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Thread: Bigger Throttle Body

  1. #1
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    Bigger Throttle Body

    So I've been doing a bit of reading and comparing of part numbers and calibration files from the 2013-2015 5.7L 6.4L and 6.2L engines when it comes to throttle body flow data. My past history with work on GM LS engines was that if you changed throttle bodies, ported throttle bodies or had someone drill a hole(really old school) you would introduce phantom issues while driving and idle if you didn't change your throttle body scaling to account for the new size. I see that the Dodge calibrations for throttle body flow are rates that the TB flows while on a flow bench when the blade is at a certain reported voltage. So in theory I could take the 6.2L Hell Cat TB and put it on my 5.7L and copy the flow table over? But what has be curious is when I compare part numbers of a 2013 5.7L to a 2014 6.4L TB they are the same yet the flow rates are slightly different. Where and why could this be? Do they flow test the TB with the intake filter assembly on it as well and that differs between vehicles?

  2. #2
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    Although labeled as bench flow numbers, I believe there is compensation in there for the various flow rates of the different intake manifolds, intake tubes, air filters, etc etc. I have also noticed variations from the same engine/TB from one model year to the next, indicating through testing they decided to amend the flow rates.

  3. #3
    Here's a few files, one from a stock SRT8 Grand Cherokee, and one from a SRT8 Grand Cherokee fitted with an 88mm Arrington throttlebody with a CAI. You should be able to compare to get an idea on what changes were made.
    Attached Files Attached Files
    Level 3 Master Chrysler/Jeep/Dodge/Ram technician
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  4. #4
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    Quote Originally Posted by Monzsta View Post
    Here's a few files, one from a stock SRT8 Grand Cherokee, and one from a SRT8 Grand Cherokee fitted with an 88mm Arrington throttlebody with a CAI. You should be able to compare to get an idea on what changes were made.
    Interesting you had to make no changes to any of the throttle body or airflow tables.

  5. #5
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    I'm wondering the same thing too. What I am seeing is the possibility of using a 6.2L 92mm TB off the HellCat and just copy over the TB flow characteristics from the appropriate tables. Now you have a big factory TB with as accurate info as you can get. I am all for using aftermarket as well but from what I can see there aren't any flow numbers available for these TBs to accurate tune for them. What I don't know yet is if the TB is plug and play or if it is possible to just repin a 5.7L harness to accept the plug for a 6.2L if it doesn't match up.

  6. #6
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    believe a2speed makes a plug and play harness to change over. what other mods you have done to your 5.7L? That is a fairly big throttle body for that setup unless it has a good bit of cam/head/exhaust work. I would hesitate just pasting in all the values given just how different the setups are, especially because of the blower on the 6.2L.

  7. #7
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    Well it's nothing I am going to doing right now as the only thing I have done are headers and an intake on a 2013 Durango R/T. What I am looking at is down the road with an Edelbrock Supercharger what else I can add on to it. Based on what the tables say, it should just be characteristics for the TB itself and not the rest of the engine, so in theory it should work plugging in and go.

  8. #8
    Not my tune. I scalped it from a vehicle I worked on. I like to collect tunes.
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  9. #9
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    Take the factory flow numbers with a grain of salt.
    Don't be afraid to play with them.
    I have a 700whp Whippled 6.4 with a hellcat 95mm TB that has the max TB airflow number as 400.
    Why?? because P/T responsiveness/drivability is soooooo much better with smaller numbers.
    The factory numbers above 1v are too big. Above 1.5- 2v, they are waaaay tooo big.
    Fit a larger TB and drive it and it will feel better...Add 10-15% to TB tables as you 'should' do and it goes back to feeling like it did prior to the mod.
    So try a bigger TB and smaller numbers and hey it now feels even better... go figure!!
    The idle areas 0 -.5v will sometimes need adjusting to a slightly larger number to get that area correct.
    Last edited by Hemituna; 01-06-2017 at 07:26 PM.

