I had a 95 Honda Prelude with the 2.2 VTEC. Same principle of VVT on the 2.4 Ecotec. Never had ANY probs with that motor and it was also 10.5:1 comp. Ran a 50 shot wet for a while. Moved to a 75. then finally a 125 (after some minor mods). Nothing like racing down the track and being able to put the "squeeze" on your opponent when you need it!

 

Completely different.
vtec changes valve lift durration, and sometime on some vtec cars opens and closes an extra intake valve.
vvt changes timing, advances or retards timing up to 10 degrees using the cam shafts.

Both are done by oil pressure opperating cams. But that is the only place they are simular.

 

The HHR's Variable Valve Timing is done electronically using solenoids which are mounted in the top of the valve cover.

Just a FYI.

 

The ecu on the hhr would be able to recognize any amount of detonation/pre-ignition that may happen while spraying. This ecu has gm's high speed lan databus communication system. It has a baud rate(bit rate/ speed, whatever u know it as) of 500,000 kbs, which is just god awfully fast. So if there were to be any problems the ecu would see and make the necessary corrections to fuel trim/ timing advances and what not before any harm could be done. But odds are nobody here is gonna spray more than a 50/75 shot on a hhr, so its not like thats enough to actually hurt anything, unless u just completely abuse the spray. My 0.02 cent...use it wisely lol.