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Thread: Another 6.4 Whipple throttle flutter thread- Yes I searched

  1. #1

    Another 6.4 Whipple throttle flutter thread- Yes I searched

    2018 Jeep SRT8 GC. I do alot of Mopars and I've not really had major issues tuning the boosted ones for the most part, at least not anytime recently.
    Customer is at high elevation. (Denver- so think 6000 ft)
    I first tuned this jeep remotely when stock , went great.
    Customer then added a TSP custom ground camshaft and MMX Drop Ins- I do a ton of TSP Hemi cams- cam is a 224/237 on a 115 LSA. The cam is locked out and the tune reflects that. NA tuning was a breeze.
    Customer then added Fore system, 2.9 Whipple, and Hellcat TB. along with a 18% lower. This is where things have gone afu.......

    I have the dreaded part throttle flutter. Anywhere from 1.0 to 1.6 volts or so, throttle/map/pulsewidth all oscillate. this also tends to coincide with 1.0 p-ratio as well.
    I have read essentially any and all of the whipple related Hemi threads here, and have implemented most of the changes. I have reduced TB airflow/desired large range to about 60-80 g/s and while the flutter is FAR less severe, and oscillates slower, it is still present. I believe I have gone as far as I can with those changes specifically.

    I have also noticed in my log that as rpm/tp increase into "the flutter zone" , once it goes into flutter "Total Airflow" rapidly drops to almost zero.

    I have never been one to copy/paste out of other files but I did look into Hemituna's files supplied and did implement some changes that did provide some benefit, but it has not gone away.
    As I understand it, if I dial up a higher pedal pct% torque request at the flywheel it will only make the problem worse, bumping into the corresponding tq or airflow limit even harder.
    I believe due to the reduced vacuum due to the camshaft, combined with the high elevation, I believe this issue is beyond what can be solved in the calibration, and requires a modified bypass so that it is not so quick to close.

    Any suggestions?

  2. #2
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    Try lowering Sensed Map to maybe 0.75, setting Min Phi to 1 on both values, and making ETC Proportional Gain no larger than 1

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    Quote Originally Posted by tbrtuning View Post
    Try lowering Sensed Map to maybe 0.75, setting Min Phi to 1 on both values, and making ETC Proportional Gain no larger than 1
    What he said ^^

    I see cam LSA is 115, but what adv is it installed at??
    Will be a better NA cam than blower cam but hey its in there so what can you do.

    Also to those who think a modified (later closing) bypass is the answer, you are actually going about it backwards.
    The longer you wait to close bypass, the more open the TB is as you press on the gas (moreso with a wheezy, cammy, gutless-no vacuum engine)...so when bypass finally closes, there is so much TB flow to blower that it comes on with a rush and you have the dreaded lightswitch effect. You can hold off for an eternity to close bypass and yes it will drive like an NA....but this is a blower engine and should make a heap of boost at 2k.
    They actually work better if bypass closes at a small vac (-5 to -10") and then the TB controls airflow into blower.....They are dead smooth like this...just like a big NA engine.

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    Quote Originally Posted by Hemituna View Post
    What he said ^^
    Also to those who think a modified (later closing) bypass is the answer, you are actually going about it backwards.
    The longer you wait to close bypass, the more open the TB is as you press on the gas (moreso with a wheezy, cammy, gutless-no vacuum engine)...so when bypass finally closes, there is so much TB flow to blower that it comes on with a rush and you have the dreaded lightswitch effect. You can hold off for an eternity to close bypass and yes it will drive like an NA....but this is a blower engine and should make a heap of boost at 2k.
    They actually work better if bypass closes at a small vac (-5 to -10") and then the TB controls airflow into blower.....They are dead smooth like this...just like a big NA engine.
    Makes one wonder why the restrictor pill is used on the bypass straight from the manufacturers?

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    Quote Originally Posted by Homer View Post
    Makes one wonder why the restrictor pill is used on the bypass straight from the manufacturers?
    Cos they can't tune but really need to sell blower kits

    I've tried everything over the years and when it comes down to it always end up with the stock actuator, no restrictor, correct adjustment and they work great.

    Hell, some even work real good with the bypass locked closed (zero bypass) just for giggles/testing.....u should try it...makes you realise that holding off on closing the bypass is not a good plan
    if you want it to go like a proper blower engine.
    Last edited by Hemituna; 05-15-2020 at 04:07 PM.

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    Quote Originally Posted by Hemituna View Post
    Cos they can't tune but really need to sell blower kits

    I've tried everything over the years and when it comes down to it always end up with the stock actuator, no restrictor, correct adjustment and they work great.

    Hell, some even work real good with the bypass locked closed (zero bypass) just for giggles/testing.....u should try it...makes you realise that holding off on closing the bypass is not a good plan
    if you want it to go like a proper blower engine.
    Oh that is interesting. I recently bought a smooth boost controller but holding off on the install because it is a PITA to remove the stock actuator on a TVS 2300. Not sure if you are familiar with the actuator but it basically ties the bypass control to the pedal signal and you can adjust it for 0 to max boost. It also has a valet mode and can be used as a failsafe.

