So the other day i was driving down the interstate and there was a road construction truck infront of me. The back of it had a ton of signs. The truck went over a bump and 4 or 5 signs cma flying out of the back of the truck. I stomped on the brakes but there was no where to go. i tried to avoid as much as possible. The only thing damaged was my racing beat presilencer. The things pratically cut in 1/2. i'm guessing the sign flipped up when i ran over it and got caught. i pulled over whipped out the tools and got the presilencer off because it's pretty much crushed. Drove it home 30 miles away on a straight header i'm slightly deaf now. I think the rest of the city heard be coming into town from a couple miles back. After i got it back into town i put it up on the lift and check everthing. Nothing else, thankfully was damaged. I called the police to come out to my place and look at what had happened. I have the sign and my presilencer to show him. I got the licence plate of the truck that the signs came off of. I retuned the mangled sign to them to turn over to the dept of roads bu not before i got a ton of pics. Well here's the questoin. I'm puting my full ported s4 4 port 13b with my Megasquirt and turbo in my car this winter. I realy can't justify spending money on another presilencer so i was wondering how to hook up the 5th and 6th port on my n/a s4 if i just weld in straight pipe? is it even possible. i know they open with 4psi of back preasure. I'm very against wiring them open, please don't sugest that. someone enlighten me.

 

I know some of the second gen guys use what is called a lumbar pump to acctuate the 5/6 ports. It is an electric pump that puts out a couple psi. You could easily control this with the MS. All you would need is a relay and a little code mod. This way, you could also control when the 5/6 ports open (based on just RPM, RPM and MAP, RPM/MAP/ and engine warm, etc.).

Here is one on ebay. I don't know if this is one that they use or not. Maybe post or search over there to find out.

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

This should be a lot better than trying to use exhaust backpressure or the air pump to do the job, as you would have full control with this method.

Kent

 

i've just used the air pump and it works fine. sure some people like to remove it but eh. i just took a few hose fittings to accomplish it.

 

So if the air pump belt is not attached are the 5th and 6ths not going to open...?

 

Stock, the SE uses exhaust backpressure to open the 5/6 ports. However, if you change the exhaust to a more free flowing one, the 5/6 ports may open late or not at all. It is possible to convert them so that the air pump opens them as Gavin did. This is a good option. However, many times when people add a free flowing exhaust, they have no need for the air pump. In this case, the lumbar pump setup with either an RPM switch trigger of better yet use the megasquirt (aftermarket fuel computer) to control the 5/6 ports.