C6Z Big Cam Tune Review

[Indepth]

Hey Guys,

First post here, like most that decide to go with a big cam on these cars I struggled to get the car running right until I stumbled upon a great tuner in my area.

We tuned the car about a year back in SD and really smoothed out the driving characteristics of the car.

Since then I've added 2" headers (up from my original 1 7/8" headers) and a ported FAST102 intake manifold - which we adjusted the tune for.

Now, I've gone a step further adding a ported MSD intake manifold, NW102 throttle body, and swapping my Halltech intake for a Vararam intake (all in the search for minimal MAP loss at WOT).

I've adjusted my tune on my own this time by adjusting the ETC Scalar to what others have used with success for their NW102 throttle bodies and have tried adjusting things with small tweaks here and there in the VE tables.

After adding these parts and even after attempting to tweak the tune myself the car does buck a little on partial throttle during cruise.

I've attached my current log file and current tune (added 10% fueling to the lower portion of my VE tables because I had assumed I've increased airflow at this point).

Any insights that some of you more experienced tuners might see in my logs or tune are greatly appreciated.

NOTE: I reverted my tune files VE tables backwards. In the log file posted I had added 8% fuel from 1000-2200 to see if it was a fueling issue, judging the STFTs I saw in the log I think I was wrong seeing how much fuel was being pulled.

18-08-30 22-13-30.hpl

2007 - Corvette Z06 - DTM - Speed Density - 2in Headers - NW102 TB - MSD Intake Vol Adjusted - A.hpt

[Kfred 513]

Hey man, Im far from experienced but over time was able to get my 06Z running very well. The biggest thing that helped my bucking/trailer hitching was adjusting the End of Injection Timing. I compared your EOIT to my modified file, and a Stock 2010 Z06 and yours seems untouched. The idea is you are trying to prevent unburnt fuel from escaping the cylinder during cam overlap. By telling the ECM the last possible time it can inject fuel, it calculates the start of injection by adding (subtracting) the pulsewidth. It is also based on 720 degrees of rotation since two crank rotations is a complete cycle. Ed Mowton has a great spreadsheet that I used to help dial mine in. The numbers are going to be specific to the cam, but if you just want to experiment you can try moving your tables closer to where mine are to see if it helps. You are looking for Fuel>General>Injection Timing

-Kevin

[Indepth]

Hey man, Im far from experienced but over time was able to get my 06Z running very well. The biggest thing that helped my bucking/trailer hitching was adjusting the End of Injection Timing. I compared your EOIT to my modified file, and a Stock 2010 Z06 and yours seems untouched. The idea is you are trying to prevent unburnt fuel from escaping the cylinder during cam overlap. By telling the ECM the last possible time it can inject fuel, it calculates the start of injection by adding (subtracting) the pulsewidth. It is also based on 720 degrees of rotation since two crank rotations is a complete cycle. Ed Mowton has a great spreadsheet that I used to help dial mine in. The numbers are going to be specific to the cam, but if you just want to experiment you can try moving your tables closer to where mine are to see if it helps. You are looking for Fuel>General>Injection Timing

-Kevin

I'm surprised Fran from RPM didn't tune in the EOIT adjustments on your tune (I'm assuming since you're running a RPM B3 cam it was done at their shop).

I ran the calculations on my cam and am having difficulties trying to interpret the spreadsheets results for adjusting my specific tune to my specific cam. I've attached the spreadsheet to this post in hopes you might be able to guide me through some of the process of adjusting it.

INJECTOR TIMING TOOL GEN IV - Black Charts-Fbody.xlsx

[Kfred 513]

Edited to correct the question mark plague. I typed it in Word and pasted it here, not sure why that happened.

I live in Vegas and installed the cam myself and started my tune from a stock file. Fran never tuned my car, but I'd love to see one of his tunes because he makes idle sound amazing with this cam, and mine sounds mild in comparison. I'm glad I read your post and revisited my EOIT tables because I realized that I made a mistake and have my EOIT target 50 degrees earlier than I would like it, so I will be changing that ASAP. I'll explain my understanding of the process and you can go from there.

