i have a 91 si and i was just wondering what is the best fuel to use performance wise? do i just use unleaded or should i use a higher octane? if i use a higher octane will it hurt the engine or anything?

 

If you havent messed with the compression (pistons, head gasket etc) then 87 is perfect, you can use 89 but I wouldnt run with anything higher, my car acts up with high oct.

 

if i use 89 will it kinda **** the car a little ?

 

no

 

use the highest octane available! i have a std base model 88 hatch, and i use all-91 octane, runs perfectly fine. higher octane fuel just burns more efficiently

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thevtecnician &raquo;</TD></TR><TR><TD CLASS="quote">use the highest octane available! i have a std base model 88 hatch, and i use all-91 octane, runs perfectly fine. higher octane fuel just burns more efficiently</TD></TR></TABLE>
Waste of money, theres a reason your manual recomends 85 or higher, your compression doesnt warrant any higher than 87. Higher oct doesnt burn more "effeciently" octane is the ability to resist detonation.

 

higher octane fuel just burns more efficiently
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not so efficient on your pockets though
87 is fine, use it save money for a swap