NA 6 port half bridge build (zenki FC)
 

Hello all.. so my original motor blew a coolant seal in winter storage (-45 below @ 96,xxx) a few years ago.Im second owner bought with 70,002 miles with all records including all oil changes, gas fill ups, you name it. Even got the window sticker and dealership brochures.Chassis is tip top.A friend of mine gave me a new(used) motor. It lasted 800 miles some how... seized on start up.

This is my only pic of it now(My gf doesnt know how to work buttons)
http://img.photobucket.com/albums/v2...h/116_0223.jpg

This is how its suppose to be (exept this is an SE)
http://img.photobucket.com/albums/v2...h/IMG_0179.jpg

So now i have started a rebuild on the stock engine(I think she got mad at me for tossin in a used motor).

I should be able to re use the hard seals. But im not sure about 3 piece seals on a half bridge. Any insight? Im not sure they are even 3 piece but i am assuming so because its an S4

Im trying to run a stock ECU as judge ito has done it and I have seen how fast it was
(RIP) He ran to my knowledge stock premary inj @460cc and S4 turbo secondary@ 550cc

I have found no more info as of yet, I PM'd him tho

Mods so far i have done 20k miles on this setup to try to learn chassis dynamics at the limit of grip with low power
Tein drift spec coil overs
AWR lateral rods
AWR rear control arm sperical bearing
AWR camber links
Racing Beat DTSS eliminators
Poly bush A arms
Racing beat sway bar end links
AC/PS/smog delete (finding elec pw steering pump)
CAI off a ford diesel (still not enough airflow)
Hawk Hps+ pads (suck)
Short shifter
S5 tranny
S5 tails

Stuff im adding while i build(Already have, or free ish)
I have a full stainless dual roadrace setup im running paralell for about 113-118 inches( not sure how to tune this yet)
Mazdatrix heim joint endlinks
Mazdartix bumpsteer/angle tie rod ends
Tanabe Sustec strut bar
Stich weld
Chassis/engine harness diet
Sound deadening removal (keeping ugly maroon interior cus it makes my tornado grey silver look PIMP)
S5 bumpers and trim(keepin it black)
Shimmed LSD


Stuff Im adding later
Adjustable sway bars
Heim joint ball joints
Full cage and Huge diet
Fuel cell and auxiliaries to support
NA Rtek?
Gilmer belt drive
Crown Vics
Downforce?
80s Boatflake gunmetal paint?

K so enough of all that, gettin down to business.
Can i use stock ECU and 3 piece seals?
Would swtiching the direction of a worn in apex seal towards the center iron mess stuff up becuase it was bedded in rotating the opposite direction.

And finally does longer piping (118") boost low end or high RPM? Or shorter (113")
Im shooting for a Helmholtz resonance effect at around 5500 rpm

Day one. Shoulda gotta flatbed tow truck. Low cars suck

Attachment 477701

Stock three piece seals are terrible in any circumstance. They beat the hell out of the rotors. Use two piece, and if half bridge, position the corner pieces on the opposite side of the bridge.

Do it properly with a standalone. You'll need to ditch the stock S4 NA intake anyway to get the most out of the ports. Regardless of whether a stock ECU works at WOT (any ECU can throw fuel at an engine), it's the 99.9% of other driving where the quality of the tune matters.

In general terms, longer piping on the intake side is best for low RPM. But it's not a simple question to answer. With the stock S4 NA intake manifold, you're going to be fighting that restriction.

A bridged 6 port NA block isn't going to be making peak power anywhere near 5500 RPM. You're looking at around 8K to make peak power.

Theoretically the stock ecu should work. The stock pump flows 1300cc/min .And the stock ecu only does 65% cycle right? So with 460x2 primaries and 550x2 secondaries, I ended up with 1313cc/min

I found a bunch of training manuals and competition manuals and found out 3 piece seals are only made to be run one direction anyways, so those are out. I ordered RA seals and I'm using new oem springs

My reasoning for the low rpm heimholtz effect is I wanna broad power band and kinda choke off the top end. 8000-9000 rpm. Not really choke it off but I know the intake manafold can't flow too well. So I'm shootin for the most usable power on the restrictive intake. Ya dig. Does anyone know what the stock intake is tuned for? Rpm wise. flow benched?

So I've been thinkin going in the middle with a 115" length twin 2" pipe to a RB road race pre silencer to a RB collector with 4" megaphone with a 3" reverse cone then 3" to the rear muff

Build started yesterday. Awwww yea

Of course the stock ECU will run the engine. But will it work? Well personally, I prefer my cars to be drivable and run at a reasonable A/F ratio and timing values at idle, light load, cruise and WOT. The requirements of a bridgeported engine are far outside of what the stock ECU can handle properly. Sure, you can compensate roughly for the fuel by tossing in larger injectors. But that's a pretty rough method of "tuning", worse than a carburetor. And timing...the stock ECU idles the engine at about -5 degrees, while a bridgeport is far happier idling at around 10 - 15 degrees advanced.

