The indecisive and slow S4 build

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Old Oct 21, 2021 | 03:06 PM
  #226  
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Not really an update... but I'm hypothetically considering turbocharging this engine.....I'm not positive how turbo sizing works on peripheral ports, and my power goals would be modest. I'm thinking 350whp to run a smaller, more responsive turbo. @j9fd3s ?
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Old Oct 22, 2021 | 08:35 AM
  #227  
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From: https://www2.mazda.com/en/100th/
Originally Posted by djSL
Not really an update... but I'm hypothetically considering turbocharging this engine.....I'm not positive how turbo sizing works on peripheral ports, and my power goals would be modest. I'm thinking 350whp to run a smaller, more responsive turbo. @j9fd3s ?
big! it ends up being a BIG hp setup, the engine doesn't like backpressure so you need a big turbo. the friend of a friend who has one is a T62 turbo, 860hp, doesn't get driven much i think
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Old Oct 22, 2021 | 08:39 AM
  #228  
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I can't claim any firsthand experience, but I think like J9 says you'd need a large turbo. And then you'd just need to keep boost really low if you want to stay at only 350hp.

Your engine already flows more air NA than many turbo cars.
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Old Oct 22, 2021 | 11:12 AM
  #229  
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Well crap. I was thinking if I sized it relatively small, I could create more torque down low and just add a bit more peak hp. Fill in the gaps, if you would. I was thinking along the lines of an EFR 7670. Once again, this is all hypothetical :p
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Old Oct 22, 2021 | 11:36 AM
  #230  
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Originally Posted by djSL
Well crap. I was thinking if I sized it relatively small, I could create more torque down low and just add a bit more peak hp.
As long as we're speaking hypothetically...

A supercharger would do what you want for low down torque. You could get something like a Toyota Previa supercharger that has a built-in electromagnetic clutch, then trigger it to go offline when you pass say 4k and come into your engine's existing power band. This will prevent damaging the supercharger with the 10,000rpm redline of the peripheral port engine.

Then have a secondary 2.5" (or whatever you're currently running) intake with filter parallel to the supercharger with a large one-way valve. When at idle the pressure from the supercharger will hold this valve closed, then when you outflow the supercharger at high rpm vacuum will suck air through the one-way valve.

Hypothetically.
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Old Oct 23, 2021 | 05:44 PM
  #231  
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Originally Posted by WondrousBread
As long as we're speaking hypothetically...

A supercharger would do what you want for low down torque. You could get something like a Toyota Previa supercharger that has a built-in electromagnetic clutch, then trigger it to go offline when you pass say 4k and come into your engine's existing power band. This will prevent damaging the supercharger with the 10,000rpm redline of the peripheral port engine.

Then have a secondary 2.5" (or whatever you're currently running) intake with filter parallel to the supercharger with a large one-way valve. When at idle the pressure from the supercharger will hold this valve closed, then when you outflow the supercharger at high rpm vacuum will suck air through the one-way valve.

Hypothetically.

That's an intriguing idea. Mounting it would likely be a pain in the ***, but the actuation probably wouldn't be too difficult with my new ECU. Hmm...all good food for thought.
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Old Oct 24, 2021 | 09:09 AM
  #232  
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From: https://www2.mazda.com/en/100th/
positive pressure (and or less vacuum) in the intake fixes all the PP drivability stuff too
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Old Oct 24, 2021 | 01:29 PM
  #233  
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Hey, I dont know yout build, but j9 is right.
You need a huge turbo (turbine) to not build too much back pressure, or you will hurt your high rpm power.
Back pressure usually raises with rpm, while boost stays the same.
So there is one point when back pressure gets bigger than boost, in a stock FC T2 this is at 5000 rpm.
In my bridgeport I chose a EFR 8374 to move this point to 6500-7000 rpms.
After that your overlap will hurt power output

-Patrick
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Old Oct 24, 2021 | 01:40 PM
  #234  
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Check this out:

matchbot example I just made

Edit: go for " Engine Delta Pressure (dP)"
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Old Oct 26, 2021 | 08:46 PM
  #235  
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Well, I suppose plans for turbo power will be shelved for now.


In other news, I picked up something I've been searching for, for years....and for a decent price!


My plan is to use this cluster with the rx8 transmission. I'll be using a speed hut analog to GPS speedometer converter box in order to utilize the FC speedo.

