whats up guys, im in the process of rebuilding my S4 NA and I came across a choice to make.

1) completely remove the 5th & 6th port sleeves along with removing the device that turns them.

2) leave as is.

Ive been researching and there have been statements that completely wiring open the port causes a loss in low end torque and hp, up to a 15hp loss!!!

So I was wondering if i may get some feedback from you guys that have removed the VDI. give me all the info you guys have, thanks a lot

 

if you are rebuilding it, i would port them(the 3rd and 4th; 5th and 6th. into one and remove them, then port match the manifold, and port the hell out of the primary. also run 9.7 s5 n/a rotors.

 

dang i didn't think of that. I already ported the intake with pineapple racing's large street port.

porting the hell out of them is out of the question cuz the block is already assembled.

 

You definitely dont want to blend port. If you port that big you will lose intake velocity, and any hope of torque or usable power. Your S4 does not have VDI it only has 5th and 6th port actuators. Id say keep it if it works. It keeps the intake velocity higher under 3800-4000 increasing your low end. VDI can be made to work on an S4, I believe Arron Cake has a write up. Suppose to be good for a couple hp up top. If you can make it work properly

 

You gain very little (perhaps a negligible weight reduction) by removing the system.

You lose a lot (low RPM torque - something rotaries are already criticized for a lack of) by removing it.

I would keep it as is and make sure it functions as it is supposed too.

 

JerryLH3>> +1
Keep 5th/6th ports, do the airpump activation.

Consider buying Pineapple Racing's 5th/6th port sleeve inserts.

If you actually want VDI, go electronically controlled 5th/6th and an S5 intake swap to give you VDI.

Properly functioning VDI will give you ~ 0.75LBs of 'boost'.... So I've been told by Pineapple.
From driving an S5 vert. I can tell you VDI is VERY noticeable.

 

I went from s4 NA to s5 NA and I can tell you from experience everything you want to know.

S4 with stuck closed Aux sleeves: good torque down low but really lacking power @ Redline.
S4 with removed Aux sleeves: missing torque down low but power @ Redline dramatically increased.
S5 with removed Aux sleeves & unknown working VDI: little low on torque down low but still good drivability and smooth acceleration to Redline.
S5 with Atkins Aux sleeves and confirmed working VDI: great torque down low and definitely rising power until around 7k where it starts to level off to about 8k.

Personally, I would go with the Atkins 6 port sleeves for a number of reasons: slightly lighter than the OEM ones, they have a tapered lip on the entrance of the sleeve for air to smoothly flow around, the ramp for the air is machined into the sleeve and really does a good job at flowing the air how it wants to where it wants to (air will always want to flow around the outside edge of any intake runner, confirmed by the LIM I pulled off my car and where the runner walls were clean compared to where they were soaked in oil), and the edge of the 'port' on the sleeve is tapered inward. Theres a lot more engineering to the sleeves than people give credit for and is another reason why I wouldn't buy the pineapple inserts.

Now, another thing to take into consideration is getting ahold of a full s5 intake and using that instead since the air pump is what's opening the Aux ports rather than questionable exhaust back pressure. Also, when servicing the LIM, be sure to completely remove the actuators and rods, replace the rubber seals that sit in there, and COMPLETELY clean the rods and actuators. Would be very wise to polish out the rods and the Aux sleeves. You wouldn't believe how much easier everything turns with them polished up. Make sure to also clean out the 5/6th port runners on the front and rear irons free of debris and do a good 2000grit sand on the inside. A polish would be better though.

Here are some pictures of what my set up is, and it works perfectly every day with no problems or hesitations from idle to redline:

http://www.flickr.com/photos/globekidd/7584127698/http://www.flickr.com/photos/globekidd/7584127698/ by http://www.flickr.com/people/globekidd/, on Flickr

http://www.flickr.com/photos/globekidd/7584132526/http://www.flickr.com/photos/globekidd/7584132526/ by http://www.flickr.com/people/globekidd/, on Flickr

All new gaskets and vacuum lines too. I'm sure all the maintenance I did contributed to the result but the driving speaks for itself.

 

thanks alot for youy guys input, imma try and get the Aux ports and try to get the axtuators working. thanks guys

 

REAmemiya_fan: did you polish those sleeves? Did you do it just so they would resist buildup?

 

Yes, we did it mainly because the sleeves had a much easier time rotating in the ports after polishing than before. Same reason why we polished the rods that go from the actuators to the sleeves themselves. Everything moves rather effortlessly.

 

i have 5th&6th ports removed, and the only complaints i have a little less torque than normal, but it doesn't bother too much since I'm never under 4k when racing/drifting..

 

any complaints about taking off from a stop?

 

if i do decide to go with an S5 intake swap, would I need to do major mods?

 

i'd say it feels a liiiittle sluggish from 1-1.8k.. but even then, with my stage three(on or ******* off) clutch i'll get a tire screech sometimes from a take-off.. trust me, it isnt as bad as people make it seem. but if i had a choice i'd use'm.. i trust mazda, and what they intended their parts for

 

Not too bad: eliminate the EGR valve [which doesn't help anyway...], grab a couple RPM switches and solenoids [see electronic aux port writeup], modify or remove the rats' nest [there's a writeup to keep all of your emissions equipment if you want to], extend the BAC wiring, and you're good to go.

 

Well fellas' i cant thank you guys enough for your feedback you have all helped me out tremendously, i hope to see you all at seven stock so you guys can take a look at my project.