that is odd, i was going to say the fuse, its like 7.5a, so its easy to pop it

 

It seems that if the male antenna connector grounds out, that kills the 12v power wire.

 

weird, but ok

 

I stand corrected. It seems the plugs were just a coincidence.

Went to turn the key today, and the unit won't turn on. Pulled everything apart, and the red/blue wire is only getting .25 volts....

What the actual *#;$@!

So my switched 12v wire is fine (blue/white), but my constant 12v (blue/red) is barely getting power. What does that wire connect to? The fuses all work (checked with a multimeter, just that wire is getting less than a volt.

Is it tied somewhere into the logicon and maybe bumping stuff under the dash is causing intermittent voltage?

 

I was correct. After looking at the FSM, I found there's a connector under the dash and above the AC evaporator core that ties into the stereo harness. I took the core back out and sure enough, that connector had come unplugged. Once it was plugged back in, 12v constant was back!

The culprit.



What an annoying issue.

 

While taking things apart under the dash, I damaged my old (10+ years) Kenwood 4" dash speakers. I figured at the very least, it was time for a small upgrade. Audio is a low priority in this car as its already so loud, but I do like to listen to music. For now, I replaced these with a set of
Rockford Fosgate R14X2 Prime 4" speakers. Obviously 4" speakers don't put out a ton of sound, but the clarity over the old Kenwood set is definitely much better.



Regarding the ECU install, I have one more wire to pin and then it's done. My first start tune is set for this coming Sunday!

Now that the ECU harness has been done in a professional manner, I may tackle fixing my chassis wire tuck. Everything still works, but it was definitely a messy job when I did it years ago.

 

Base tune acquired! Had to reschedule the remote base tune a couple times due to sporadic ignition spark issues. After tracing the wiring, turns out my power wire for the ignition relay was loose and not really connected to the battery. Fixed that, set the timing, and Shawn from Tuned by Shawn got her fired right up!

I didn't take photos as I'm rushing to put the car back together, but I finished installing the sound/thermal barrier, and started putting the interior back together. Once that's done, I can finish the little bit of cleanup wiring in the engine bay and put some miles on the new ECU in prep for dyno day! I'm excited to see if this new ECU will net higher numbers than the ancient E6X.

 

The car is finally out of the garage after around a month of work on the ECU install and some other odds and ends. Currently, putting around on the base tune to get some miles on it. The full dyno tune is scheduled for next Thursday.


I really need to get some better coilovers at some point. The 12+ year old stance coilovers are starting to show their age. I was really hoping those Sake Bomb Ohlins were going to come out, but it doesn't look like it will happen.

 

Womp. Only made a peak of 263whp on the dynapack dyno. I'll post the dyno sheet when it's sent to me tomorrow. Everything looked great and then torque started falling off at around 8000 RPM. No timing changes or fueling made a difference, it didn't want to make any more.

Based on the math, if my peak torque stayed constant through to 9500 rpm, I'd be right around the 300whp mark.

I ran the car with a filter and with open velocity stacks, and there was basically no change in peak torque or power. Graph looked virtually identical too.

 

Great build thread. Thanks for sharing, lots of nice details.

 

Here's an image of the most consistent power runs. While fairly linear, you can see the torque falling off around 7200-7500 RPM. I'm thinking my intake manifold runner length is not optimal. If I can keep the torque up to 175ft/lbs to 9200-9500 RPM, I'd hit the 300whp mark.

I managed to find an IDA style peripheral port manifold that has much shorter runners. I think I'll give that a go for testing purposes.

 

Fantastic numbers, can you give a quick summary of the engine/drivetrain build for someone that doesn't want to read the whole thread?

 

@j9fd3s Do you mind if I message you about MFR timing and comparisons to my current engine? I know you have lots of knowledge as it relates to MFR/PP setups.

 

not at all!

 

Well, the search for power is over for now. The car started running weird. Did some diagnostics and found out that compression on the rear rotor is low.

Rear Rotor

• Cold readings: not normalized for higher cranking RPM
  • ~95psi across all faces
    • Compensating for 329 RPM, compression is 79PSI
• Warm readings: not normalized for higher cranking RPM
  • ~85psi across all faces
    • Compensating for 329RPM, compression is 69PSI

Front Rotor is at ~114 PSI on all faces (not normalized), and ~104PSI on all faces normalized. For a peripheral port, that is stellar compression.

This is a rather unfortunate turn of events. The engine only had around 4-5K miles on it and dyno'd at 260whp last month. Since the housings were custom made by Pineapple Racing, nothing in existence matches what I have. This means that despite the front rotor having good compression, I need to replace both machined housings and make a new intake manifold that isn't flanged. Just to get the motor back up and running will run me around 3-5k.

