Ok lets see I took off the factory exhaust off my 87 n/a and went to a shop and they put on one high flow cat and all new 3 inch piping front to back into 2 high flow hks dragger mufflers how can I check to see if I still have enough backpressure to open the 5th and 6th ports.Help me out and if not enough how can u fix them so that they open.

Justin

 

Will the car pull smoothly to 7K rpm? Does the car seem to really hesitate and/or die after about 3500 rpm?

Also, is this a S4 (86-88) or S5 (89-91) model? I am not sure if wiring them open is the same on the S5 models, but I know you can just wire the 5th and 6th ports open on the S4 models (can't imagine why not on the S5, but who knows)

 

on s5's the ports open up from the air pump. instead of exhaust back pressure like on the s4's. is there still a little pipe comming from the cat to the ports?

 

from what i understand u need 3-6 psi to open up at the right time. Ive heard of people installing a nipple on their straight pipe where the sensor would normally be and its worked fine. also u can tap into something else cause it gives proper pressure but i dont recall what it was. im sure someone else on here will be able to point u that way.

 

I ran my 6-port hose to the acv "exhaust" hose via a 90 degree nipple fitting, seems to work fine, ports open about the same time as when I had the stock exhaust on

 

tap a nipple into the exhaust manifold below the o2 sensor. i used a 5/16 (8mm) brass fitting and then ran a brake line to the actuators. you have to mess with it until you get the angle and size just right for them to open at the right time.

to check if they work:
put some heavy grease on the shaft of the 6p actuator. dab it on right where it goes into the actuator. go drive a mile...keep the revs high and put some pressure on it. if the grease is all pushed to the other end of the shaft, they opened.

pat

 

here's what you do... you know the little line that (should) be hooked up to the pipe going to your cat to get enough pressure to open the ports? well that line can be ran into the ACV relief line and get enough pressure to open the ports as well... then you no longer need exhaust back pressure to open the 5th/6th ports

and btw, 3in piping? thats a bit overkill for an n/a..... it's probably robbing you of power... torque is made from backpressure, and you probably have almost none... that size of piping is for turbos, and definately not needed in an n/a unless you have some major porting