Hi i have seen in a thread of the octane for the tbi but i have a question my LO3 has 170k do i still need to put 87 or should i put 91 or 89.

 

the cheap stuff will do fine.

 

So i should just keep on using 87

 

yeah you dont have high compression so just use the cheap stuff

 

Ok thanks i have been using 91 since i thought thats what the car needed

 

That's easy. The LOWEST octane that does NOT knock on your hardest pull, like the freeway ramp.

 

As engines age and carbon builds up inside them changing their compression ratio, doesn't their octane requirement go up slightly? I stick 89 octane in my 'bird because of that.
Wouldn't the knock sensor prevent knock from happening in the first place? The car could be running with retarded timing and the driver wouldn't know it. Just like how modern cars which require 91 octane can be run on lower grades without knocking, but with decreased performance and mpg.

 

NO !
The knock sensor senses that knocking is ALREADY occuring, and tells the ECM to react to it ASAP to save the engine. The ECM will then try to restore timing to where it should be, see knock again, and again retard timing, so you're running *past* the ragged edge that way, at least some of the time.
Most engines can stand some degree of knock without severe damage, but over the long haul, I'm not sure anyone knows !
Running on the edge of incipient knock will keep the chambers clean, and not do any damage, but is also before the sensor will detect it so is almost impossible to hit. It may also be more advance than produces best performance anyway, depending on chamber design, and a host of other things.

 

also some people have heard that higher octane cleans your motor this is false. just creates more deposits in your engine

 

What people think is that higher octane burns better,,,this is absolute BS, the lower the octane the faster it burns.
The only thing with high octane ,,it runs cooler and is easyer on the valves.

87 is the way to go.

 

A higher octane than what your engine needs could actually hurt performance and emissions due to the fuel charge not completely burning during combustion.

Plus it's more expensive.

 

You only need enough octane to keep your motor from pinging. Running higher octane can slow the car down. You motor for sure needs the cheap stuff.

 

All of my research suggests that octane, real or "oxegynated" additive, ( pre-burnt alcohol ) changes the chemical decomposition *rate* in the very high temp high pressure end gases *just ahead of* but not *in* the flame front, thereby preventing the spontaneous combustion ( detonation ) of the remaining unburned charge, but has NOTHING to do with burn rate of the normal flame front as it consumes the much lower temp mixture.
If there;s is any definitive information about octane affecting burn *rate* in any way, I'd certainly like a reference ???

 

104 OCTANE.

I have used it a lot. When I have money to blow we run the Camaro down to empty and put about 10 gallons of 104 in it and go cruise the strip!!! Lol it's pretty funny. Suprised it hasn't thrown a rod yet.

 

Double post.