16 Hellcat Bypass valve bleeding boost???

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Hoping to get some experienced eyes on this file.. I have only done a handful of Hellcats and this one is modded the most.. and I believe I have the bypass valve is staying open and then shutting as RPMs increase??? Also only able to get around 6-7 degrees of spark advance at high aircharge loads.. Figured this pulley setup on 93 I could get away with 12

16Hellcat A8 (stock trans file)
220bosch injectors
2.50 pulley/93 octane
Catless H pipe
No mufflers
6" inlet that necks down to factory TB

Makes roughly 18lbs

Thanks for any feedback. If I can help any of you dodge guys on GM ECMs please let me know

Anyone have any thoughts?

I think you're getting near the max efficiency of that blower. I will try to check log and tune when I get on the computer to see if I see anything. Is MAP flat or dropping off with RPM?

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IT sure would help if I added the LOG


Fuel is between 78-81 lambda.
Timing looks a little soft to me (looks like I'm loosing around 6-7degrees)
boost stays between 17X-22X boost doesn't drop up top (that's when it makes peak pressure)

Something that looks interesting is Bypass valve PIDs
Desired SC bypass valve shows around 1.07 till upper RPMS and then goes to 0.00 volts and I get additional PSI... This is why I believe the bypass valve is staying open

Figured out what was happening, in case anyone reads this!!

Put bypass valve settings back to stock.. shoots too 220kpa and holds there... no linear increase in boost now..

Over several tunes I didn’t adjust the max airflow table under engine diag. So I was chasing my tail with the bypass valve settings.. the ECU was indeed bleeding boost but only Bc it was told too by the max airflow table.

Also should add if you are experiencing a LV2 torque limit (which causes ECU to pull tuning and close throttle) this is directly related to the bypass valve

I completely forgot about this. Sorry. Figured it was a limit though because if anything I see boost drop at high RPM on a setup like that not like you were describing.

As far as the timing goes when spinning Hellcat blower that fast they get really noisy so you have to dial knock sensors back a lot. You can log knock sensor voltages to look for spikes that would indicate actual knock. That is more boost than I recommend to customers on 93 but have done it and running more timing than you were saying.

I did adjust the voltage settings (increases them)

Basically a stock timing table with 3-4 degrees less since blower speed is around 20k..

I agree on this amount of boost on 93, customer wants to swap to e85 soon when the low side can keep up..

Haven’t messed with the custom E85 OS for the cats so that should be fun

I will add this voltages and look, but total knock retard PID didn’t show any being pulled

Hi friends you dont figure out to lower the boost on this setup bypass via maybe to 15 16 psi and the increase the timing ? for 93 pump maybe is better lower boost and more timing due a increased iats on thats boost levels

Mine is falling on it's face in the middle of 5th gear while racing. Your thoughts?Attachment 100964

Would need to see a log and tune. Just from glancing at that screenshot I really don't know what kind of vehicle or setup I'm looking at. If Hellcat they will hit ACT limit in Torque Reduction section if tune in the summer later in pulls sometimes especially at drag strip when sitting heat soaked between runs. If fuel pressure is good and it just drops boost bad then I would check that.

Looked more at screenshot you posted and intake air temp is low so not what I was thinking. I was assuming the normal limits needed were raised and it was doing something unusual but seeing that screenshot makes it hard to tell. You had some big time torque reduction request from something it looks like

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Originally Posted by tbrtuning

Would need to see a log and tune. Just from glancing at that screenshot I really don't know what kind of vehicle or setup I'm looking at. If Hellcat they will hit ACT limit in Torque Reduction section if tune in the summer later in pulls sometimes especially at drag strip when sitting heat soaked between runs. If fuel pressure is good and it just drops boost bad then I would check that.

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can't it be belt slip?

Possible I guess but to lose all boost at a similar point in pulls I doubt it. Would have to be slipping bad to cause that kind of boost loss.