this is all the info from the guy off the turboforums that said he knows how to read the spark advance chart.im reading it over and over trying to understand it all.




Load is the engine load. 1 is 100%(most you can achieve with a naturally aspirated engine without ram air or something). Basically multiply the numbers by 100 to get the actual. Anything below 100% means you have vacuum in the engine. Anything above 100 means you have positive pressure(boost) inside the intake manifold. You just match up the load number with the rpm you are running to find the spark. Anything not specifically listed is determined from other values. So in between all the numbers you see, the computer just draws a straight line connecting the info. Right now the ambient pressure is around 14.7 psi, that's considered atmospheric pressure, it varies slightly when you change elevation. Anything above that is referred to as boost. So 1 psi of boost in your engine is really 15.7psi TOTAL. To get the amount of boost(roughly due to changes in elevation) just multiply the load number by 14.7. This is all psi. 100kpa is the same as 1 in the load value. 200kpa is 2 in the load value. The number you get when you cross reference load and rpm is the actual timing you are supposed to be running


The timing is set to make decent power until 6500 rpms below 8 psi. Above 8 psi the timing falls off a lot. If you add 4 degrees by twisting the dizzy then it will be four degrees above what you have now ASSUMING CURRENT TIMING IS AT 10. All those calculations are done by the computer thinking the base timing is at 10. You don't need to keep the spout out once you twist it... the problem is you will be running 22 degrees timing under boost at 8 psi. That might be enough to detonate...
Looking through your recent posts, if it's the thing you mentioned about hitting a brick wall, the likely culprit seems to be spark blow out. 11.5 degrees timing shouldn't make the engine just stop climbing in rpms.



You have 10.5 degrees timing from 3000 to 4750 rpm at 14.7 psi. If you have close to 13.5psi boost at 3k rpm and up, you are only losing one degree of timing when you hit 4750rpm. One degree shouldnt cause it to dropoff that sharply.
In one of your posts you said you are having issues with the psi dropping. That combined with the dropoff in power seems to indicate that the turbine housing is too small or some other restriction in flow. Assuming you are running the Turbonetics 76mm turbo from another one of your posts, the compressor should have plenty of power left. What size turbine housing do you have? What is the exhaust like after the turbo? Are you running a carburetor? If not what is the intake like other than the spyder intake?


It is low, I believe you should take it to the tuner and have him bump it up some, stuff like this is why I learned to tune on my own. I don't think it will fix the problem of the car falling on it's face though, but it might be. You should get that taken care of FIRST, and I believe the tuner should do it for free, but since you left there with it like that he might not fix it for free... 1 degree of timing ADVANCED should not make the car fall on its face all of a sudden, it should help make more power. That's why I believe it's some form of restriction in airflow


I am assuming you build full boost before 4800 rpm. Correct?
From 3000 rpm-4750 rpm, you have 10.5 degrees of timing at 14.7 psi, you have a little more at 13.5 psi. When you hit 4750rpm, at the same boost pressure, you GAIN 1 degree of timing. If you ran 8 psi you would have 18 degrees of timing, or if you don't build boost until 4750 rpms it will drop from 18 to 11 degrees when pass 8psi.
At 8 psi(right at 1.5 in the load row) from 3k-6500rpm you have 18 degrees of timing. But you are running more boost, close to 14.7, so you will be really close to the values in the 2.0 load row(horizontal) under boost. Which means at constant boost pressure of around 13.5 psi, if you build full boost before 4750rpm, when you hit 4750rpm you GAIN 1 degree of timing. The chart pulls timing as boost gets higher, but I'm sure you have full boost by 4750 rpms, which means you aren't losing any timing at 4750, you are gaining 1 degree