating only determines how much a fuel can be compressed before spontaneously combusting without the spark from the spark plug. NASCAR drivers put higher octane fuel in their cars because they have no choice. they have to put it in. the engine compression ratio is too high for a lower octane fuel. and that is no BS.

91 only

With our ecu it is optimised for 89 i believe. YOu are just wasting money putting higher octane in. If i can find the thread i learned this on i will post it up.

98 ron all da way babeeee in perth premium is 95 ron, i go BP for BP ultimate cos they are the only ones that have 98 ron, my baby loves me for spoiling it

celi4me said "this topic has been covered so many times, here we go again."

I didn't ask question about what kind of gas do you put in your car or what do it do! I just tested it on longue run and shared my impressions.

95 is the lowest over here. Followed by 96 and 98 octane.

celi4me is correct however you do lose some performance if you arent using the correct octane @ higher comp ratios. Whoever blasted him by saying his comment is bullshit should do some research before running his mouth. Anyone driving a Celica GT and puts 91 octane in there vehicle is just blowing their money (GT=low comp ratio).

the definition of compression ratio is the ratio of the max volume in the cylinder over the minimum volume in the cylinder (ie compressed volume) so it looks like this comp
ratio= Vmax/Vmin

@ higher compression ratios the temp of the air-fuel mixture rises above the temp @ which the fuel ignites without the help of a spark. SO in your GTS if you use anything less than 91 octane(because of its compression ratio 16.5/1) your looking at your fuel igniting prematurely and this is called engine knocking because you will actually hear a knocking sound coming from the engine. This causes losses in performance and engine damage.

If you look @ toyotas specs they actually recommend you use 87 in your GT because it does not need anything higher.

Vmax/Vmin...thats the volume of fuel air mixture in cylinder..i left that out.

The compression theory is correct. For GT, it is waste of money to put higher octane. I had experimented with different octane level. There were no differences in performance or gas milage.

"SO in your GTS if you use anything less than 91 octane(because of its compression ratio 16.5/1)"

It s not supposed to be 11.5 instead?

Ratio of the 2002 model
Ratio of the 2003 model [toyota.ca]

[ 05-23-2003, 11:27 AM: Message edited by: NeXuS ]

my mistake with the compression ratio of 16.5 i was typing like mad to end the novel i was writing and i think the stock rims dimension popped into my head. it is 11.5 compared to 10 of the GT. and yes it is a big difference.

I use 76 gas 91-with Turbo 108 octane booster so I have like around 97 octane!!!

sounds right, i was using 91 for the first 5-6 tanks... then after a lil thought and discussion with some car enthusiast friends, i switched to 87 and not only did it feel and perform the same, my gas mileage stabilized...

higher octane gas burns hotter and cleaner then lower octane. so for you guys who say it gives absolutely no gains are wrong, but it is very min. the only way to tell a difference would be to put it on a dyno.

if it did nothing then octane boosters would be worthless and all of them claim horsepower increases

look...if you put racing fuel in your car you get more power...its true.in the toyota celica owners hand book it calls for 91 octane in the gts.the higher the octane, the more efficient it burns, the more power you get.thats why cars over seas get higher hp ratings than ours, because we get crap gas and they get 96+ octane, they also pay around $4.00 a gallon. thats why they sell octane booster in a bottle, it gives you a little bit more power.

Well said clockwork!!
Doesn't matter what car you use just put in some good gas don't settle for other people say maybe their cars run great with 87 i'm sticking with 91 with octane booster.And my car runs clean with great accleration,and once again it's not in my head.May be you guys think your car's faster with 87 than good for you.Everybody is different some settle for the middle others good to the extra mile so their cars are always ahead of others!

maybe you guys need to realize that we are talking about a celica gt..honestly be my guest by putting 91 + octane in a GT..the point of the forum was to discuss the individual who felt power loss in his GT because he used 87 octane...remember the soul purpose of using higher octane is for higher compression ratios..read the theory it's right..if you dont think so then mechanical engineers have been wrong for a very long time(and i dont think this is the case)