The Hellcat supercharger uses a electric throttle body as a bypass when not building boost. A regular supercharger uses a vacuum bypass I believe. I am looking for ideas on what would be needed to either run the electric bypass or retrofit a vacuum unit.

The pic is showing the bypass itself for reference.

Thanks for any help as this is the last hurdle to make our swap work.

Could be tricky, Efisource was saying they had one running. Wonder why Mopar doesn't offer a plug and play for these as well.

Which EFI controller are you using? Some have built in waste gate controls, you could probably fab one in with a waste gate valve and let the ecu handle it.

Have not bought a controller yet. The main throttle body is drive by wire so I was thinking Holley Dominator. Talked to EFI source today they are building one for the Hellcat but who knows how long it will take.

I am in over my head here a little but want to learn. I have been thinking of ways to gut the bypass valve and make it work with a vacuum. Time to do some hot rodding on this.

Had another thought. If this were to be converted to a vacuum unit, it would function no different than a magnuson, whipple, etc. The mopar plug and play kit could be tuned to work with this engine.

Or get the 4.5 Whipple that bolts to the Hellcat engines.

Are you keeping the factory EFI system? I know a guy who's tuning them now and getting noticeable gains over stock. He started out doing the 5.2/5.9 magnum stuff in Dakotas using SCT, but is now tuning all the hemi stuff as well as viper v10 stuff.

Flyinryan performance. Look him up on FB or his website.

Already have the Hellcat blower, and the Whipple uses the stock hellcat bypass.

As far as EFI, don't know yet. The EFI source sounds good, as well as Mopar's new plug and play if I can get it to work with this engine/Blower

I wonder if an oil pressure sending unit would work, or something along those lines. 0 pressure and below it sends 12v to a relay which then energizes the bypass and opens. Anything above 0 and it cuts power closing the bypass. Super simplified explanation but that'd be my angle

I would try to get a vacuum operated supercharger bypass valve and piece the two together

I THINK that a vacuum retrofit would be the best ticket as of now. After looking at the electronic bypass it looks like it could be gutted and a vacuum unit bolted on.

Lots of hurdles when doing this swap on the cheap lol!

I wonder if the EFIsource box maintains some outputs that the megasquirt has. IF it did it should be fairly straight forward to have it open and close based on the MAP sensor. As long as the voltages are known.

Why are you wanting to get rid of the electronic bypass?
If it is for performance gains, but still be streetable, you would be better off to keep it and get a tune to achieve what you want.
The electronic bypass is much better from an overall standpoint than the vacuum bypass. The vacuum bypass is like a rotary dial phone vs. an I phone.
If you don't get the vacuum set up right or have a problem with it, you can cook you blower. The electronic is fail to open while the vacuum fails to close.

The Electronic bypass is hard to manage without the proper computer, and since hellcat swaps are not just real common yet I am not sure who has the ability to run it properly.

I do know there was a shop out of a Florida that did a Hellcat swap on a 60s B body and was using Holley EFI. I saw this in the G3 Hemi Swap group on Facebook.

Thanks for the info guys- I want to get rid of the electric bypass because of the complexity in has with it, especially for us as we are learning as we go. The way I see it, if you can get rid of that part there is no difference between a Hellcat with a vacuum bypass or a 6.4 hemi with a supercharger and vacuum bypass.

There is lots of tuning info for the supercharged 6.4's.

One last thing I have learned- the bypass is actually the only thing that changes between the 500 hp black key and the 700 red key. Just thought I would share.

I would ask this question on the MS3 forum (ms3efi.com). I think you would get the best drive ability with the electronic throttle body vs. a vacuum motor with no feedback to the computer. Do you know if the OE bypass is a stepper motor or full open/full close kind of deal?

Why not just block the bypass off and let it act like the rest of the blowers out there?

I would stay with the electronic valve and use the Holley Dominator. You can easily configure an I/O based on MAP to open and close the valve.

It causes them to overheat when you have little throttle opening

RPM switch set to close the bypass at somewhere above 2200 rpm, and a pressure valve plumbed from the pressure side to bleed off excess pressure back to the inlet side of the intake? The extra pressure sensitive bypass may be needed at some point in the rpm range to stay below your chosen boost level.

Thanks everyone for the advice- I will let you all know what I do and how it works.

Bumping an old thread - I have a Megasquirt Gold Box/EFI Source, anyone have an update on how that wires up and works out?

FYI, you only want the bypass closed at WOT or close to it. Otherwise you will have problems in the long run. Lots of guys burning them up because they think disabling the bypass is a good idea...

IIRC your motor is built a little better than stock correct? I think a Whipple, or Magnuson would be a more cost effective solution that would work with your EFI without any additions.

I'm investigating both options. The pre-eagle 5.7L i have is stock with the only modifications being an upgraded cam, opened ring gaps [for this very reason] and headers.

I figure a whipple would run about $5-6k, Hellcat setup is looking around $8500-$9000 if I were to sell the 5.7L off for a couple of bucks and add another 80-100whp I figure. The bragging rights that go along with owning a "Hellcat Cuda" is also appealing.

I have done several of these using the Holley Dominator ECU. I replaced the DBW bypass with a vacuum operated one that I got from Magnuson. Bolted right in.
efiexpert.com

Rich,

Thank you for that information. I searched on their site. Do you have a part number handy?

Another option is www.SmoothBoost.com they have a plug and play controller that runs the hellcat valve regardless of what efi system your using

EFI source gold box will run the bypass without any extra stuff added on.

This is what I'm using on our Hellcat swap. Just got the car running but it will be awhile before it can be street tested. I have a Holley Dominator EFI