This is the way I set mine up, which may differ from person to person after talking to Ed. My injection Boundary table is set to the latest "time" in degrees, that the engine will finish injecting fuel for any circumstance. I used IVC - 30, which is also what your worksheet recommends. Based on your IVC at 598, it looks like a good Boundary would be 568 straight across that table.

Keep in mind that all three tables work together and my understanding of the formula is EOIT= Boundary - (Normal RPM + Normal ECT). My error was setting 50 in the ECT cells at normal operating temps, which is moving my EOIT 50 degrees earlier than I want. I think I will be zeroing out my Normal ECT table at operating temps, and using only the Normal RPM table to make adjustments. The factory has lower ECT cells set higher and I will be leaving those stock for now.

Assuming you Zero the Normal ECT table from 176-max, you will be using the Normal RPM table to make the rest of your adjustments. The worksheet says from 3000-4500, your EOIT target should be IVO peak. For your cam 474 is your IVO peak, so set the 3000-MAX cells to 94. (568 - 94 = 474)

Idle EOIT is where you need to know your pulse width, and calculate the time into degrees of rotation. The target here is for SOIT to be just after EVC. Your EVC is 374.

Take a look at the "Table" tab on your worksheet. At the top it has "PW in crank degrees total" which varies with rpm. If you add each PW number to 374, that becomes your EOIT Target for that RPM. That is not the number that goes in the cell though. Subtract your EOIT target from 568 to calculate the cell input. Formula looks like: Cell = 568 - (EVC+PW)

I used the PW calculation up to 2048 because that cell came out to 94 which was your target for 3000-4500 anyway. I wasn't going to start the PW later in the cycle, to then make it earlier a few hundred RPM later.

You will see that the Normal RPM table is maxed out at 4,096. Any RPM after that point has an EOIT target of whatever is set in the Boundary table minus the Normal ECT table, which in this case is 568 - 0.

I hope that all made sense, hopefully we both learned from it...I know I will be making changes after this closer look. I also took a screenshot of how I would set your car up based on the worksheet you provided. All of the numbers below 2048 in the Normal RPM table assume you put correct PW data in the worksheet.


EOIT Example.PNG

[Indepth]

I live in Vegas and installed the cam myself and started my tune from a stock file. Fran never tuned my car, but I?d love to see one of his tunes because he makes idle sound amazing with this cam, and mine sounds mild in comparison. I?m glad I read your post and revisited my EOIT tables because I realized that I made a mistake and have my EOIT target 50 degrees earlier than I would like it, so I will be changing that ASAP. I?ll explain my understanding of the process and you can go from there.

This is the way I set mine up, which may differ from person to person after talking to Ed. My injection Boundary table is set to the latest ?time? in degrees, that the engine will finish injecting fuel for any circumstance. I used IVC ? 30, which is also what your worksheet recommends. Based on your IVC at 598, it looks like a good Boundary would be 568 straight across that table.

Keep in mind that all three tables work together and my understanding of the formula is EOIT= Boundary ? (Normal RPM + Normal ECT). My error was setting 50 in the ECT cells at normal operating temps, which is moving my EOIT 50 degrees earlier than I want. I think I will be zeroing out my Normal ECT table at operating temps, and using only the Normal RPM table to make adjustments. The factory has lower ECT cells set higher and I will be leaving those stock for now.

Assuming you Zero the ECT table from 176-max, you will be using the Normal RPM to make the rest of your adjustments. The worksheet says from 3000-4500, your EOIT target should be IVO peak. For your cam 474 is your IVO peak, so set the 3000-MAX cells to 94. (568 ? 94 = 474)

Idle EOIT is where you need to know your pulse width, and calculate the time into degrees of rotation. The target here is for SOIT to be just after EVC. Your EVC is 374, but you can?t simply subtract 196 because that would set your EOIT and your entire injection event would happen with the exhaust valve open. Take a look at the ?Table? tab on your worksheet. At the top it has ?PW in crank degrees total? which varies with rpm. If you add each PW number to 374, that becomes your EOIT Target for that RPM. That is not the number that goes in the cell though. Subtract your EOIT target from 568 to calculate the cell input. Formula looks like: Cell = 568 ? (EVC+PW)
I used the PW calculation up to 2048 because that cell came out to 94 which was your target for 3000-4500 anyway. I wasn?t going to start the PW later in the cycle, to then make it earlier a few hundred RPM later. Also, i just roughly interpolated between cells since the table has many more columns than the worksheet.

