SA tables

[RooThunder]

Since I am using EBL that has, what I believe, is a proprietary mask, all tuning has to be manual outside a VE learn. Copy and paste doesn't work,
as the tables also present differently. The truck pulls pretty hard after about three hours adjusting VE, with low knock counts. I figured, being new to
tuning, that I should tackle timing next to get the most out of the cam with the somewhat limited TBI heads. I was looking for a table to wrap my head around
the SA difference to point to the areas i could start adjusting the timing. The caprice iron head 9C1 is also a good starting point.
The attachments are the Corvette LT1 and the table I am using (L05, 5spd, '90 c1500)

Bryan

VetteLT1.PNG
90L055spd.PNG

[dave w]

Ok, some members are really challenged with "Laptop" skills. The post above demonstrates good "Laptop" skills. The Dynamic EFI system is a good system with several features the factory TBI computer does not have. I agree, not sharing proprietary Dynamic EFI information is a good plan. I agree, sometimes the Dynamic EFI user needs to "Course Tune" prior to VE Learns. The attached screen shots below are from my Dynamic EFI WBO2 spreadsheet I configured for EBL WBO2 tuning.

To copy paste timing tables from different Masks ($EE vs. Dynamic EFI), interpolation is required. Different Masks have different table sizes or dimensions. Dynamic EFI has the main SA 12 cells (columns) MAP and 17 cells (rows) RPM. The Main $EE SA has 16 cells (columns) MAP and 15 cells (rows) RPM. TunerPro can only copy / paste identical table sizes. To copy / paste the $EE table into Dynamic EFI the $EE table has be interpolated to 12 cells (columns) MAP and 17 cells (rows) RPM.

Tuning is Trial and Error. The option to use $EE or $EEB SA tables interpolated to fit the Dynamic EFI table is tuning.

dave w

Lower AFR's 3-17-20.jpg

Upper AFR's 3-17-20.jpg

[Fast355]

Ok, some members are really challenged with "Laptop" skills. The post above demonstrates good "Laptop" skills. The Dynamic EFI system is a good system with several features the factory TBI computer does not have. I agree, not sharing proprietary Dynamic EFI information is a good plan. I agree, sometimes the Dynamic EFI user needs to "Course Tune" prior to VE Learns. The attached screen shots below are from my Dynamic EFI WBO2 spreadsheet I configured for EBL WBO2 tuning.

To copy paste timing tables from different Masks ($EE vs. Dynamic EFI), interpolation is required. Different Masks have different table sizes or dimensions. Dynamic EFI has the main SA 12 cells (columns) MAP and 17 cells (rows) RPM. The Main $EE SA has 16 cells (columns) MAP and 15 cells (rows) RPM. TunerPro can only copy / paste identical table sizes. To copy / paste the $EE table into Dynamic EFI the $EE table has be interpolated to 12 cells (columns) MAP and 17 cells (rows) RPM.

Tuning is Trial and Error. The option to use $EE or $EEB SA tables interpolated to fit the Dynamic EFI table is tuning.

dave w

Lower AFR's 3-17-20.jpg

Upper AFR's 3-17-20.jpg

B-car LT1 is what the TBI and Vortec maps I have posted are based on. They max out about 28° at WOT and have a conservative advance rate given many had 2.56 gears in a 4,000 lbs car.

[84Elky]

Here's a fool-proof technique to build a Spark Table. It does not follow the GM model where spark is all over the place. It works much better. Agree with Fast355 that Vortec heads should max out at 28-30* advance. RPM at that advance subject to engine build, but generally 2800-3200.
https://www.thirdgen.org/forums/diy-...ml#post6301288

[RooThunder]

Thank you for your reply, very informative post !! Got some studying to do !!

[lionelhutz]

Here's a fool-proof technique to build a Spark Table. It does not follow the GM model where spark is all over the place. It works much better. Agree with Fast355 that Vortec heads should max out at 28-30* advance. RPM at that advance subject to engine build, but generally 2800-3200.
https://www.thirdgen.org/forums/diy-...ml#post6301288

Interesting post, but I don't understand why at full throttle (100kpa cells) you would ramp to max advance, for example 28* for Vortec or 36* for conventional at around 3000rpm, and then start ramping the timing back down again. The example of dropping to 24* @ 4800rpm Seems like a good way to kill upper rpm power. Good way to stop knock though.

[dave w]

The piston speed vs. fuel igniting lag time is an important dynamic for spark advance. Fuel takes time to ignite, then explode. As the piston speed increases (aka RPM increase) the timing of the IGNITING Spark needs to occur when piston is further away from TDC.

dave w

[lionelhutz]

That's my belief Dave, following that post's info but ramp to max timing at 100kpa and then flat line to redline, not ramp back down.

[84Elky]

Interesting post, but I don't understand why at full throttle (100kpa cells) you would ramp to max advance, for example 28* for Vortec or 36* for conventional at around 3000rpm, and then start ramping the timing back down again. The example of dropping to 24* @ 4800rpm Seems like a good way to kill upper rpm power. Good way to stop knock though.

Admittedly, I'm not a timing expert. And the amount of timing reduction in the example may not work for everyone. Maybe it should not be reduced at all. It depends on many factors because every engine is different. But two things cannot be disputed:
1) Any timing advance past MBT (Maximum Brake Torque) reduces power, regardless of the octane of fuel used.
2) Advancing the timing past what's needed will only increase cylinder pressure at TDC, and what is all that extra cylinder pressure doing at TDC -- it's trying to push the crankshaft out of the bottom of the engine.

Below are some excerpts supporting the above from my notes. Attributions are not available except where links are provided.

Engine Ignition Timing - Basics & Overview (Daytona Sensors)
http://www.daytona-sensors.com/engin...uidelines.html

The most significant factor to determine ignition timing will be the combustion chamber/cylinder head and piston design, this can vary significantly on different setups.

So when you're tuning ignition and isn't limited by knock, you'll keep adding timing until the power stops increasing. If you keep adding timing it will eventually start decreasing due to the combustion working against the piston moving upwards.

The best way to set ignition timing is on a load type dynamometer is to slowly advance the timing until peak torque output is reached.

We can apply this prairie-fire analogy to the combustion space. At WOT, the air and fuel are tightly packed and burn quickly, so we don't need as much timing. At 2,800 rpm at WOT, 32 to 34 degrees of timing could be just about perfect for a typical pump-gas street engine. However, at very light throttle (14 to 16 inches of manifold vacuum), the air and fuel are far less densely packed in the cylinder. To make the most power possible at part throttle, we need to start the combustion process much sooner—perhaps as much as 40 to 44 degrees BTDC, depending on the engine's individual demands.

On a dyno you can easily find where MBT is by using the method described in the above example, on the street it may be harder to tell, typical dyno loading allows for an engine to hit MBT where that's not possible on the street with actual loading as it will almost always result in pinging thus detonation before getting there. Its not uncommon for most dyno tuners to remove a global 3 degrees of timing or the like when removing a vehicle from a dyno to prevent detonation on the street.

[lionelhutz]

Yes, it's all good stuff. But, I still haven't seen anything that says to run to a peak timing value and then ramp it back down as the rpm further increase.