Dynamic Airflow/Manifold Volume

960 Views 8 Replies 2 Participants Last post by 07GTS, 7 mo ago

kittyboy

Discussion Starter · 7 mo ago

Hey,
I'm doing some comparisons between stock CTSV and ZR1 Dynamic Airflow values. I see that the CTSV is 13,487 and the ZR1 is 10,328? I'm working on dialing in my transient fueling at this time because I am now running a dynamic MAF/SD setup. I've gone through some logs and haven't noticed any extreme transient fueling issues. I do understand that there is always a bit of lag simply due to the distance to the WB. So with that said...

I have a couple questions:

I noticed that both stock CTSV tables, 'Evap Factor' and 'Impact Factor' are only scaled out to 100kpa N/A, why is that on a supercharged engine? Seems the values should be scaled out to at least 2 bar? Maybe it's due to the assumption that the 4000rpm SD is applicable and it's non-applicable?

Thanks in advance for clearification and maybe even some experienced advice regarding transient fueling.

PS: I have a B15 which has an LS7 cam, very similar to the ZR1 cam profile, and an LS7 throttle body with 5636 setting. thanks...

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07GTS

· #2 · 7 mo ago

manifold volume is the space that the transient has to think of ingestion wise when the throttle is moved/stomped, moving that value is an blanket style adjustment can be easier then the impact/evap adjustments if it works, i dont think that the transients are needed above 100kpa might be that the airflow entering is faster (pressurized) on boost so it negates the need for adjustment after that point (just my thinking)

transients are only during throttle movements once its steady its no longer in play just make sure that if fueling is smooth VE and MAF if u go from say cruise to 50% throttle and stay there (keeping possible PE enrich in mind) the WB should show if the fuel meets commanded or if it dips richer and then back to commanded (too much transient) or if it stays little leaner then commanded ( to little transient) can take alot of messing around but mainly just have it so ur at least a smidge rich on stomps is better then leaner

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kittyboy

Discussion Starter · #3 · 7 mo ago (Edited)

07GTS said:
manifold volume is the space that the transient has to think of ingestion wise when the throttle is moved/stomped, moving that value is an blanket style adjustment can be easier then the impact/evap adjustments if it works, i dont think that the transients are needed above 100kpa might be that the airflow entering is faster (pressurized) on boost so it negates the need for adjustment after that point (just my thinking)

transients are only during throttle movements once its steady its no longer in play just make sure that if fueling is smooth VE and MAF if u go from say cruise to 50% throttle and stay there (keeping possible PE enrich in mind) the WB should show if the fuel meets commanded or if it dips richer and then back to commanded (too much transient) or if it stays little leaner then commanded ( to little transient) can take alot of messing around but mainly just have it so ur at least a smidge rich on stomps is better then leaner

Update: I'll first make change and log the manifold airflow prior to Evap/Impact, it just seemed confusing after making comparison to the ZR1 value? Then maybe play around with 10-20 percent 80-100kpa range on both the Evap/Impact, see if it helps with the transient during gear change up to the 6200rpm cutoff I have set.

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07GTS

· #4 · 7 mo ago

try about 10% at a time i usually do blocks not cells and i like to keep the lowest two map rows 20-30kpa the same value for each given IVT temp for deceleration, the the top 40-100kpa i have the same but slightly higher for driving, seems to get more stable fueling if they are that way but if u have each map cell different as it travels thru them it as well as reacting to each value it reacts to the difference between each value, but just see how u go testing is tuning got to see what your engine likes

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kittyboy

Discussion Starter · #5 · 7 mo ago

07GTS said:
try about 10% at a time i usually do blocks not cells and i like to keep the lowest two map rows 20-30kpa the same value for each given IVT temp for deceleration, the the top 40-100kpa i have the same but slightly higher for driving, seems to get more stable fueling if they are that way but if u have each map cell different as it travels thru them it as well as reacting to each value it reacts to the difference between each value, but just see how u go testing is tuning got to see what your engine likes

I added 10% row 80, 15% row 90, 20% row 100. That sound right? Wasn't sure about the normal driving range areas 20-70.

So taking into account I have an LS7 cam and throttle body. you think I should also add to rows 20-70 in the normal driving areas, think 10%?

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07GTS

· #6 · 7 mo ago

see what its like or even just do the 30-100 map just add same % to all as the higher numbers will increase more but keep in line, or just set the 30-100kpa all the same value and adjust as needed, it can be a good rabbit hole so just get it good or at least smidge richer on tip in and call it done otherwise u could be there for months and weather changes

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kittyboy

Discussion Starter · #7 · 7 mo ago

07GTS said:
see what its like or even just do the 30-100 map just add same % to all as the higher numbers will increase more but keep in line, or just set the 30-100kpa all the same value and adjust as needed, it can be a good rabbit hole so just get it good or at least smidge richer on tip in and call it done otherwise u could be there for months and weather changes

Thanks for the help, I'm just trying to tweak a few outlying areas of my tune, been putting it off for awhile as I focused on the mechanical side of things. But now everything is running so well I have time.

I keep a mechanical journal, as well as general visuals before going out for runs. Overkill probably, PTSD from the last engine I killed, I even have Blackstone reports. The new ST-246 clutch is awesome!

Next up on the tuning list is using airflow and torque values to model with the throttle angle to control the throttle opening as a rev limiter feature.

Thanks again

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07GTS

· #8 · 7 mo ago

kittyboy said:
Thanks for the help, I'm just trying to tweak a few outlying areas of my tune, been putting it off for awhile as I focused on the mechanical side of things. But now everything is running so well I have time.

I keep a mechanical journal, as well as general visuals before going out for runs. Overkill probably, PTSD from the last engine I killed, I even have Blackstone reports. The new ST-246 clutch is awesome!

Next up on the tuning list is using airflow and torque values to model with the throttle angle to control the throttle opening as a rev limiter feature.

Thanks again

yea having it mechanically spot on is first step then tuning is easier and repeatable, just dont adjust the virtual torque it should be close its only estimated engine torque, rev limiter has its own torque tables that work quite well, there is the table that stops the rpm going higher then another table for when its held under control by the limiter, can be hard with the PD blower but can make them so ur not bouncing off a hard cut can be much softer

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07GTS

· #9 · 7 mo ago

when ur testing the limiter just set it lower like 4000rpm then u can just hold the gear and roll into it to see how it acts without smashing the high revs

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