I hope that all made sense, hopefully we both learned from it.I know I will be making changes after this closer look. I also took a screenshot of how I would set your car up based on the worksheet you provided. All of the numbers below 2048 in the Normal RPM table assume you put correct PW data in the worksheet.

-Kevin

EOIT Example.PNG

While I followed some of this, your post seems garbled from some form of transcoding issue - lots of ?'s throughout the post itself.

I'm glad you had a chance to revisit this, I don't have accurate data for my PW I left the spreadsheet alone when I opened it on that regard and I also realized I forgot to add the +4 ground-in advance on my cam. See below for my updated spreadsheet...

The only info I have on my PW is that I'm still on stock LS7 injectors - if you are as well I would assume that the PW would be identical between our cars, correct?

INJECTOR TIMING TOOL GEN IV - Black Charts-Fbody.xlsx

[Kfred 513]

I corrected my previous post so hopefully it should make more sense. I also made a few changes to make it easier to digest.

While our PW is probably very close, it will be different due to fueling requirements based on our setup. I would argue that if you are taking the time to figure this out, you should take the time to log PW and get yourself some truth data so its not a guessing game.

I just looked a scan of mine and PW at 1024 RPM varies from a max of 9.4, to a min of 1.8MS. 3.0MS is what I would call average for 1024RPM under steady state driving. I verified that by viewing only zoom data and checking number of cell hits, which is important to make sure you aren't looking at an anomalie...eg. one cell hit at 9.4MS. It is important that you are getting accurate numbers. Your worksheet mentions 1:1 for the engine/trans so i think thats 4th gear, but double check.

If you don't have one already, make a graph that matches the rpm in the Normal RPM EOIT table.



The parameter is Injector Pulse Width
Unit: Millisecond
Column Axis Parameter: Engine Speed
Unit:RPM
Values: Copy row axis from the Normal ECT EOIT table.

Then go back through the worksheet and fill in all of the data correctly. At that point you should be able to adjust all three EOIT tables based on my post above. If you are still having trouble I will take a look at the updated worksheet. Your finished EOIT tables will look similar to the screenshot i posted, but they will be off slightly due to updated PW and +4 advance.

[07GTS]

best to use the fuel error test for EOIT also as its not always an exact measurement and time the fuel actually takes with reversion also can affect it, my stock settings were calculated as ok but i still needed a further 30 deg delayed for actual results for idle

[Kfred 513]

best to use the fuel error test for EOIT also as its not always an exact measurement and time the fuel actually takes with reversion also can affect it, my stock settings were calculated as ok but i still needed a further 30 deg delayed for actual results for idle

Can you expand on that? I've never heard of a fuel error test. I would assume you wouldn't just delay the EOIT 30 degrees across the board because 30 degrees is a much longer time at lower RPM than higher RPM.

[Indepth]

Can you expand on that? I've never heard of a fuel error test. I would assume you wouldn't just delay the EOIT 30 degrees across the board because 30 degrees is a much longer time at lower RPM than higher RPM.

This.

I'm now officially confused at this point. lol

[Kfred 513]

This.

I'm now officially confused at this point. lol

Running the calculator and getting your tables set is probably more than most people do. It may not be perfect but it will get you in the ballpark and probably get rid of your issues.

[07GTS]

Can you expand on that? I've never heard of a fuel error test. I would assume you wouldn't just delay the EOIT 30 degrees across the board because 30 degrees is a much longer time at lower RPM than higher RPM.

just with the cam timing may not always be spot on, the time fuel is injected and delay it takes to reach chamber can be different and if u inject as the piston is still coming up as the overlap point it may disrupt fuel entering nicely from reversion, fuel test is just the trims error or wideband error see what it is stock and then adjust EOIT until idle goes richest meaning more/most fuel is going into chamber getting burnt then u can lean it back to stoich saving fuel, doing the test with fuel helps u know when the actual injection is getting into the chamber not just based on timing events then when u know u can base your other changes on that point,
i set boundary all 520 (zero out rpm table) then lower ECT table until fuel is richest then i know thats good then i use boundary table to delay injection as the rpm increase to suit cruise and for best torque/hp just remember to keep it smooth as rpm increase, increasing boundary delays injection