Ironically, the one thing that the stock ECU will give you is the AFM. Tuning high overlap ports with an AFM is easier than speed density. Then again, you can run an AFM on most standalones (Megasquirt for sure).


It's not so much the restriction of the stock intake that is the problem, it's that the DEI is tuned for stock ports. The training manual shows how it resonates and takes advantage of the aux ports, feeding them with the closing pulse of the opposite rotor. Bridgeports don't close, they are always open somewhat and the powerband shifts so much with that overlap that the stock intake isn't going to do it.

You want a broad powerband on an NA bridgeport? Not going to happen. No way, no how. You'll come onto power above 6000 RPM with a 6 port bridge, you'll really feel it around 7K, and it will carry above 9K if the intake was not a restriction.

So you have some choices. The easiest is to gut the dynamic chamber, basically tuning the intake manifold into a fixed long runner manifold. The runners are going to be a bit long but you'll at least not be fighting the DEI.

Another option is the TII intake. Still has DEI, but not the horsehoe like setup of the NA.

I'm not sure what you'd need for exhaust. You'll need to experiment with several sets of headers because for the most part you are in uncharted territory here with the stock intakes.

That sounds s reasonable as any place to start. This will be very, very loud.

I know you aren't going to want to hear this, but all this work is going to get you what, 250HP at the absolute most at the most upper end of the RPM range. You'll need to balance the engine to go further. And 8MPG around town, a seriously loud exhaust, and a car that is hard to start, doesn't idle well, bucks while driving and stinks. Then any new V6 Mustang is still going to be faster in a straight line than a narrow power band bridgeport NA FC.

Hmm. I do have a s4 turbo intake, but in trying to keep the aux ports working with Atkins sleeves.

I realize its not ideal or practical or economical. It's just sounds fun.
And until I find a ecu I like I just want it to run.
I'd like to find something similar the Japanese freedom ecu which can almost tune itself and mainly I want altitude fuel/air correction.


Once I find something I like, ill go itb's and all that

Any idea where to weld up a emap sensor? Or back pressure pick up tube?

Thanks for the help Arron

There is little point in doing this on a bridgeported engine since the secondaries are open all the time with the bridge. You're trying to preserve low end torque in a high overlap engine by keeping the aux ports closed...but your low end torque is already gone because it's an NA high overlap engine.

Most ECUs on the market these days support autotune. But it won't work on a bridgeport because the misfires induced by the charge dilution from the overlap confuse the wideband. All ECUs except the really backwards ones (ie. Microtech) support realtime barometric correction using a second pressure sensor. Even the stock FC ECU does this.

The backpressure tube should be about 12" from the exhaust port. Weld a stainless tube into each runner of the headers and extend each tube up to the firewall, then connect to your sender.

I just noticed you have the same thread in the NA forum and they are giving you the same advice I am; not to do it.

Thanks i guess.. still doing it anyways. I never asked if i should do it or not. Its not like im doing a aux bridge port

And yes i know the stock ecu does altitude correction, thats why i want to use it

Update on the build
Parts are ordered, seized engine is out and apart and nothing is useable,
pulling apart the good engine tonight porting will start as soon as templates come.

Still trying to decide on RA classics or atkins. They would be the same price becuase i will be using oem springs

You may not have asked whether you should do it, but it's a responsibility of those giving advice to at least tell you if the whole plan is fatally flawed. Just saying that modding is supposed to improve a car.

The altitude correction on the stock ECU is irrelevant in this case because it will be running the bridgeport so poorly, a little AF and timing change due to altitude isn't going to make a difference.

Damn brother, this thing probably shreds gnar and exudes excellence. Can't wait to see it with a V8 in it, then it'll be classified as "el fuego".

