Gas Prices

[Mr. Pockets]

Originally posted by deruvian


It all has to do with the tuning of the engine. The timing advance assumes combustion at a certain rate, and using a different octane will change that rate. This is one thing that causes detonation ("pinging"). The fuel does not combust properly because the timing advance makes the spark plugs fire at the inappropriate time for that specific octane's rate of combustion. With enough detonation, your internals will suffer from one type of damage or another.

This is a slightly inaccurate description of what will happen if you put regular fuel in an SVX. Lower octane fuel ignites more easily, and in a high-compression engine like the EG33, the fuel can ignite just from temperature and pressure alone, before the spark plug would ignite it. That's called detonation, and it's not difficult to figure out how it's bad for an engine.

The knock sensors, however, will detect this. The ECU will start cutting fuel and spark to try to eliminate the problem.

The end result is the same. Don't put regular fuel in the SVX. Yes, there are more modern cars that can adapt to regular fuel even though they say 'use premium only.' The SVX is not so adaptable.