  10. #10
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    Let me explain the above a little more.........
    A stock 6.4L tune has the WOT airflow limit as 353 g/s.
    But the TB table goes to 1100 g/s ??
    So how does that work??
    Now, if you log max airflow on a stock 6.4, the biggest number will be 350-360 g/s.
    So 350 g/s makes 475hp it seems....So why is everyone using 1000 - 1500 g/s to make 100-300hp more???
    The factory it seems has imbedded an airflow model in the PCM, hence why you must designate an engine capacity.
    Now this model only affects P/T operation. Between the TB airflow and what they deem the engine requires at P/T,
    the TB will track an airflow target. Now WOT is WOT and the TB will open 100% no matter what the numbers are in the tables.
    But P/T between 25 - 75% throttle, you are limited to the numbers in the model. So if the 6.4 is in P/T mode it will never open the TB past 353 g/s whether at 30% pedal or 70%. Most never notice this. If you move WOT threshold lower, you notice it less. BUT, if you make the airflow tables bigger, the gap between P/T and WOT gets even greater.
    If you make the numbers bigger, the TB will be opened less until it goes WOT.
    If you try and increase the ETC tables, what often happens is the ETC opens the TB, the airflow exceeds what's allowed and the ETC is forced to close the TB. So you get this strange surging effect.
    Why the factory has done this is to give the engine the amount of TB that they feel it needs at certain rpm to maintain velocity/airflow/smooth the torque curve or whatever!
    However, when modding or adding a blower, this is now not ideal.
    So following their lead with TB flow tables often wont get the result you are after.
    On a blower engine, 50% pedal, wont give enough TB opening to make much boost so you don't get 50% power. so you keep leaning on the pedal till finally it goes WOT and BAM - full boost and look out! The often talked about light-switch effect! This same response is felt when NA also.
    The trick I have found is to lower (a lot!) the 3 TB airflow tables in the .75 -1v and above areas.
    This will give a much more linear pedal to the point where the transition to WOT is seamless.
    The added benefit is that you no longer hit lots of Airflow/Tq mgmt limits!
    Keep in mind the stock airflow max numbers and give it a try.
    We can talk more about NOV and Wheel Power tables later.......
    Last edited by Hemituna; 01-07-2017 at 10:02 PM.

  11. #11
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    Quote Originally Posted by Hemituna View Post
    Let me explain the above a little more.........
    A stock 6.4L tune has the WOT airflow limit as 353 g/s.
    But the TB table goes to 1100 g/s ??
    So how does that work??
    Now, if you log max airflow on a stock 6.4, the biggest number will be 350-360 g/s.
    So 350 g/s makes 475hp it seems....So why is everyone using 1000 - 1500 g/s to make 100-300hp more???
    The factory it seems has imbedded an airflow model in the PCM, hence why you must designate an engine capacity.
    Now this model only affects P/T operation. Between the TB airflow and what they deem the engine requires at P/T,
    the TB will track an airflow target. Now WOT is WOT and the TB will open 100% no matter what the numbers are in the tables.
    But P/T between 25 - 75% throttle, you are limited to the numbers in the model. So if the 6.4 is in P/T mode it will never open the TB past 353 g/s whether at 30% pedal or 70%. Most never notice this. If you move WOT threshold lower, you notice it less. BUT, if you make the airflow tables bigger, the gap between P/T and WOT gets even greater.
    If you make the numbers bigger, the TB will be opened less until it goes WOT.
    If you try and increase the ETC tables, what often happens is the ETC opens the TB, the airflow exceeds what's allowed and the ETC is forced to close the TB. So you get this strange surging effect.
    Why the factory has done this is to give the engine the amount of TB that they feel it needs at certain rpm to maintain velocity/airflow/smooth the torque curve or whatever!
    However, when modding or adding a blower, this is now not ideal.
    So following their lead with TB flow tables often wont get the result you are after.
    On a blower engine, 50% pedal, wont give enough TB opening to make much boost so you don't get 50% power. so you keep leaning on the pedal till finally it goes WOT and BAM - full boost and look out! The often talked about light-switch effect! This same response is felt when NA also.
    The trick I have found is to lower (a lot!) the 3 TB airflow tables in the .75 -1v and above areas.
    This will give a much more linear pedal to the point where the transition to WOT is seamless.
    The added benefit is that you no longer hit lots of Airflow/Tq mgmt limits!
    Keep in mind the stock airflow max numbers and give it a try.
    We can talk more about NOV and Wheel Power tables later.......
    Good work ,

    You mean with boosted and bigger tb we should lower airflow number in tb airflow table and large range ??