I'll be swapping the boost gauge in the cluster for a spare FC NA volt gauge (as I have no turbo anyway)

Last edited by djSL; Oct 27, 2021 at 01:59 PM.
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Old Nov 4, 2021 | 10:04 AM
  #236  
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Dang, I've been sleeping on this thread. Great work man! Excited to see where you go with things next.
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Old Jan 16, 2022 | 12:28 PM
  #237  
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After three long months, I'm finally back from my work contract and was reunited with my car. Unfortunately, it's still in a million pieces after the paint job. :/

Since I'm prepping for my RX8 6 speed swap, I needed to tackle the speedometer issue (digital VSS versus analog capable). After poking around, I discovered that Speedhut makes a GPS speedometer conversion box that converts an analog cable to a digital signal. The kit I picked up comes with a 3 ft ford style speedometer cable that plugs into the conversion box. I gambled on the ford style as it looked similar to the OEM Mazda speedo cable style. Lo and behold, the gamble paid off. The ford style cable clips directly onto the back of the OEM mazda cluster. A word of warning though: the ford cable attachment is physically smaller than the Mazda, so its a very tight fit and it's a giant PITA to remove once you've connected it.




I've begun mounting the system in my car, but have yet to finalize routing and wiring. Seems super simple and will update with photos once I get it installed.


Until I get the RX8 transmission installed, I need to remove the OEM FC speedo cable and block off the threaded hole in the transmission (prevent dirt and grime from getting in there). Off to the hardware store!

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Old Jan 16, 2022 | 01:00 PM
  #238  
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Very cool. I've been kicking around selling my spare TII transmission and picking up a S2 Rx8 box but haven't come up with a good speedometer solution. I had thought about taking a spare cluster and putting all autometer gauges in it so all the gauges would match the GPS speedometer, but this definitely looks promising. Though the Speedhut isn't cheap it's probably cheaper than buying all those gauges for my spare cluster.
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Old Jan 16, 2022 | 11:42 PM
  #239  
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Time will tell if this option will be fruitful. It is GPS based and I live in a place with heavy forest/tree coverage so signal may be spotty for me.

Like you mentioned, this option is rather expensive but I'm a sucker for retaining the oem gauges.
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Old Jan 19, 2022 | 09:57 AM
  #240  
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In other news, I think I screwed myself. I'm moving to my new home and discovered my car won't make it up the driveway . I had the slimmest hope it would, but it looks like I need to install an air cup system. I reaaaaaaaaaaally didn't want to have to do this.
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Old Jan 19, 2022 | 10:18 AM
  #241  
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Originally Posted by djSL
In other news, I think I screwed myself. I'm moving to my new home and discovered my car won't make it up the driveway . I had the slimmest hope it would, but it looks like I need to install an air cup system. I reaaaaaaaaaaally didn't want to have to do this.
Is it possible to back into the driveway and front out slowly?

There's a speed bump in a parking lot near me (a particularly vicious speed bump) that I can carefully back the car over without issue but can't front over without scraping the front bumper.
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Old Jan 19, 2022 | 10:58 AM
  #242  
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Originally Posted by WondrousBread
Is it possible to back into the driveway and front out slowly?

There's a speed bump in a parking lot near me (a particularly vicious speed bump) that I can carefully back the car over without issue but can't front over without scraping the front bumper.
Not at my current ride height. The car isn't really that low, but 16's and a rear diffuser/skirts/aftermarket bumper aren't doing me any favors. I might just bite the bullet and get the air cup system. The annoying part is I'm due to upgrade my coilovers anyway, which means I need to buy those first (have to measure the shaft ID's so the air cups seal correctly. In addition, nearly every good coilover option for FC's is sold out due to supply chain issues and I'd be looking at 8 or more weeks.

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Old Jan 24, 2022 | 08:42 AM
  #243  
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Spent some time over the weekend and got the cluster and Speedbox installed/wired in. It seems to be working but will need calibration to get the speedo to read accurately. Other than that, I started putting my interior back together and experienced a moment of complete and utter failure. I recently purchased a BRAND NEW cluster surround from Mazda, just to find out it's specifically for an S5. While the surround does fit an S4 or S5, the turn signal switches are both physically and electronically different. Therefore, I can't physically install an S4 turn signal switch in the new cluster surround nor can I use an S5 switch in my S4. Even after some modifying of the cluster and switch, it still doesn't fit. Sooooo, I guess I'll have to trade someone locally for an S4 version. Here's to hoping I can find one in excellent condition.

