I was curious about the boost bypass. How much hp can one expect with this mod? What all is involved with this mod? What kind of reliability can I expect with a daily driver? I already have an Anderson power pipe, Diablo chip, Mac cat back exhaust, and a 6# lower pulley. Thanks for any advise.

 

boost bypass kit is just a few tubes. i think you may have to cut one tube and install a t-fitting or something like that. not very difficult. most people prefer to live with the soft code and just unplug the bypass saving $25....do a serch and im sure you can find a pic of the harness your are supposed to unplug...good luck

 

$25? I spent $3 at PepBoys and got the same thing!

 

I wrote this for Doug. This should help.

The Lightning motor has a valve on the near the back of the blower on the drivers side that relieves or bypasses air past the blower. This valve serves two purposes on the Lightning motor. During high vacuum situations (when you are not requiring high power), air leaks around the blower to avoid ware on the blower drive and heat. Once the motor gets to 0 vacuum on it's way to boost, the valve is designed to close and allow the motor to build boost. The other function that this valve is designed to do is protect the motor from over-boost when the motor hits the rev limiter. The problem is that when this boost bypass is energized, it remains in that position for quite some period of time. This only seems to happen when doing tire warming at the track and the first time you find out that the bypass is in 0 boost mode is about 30 ft from the start line on your way to a 17sec @ 78 MPH pass. This mod is the 10 min and $3 solution to this problem. Note: I have heard that the boost bypass my come in with an over-heat situation and may also come in with the torque reduction if still active in your chip.

Remove the pink line from the top of the boost control diaphragm valve, (not the solenoid valve) and plug it. I used a 1/4" bolt cut to about 3/4 inch long but that still has about 1/4" of smooth shank so you don't get an air leak. You can use a 1/4" hose mender and a 1/4" cap.

Next, get 3/16" Tee at the auto parts store. Put this Tee into the boost hose that goes into the firewall and up to the boost gauge(there is a white 3/16" hose mender in this location stock). Get 9" of 3/16" rubber fuel line to go from this Tee to the top of the boost control valve.

The result is the computer will no longer have the ability to dump boost at the shift (torque reduction) or as part of the over-rev protection. The computer will never know and will not throw a soft or hard code. The boost bypass will still be active at idle through near zero vacuum, and closed shut in all boost conditions. Just be careful, The computer can't help protect you from over-revving and over-boosting or over-heating and doing
damage to the motor.

see http://www.ncs-stl.com/Images/BoostMod.jpg for photos

Hope this helps

Andy

 

This kit is designed to allow your engine's PCM to continue to control your engine smoothly, with not interruption of boost output from your supercharger

The bypass valve is a release which vents off pressure in a rapid de-acceleration situation. When the Supercharger is producing boost and you abruptly let off the gas, closing the throttle plates, the boost has nowhere to go (also known as compressor surge) kind of hard on everything. The Bypass helps relieve this and also helps smooth out your idle. It is also helpful in building up boost faster, and as a bonus it helps to prevent parasitic power loss. Under idle or normal driving (vacuum) the valve is open. When it sees a boost signal it closes.

 

Well, im confused.

The last two posts have me wondering. Do the boost bypass or not?

Has there been any documented performance gain from a Boost Bypass mod? Im familar with Centrifugal blowers. If you do not have a bypass and you close down throttle as described above, you get some serious surging.

Now, seeing that this is a roots type blower and boost is added after the TB, it makes it kind of hard to control surging and heat obviously if you have this bypassed. There also would be no way to plumb a quality, vaccum boost bypass unit from a Vortech unit because of the boost hitting the TB after the fact.

I always find this a good topic but im also left confused at the same time. If there was a manual non electronic boost valve available from eaton, it may just solve this question once and for all. Dump boost only when throttle blade is closed.

 

Both methods that are commonly talked about on this board do allow the boost bypass to bleed boost at idle and part throttle. Both methods also make it impossible for the computer to dump the boost to limit hp. The primary differance between the two methods is that when you unplug the power to the valve...the computer sets a soft code (that does not seem to cause any problems unless you go to the dealer and forget to reset the code and they come to the conclusion that you were racing the truck)

Hope this helps

Andy

 

Me too I just wonder if the long term effects out weigh the short term gains

 

According to the JDM boost bypass kit instructions, you unplug the pink line under the boost actuator solenoid. The pic awhittle posted above shows something totally different.

Anyone care to comment?

 

As far as I can tell, the instructions along with JDMs kit are wrong. They result in the permanant closure of the boost bypass (you want it open for idle).

A Boost Bypass kit will get you ZERO hp. It's benefit is that the computer can't cut boost on you unexpectedly.

Coldie

 

This is what the boost bypass looks like installed. The round rubber grommet is on the firewall on the driver's side.

 

Chicken, that looks wrong.

It looks like you followed JDM's instructions which result in the boost bypass ALWAYS being turned off.

What you really want is a tube fron that T fitting to where the pink line was connected, then stop up the pink line.

That will get the boost bypass to work in idle situations.

If you want to check, start your engine and give the throttle some gas (via twisting the throttle). If the BB is on correctly, you should see the valve move...

Coldie

 

Hadden,

I did your test and the valve is moving if I'm seeing what I think is right. It's under the boost bypass module, moving down on acceleration. Is this correct?

Tim

 

That's correct. Hmm.. what do you have connected to the valve? (where the pink line used to go)

Hadden

 

The screw that came with the bypass kit is inserted into the boot that the pink hose came out of.

Tim