Dude if you knew anything about this site and FCs you'd know this...If Aaron Cake gives you advice, then listen to his ass because he's saving you time and money. He's not telling you how to live your life and how you should build it. He's the one that takes all this time out of his day to experiment on what works and what doesn't. I'd take what he says to heart because he lives and breaths 7s everyday, from tech questions to wrenching. Now I have no ideal half the questions you're popping off but if more then one person is saying no in a different thread PLUS Aaron.....its time to think of a new game strategy and not be thick headed and try to do a stand alone that maybe new to you to use. I'll admit I know nothing about it but if they said that'd be my best bet I'd start learning. k...I'm stepping off my box.

op, the problem with bridgeports is they need a lot more fuel from idle to about 3000 rpm due to the overlap. they can run more lean from 3000 rpm and up, but then when it gets into its power band (5000+) you need to start dumping more fuel again. the key to getting the stock ecu to work is you have to try to get this response out of it, which is possible, but its going to take some work :)

you have these options to play with
1. fuel injector sizing
2. tune the s4 AFM by adjusting the spring tension
3. use in-line fuel injectcor resistors to adjust fuel injector response, sized appropriately

try using 550 primaries and 460 secondaries on the stock ecu. the 550's add the extra fuel needed below 3000rpm, but it will try to flood out everytime you try to start it, so fuel cut switch is required. if 550+460 ends up being too rich, try playing with the spring tension in the AFM to dial it back

here it karacks thread on afm tuning

https://www.rx7club.com/2nd-generati...uning-1014227/

Define "low end". The highest numbers in my VE table are in the 2900 and 4000rpm bins.

Note that I'm NOT running a 6 port anymore. The aux ports just close WAY TOO LATE to make any decent low end power, and then the ports are too restrictive to make high end power.

It's definitely a learning experience. I used to be able to use full throttle in 2nd gear, now more than 3/4 just blows the tires away below about 5000rpm. It's not the overlap that kills low end (the new engine actually has a lot MORE overlap) it's the intake closing point.

Heavily THIS.

You can use autotune to an extent in the high load regions, but the cruise areas are where the magic has to happen, and autotune can't do that. At least, there aren't yet any autotunes that can detect lean misfire (or dilution induced lean misfire) and richen accordingly.

Backpressure tube for what? A sensor? That's a neat idea, I always just stuck a vacuum/pressure gauge on a hose and ziptied it to part of the dash, for testing.

For the aux ports? If the exhaust has enough backpressure to work aux ports, it is too restrictive for any high overlap engine. RB sort of gets around this by aiming the tube into the exhaust flow, so the port sees velocity pressure and not static pressure.

Just so every one know I am planning on using a stand alone. I'm just trying to get it to run to get it to another shop to park for the winter and do more work.
I'm trying to find one that I like still

And yea I did ask for advice, but I'm lookin for inspiration not discouragement.

I'm doing a baby bridge now I guess
My second motor I tore apart last night is perfect and I don't really wanna notch the housings

Maybe that will help a little not having as much overlap

And. I was talking about back pressure pick up for the aux port. And emap

I'm going to try to copy RB style but maybe have two to one tubes

Then I'm adding bungs for wide band and egt

Not much to to today I can't order more parts till tomorrow.
I need to talk to pineapple racing and see how big of exhaust port I need

I'm putting in turbo exhaust sleeves today and starting on exhaust.

Engine should be together soon I hope just waiting on parts now
And I still need to order templates from pineapple

And just so ya know my inspo was a judge Ito car, it had extended port 6port, full bridged with big primaries, stock ecu and crappy exhaust with 240 hp

Good to hear the other engine is in good shape.

Yea everything is mint.
Even the coolant seal failure was very minimal.
Side seals are within competition build specs,and they're stock.
A little step wear on the irons but within spec.
I forgot to order corner seals, feel kinda dumb cus I ordered corner seal plugs.
But new corner seals come with the plugs. I hafta call Atkins tomorrow and see if they sent it out er not and add corner seals.

I lied. Everything is not mint.
I have been takin it apart slow and cleaning as I go and didn't notice this until last.
Front iron death :(

Attachment 478592

Good thing I have a spare :)

Doesn't Rotary Evolution have a fix for those? Coolant savers or something like that.

Yea they do. But I have a spare iron and I ordered all oem rubber seals a few days ago before I saw this

IMO there's no point to doing a small bridge... the drivability's the same, you just don't make as much power.

I used to play with small bridges, then I built one that was full port height and as large as I felt I could go without hurting the coolant seal integrity. Same drivability, more power.

So which one worked best. Large half bridge? I just talked to the guy at pineapple racing. He said a small full bridge would work better with the stock intake. I'm all conflustered now. Might just street port to get it to run eh. It's getting cold here in Montana and I'm swapping the motor outside

Found something out I haven't heard about yet.


Attachment 478666

There's a spacer In the N/A housing that has to come out to fit a turbo exhaust sleeve in.
I think it was a S5 turbo housing I pulled the sleeve from,
and put into a S4 N/A housing, after the spacer came out.

Had a oh shit moment before I found that there was a spacer,
And it was removable

And if this is common knowledge, I blame my rotardedness... It's real

Attachment 478964
My first exhaust port
Mediocre at best...
This is the pineapple ep2
Doesn't change closing time at all really
Turbo sleeves were fitted after the pic