[Kfred 513]

just with the cam timing may not always be spot on, the time fuel is injected and delay it takes to reach chamber can be different and if u inject as the piston is still coming up as the overlap point it may disrupt fuel entering nicely from reversion, fuel test is just the trims error or wideband error see what it is stock and then adjust EOIT until idle goes richest meaning more/most fuel is going into chamber getting burnt then u can lean it back to stoich saving fuel, doing the test with fuel helps u know when the actual injection is getting into the chamber not just based on timing events then when u know u can base your other changes on that point,
i set boundary all 520 (zero out rpm table) then lower ECT table until fuel is richest then i know thats good then i use boundary table to delay injection as the rpm increase to suit cruise and for best torque/hp just remember to keep it smooth as rpm increase, increasing boundary delays injection

That makes sense. Also not a bad idea to zero normal RPM and make the adjustments to the boundary table. I wonder why GM chose to leave the boundary table with one value across the board. There is a lot more rpm columns than in the Normal RPM table.

[Indepth]

The thing that gets me is your post above states multiple equations to formulate the different values you end up putting into the various cells within tables.

If this can all be distilled down to formulas based on the outputs we see in this spreadsheet then why hasn't someone updated the spreadsheet to take the calculated results from the spreadsheet and spit those results into another formula that will give you a completed set of tables for you to just copy and paste into the 3 different tables?

Maybe I'm thinking too much on this one, but I can't help it when I see something can have a little work up front to have it be stupid easy in the long run. I think it's the engineer in me.

[G8NOOBIE]

have you tried installing an air straightener in the maf housing? ive seen where using a vararam it will create a surge buck condition driving

[Kfred 513]

Well like I said from the very beginning, there are multiple ways to get the same result. I chose to keep the boundary table set to the last possible EOIT, zero ECT table, and use the Normal RPM table to fine tune.

07GTS chose to zero Normal RPM, use ECT to set a max EOIT and use the boundary table to fine tune. Both work, but his version gives more resolution than mine since the boundary table goes to a higher RPM.

I'm sure you could modify the spreadsheet to spit out values for the tables for both methods. I am not an excel wizard so I chose to just do a few quick calculations lol.

[Kfred 513]

Also don't forget that different setups will require different target EOIT depending on if your cam has overlap or not, boosted or not, etc. So the number of calculations and outputs would stack up real fast.

[Indepth]

have you tried installing an air straightener in the maf housing? ive seen where using a vararam it will create a surge buck condition driving

Can't speak for Kfred but I'm SD tuned - MAF is failed at all times for me so I'm not concerned on the Vararam on my car messing with my driving characteristics.

[07GTS]

yea many ways to skin a cat, as mentioned i like the boundary way because it has better rpm resolution mine slopes up from idle to 6k then flat after that, also what u can do is set the idle then set your hwy cruise rpm and then slope from idle to cruise then increase (delay) more for power after that as rpm increase, if u have overlap u can save fuel at cruise also once u get spark timing right just adjust eoit for that area and look at your instant fuel usage (cruise control on hwy) see if it goes up of down if it goes down then ur getting better torque

[Indepth]

yea many ways to skin a cat, as mentioned i like the boundary way because it has better rpm resolution mine slopes up from idle to 6k then flat after that, also what u can do is set the idle then set your hwy cruise rpm and then slope from idle to cruise then increase (delay) more for power after that as rpm increase, if u have overlap u can save fuel at cruise also once u get spark timing right just adjust eoit for that area and look at your instant fuel usage (cruise control on hwy) see if it goes up of down if it goes down then ur getting better torque

There's no way to edit these tables in the VCM Scanner like you can adjust some fueling and timing tables while scanning, is there? That would make it too easy...

[07GTS]

There's no way to edit these tables in the VCM Scanner like you can adjust some fueling and timing tables while scanning, is there? That would make it too easy...

unfortunately not