That's why yours runs better with the timing advanced. The cam is going to probably change a LOT of things. In a normal engine it can't get it close to the point of pre-ignition, so by starting the timing advanced, you are allowing the total advance to be more.again ask the experts.

The only thing that makes sense for you is that the stock ECM can only advance the time so far. If you go to one of the EFI boards, I'm sure someone could give you a definitive answer as to what exactly happens when you run advance other than 0 on your ECM controlled motor (keeping in mind it is NOT a stock motor). On that note, a person with a regular distributor (no electronic advance), will not benefit by running higher octane, without resetting the timing and/OR re-setting the advance curve of the distributor (weights, springs, and vacuum advance). You will probably notice a significant loss in power. Run a couple of tanks of 87 through your rig and then take it out for a cruise. Running higher octane will allow the ECM to bump the advance up higher through all RPM's and loads, which will effectively increase performance. No matter what though, maximum advance is governed by the knock sensor (regardless of baseline timing) in an ECM controlled vehicle. Crate motors aren't the same as factory spec'd motors either.Īs far as EFI motors, I was pretty sure (not an expert here), that the computer 'governed' advance even if base was not exactly '0'. That being said, I don't doubt YOU see a gain, especially with higher octane fuel (which won't pre-ignite at the same advance as someone running 87). Right from the factory, most vehicles could gain performance with a tweak or two here and there. They take into account what environments a stock vehicle will see, and then build in a buffer. Stock compression ratio?, stock materials (cast, forged, hyperutecnic pistions)?, stock cam profile?, stock rocker profile?, Octane?, intake mods?, exhaust mods?, etc. By advancing the timing, you will see performance gains (to an extent), but alot depends on the rest of the motor. With that in mind they build ECM's, distributors, etc to make use of that octane in a realiable AND fuel efficient way (thanks to new emissions standards). When auto manufacturers design/test/build engines, they ASSume a safe Octane rating (usually 87 or below). Higher pressures = higher heat, higher heat will cause pre-ignition if the fuel mixture is not stable. Advancing ignition timing (to a point) increases optimum cylinder pressure. PLEASE COMMENT FOLKS! I am excited to hear all the opinions on this one out there! /forums/images/graemlins/grin.gifĬylinder Pressure is the key to power. I am really interested to see where this one goes! Has anyone else out there advanced their base timing and found increased performance as a result? I cannot claim to know why advancing base timing (with the brown wire disconnected) has an effect on performance, but it DOES! I’ve had trucks that had little to no mid-to-upper end power, but after turning the timing to 11-12* the truck regains A TON of power. You are correct saying that the knock sensor allows the ECM to make its own timing adjustments by cranking the timing out to the edge of knocking and then retard it slightly. I am tempted to start a new thread! I have ALWAYS advanced timing on EVERY EFI motor I've ever encountered, and have benefitted significantly from these adjustments. Grimmy (DISCLAIMER:this is not an attempt to flame Grim by any means) made the comment that adjusting your timing from the recommended 0* yields no performance gains. This is a quote from another thread that I had running, but I felt this subject deserved more attention.

The 4degrees advance is about perfect to make it start real easy and once the ECM finds it's place it will advance as needed. What you are accomplishing is making it harder to start. The timing is run as advance as it can be till it gets spark knock and then the ECM retards to just under that point. The computer will retard the 4 degrees right back out of it. There is no performance gains in doing that on a EFI motor. Put the timing back to where it says it should be.

Backups timing out backup buddy