??? Why would that matter? VDI has nothing to do with 5/6 ports.... 5/6 ports will work without VDI.... you can wire your VDI shut and your 5/6 ports will still work. All VDI does is change the intake runner length to play on the pressure bounce effect... its an attempt at variable intake runners..

However, last time I checked, it doesn't block off the pathways when it is closed.

 

And you don't think improving performance and drivability across the entire rev range helps sales? Compare the S4 13B to the early 4-port 13B's and the benefit of 6PI is pretty clear; more power over the whole rev range. Compare the S5 13B to the S4 13B and the benefit of VDI is also clear; again there's more power over the whole rev range. Average power is what makes a car fast, not peak power. That's why Mazda (and now everyone else) uses systems like these.

Wrong, see above. The improvement was across the whole rev range. And I'd hardly call a 10% peak gain "eeking out an increase".

This sounds far more like you started with a system that was opening the auxilary ports either too late or not at all. I've yet to see anyone offer any hard evidence of worthwhile gains from removing the sleeves.

 

there are dyno sheets. i dont feel like looking for them.

 

just watched the video and I think your car accelerates nicely. In second from 4k to redline I counted to about 4. I did the same in my car and it took a little longer. There's nothing scientific about that but for comparison my sport has lightweight vert rims, a RB aluminum flywheel, modified airbox, Bonez highflow cat and Apexi Exhaust. Also, my aux ports are wired open at the moment. I know you have a streetport but my sport may be lighter (I've removed a good bit from what was already a light car). How much does your flywheel weigh? you have stock rims? Also, if your intake isn't getting cold air, it may be doing more harm than good. Get a box around it with a duct to bring in cool air and you'll really notice a difference.

 

My flywheel is 17lbs lightweight steel racing beat flywheel stock is 23.9 lbs but im not sure if the weight racing beat gives is the weight of just the flywheel or the weight of the flywheel and rearcounterweight , if the flywheel weight is given for only the flywheel then my flywheel is only 2.9 Lbs lighter than stock 23.9lbs w/ counterweight. If its only a 3lbs difference I think it will still help faster smoother shifts and on there site it says it helps improve lowspeed acceleration.

I plan on extending my intake under the light by adding another 45 degree pipe onto it.

My rims are s5 na 91 rims with 205 50 15" Kumho Ecsta Spt tires.

My car also has stuff removed for weight and quite a bit of things.

1. Everything from a/c
2. All power steering
3. 5/6 ports and rods
4. Emissions rack and all emissions related components
5. Coldstart , Acv, Bac, Egr valve, airpump
6. All charcoal canisters
7. All rugs , rear trays and spare tire
8. Radio, front speakers and rear speakers

Im guessing around 100lbs alltogether.

Only weight I have added was putting on the 5 lug conversion and I still have no posi , i need a lsd

 

cool, I was wondering if you had the steel one. I've read that's the one to get. While the AL is very light and good for acceleration, it also causes a rougher idle, jerkiness when launching, quicker falling revs, etc. The steel piece a good compromise and you're right, even if it's only 3 lbs, it helps.

The 91 n/a rims are the five spokes I believe; those are pretty light too.

And I see you have an SE; with all that removed it's pretty light I bet. I don't think there was any real difference in weight between '86 and '88 assuming the same trim. Here's some other suggestions for weight reduction if you haven't already done it:

-AL hood
-lightweight battery (miata batteries are 10lbs lighter and work great, you could save an additional 10lbs with a motorcycle battery but I wouldn't trust it, and with your steel FW, you seem to be about compromise)
-washer tank and lines
-coldstart assist (if you meant AWS when you said coldstart)
-cruise control

 

Car doesnt have cruise contol (i think my care is base model with se on the title) and ive already taken out the coldstart assist, i actually need to fix my windshield waster, the lines themself arent even hooked up so i cant even use it.

Aluminum hood I would get once my car finally gets bodywork and a paintjob , I already need a new hood. I have another used one thats up in Rhode Island thats steel but it needs painted and would cost just alot to ship.

Dont really have money for another battery right now, but aside from the miata battery ive seen smaller battery's that are alot lighter but I will need to fix the spot the battery is held, right now nothign holds it down besides the holder underneath but its not held tight in there the walls around the bottom are whats stopping it from falling need to come up with a fix for it, tried to take out and replace the holder and couldnt get it out.

Edit - Also in the vids you said your car takes alittle longer to get to the redline..i was double clutching while i was in gear, basically like tapping the clutch while flooring it to make the rpms rise faster through the gear..I dont know if that made me go through the gear faster. I dont even know if its a good thing to do to the car, I dont think it is necessarily bad but I dont think its something you should do often.

 

yep, the SE was the base model in '88.

Never heard of anyone doing this before? I've heard of people double clutching when shifting to be easier on the transmission. But then synchros came along.. and Vin Diesel was the only one doing it anymore.

 

Yeah maybe doing what I did is a bad idea, i mainly did it just for the vid and in the past ive done it while racing just to accelerate better, but maybe I should quit it maybe its a bad habit.

 

Wrong
And wrong.

Think about it logically guys. What is the purpose of them? They are there for a purpose, remember that.

They add power by tuning the intake pulse reversion timing based on port timing and estimated RPM/load. By removing them you completely kill the intake reversion timing except during when they would be fully open. Yeah how often is that when you drive? about 5 seconds in each gear when you race and umm about 1% of the time when you're driving. So that’s around 97% of time you are on the down side. As well look down the runner with the sleeve removed, if you ask me I think the air would like the sleeve more ;-).

If your 6pt system is not function why remove them? Why not just fix it? I mean do it right for crying out loud.

 

Give it up, they won't listen. Many of us here have been trying to make this point for the past 9 years yet people still don't get it. In fact I have had lengthy IM conversations with the original poster on this EXACT issue and already explained everything. Honestly I'm slightly insulted that he now decides to post a thread an ask the same question.

Even if there was an actual top end gain, it wouldn't be worth loosing all the low and midrange torque where the car spends 99% of it's life.

 

How will the car accelerate any faster when the enigne isn't connected to the wheels?! That's just plain dumb. Stop watching TFATF and learn to use a manual gearbox properly. Double-clutching (which isn't even what you were doing) will only make you slower.

No it's right actually. The S5's 6PI solenoid is activated at 3850rpm. The S4's port open when when there's enough exhasut pressure, which is too late in most S4's because of the exhasut mods.

What you've described is how the VDI system works, not the 6PI system. 6PI alters the intake port velocity. It has little effect on what happens upsteam in the runners themselves.

 

you are wrong you wanna-be so called rotary mechanic.
try and prove that 3850rpm isnt the activation point for a car that has 5/6th port and vdi

 

Ok , I think I'll stop doing what I did with the clutching although I did do it earlier today while messing around with these two guys driving in a corolla that decided they would hit 110+ try racing me. I first stayed in 5th gear for a few mins, then realized even trying to catch up to him in 5th wasnt gonna work, so then i downshifted to fourth gear when i was at 4500 rpm in 5th ( didnt do the clutch thing tho), then in seconds I hit 7200 rpm in 4th gear.

We then slowed down and I was trying to ask him how my car accelerated because I saw him taking a video of my car with his cell phone or something, the passenger was taking the video it was 2 black guys that were in the car. After asking him if it accelerated good I then did the thing with the clutch again but in 2nd gear while we were going slow side by side, thats when i did the clutch thing again.

In short, I just need to stop doing the clutch thing and just stop driving stupid period. I also swerved into the lane next to me when a car was in it while I was driving back after messing with the corolla , which wasnt good either.

I just need to quit driving stupid and start driving smart. Life just sucks here in the country in the middle of nowhere, theres nothing to do.

 

Im starting to think Id be better off getting an s4 lower intake and putting that on my car and using the s4 intake manifolds just to see the difference in low end.

From what I read the s5 vdi intake will yield more peak power at 7000rpm but not more overall power across the powerband (which is what i want).

 

if there is a power gain ebtween them, the gains are all pretty minimal. remember, the s4 and s5 only have 14 peak hp difference. but a bunch of **** have been changed, from 1 less cat, to ecu, afm, manny, and higher compression.

start by making sure your car is functioning properly... with the shape these 20 yrs old cars are... you will probably see a gain just from making it run like mazda intended.

 

Since we've all chimed in, I'm here to say that removing the sleeves kills you if you have any type of street driving.

I never had fully working aux ports until I went electric activated with triggers from the stock ECU using the solenoids.

The difference is flipping amazing. I wish I had dyno'd both times. Functioning aux ports and vdi is absolutely amazing if you've never driven with them actually working.

Your powerband simply doesn't stop until around 8-9, well above where you would shift on the street. The important thing though, is you actually have power below 3k. I can pull from 2nd gear with aux ports functioning. Trying to do the same with them removed is a nightmare of clutch slippage.

 

Well my car is s4 na so it wont have vdi but will still have the 5/6 ports if i get a new lim and some 5/6 port sleeves. Then I'll do electronic rpm activation with electric airpump, I would think I probably wont really lose much of any hp/tq up high from what I read and will gain 10+ hp/tq downlown.

Which will make the car faster if the overall average of power across the power band is higher, peak power doesnt matter if the average power is lower. It will also make the car alot better streetwise driving so im not having to rev up as high to accelerate (at least i would think).

 

No not really. Intake reversion and runner design is directly related to port timing period. The later the port closing the higher the RPM band is needed and or longer the runner is needed. The sleeve function is to allow the RPM usage to correlate with the later closing while keeping intake velocity higher in the lower stream rpm region.

No, 1.2psi to 2.1psi there is no magical rpm. Only electric controlled devices can have absolute RPM functionality or gears mechanisms.

 

Aren't S5 auxiliary ports controlled electronically? And I'm assuming he meant S5 because he said "5/6 port and vdi", which only S5 have (disregarding a bastardized S4).

 

i just want to mention that an interesting thing i noticed is that having the aux ports open below 3800 RPM has a noticeably negative affect on the S4 intake, but when i tried this with an S5 intake it didn't seem as bad. this is with the sleeves still in, but open all the time, and with Pineapple Racing inserts.
i suppose this could be attributed to the VDI. just an observation.