Compression. That's why. Octane rating is very directly related to detonation resistance and combustion stability, so high compression engines like B16s and B18C/C5 need high octane. It's only really needed for high RPM / high load though, if you're just running around town like an average joe then lower is fine.

 

I HAD THE SAME PROBLEM CHECK THE VTEC PRESSURE SOLINODE AND THE OIL LEVEL SOMTIMES THE SOLINODE GETS CLOGGED UP AND IT WILL MAKE IT DO THAT AND CHECK TIMING

 

now that makes sense. it's not b/c it has vtec...but b/c of the compression. i couldn't for the life of me figure out what the octane had to do with vtec. thanks!

 

you might even have to change your oil, i heard that if your oil is bad v-tech wont work correctly

 

Your oil viscosity would have to be really high to make vtec not work..