A (semi) Definitive Guide to 6 Port ITBs.
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A (semi) Definitive Guide to 6 Port ITBs.
Alright- a quick introduction. My name is Cooper, I’m a random engineering student with not enough time and a “““practical daily driver”””(‘86 GXL). This summer, to keep myself occupied (as if grinding overtime at work didn’t give me enough to do…), I decided “hey, ITBs could be cool, how hard could it be!?” Turns out, it was pretty annoying, and 6 port ITB builds aren’t super well documented, so figured I’d put this here as a guide on how to do it for any future people who want to go through this process (hopefully less painfully)
First off, why ITBs?
I built this keg specifically for this setup, focused on streetable NA power. It includes the following:
-S5 rotating assembly, balanced by Pineapple Racing.
-RX8 6 port stationary gears
-FD oil pressure regulator
-S5 irons with Pineapple large streetport
-Pineapple aux port sleeves/ramps
Engine Management:
For engine management, I went with a MaxxECU mini. If I were to do this again, I would use a MaxxECU Street, but I’ll go into that more later. Anyways, I like Maxx’s software and they offer really great build quality and an amazing feature set for their prices- hence the choice. The mini is really meant for running bikes, but since my objective is to make this as trim and sleek as possible, it served my needs. I made a completely custom harness (not that hard, but wiring tools are expensive) and used Deutsch connectors for all my connecting needs. For TPS, I’m running Haltech’s 8MM D shaft TPS since it bolts right up to my throttle bodies, for water temp I’m running the stock sensor on the water pump, for IAT I’m running some generic ACDelco one, and for lambda I’m running an AEM wideband controller.
Ignition:
On the ignition side I’m running 4x IGN1A Coils, and since the Maxx Mini doesn’t have the capability to run a VR home (like the stock CAS), I had to install an FFE trigger wheel (Hall) and modify my pulleys to make it fit with AC and power steering (there’s a guide somewhere on rx7club, I’ll link it if anyone needs). That said, this ignition setup works flawlessly. I also used the MSD plug wire kit to make my own plug wires cut to length so things are nice and tidy.
Fueling:
For fuel, I overhauled basically the whole engine bay side of the fuel system. Injection is done by 2x Injector Dynamics ID1050XDS sitting in the primary rail. This is PLENTY of fuel for the setup even revved out all the way. Fueling is done using TPS as load in the ECU, like most other ITB setups. As for the pressure regulator, I’m running Radium’s fixed 3 Bar FPR.
Hardware:
This is where I would’ve done things differently. For my Intake Manifold, I used Atkins’ wraparound DCOE 13B manifold. This was not because it’s a good manifold choice, but instead because my friend had one laying around. For throttle bodies, I’m running Jenvey’s 118mm long DCOE replacement ITB setup, with an eBay knockoff of the Jenvey linkage. I tapped the manifold with a vacuum T off the rear rotor with one large fitting for the brake booster and a smaller fitting to run a vacuum line to the MaxxECU’s integrated MAP sensor. It’s an okay setup, and probably the most likely part to be changed in the future.
Weird Miscellaneous Things:
I’m running an FD alternator because my friend was parting out a car with one. That said, alternator wiring is kinda annoying- so to save you some hassle, for S5/FD alternator, one pin on the factory engine harness can just self reference the top post on the alternator, and the other goes to a white and black (NOT BLACK AND WHITE) wire on the FEM-01 connector (front harness to stock ECU). Make sure you go to the white with black stripe and not the black with white stripe otherwise your car will not turn off (ask me how I know). Additionally, since some geniuses at Mazda in the 80s decided to run the wiper control harness through the factory engine harness, you’ll need to cut that sub harness out of your stock harness and use it to run your wiper controls. The pins are in FEM-01 and the wires match color, so I just cut up FEM 01 and replaced with a 4 pin Deutsch connector to run the 4 wiper wires to the motor. Ugly but functional. Also- removing the stock ECU removes your power steering privileges it appears- I’m still trying to figure out how to fudge the stepper motor and make stiffness manually controllable, but until I do, it’s a big question mark haha. Furthermore, this setup has no IAC at the moment. I plan to add one in the future, but I’m lazy and a high idle in some weather conditions doesn’t bother me too much.
Tuning:
Tuning is kinda simple(?). Still trying to figure out exactly where injection angle likes to be and get some quirks ironed out, but with data logs and a little time you can figure it out. Only real thing of note is that the car loves to dump fuel after pulls, but I fixed that with decel fuel cut. My rev limiter is set at 8500 because that’s what I built the motor for.
Build Results:
This setup is insanely streetable. I have no qualms with it as a daily driver, and it rips at autocross. It gets similar if not slightly better fuel economy than my car did on stock s5 setup (my odometer is busted so I can’t give you exact numbers), and it drives like a dream. Power curve is super smooth, throttle response is excellent, and it feels much peppier at the high end- and surprisingly even in the 3500-4000 RPM range. I’ll get it on the dyno soon when I stop being lazy and update this thread with numbers.
If I Were to Start From Scratch/Recommendations for Others:
I spent a lot of money in R&D so you don’t have to. There were a LOT of trials and tribulations involved in getting this thing together. If I were to do it over again, I would make a few changes that are as follows:
I love this setup, it’s sick. Makes cool noises, is daily drivable, and is very peppy. It’s the best this car has ever felt and it’s perfect power for an NA FC, in my opinion. If you have any questions, leave this thread a reply or hit up my Instagram, @notthat.fc3s
Thanks for reading, I’ll get around to updating this at some point soon.
First off, why ITBs?
- ITBs make cool noises.
- Rotaries love to breathe.
