What will happen with cars that require premium if you run 87oct. in them.

 

Low octane fuel causes detonation. Detonation can break ring lands, burn holes in pistons, damage heads, blow head gaskets, etc.

In a computer controlled air/fuel/spark system, the knock sensor will detect the detonation, and retard timing to prevent damage. Whether is actually prevents damage will depend on how severe the knock is, and what the capabilities of the knock retard system are. If the computer is capable of pulling enough timing, there will be no damage, but you will probably notice a loss of performance. The key is.... if you can hear knock, its probably doing damage. If you can't hear it, you're probably safe.

In a non-computer controlled environment (ye olde carbed engines), severe detonation can damage an engine in a matter of weeks to a matter of months. Hyprereutectic pistons are very brittle and more susceptible to damage from detonation.

 

That's some good info. Thanks. I had a toggle switch in an SVO Mustang that I could select high or low octane. I guess the computer couldn't automatically do it.

 

depending on the year tpi motors will pull 15 degrees timing out under knock. seen on dyno, this may not be enough and can cause damage due to the fact it is not quick enough if the knock is hard enough, seen motrs burn pistons before second gear is even near. they said they never heard it till it was to late, octane booster that adds 5 points mean 87 to 87.5. don't waste your money, if you mix 88 and 92 you will get 90 octane. best to stay with same brand due to additives