Your motor has an internal air temp sensor? Lucky

Hi everyone. This is my Regal that Geforcextreme posted. He just let me know about this thread, so I registered over here to answer some of the questions.

The twin-charge setup has been around for a while on the 3800 supercharged cars. ZZP sells this setup as sort of a kit. They ran it on a Grand Prix GTP that trapped in the 140's on 27psi. The kit is designed to use the supercharger at low rpms for boost off the line, and then the supercharger bypasses and the rotors freewheel as the turbo kicks in. This helps eliminate spool lag on the turbo, and allows a larger turbo to be used if desired. This is from the ZZP FAQ:

What is the twin charged configuration?

This setup is made for running the blower and the turbo. It uses a different style of exhaust housing on the turbo and works with supercharged or symetrical cams. It requires an intercooler below the supercharger. This setup is recommended for running anything larger than a 67mm turbo. It works well with lower stall converters and can spool up to a 80mm turbo. We ran this setup on our 9 sec street grand prix. It comes with electronics to open the supercharger bypass when the turbo spools.

One of the benefits of this setup is that it allows people with highly modified M90 configurations an easy, affordable upgrade path. By selling your airbox, headers, and 42# injectors, you can make back some of the cost. Additionally, cars running a intercooler can keep most of the existing setup. The twin charged kit works well with supercharged cam profiles. A twin charged setup, given similar mods will always outperform a turbo only solution.


I will also add that this setup seems much better for a street car. At the track, the turbo alone could be spooled sufficiently off the line (or nitrous added), and there really isn't that much of a need for the supercharger boost. But, on the street the supercharger really helps to power up quickly and then the turbo makes sure there is no top end loss.

My car is intercooled with a 2.5" W/A core that sits below the supercharger. I run a Frozen Boost FMHE (type 101) with a large reservoir/icebox. If I load up the icebox at the track, I can safely run larger amounts of boost as the water temps in the core drop down to 10-20 degrees below ambient air temps for the run. I just ran a few days ago for the first time with the twin-charge setup and pushed about 15-16psi (not sure exactly how much as I only have a 2-bar MAP right now, and my boost sensor hasn't arrived yet to install).

My plan is to install another W/A core for the turbo charge. This will make a twin-intercooled setup that will allow me to push the boost into the 20's. The setup right now with the u-bend charge tube is just temporary. However, it works fine and the tube is short enough to avoid surge at the boost levels I'm running. The T72 is a BB unit and runs surprisingly cool. I also put a blanket on it after the pic was taken. That will also help make this a great street setup and keep underhood temps down.

Before I get to high boost, I have to upgrade the transmission. That will get done this winter. I'm not worried too much about the engine bottom end. There are plenty of 3800's running much more power on stock internals. This is a very stout block. I do want to change out the cam though. Not sure which one yet. There are a few selections that make good power. I'm just trying to find one with decent street manners. I'm not interested in making this car a track queen yet. I also want to see how far a stock cam will go. There are a few guys running mid-high 11's on a stock cam, so I know I can get at least that fast. If I do chip a piston, there are 3800 short blocks available, and I can rebuild pretty cheap. There are also JE forged pistons available now, so that is another option for the future.

Anyway, thanks for checking my ride out. I'll try to post over here more as I see there are a lot of local members that I'll probably run into at Atco. I also have a '98 supercharged 5.9L Durango that I am going to rebuild soon. That is getting a bore, new bottom end, new heads, and some other goodies.