- Simplifying basically everything (it takes 10 minutes to strip to a bare keg).
- ITBs make cool noises. (again)
I built this keg specifically for this setup, focused on streetable NA power. It includes the following:
-S5 rotating assembly, balanced by Pineapple Racing.
-RX8 6 port stationary gears
-FD oil pressure regulator
-S5 irons with Pineapple large streetport
-Pineapple aux port sleeves/ramps
Engine Management:
For engine management, I went with a MaxxECU mini. If I were to do this again, I would use a MaxxECU Street, but I’ll go into that more later. Anyways, I like Maxx’s software and they offer really great build quality and an amazing feature set for their prices- hence the choice. The mini is really meant for running bikes, but since my objective is to make this as trim and sleek as possible, it served my needs. I made a completely custom harness (not that hard, but wiring tools are expensive) and used Deutsch connectors for all my connecting needs. For TPS, I’m running Haltech’s 8MM D shaft TPS since it bolts right up to my throttle bodies, for water temp I’m running the stock sensor on the water pump, for IAT I’m running some generic ACDelco one, and for lambda I’m running an AEM wideband controller.
Ignition:
On the ignition side I’m running 4x IGN1A Coils, and since the Maxx Mini doesn’t have the capability to run a VR home (like the stock CAS), I had to install an FFE trigger wheel (Hall) and modify my pulleys to make it fit with AC and power steering (there’s a guide somewhere on rx7club, I’ll link it if anyone needs). That said, this ignition setup works flawlessly. I also used the MSD plug wire kit to make my own plug wires cut to length so things are nice and tidy.
Fueling:
For fuel, I overhauled basically the whole engine bay side of the fuel system. Injection is done by 2x Injector Dynamics ID1050XDS sitting in the primary rail. This is PLENTY of fuel for the setup even revved out all the way. Fueling is done using TPS as load in the ECU, like most other ITB setups. As for the pressure regulator, I’m running Radium’s fixed 3 Bar FPR.
Hardware:
This is where I would’ve done things differently. For my Intake Manifold, I used Atkins’ wraparound DCOE 13B manifold. This was not because it’s a good manifold choice, but instead because my friend had one laying around. For throttle bodies, I’m running Jenvey’s 118mm long DCOE replacement ITB setup, with an eBay knockoff of the Jenvey linkage. I tapped the manifold with a vacuum T off the rear rotor with one large fitting for the brake booster and a smaller fitting to run a vacuum line to the MaxxECU’s integrated MAP sensor. It’s an okay setup, and probably the most likely part to be changed in the future.
Weird Miscellaneous Things:
I’m running an FD alternator because my friend was parting out a car with one. That said, alternator wiring is kinda annoying- so to save you some hassle, for S5/FD alternator, one pin on the factory engine harness can just self reference the top post on the alternator, and the other goes to a white and black (NOT BLACK AND WHITE) wire on the FEM-01 connector (front harness to stock ECU). Make sure you go to the white with black stripe and not the black with white stripe otherwise your car will not turn off (ask me how I know). Additionally, since some geniuses at Mazda in the 80s decided to run the wiper control harness through the factory engine harness, you’ll need to cut that sub harness out of your stock harness and use it to run your wiper controls. The pins are in FEM-01 and the wires match color, so I just cut up FEM 01 and replaced with a 4 pin Deutsch connector to run the 4 wiper wires to the motor. Ugly but functional. Also- removing the stock ECU removes your power steering privileges it appears- I’m still trying to figure out how to fudge the stepper motor and make stiffness manually controllable, but until I do, it’s a big question mark haha. Furthermore, this setup has no IAC at the moment. I plan to add one in the future, but I’m lazy and a high idle in some weather conditions doesn’t bother me too much.
Tuning:
Tuning is kinda simple(?). Still trying to figure out exactly where injection angle likes to be and get some quirks ironed out, but with data logs and a little time you can figure it out. Only real thing of note is that the car loves to dump fuel after pulls, but I fixed that with decel fuel cut. My rev limiter is set at 8500 because that’s what I built the motor for.
Build Results:
This setup is insanely streetable. I have no qualms with it as a daily driver, and it rips at autocross. It gets similar if not slightly better fuel economy than my car did on stock s5 setup (my odometer is busted so I can’t give you exact numbers), and it drives like a dream. Power curve is super smooth, throttle response is excellent, and it feels much peppier at the high end- and surprisingly even in the 3500-4000 RPM range. I’ll get it on the dyno soon when I stop being lazy and update this thread with numbers.
If I Were to Start From Scratch/Recommendations for Others:
I spent a lot of money in R&D so you don’t have to. There were a LOT of trials and tribulations involved in getting this thing together. If I were to do it over again, I would make a few changes that are as follows:
- Use a MaxxECU Street since it has a VR home, and a trigger wheel kit costs more than the price difference with the mini. This would allow me to use stock CAS.
- Go with a downdraft IDA layout manifold and IDA layout throttle bodies. The DCOE wrapping around on top of the motor is kinda annoying. Options for getting cold air to the intake(s) are very limited, it screws you on filter choices (only socks really fit), and also kinda screws you on coil mounting (can only fit two on top of the block). The Atkins manifold also just kinda sucks. The ports don’t match up super well, and there aren’t really any good places to tap for vacuum or sensors (I kinda just sent it lol).
I love this setup, it’s sick. Makes cool noises, is daily drivable, and is very peppy. It’s the best this car has ever felt and it’s perfect power for an NA FC, in my opinion. If you have any questions, leave this thread a reply or hit up my Instagram, @notthat.fc3s
Thanks for reading, I’ll get around to updating this at some point soon.
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