Blaznkwest

I've been thinking about getting a DD project started, and with gasoline as a growing concern, I want to know what motors require premium gas?
I was thinking something simple like an LS swap or B16, nothing major but something with more than 100hp.

Also, what would happen if I didn't put premium gas in a motor that recommended it? In my old GSR hatch I didn't put premium because I didn't know, and I got a check engine light every so often (not sure if it was the acutal problem or not). I drive a teggy gsr now and have been putting premium gas in it since day one, and don't really want to jeopardize the engine to save a few pennies each fill up.

OwManThatHurt

well decreased performance is the first thing you notice, especially in a turbo motor. i've heard of other problems arising as such as pre-detonation or not igniting all the way or something like that.

IEAT50S

Depends on the compression ratio and if its FI (forced induction) or what...lots of factors.

For example in my car the stock motor had a 10.5:1 or so compression ratio and required 91 or higher octane gas. It would run on 87 however the computer would pull the timing back on the motor and you'd lose power. Someone did a track test premium vs regular and the car would actually slow down .5-1.0 seconds in the 1/4 mile now the gain MIGHT not be as large on a smaller 4 cylinder engine but it would definately be noticeable and as someone pointed out above you run the risk of pre-detonation.

Fabrik8

Do you mean pre-ignition or detonation? Pre-detonation isn't a real word..

Low grade gas isn't as stable when it combusts, which is why pre-ignition (before the spark plug fires) and detonation (after the spark plug fires) can sometimes occur. You have to have a knock sensor for an ECU to retard timing or lower spark energy though, so if you have an LS or whatever engine without a knock sensor you will have to tune a little more carefully.

Honestly there isn't any reason why you need premium gas all the time if you're just commuting or whatever. If the engine is driven normally, at low loads, there isn't much danger with a standard tune. When you do actually want to use the full performance though, it's nice to have the right gas on tap though..