    My car have 85mm tb and flow more with adding airflow in both table

    With stock value i have only 3xx g/s and with modify airflow table i get 5xx g/s

  12. #12
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    Quote Originally Posted by Hemituna View Post
    Let me explain the above a little more.........
    A stock 6.4L tune has the WOT airflow limit as 353 g/s.
    But the TB table goes to 1100 g/s ??
    So how does that work??
    Now, if you log max airflow on a stock 6.4, the biggest number will be 350-360 g/s.
    So 350 g/s makes 475hp it seems....So why is everyone using 1000 - 1500 g/s to make 100-300hp more???
    The factory it seems has imbedded an airflow model in the PCM, hence why you must designate an engine capacity.
    Now this model only affects P/T operation. Between the TB airflow and what they deem the engine requires at P/T,
    the TB will track an airflow target. Now WOT is WOT and the TB will open 100% no matter what the numbers are in the tables.
    But P/T between 25 - 75% throttle, you are limited to the numbers in the model. So if the 6.4 is in P/T mode it will never open the TB past 353 g/s whether at 30% pedal or 70%. Most never notice this. If you move WOT threshold lower, you notice it less. BUT, if you make the airflow tables bigger, the gap between P/T and WOT gets even greater.
    If you make the numbers bigger, the TB will be opened less until it goes WOT.
    If you try and increase the ETC tables, what often happens is the ETC opens the TB, the airflow exceeds what's allowed and the ETC is forced to close the TB. So you get this strange surging effect.
    Why the factory has done this is to give the engine the amount of TB that they feel it needs at certain rpm to maintain velocity/airflow/smooth the torque curve or whatever!
    However, when modding or adding a blower, this is now not ideal.
    So following their lead with TB flow tables often wont get the result you are after.
    On a blower engine, 50% pedal, wont give enough TB opening to make much boost so you don't get 50% power. so you keep leaning on the pedal till finally it goes WOT and BAM - full boost and look out! The often talked about light-switch effect! This same response is felt when NA also.
    The trick I have found is to lower (a lot!) the 3 TB airflow tables in the .75 -1v and above areas.
    This will give a much more linear pedal to the point where the transition to WOT is seamless.
    The added benefit is that you no longer hit lots of Airflow/Tq mgmt limits!
    Keep in mind the stock airflow max numbers and give it a try.
    We can talk more about NOV and Wheel Power tables later.......
    Good stuff! I will have to take some time and dissect everything you are referring to so I can start logging that to watch it happen. I appreciate the input!

  13. #13
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    Quote Originally Posted by Hemituna View Post
    Let me explain the above a little more.........
    A stock 6.4L tune has the WOT airflow limit as 353 g/s.
    But the TB table goes to 1100 g/s ??
    So how does that work??
    Now, if you log max airflow on a stock 6.4, the biggest number will be 350-360 g/s.
    The throttle flow table is g/s at sonic condition (mach 1 flow through the throttle), NOT at running condition. At MAP < ~52.8kPa they are the same. At high MAP, the sonic flow will be far higher than the actual flow.

    You should be able to copy a throttle flow table between any Chrysler tunes without issues.

    If you take a naturally aspirated setup and add a turbo, it won't calculate the throttle pressure ratio correctly (since it only measures MAP and assumes barometric pressure), and all of the throttle flow calculations will be way off. As far as I know there's no good way to fix this.

  14. #14
    I am doing this very thing to my 2007 6.1 with a Magnuson TVS2300. I am going to be using a Hellcat Tbody with the wiring adapter from A2 speed. My plan was to copy the flow tables from a stock hellcat tune and adjust the idle areas if needed. Modern Muscle makes an adapter plate to fix the mounting issue BTW.

  15. #15
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    Put the tables back to stock and drive it...betcha it feels better..
    Then chop 20% outa the tables above .5v and drive it....betcha it feels even better
    You will get the idea.....

    The airflow numbers are just that, numbers.
    Its really a glorified SD system FFS.
    The airflow and torque numbers are really only used to quantify air/fuel/spark to control & correctly drive accessories/ auto trans etc.
    These don't speak/care for the usual Tuner language such as vacuum/boost, spark and cam timing so need to be told torque or airflow numbers.
    I used to think it was some crazy voodoo till I worked out it is actually rather simple.


