I have an '86 IROC and want to tune it a bit better. I am currently using the 32B mask to tune the car. I have been reading lately that the 6E mask is better.
Can someone describe why it is better and what benefits are there to using that mask? Next what bin should be used as a base?

 

I dont know if its "better" per se, but I like it more than the 32/32B. It doesnt have the pulsewidth tables that the 32B has. I find 6E fairly easy to use and tune. Normally just have to adjust MAF tables slightly and use PE vs RPM enrichment for WOT tuning.

I have used AUJL bins for $6E for my 383 and worked well. Another member here uses my base tune for his motor. I have tuned another car using ARAP modified with a slightly different timing table, abit less aggressive. Those are the main 2 I worked with and like the best. ARAP works pretty well for alot of builds just need to watch the aggressive timing table.

 

When you say aggressive timing, do you mean it ramps in quick or that it is too much timing. If I am not mistaken the ARAP is for a aluminum headed vette? What is the AUJL bin for?

 

aggressive in that it does ramp in quick from off idle to part throttle but the WOT isnt too aggressive as far as RAMP in is concerned. Its aggressive in that it is high timing. Common to see 40-41 deg in part throttle areas. Not all cars NEED that much timing, it all depends on how well the heads are working. Older inefficient burn heads like the stock L98 aluminums and old AFR 190's need the extra timing. New AFR's are better and only need 35-38 deg at cruise to be happy.

AUJL is the iron headed fbody spec motor, 350 L98. Look at its timing table compared to an ARAP. 5-6 deg less in most areas. Sometimes more.

Your sig states you have vortecs? Those heads are pretty efficient burn rate heads, and typically I see them running 30-32 deg timing but you will have to play with it. Certainly an ARAP bin in that application would be far to high on timing. I like to mix an iron head timing table with the ARAP overall bin for a starter and then work timing as necessary once my air fuel is somewhat in line.

Stock timing tables arent very smooth and you can see that by the graph view. I like to smooth them out as well before running it in the motor.

 

Thanks. Yes I do have the vortec's. You think that 30-32* of timing is good for those heads? I have noticed that as well. The timing table has peaks in very odd places. Now I have read somewhere as well that in higher load you want less timing then in an area with less load. One obvious reason would be detonation, is there any other reason that is?
Are there many other differences between the arap and aujl bins? I will have to compare them, but just thought i'd ask.

 

higher loads have higher cylinder pressures generally so you want less timing to prevent detonation.

Higher rpms generally want more timing because you need to start spark earlier inorder to have enough time to burn the mixture. Piston speeds are moving very fast the higher you rev.

So the timing curve should rise with RPM and should decrease with higher loads.

Free reving in park or neutral will have the least amount of load and can have the highest amount of timing. WOT in gear will have MOST amount of load and the least amount of overall timing.

 

Makes sense. I will take a look at both bins then see which one to use.