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    Quote Originally Posted by Homer View Post
    Oh that is interesting. I recently bought a smooth boost controller but holding off on the install because it is a PITA to remove the stock actuator on a TVS 2300. Not sure if you are familiar with the actuator but it basically ties the bypass control to the pedal signal and you can adjust it for 0 to max boost. It also has a valet mode and can be used as a failsafe.
    The ONLY reason guys use these type of controllers is to remove the lightswitch effect caused by lack of tuning (knowledge).
    If you log hard enough, you will see the TB is not following the pedal in a linear fashion with the stock settings.
    This is because it was NA from factory. The airflows, DD and flywheel power are all to suit NA.
    If you add a centri blower it still works okish. A PD blower however totally changes the game and needs a host of changes.
    Once you trim back the airflow numbers so the TB at PT follows the pedal, you can trim the DD and flywheel power to get the pedal feel/engine response you like.
    This results in a super-smooth controllable progression towards WOT that even your wife will love to drive, but with a ton of tq everywhere like a blower engine should have.
    Holding off closing the bypass is effectively making it act more like a centri....and who wants that.

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    Quote Originally Posted by Hemituna View Post
    The ONLY reason guys use these type of controllers is to remove the lightswitch effect caused by lack of tuning (knowledge).
    If you log hard enough, you will see the TB is not following the pedal in a linear fashion with the stock settings.
    This is because it was NA from factory. The airflows, DD and flywheel power are all to suit NA.
    If you add a centri blower it still works okish. A PD blower however totally changes the game and needs a host of changes.
    Once you trim back the airflow numbers so the TB at PT follows the pedal, you can trim the DD and flywheel power to get the pedal feel/engine response you like.
    This results in a super-smooth controllable progression towards WOT that even your wife will love to drive, but with a ton of tq everywhere like a blower engine should have.
    Holding off closing the bypass is effectively making it act more like a centri....and who wants that.
    Thanks for the share. I was actually hoping to use it as a valet mode and to better control max boost as opposed to always swapping out the pulley. I would think grabbing the signal direct from the pedal as opposed to the throttle blade or MAP would make it respond faster than a manifold vacuum signal (i.e. the OE vacuum bypass actuator)? One of my forum buddies he has seen a few guys use the smooth boost controller at MSHS series. Never used one of these before on a PD setup.

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    Bypassing air to control boost recirculates hot air. Setting up tune to limit throttle would be my recommendation to limit power without swapping pulley. Like HemiTuna was saying so much of the behavior people describe on PD blower driving bad is all in tune.

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    Hi I've been learning to use HP tuners for about six weeks on my 19' scat pack 8 sp. This is my first post and don't really know forum etiquette. I've got a whipple stage 2 kit ordered. I don't have a Mopar guy around here, so I will likely use a remote tune. I'm not sure if it's ok to ask for recommendations here. I am a competent auto tech, but I am a little scared to ''just do it'' even with all of the info you all have posted on here. I'm not blowing smoke when I say that I am impressed and relieved to see all of the help offered by some of you to folks to people you don't even know. Thanks!

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    Quote Originally Posted by tbrtuning View Post
    Bypassing air to control boost recirculates hot air. Setting up tune to limit throttle would be my recommendation to limit power without swapping pulley. Like HemiTuna was saying so much of the behavior people describe on PD blower driving bad is all in tune.
    So instead of swapping the pulley...or using a controller...are you suggesting to upload a tune when I want to limit boost levels?
    Last edited by Homer; 05-17-2020 at 11:08 PM.

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    Quote Originally Posted by Bryan Spanjer View Post
    Hi I've been learning to use HP tuners for about six weeks on my 19' scat pack 8 sp. This is my first post and don't really know forum etiquette. I've got a whipple stage 2 kit ordered. I don't have a Mopar guy around here, so I will likely use a remote tune. I'm not sure if it's ok to ask for recommendations here. I am a competent auto tech, but I am a little scared to ''just do it'' even with all of the info you all have posted on here. I'm not blowing smoke when I say that I am impressed and relieved to see all of the help offered by some of you to folks to people you don't even know. Thanks!
    Hopefully you are going to run a wideband? Most email tuners will require you to do so.

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    Quote Originally Posted by Homer View Post
    So instead of swapping the pulley...or using a controller...are you suggesting to upload a tune when I want to limit boost levels?
    I typically have people change tune to limit power if they have a good way to flash changes. Also do power limiting by gear to get them to hook up better

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    Just wanted to clarify on the limiting power thing.... Are you talking about because of octane limitations from fuel swap?

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    Quote Originally Posted by tbrtuning View Post
    Just wanted to clarify on the limiting power thing.... Are you talking about because of octane limitations from fuel swap?
    In my case I wanted a valet type control. But your method to limit power through the tune makes total sense for different fuel types.

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    You can do it in tune either way. Was going to say if when switching fuel you want it probably be best to switch pulley and just tune for the fuel really if you want the most out of it.

    Limiting power for someone else to drive it kind of thing like you're describing is easy enough just in the tune. It gets more complex when you want to start doing by gear and getting the most out of it for different road conditions or tire kind of thing.

    Quick and easy thing for you would be to set the Max Throttle table but let it get enough throttle to get Enrichment if you floor it. Some OS don't like really low PE pedal positions but you could take it down to 2v at least on about any of them.

    Not sure what your current tune is like but you could pull timing too if on aggressive E85 or race gas tune. If already pretty octane limited and running low timing as a result I wouldn't pull more out though

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    Quote Originally Posted by Homer View Post
    Hopefully you are going to run a wideband? Most email tuners will require you to do so.
    I've got an AEM obd2 type I will install in the next few days.

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    Quote Originally Posted by Bryan Spanjer View Post
    I've got an AEM obd2 type I will install in the next few days.
    Do yourself a favour and get TBR to remote tune it for you....Travis is a great tuner, knows all the tricks and is VERY patient with newbs.....unlike me... lol.
    Last edited by Hemituna; 05-18-2020 at 08:27 PM.