It seems strange the GT only uses 87 octane

[Maelfyn]

Do all 10:1 compression cars use 87 octane? I would think I would need higher octane for that kind of compression... at least 91 or something. The GT-S has 11.5:1 and uses 93 octane but is only a 1.5 higher. What kind of compression is normal for 91 octane? It seems no car ever recommends 91. Only 93 or 87. :confused:

[z6joker9]

hehehe, mine does... powerchip instructions specifically say not to use anything under 93 after it's installed ;)

just because it needs to be higher doesn't mean better... if indeed i am running too high octane i'm not getting full potential cause it doesn't burn it all...

i thought the gts recommended 91 to 93?

think higher octanes are better? go drop 104 in your car and see if you can pull out a low 15...

people use 104 either cause their engine burns that hot cause it's a drag only car or they want to turn up the boost(which we dont have :mad: )

[Maelfyn]

Originally posted by z6joker9
think higher octanes are better? go drop 104 in your car and see if you can pull out a low 15...


I'm positive I can run a 14 but no tracks are open~ I doubt higher octane will help me. If anything it might work against me. Octane simply dictates the resistance of the fuel to combust.

[DaksGT]

I'm not gonna rage another octane war but nothing under 91 ever went in my car.

[DaksGT]

and I'm pushing 126.7 at the wheel stock

[Maelfyn]

Okay... so would 91 be reasonable in a GT? I would think a GT might combust the a/f mixture prematurely with 87. Perhaps Toyota markets it as 87 octane for marketing purposes? Is this common practice by some companies or even remotely possible?

[oldster]

Originally posted by Maelfyn
Do all 10:1 compression cars use 87 octane? I would think I would need higher octane for that kind of compression... at least 91 or something. The GT-S has 11.5:1 and uses 93 octane but is only a 1.5 higher. What kind of compression is normal for 91 octane? It seems no car ever recommends 91. Only 93 or 87. :confused:

Don't know about eveyone else's but my GT-S calls for 91.

[Maelfyn]

Really? haha all my goober friends fill up with 93 :D

[Symbolize]

Originally posted by Maelfyn
Do all 10:1 compression cars use 87 octane? I would think I would need higher octane for that kind of compression... at least 91 or something. The GT-S has 11.5:1 and uses 93 octane but is only a 1.5 higher. What kind of compression is normal for 91 octane? It seems no car ever recommends 91. Only 93 or 87. :confused:

So what do you do if 91 is the only highest available in your state ?

[Gaps]

[QUOTE]Originally posted by Maelfyn
[B]Do all 10:1 compression cars use 87 octane?
No

I would think I would need higher octane for that kind of compression... at least 91 or something.
Compression ratio is not the only factor in choosing a proper octane rating...more important is cylinder head design...for example a design that reduces hot spots in the combustion chamber can get away with lower octane fuel.

What kind of compression is normal for 91 octane?
There is no 'normal'...it is a matter of design. Toyota knows what the stock motor needs to run properly, trust them.

[oldster]

Originally posted by Symbolize


So what do you do if 91 is the only highest available in your state ?

You read my previous post. :)

[DaksGT]

92 is the lowest i ever put in my gt

[Johan]

In Europe it is advised to put in 98 octane by Toyota.
We only have here 95 and 98 octane.........................


:) :) :)

[DaksGT]

Originally posted by Johan
In Europe it is advised to put in 98 octane by Toyota.
We only have here 95 and 98 octane.........................


:) :) :)
Bastards I love europe and its respect towards cars

[oldster]

Originally posted by Johan
In Europe it is advised to put in 98 octane by Toyota.
We only have here 95 and 98 octane.........................


:) :) :)

I'm really not sure but maybe the octane rating method is different?

[Deaks2]

In Europe they measure octane by the RON number, and noy by the average octane rating.

So 98 octane Euro gas is about 91-92 octane US-spec gas...