Anyone know what the effects of very high octane fuel (racing fuel) mixed with regular fuel have on the trailblazer. My friend wants to out some in, will it make the engine run alot hotter and possibly damage the pistons and rings or other components??? This is a stock machine that has had no mods on it at all.

 

I personally would not run anything higher than what is recommended factory. Higher octane will not hurt things, but your friend will just be throwing away money. You do not need a higher octane gas without mods and he may also experience some paerformance loss with a higher octane, I have seen cases were a person lost performance from using 93 instead of 87.

 

Yeah, to high can cause bog and it will seem like it's running rich. To low of octane will cause pre-ignintion and will lead to engine damage overtime. The octane rating is when the fuel burns and under how much pressure, so if you put say 100 octane in a motor with compression ratio designed for 89 octane, the compression will want to burn the fuel before it wants to, visa-versa when running to low of octane.
I go to the races and see people running real high octane because they think it will make them faster, but makes the motor bog down and seem rich, so they change jets thinking it will fix it and usually end up burning up the motor all because of to high of octane.