Once this minor setback is taken care of, I can put the rest of the interior back together, and then work on putting the exterior together. Hoping to drive it sometime in the next 1-2 months.
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Old Jan 24, 2022 | 09:35 AM
  #244  
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From: https://www2.mazda.com/en/100th/
Originally Posted by djSL
Spent some time over the weekend and got the cluster and Speedbox installed/wired in. It seems to be working but will need calibration to get the speedo to read accurately. Other than that, I started putting my interior back together and experienced a moment of complete and utter failure. I recently purchased a BRAND NEW cluster surround from Mazda, just to find out it's specifically for an S5. While the surround does fit an S4 or S5, the turn signal switches are both physically and electronically different. Therefore, I can't physically install an S4 turn signal switch in the new cluster surround nor can I use an S5 switch in my S4. Even after some modifying of the cluster and switch, it still doesn't fit. Sooooo, I guess I'll have to trade someone locally for an S4 version. Here's to hoping I can find one in excellent condition.

Once this minor setback is taken care of, I can put the rest of the interior back together, and then work on putting the exterior together. Hoping to drive it sometime in the next 1-2 months.
oh yeah i ran into that too, i think i did use the S4 switch though, it looks kind of janky. i also had to repin the wires, for some reason my car didn't match the S4 OR S5 pinouts, so BTW every FC uses the same connector, the difference is the pinout, so you can run an S5 switch and just repin the connector

or buy the 1 touch down window switch and use your arms?
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Old Jan 25, 2022 | 12:17 PM
  #245  
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Originally Posted by j9fd3s
oh yeah i ran into that too, i think i did use the S4 switch though, it looks kind of janky. i also had to repin the wires, for some reason my car didn't match the S4 OR S5 pinouts, so BTW every FC uses the same connector, the difference is the pinout, so you can run an S5 switch and just repin the connector

or buy the 1 touch down window switch and use your arms?
You can repin the S5 turn signal switch to work with the S4 harness? If that's possible, I'd prefer to do that since I have a brand spankin' new cluster surround that hasn't been baking in the sun for years.
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Old Jan 26, 2022 | 09:24 AM
  #246  
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From: https://www2.mazda.com/en/100th/
Originally Posted by djSL
You can repin the S5 turn signal switch to work with the S4 harness? If that's possible, I'd prefer to do that since I have a brand spankin' new cluster surround that hasn't been baking in the sun for years.
yes, i'm running an S5 surround with an S4 turn signal switch. its been a while but the harness i had didn't match either the S4 or S5 diagrams and so i moved some wires around until it did
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Old Nov 30, 2022 | 07:59 PM
  #247  
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I swear, my updates are extremely sporadic.

Anyway...the FC is still running, now with a series 2 Rx8 transmission swap! Much to my pleasant surprise, Pineapple racing is gearing up to make a swap kit for this! I've known Rob for a few years, so he had me come down to the shop and we installed the beta version of the kit. The goal is a bolt in affair that requires minimal effort and a stock shifter location.

Things we discovered: My OS Giken clutch cover bolts barely hit the RX8 bell housing where the casting indents for the starter. I'll have to fix that.

Also, if you made a custom driveshaft to fit a t2 trans and NA rear end, your driveshaft will work for this swap. It's actually a little on the tight side.(775mm from center of yoke u-joint to center of yoke u-joint). I'd recommend a smidge shorter for ease of installation.

Starter and reverse light wiring is the same. Makes sense.

Shifter sits in the stock position!









Beta mounts shown above. Longer hardware is required and was later procured.

Overall, I'm a fan of the swap. the T2 trans was not made for 9-10k rpm shifts and this shifts like butter.

More to report as time passes.

If anyone wants a t2 transmission swap woth mounts and a OEM Bosch starter, I'll sell mine!

Last edited by djSL; Nov 30, 2022 at 08:03 PM.
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Old Dec 1, 2022 | 08:56 PM
  #248  
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Nice, any idea when the production version will be available?
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Old Dec 2, 2022 | 12:44 AM
  #249  
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Originally Posted by Kellis
Nice, any idea when the production version will be available?
I'd assume in the next month or two.

It's worth noting, this kit will only include the transmission mounts/crossmember, slave cylinder, and shifter relocation parts. Anyone interested in swapping would need a s2 rx8 (2009-2012) trans, rx8 starter, and driveshaft.

Also, the OEM RX-8 clutch is the same size as the T2. The NA FC flywheels/clutch will not work. So you'll need a T2/RX8 clutch setup.

Last edited by djSL; Dec 2, 2022 at 09:20 AM.
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Old Dec 2, 2022 | 08:21 PM
  #250  
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I keep getting more and more tempted to sell my TII trans and get an Rx-8 one instead. I plan to go turbo eventually though. How much hp can the S2 Rx-8 trans take? I don't want to make big power. 300 to 350ish at the wheels maybe.
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