Recently purchased an '08 Dak. Manual says to run regular. Everything but the driver runs off a computer. I was wondering if the computer will advance the timing if I run premium gas, giving more horse power?

Dont waste your monry.Run regular.Rocky

Premium gas does not and never did produce more power than regular. It actually has a slower burn rate than regular. Putting premium in will do nothing but waste money.

As I understand it the computer can only retard the timing if it detects detonation. It won't advance the timing beyond the initial set. Regular gas and pocket the savings.

If it makes any difference, it won't be much, and I doubt it would be something you could see daily driving. More compression makes more power, and less advance makes more power, so you want to run as high compression as you can with the least amount of advance. More advance is something of a crutch for low compression. Some engines MIGHT make more power with more advance if they had the right combination of low compression and cruddy cylinder heads. That COULD be an old Mopar engine, or an early GM small block. On the 90-92 Corvettes, GM basically pushed the advance as far as they could and let the knock sensor pull out advance until it quit knocking. They made great power for what they were. Running that calibration in my Valiant without a knock sensor made the car literally undrivable except at idle.

I think the heads and compression are so much more advanced in your Dak that you don't stand to gain much with premium gas. It would be an interesting experiment, though. Next time you get a chance to run it over the chassis dyno, make a run on a low tank of regular, tank up with premium, and run it again. I'd bet there MAY be 3-5hp hiding in there...

Clair

Some newer engine controls will do a octane check by purposely advancing timing to create detonation. I think this is usually only done in steady state low load conditions. This is usually done for engines that are supposed to run premium gas. Once lower octane is detected the engine will use a slightly retard set of timing curves. I think there are two basic reasons for this. One is once detonation starts it requires a larger decrease in timing advance and mixture enrichment than would be required to avoid detonation. The second is that detonation detection only really works for really large detonations and the smaller events can still fatigue head gaskets and pistons. Therefore on event based detonation mitigation will still subject the engine to significant pressure spikes and resulting damage. Therefore if low octane can be detected detonation under load can be avoided.