    Quote Originally Posted by RevHard View Post
    Good work ,

    You mean with boosted and bigger tb we should lower airflow number in tb airflow table and large range ??

    My car have 85mm tb and flow more with adding airflow in both table

    With stock value i have only 3xx g/s and with modify airflow table i get 5xx g/s

  16. #16
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    Quote Originally Posted by Hemituna View Post
    Take the factory flow numbers with a grain of salt.
    Don't be afraid to play with them.
    I have a 700whp Whippled 6.4 with a hellcat 95mm TB that has the max TB airflow number as 400.
    Why?? because P/T responsiveness/drivability is soooooo much better with smaller numbers.
    The factory numbers above 1v are too big. Above 1.5- 2v, they are waaaay tooo big.
    Fit a larger TB and drive it and it will feel better...Add 10-15% to TB tables as you 'should' do and it goes back to feeling like it did prior to the mod.
    So try a bigger TB and smaller numbers and hey it now feels even better... go figure!!
    The idle areas 0 -.5v will sometimes need adjusting to a slightly larger number to get that area correct.
    Did you develop that data yourself or did you get that from Whipple? I'm putting a 4.5 Whipple on a Hellcat and my biggest question is the TB data.

  17. #17
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    Quote Originally Posted by apalrd View Post
    The throttle flow table is g/s at sonic condition (mach 1 flow through the throttle), NOT at running condition. At MAP < ~52.8kPa they are the same. At high MAP, the sonic flow will be far higher than the actual flow.

    You should be able to copy a throttle flow table between any Chrysler tunes without issues.

    If you take a naturally aspirated setup and add a turbo, it won't calculate the throttle pressure ratio correctly (since it only measures MAP and assumes barometric pressure), and all of the throttle flow calculations will be way off. As far as I know there's no good way to fix this.
    This is why I have asked for Sonic airflow to be added to our logging ability but hasn't happened. In diablo world logging sonic airflow versus total airflow was very important so you can see the "error" the PCM was tracking.

  18. #18
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    Unlike most tuners, I drive one of these things everywhere, everyday.
    Dynotune and a trip around the block doesn't cut it.
    I'm constantly trying things to get em to drive perfect.
    Perfect keeps getting better and better though and I've found to get that means you must deviate from the so called 'rules'.
    I have chased making all the numbers line up forever, but they still don't feel right.
    So I am telling you what I do that actually works.

    Quote Originally Posted by Jay@HAP View Post
    Did you develop that data yourself or did you get that from Whipple? I'm putting a 4.5 Whipple on a Hellcat and my biggest question is the TB data.
    I develop the numbers until they feel right....as that is all they really are - a tuning tool..

    Lower numbers make the TB open more aggressively, bigger numbers open it less.

    Mess with the tables till it starts to feel good. It will vary depending on TB size, cam timing changes and the pulley on the blower.
    If the engine is more responsive, calm the table with bigger numbers, if it is lazy, feed it some more TB earlier with smaller numbers.
    Bear in mind, that with a PD blower the TB feeds the blower, so if you want a lot of blower with just a squeeze of the gas, the TB will have to open good and early......but N/A's like it too..

    If you seriously think the factory numbers are some magic numbers, then keep on using them!
    But every tune I do like this has the owner saying Wow...Wow...WOW!! Why aren't they like this factory??
    Last edited by Hemituna; 01-09-2017 at 08:41 PM.

  19. #19
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    Quote Originally Posted by Hemituna View Post
    Unlike most tuners, I drive one of these things every day. I'm constantly trying thing to get em to drive perfect.
    Perfect keeps getting better and better but that means you must deviate from the so called 'rules'.
    I have chased making all the numbers line up forever but they still don't feel right.
    So I am telling you what actually works.



    I develop the numbers until they feel right....as that is all they are...a tuning tool..

    If you think they are some magic numbers, your tunes will never be REALLY GOOD!

    Truthfully the stock tunes are far from great...that's why we are here!
    someone get an umbrella, cause it's raining cold hard truth up in here. :nod:

  20. #20
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    Hahaha

    Quote Originally Posted by Jay@HAP View Post
    someone get an umbrella, cause it's raining cold hard truth up in here. :nod: