6 port lower intake manifold mod
 

On my car I've been running with no aux port actuators/rods/bushings/sleeves etc, the 6PI is always open. Ever since I put the intake together I've been annoyed with having the pockets in the secondary runners where the bushing would come into the runner.

So I finally bit the bullet and decided to fill those pockets in. While at it, I figured I would mill off the outer wall of the LIM that normally contains the exhaust gas for the AC&CV (also used as a heat riser for the intake runners). With the outer wall and aux port junk removed, the 6 port LIM can probably clear a stock turbo setup, I will check this for certain later after it's finished.

Anyway, here are some photos of the progress:
http://pengaru.com/~swivel/cars/rx-7/pics/02-19-2005/

The last 4 pics in the thumbnails show the rear runner after welding, I had to stop after doing the rear because I caught some bag on fire and filled the shop space with smoke <grin> I will finish welding the front runner monday probably, then the welds get ground down with the carbide bur on the inside of the runner, smoothed down to a point where it's like the pockets never existed.

So, who wants one of these manifolds for their NA if it clears a stock turbo setup? <grin>

Well, interesting.

Please tell me your car is forced induction though. All that for making a disabled n/a system look better.. meh

Seriously, not sure if you have a turbo, just hoping so.

engine is currently naturally aspirated, turbo may be in its future.

It wasnt really to make it look better, the pockets created vortices in the air flow, making it turbulent, I'm hoping to pickup a bit of power out of it.

If your serious about selling these pm me.

I'm confused, wouldn't you have gained more power having the system in its stock opperating form (as for as the lim aux ports go)...

last time i checked having bushings and shafts in the airflow was a bad thing, maybe the manometer is lying but i doubt it.

this engine is built and tuned for high rpm performance, low end torque is nonexistant and the setup is being intentionally tuned peaky at high rpm for now. manifolds are cheap, I may play with valves later on down the line if I decide peak power is worth giving up for some low end torque, but I doubt it will happen.

Perhaps you are not up to date on my setup - a quick rundown:
6 port engine, s5, street ported intake and exhaust, turbo rotor and intermediate housings
rb hardened stat gears
upped oil pressure
twm individual throttles dcoe style
4x550cc peak and hold injectors
haltech e6k
11lb flywheel

9000rpm rev limit, it gets there faster than you can say 9000 rpm.

current policy is if the sorry low end is too annoying - lose more weight. It only matters when its not moving very fast - the rest of the time the revs are up and the thing screams.

http://pengaru.com/products/e6gauges...es_on_fc3s.avi

it sounds like you have some nice components there, but i don't see why you are running things like turbo rotors? is going to forced induction an immediate plan?
and for a high hp NA, i would think you would go with the S5 intake manifold. even though it may not "flow" as much, the pressure effect it creates will allow greater air velocity...

and it would be nice if you have access to a dyno to see if/how much is gained from this.

Welll.. in the list of mods, theres really nothing that suggests a major upgrade in horsepower other than teh street port... The twin throttles is great at 7000 rpm... but you aren't joking when you say theres no power at low rpms...

Low comp rotors, twin throttles, removed working 6ports, that = 90hp ford festivas are going to waste you off the line...

But... this ovbiously isn't meant for the street, so it might work out well for the track.

Don't look like he will be drag racing. Seems more like a road course setup where he will live in the higher RPM range. But I am curious about the turbo rotors.

When did he say low comp rotors? He said "turbo rotor and intermediate housings." That's housings, not rotors.

For peak/high rpm power the sleeves become a restriction, and when he is looking for only peak power and a 9k redline, why would you want the sleeves?

Screw low end torque, I have stripped 6pi system, combined aux/secondary ports with streetport, and aluminum flywheel and I daily drive my car. It's really not annoying at all, you get used to it and as you do other mods it makes up for it.

my bad, well it sounds good if specificaly high revs only. I just cant live without low end. its all good

I agree with dDuB here, having previously built a S5 n/a motor that was designed for high RPM operation. Let's face it - the FC n/a motors have virtually no low end to begin with. Why not gain a whole bunch of top end power and fun while sacraficing very little of what was there to begin with!!

Question for pengarufoo:

What are you doing with the VDI system?

The others have already corrected it, but I will just reiterate it here, the engine has S5 NA rotors, 9.7:1 CR


There is no VDI system, the intake consists of the photographed S4 LIM which has been extensively modified to turn it into a very simple much better flowing unit than stock, all the vacuum ports have been welded shot on the runner side, oil injector holes welded shut, and now the 6PI bushing holes and recesses they leave behind when removed have been filled in. The only hole left is the brake booster hole and I'm leaving that as I still have power brakes for now.

On top of the LIM is a RacingBeat DCOE upper intake manifold, then the TWM DCOE throttles are bolted to that. The intake is significantly shorter than stock, and works well at high rpms.

Those of you commenting on low end torque, you're driving the wrong car. If you have a 13B NA, the way to go fast with these engines is to spin them high and make the system efficient up there. Otherwise you need boost, nitrous, or forced induction. If you look at the Renesis mazda knew the 6PI setup from the S4/S5 NA's was a horrible compromise, look at how they implement the actuation now, a stepper motor in the lower intake manifold rotates the redesigned sleeves externally, there are no 6PI actuation components in the air/fuel path.

Look at the star mazda 6 port race cars, the previous generation (pre-renesis), they run a star mazda one piece intake manifold that is basically the same thing as my S4 LIM + RB DCOE arrangement. No 6PI actuation BS, all ports open, DCOE carb, on STOCK PORTS those things make 180HP carbureted, they run them with a conservative rev limiter too.

Heres one of these star formula mazda cars for sale w/specs:
http://www.race-cars.com/carsales/ot...64967967ss.htm

I will include some of the text since the link might break later, after car sells or whatever:
Engine

* Engine Builder: Star Mazda
* Manufacturer: Valley Motor Center
* Type: 13 B twin rotary
* Displacement: 1.3 L
* Horsepower: 175@6300
* Torque: 140@5900
* Induction: Dual Webber 48 dcoe

thats conservative too, they run relatively low rev limiters in competition, the dealers often claim 185HP out of a *sealed stock port 13b*, still pretty sorry #'s for what is a 2.6L but add porting+EFI and you exceed 200HP easy.

Heres the star formula mazda one piece manifold:
http://www.aubetamotorsports.com/valley/page233.html
@ $296 you can see why I am modifying mine instead! <grin> It just so happens the modified manifold will probably clear a stock turbo, perhaps a good solution for you NA -> Turbo conversion guys.

BTW, off the line the car is under 4000rpm for a whole... 1 second? 1st gear is short, datalogs suggest around 2 seconds short, every other shift stays up in the power band. The 90HP fiesta will not take it off the line, I raced my friends 12.8 second formula firebird just fucking around and hung with him through 1st and 2nd, he started walking away pretty bad in 3rd though. The car is weight reduced and definitely in the 13's. Kahren has run 13's on the gtech with his DIY individual throttle setup, and his car is a stock port, some of you are a bit overestimating the importance of sub 4000rpm performance, especially when you rev to 9000, and all that 6PI junk is just in the way for high rpm breathing.

I did this to my car. Mainly, I was bored. I also wanted a cleaner looking manifold. Essentially, I made plugs for all the holes and had them TIG welded in place.

There is still not enough clearance for the stock turbo unless you use a spacer.

so how many work hours are in that manifold NOW?

I gotta agree with dDub here the setup looks fine for high rpm power, if you want torque get a 3 rotor or a v8 screw it on a 13b tho its not worth the time to get more torque out of (unless of course someone makes a turbo diesel rotary). Also Pengarufoo makes the same point i've been trying to make that even in drag racing with a rotary low end really doesn't matter i never really fall below 4k even at launch sinmce i launch at redline

Not that many actually, with the new cross slide table the work went real quick. Welding didnt take long at all, i'm sure most the time will be spent grinding down the welds in the runners. I don't have an exact number if thats what you wanted.


I havent test fit the manifold with the stock turbo setup, if it still won't clear thats a bummer, I'll check it tomorrow probably, I think I have all the parts laying around here.

pengarufoo, looks like you know what you are talking about. i totally agree that you will see gains up around peak power range from removing the actuators altogether.
it'd be nice to have a before and after dyno though, so we can see how it really effects the powerband.
the FC NA intake system is definetly out of date. as you mentioned the new Renesis has a beautiful actuation system. the actutator mechanism is external for flow. it is fully electronic, and it actually activates all actuators on start-up, so i have been told. so no more sleeves and what not getting stuck, no matter how slow you drive. ;)
anyways, looks like you are building more of a upper powerband track car than street car, so your methods make sense. keep us up to date on how it goes.

That's pretty cool. What does you car weigh now Peng? If Kahren is in the 13s with an aluminum flywheel and 180rwhp, I'm amazed.

Save the the effort, it doesn't. :)