patman

iTrader: (3)

Ok guys i brought this up a while ago, and never got around to it, but with my recent rebuild i finally had a chance to try it out. Heres what i did.

On my exhaust manifold, just below the o2 sensor, and facing towards the front of the manifold as much as possible, i drilled a 5/16 " (8mm) hole and tapped it. I used a pipe thread adapter and a piece of brake line to bring that out to just below my charcoal cannister, and bent the line so it was facing towards my 6 port actuator hose nipple. then i used a piece of standard vac line to connect them and hose clamps.

Seems to work great. As far as i can tell my ports open at around 4k rpms..which is a little late, but not too bad.
The only drawback is that i had to get rid of the heat shield around my exhaust manifold. However, as long as yours isnt all rusty and fucked up like mine was im sure u could just drill a hole in it.

I do have very extensive porting (intake manifold, as big of a street port as possible, and i got rid of my exhaust diffusers and ported my exhaust some), so with stock airflow it might be better to go up one size and then regulate the pressure if needed. (can be done with just a zip tie around the rubber hose)

Anyway, just thought i should share this with all of you who want to get rid of all yoru extra **** or have an exhaust that is not condusive to stock 6p operation.

-Pat

hornbm

ok mabey its just me, but I'm not seeing the point of this mod. Except for S5's the 6 ports open through exhaust back pressure.... which is exactly what you are doing.

S5's use the air pump which is a MUCH better way to open the ports.

Whats the gain here?

patman

iTrader: (3)

yes that is exactly what im doing. The difference is that with the stock sytem, the exhaust backpressure is generated by the flow resistance of the cats. I dont have cats. I previously used the acv dump tube method, which emulates the s5 system, but my new system works better and i was able to get rid of my air pump, and acv. The only real benefit is a much nicer engine bay and about 15-20 lbs weight reduction. Which isnt bad for one hour of work and $5.

-Pat

RETed

I'm not an NA person, but doesn't the 6-ports open way after 4kRPM???


-Ted

1987RX7guy

iTrader: (3)

3800

Rxmfn7

iTrader: (4)

You may be thinking of the VDI ports on S5s, which open at ~5500 rpm. The auxillary ports (5th and 6th ports if you will..) open at ~3800RPM.

Silly turbo guys....dont you know nuthin

Aaron Cake

iTrader: (1)

Why are you running an "extensive" street port with the stock manifold? That's what I'd like to know...

silverrotor

iTrader: (1)

Chance are that If It's cheap and easy, It's not effective. However, you have provided otherwise.

This Is what I've used for over a year now with excellent results (should you try to use alternative means ro open the Auxilliary Ports up). https://www.rx7club.com/forum/showth...ht=fully+blown

hugues

If you want to use backpressure, you have to drill into the exhaust somewhere as upstream as possible if you don't have the hookup from the cat or silencer.

I wonder what pressure numbers you get whether you hook up as upstream as physically possible (like Pat seems to have done) or more donwstream where the cat would be.

Just wondering.

Hugues -

patman

iTrader: (3)

i use the stock manifold because im too cheap to buy headers. might make my own next summer tho...shouldnt be too hard to do... didnt realize the stock one was all that restrictive, tho...

im nto sure the pressure #s, hugues..all i know is it works..but i might be able to slap a guage on there if u are really wondering... all it takes to open the ports is 2 psi or some **** so i dont think its really much of an issue...

-Pat

downwinddave

How does hot exaust effect the port actuators vs. nice "cool" air from the pump?

What is the diahaphram in the actuator made of?

patman

iTrader: (3)

well..the stock s4 system runs them on exhaust, so i assume they can handle it..also..with that small volume of air its not really much heat...and..well..i havent melted them yet, been using this system for 3k miles now.