91 octane???? But why?

[Ultrashock]

In my owners manual it says: if you have the 4.3l high performance (code W) engine, use premium unleaded gasoline rated at 91 octane or higher for high power performance



why would it recommend 91 octane for high performance what could it possibly do for my engine? Its not like my engine is constantly pinging

[BlazerLT]

No real reason to use it.

It just allows for more advanced timing during applications where you need more power such as towing etc....

For normal use 87 will be fine.

[Cloud Strife]

My Blazer runs better on 91 octane but the mileage is much less. I don't know if that is because the computer is so used to 87 that it hasn't regulated itself to 91 or not.

But this will probably bring up how octane determines resistance to flamability.

[dmbrisket 51]

Originally Posted by Cloud Strife

My Blazer runs better on 91 octane but the mileage is much less. I don't know if that is because the computer is so used to 87 that it hasn't regulated itself to 91 or not.

But this will probably bring up how octane determines resistance to flamability.

lol ok fine ill keep it simple, higher octain, longer burn time, if its not sounding like bb's in a coffee can (spark ping) then run the lower

[BlazerLT]

87 is perfect for any normal duty with that engine.

MY parents drove this truck with premium all the time and had nothing but carbon problems.

EGR had to be cleaned regularly.

[Cloud Strife]

I can't remember, is yours a 97 LT?

I am just curious to see if there are any years in which may benefit from the higher octane.

[BlazerLT]

Mine is the 1995 with the same W engine as yours.

91 is not required.

[dmbrisket 51]

the only reason they say 91 in the cpi models is because of slightly higher compression, as lt said, the longer burn time carbens up the egr on the dimes...

[BlazerLT]

Mine will ping the odd time but it only happens for a fraction of a second and then dissappears.

The computer has the ability to control the timing and adjust for the fuel type.

Since only being on a strict diet of 87, the EGR has not carboned up once, not one failure.

Now if I was to tow something, I might actually use it for a tank so the computer could advance the timing more for more power, but everyday driving, hell, it won't make one lick of a difference.

[Ultrashock]

Just wanted to know the reason why they put it in the manual. I have never ever once filled up on 91 octane before and with gas prices the way they are now Im never gonna start, especially if it does not need it