canonize-ryda

only to find no information about this. i am about to purchase the entire uim including fuel rails and all the such.
but first i wanted to know exactly what was involved and i heard little modification was made and if you need anything special to make it.
the car is a 86 gxl. sorry i searched and found only fd uim on fc(like 5 times)

fc3s91

iTrader: (23)

http://howto.globalvicinity.com/gv_w...i=63&co=1&vi=1

misterstyx69

iTrader: (142)

I know one thing.In order to make the Upper assembly fit Snugly you are going to have to grind a small nub off the center iron,as the Assembly hits and won't allow the thing to sit properly.
There are really NO big gains on doing the s5 upper on an s4.You would be better off to get a Cone filter and a good flowing exhaust.
Keep your money.

canonize-ryda

Well i was shown dyno results and was told it would be the most notable mod for the s4.
according to rotaryrocket88 it wasnt a bad idea.
i do have a cone filter and need headers but other wise have free flow exhuast.
taking your advice into consideration i will wait longer to find out more information about it.
thanks

canonize-ryda

searched more, and this was said from other sites, "there were no gains in the mod, just used s5 uim for emissions".
now this doesnt sound like something i am wanting to spend time doing.
and thanks mister

lastphaseofthis

iTrader: (8)

whats your plans for controlling Aux ports and VDI? without those being operated at critical rpm's, the gains you could have will be moot.

The most common method is to get rpm switchs from summit and supply vacuum with a vac solenoid.

the s4 aux ports run off of pressure from the exhaust, whilse the s5's use vacuum.

canonize-ryda

i already have an air pump activated system.

Derekcat

iTrader: (8)

http://homepage.mac.com/carldavis/intake.html
Best writeup with [working] pictures I've seen.

He says that he can definitely feel when the VDI opens up, and if it's anything like it is on a normal S5 I can see it being totally worthwhile. [I'm planning on doing this to my S4 base/sport sometime after my current project is finished]

Also, I see no reason why this wouldn't work on an S4 car - it's nothing the ECU cares about [except for that it actuated a solenoid on an S5]

canonize-ryda

i can find everything i need for 100 bucks so i figure why not attempt it.
but if i add up all my attempts i got quite a price list.

blackrotary23

now will the s4 tII lower intake manifold fit on an N/A block snug if the bottom port in the middle is cut off and smoothed out?

RotaryRocket88

iTrader: (7)

It's actually air pressure that moves the actuators on S5s, but the diaphragms do work the opposite way that they do on S4s. Instead of pulling in, the push out to rotate the sleeves.

I have a thread on activating 6PI and VDI with RPM switches: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/activating-aux-ports-vdi-rpm-switches-907824/

Are you thinking of TII manifolds? At any rate, the main modification for a S5 NA UIM is grinding down a spot on the rear iron. It's covered in the write-ups already in this thread.

The gains were very noticeable when I did this to my S4 NA engine. Where with the S4 UIM power would drop steeply after 6k RPM, the VDI setup allowed the engine to continue to pull hard all the way to redline. Mazda has a dyno chart in the S5 SAE paper that shows torque with different runner lengths, and as expected, high RPM torque is better with a short runner design (VDI open). Midrange can also see a small gain due to the longer runner length (VDI closed) below 5200 RPM.

"d" is 400mm longer than the S4 intake (VDI closed), and "a" is 200mm shorter than the S4 intake (VDI open).

YaNi

iTrader: (2)

In a word - no. NA are a 6 port, turbo are a 4 port. The port under the two primaries is the EGR on the S4, which won't make any difference whether as to whether the manifold will fit or not. You need to do some judicious welding and grinding to adapt the 4-port manifold to the 6 port NA keg.