Given that the rear rotor has pretty even, albeit low compression, across all faces, I can only hope that maybe I just need some new apex seals, corner seals, springs, etc. That would be much better than needing to buy peripheral port housings right now.

I guess the question is, do I just call it quits? Over the last 11 years, I've put roughly 25k into this car. It might be time to retire it.

 

I am sorry to see the compression readings. This is a great looking build.

If it was me, I would take break to think it over.
Also me.... stop working on it a drive it until it breaks. Hoping it doesn't do any catastrophic damage.
Give it some time, a great answer will present itself... hopefully a cheaper option to keep it.
Best wishes!

 

apologies for being too lazy to go back and read the previous pages, but what's unique about the rotor housings? I have a full machine shop and might be able to recreate the housing for you.

 

The insert for the peripheral port housing is a custom machined, threaded insert that has a flanged face with studs for mounting my intake manifold. Nearly all peripheral port housings available just use a simple tube exit, v-band, or wiggins clamp interface. So if I have an out of spec rotor housing, I can't replace just one. I'd need to replace both the front and the rear.

My housings look similar to the MFR housings. You can kind of see the flange interface in this image.

 

I can likely help you out. PM me.

 

After consulting with a few friends, and a great friend offering up his lift, I decided to rebuild. I'm also genuinely curious as to what failed in the engine. I'll preface this with saying I don't really know what was put into this motor, as I got it built at a hefty discount back in the day. What I did learn is that it's using GSL-SE housings with older irons. Here's the story thus far.

We took the engine out. Found quite a bit of engine oil in the intake runners. As I have no OMP and am only running premix, this seems to indicate failed side seals and oil control rings right off the bat.



Looking at the hardened RX8 rear bearing, there's some very odd wear. Unlike normal bearing wear, there's also front to rear wear. Not sure what could be causing that, but I'll be replacing the bearings all around.


I didn't take good photos of the rotors, but it's very obvious from the photo below that the rear rotor experienced a lot of heat. The rotor was basically yellow.


The rotor housings have minimal wear. I didn't clean them for the photos but after wiping them down, it's apparent they didn't wear much.


That said both, both housings have the "spark plug mountain." I still need to check to make sure the housings aren't warped, but two things became very clear.

• One: There was too much heat getting into the housing, so I need to run colder plugs
  • I was running 9's in the leading and Autolite AR3932X in the trailing
  • Based on this, I think I need to run NGK 10.5's all around. Not excited to spend $45.00 per plug, but I guess you need to pay to play.
• Two: My OEM 2PC seals are warped. You can tell by the combustion marks on the housings

After inspecting the rotors and the apex seals, I confirmed that all apex seals on both rotors were warped. So I very clearly need to reduce combustion temperatures. What's really interesting is there was no clear indicator of why the rear rotor had lower compression than the front (65 vs 100). All of the apex seals were bowed very similarly and there was no damage to the housings or irons. I still need to do so measuring, but my theory is the rear rotor got too hot and collapsed the apex seal springs. Funnily enough, the front rotor had bad oil control rings/side seals and the rear didn't. I did check runout on the e-shaft and it was still true.

While I can reuse pretty much all the hard parts, I'm going to build a new engine and save these parts for spares in some other project. I happen to have a brand new S5 turbo rear iron and a very lightly used S5 center iron, so I just need to pick up a front iron. I've already purchased new peripheral port housings from PPRE in New Zealand. I'll be sending the rotating assembly out to Mazdatrix this week to get it balanced, and I'm also going to get my injectors serviced just for peace of mind. Hopefully, this next engine lasts more than 4k miles of only street use. Eventually, I'm going to make my own peripheral port housings to reduce cost on future rebuilds/projects.

Per PPRE's suggestion, I will be going to a 55mm throttle body and intake manifold in order to hit my power goal of 300WHP. Assuming lead times are accurate, I aim to be back up and running within two months.

If anyone reading this wants a 48mm DCOE ITB set-up or an OS Giken clutch/flywheel, I'm selling.

 

Hello:

I was referred to you by another car enthusiast. My car is a 1986 Mazda RX7 but my powertrain is from a 1995 RX7 Turbo II. My instrument cluster and speedometer cable is for a 1986 but the transmission is a 1995. My question is: what do I need to buy to make the speedometer work between the cable and the transmission?

Thanks for your help.

 

@Slow RX7 I guess I'm a bit confused by your question. The FC3S Turbo II was only produced until 1991. After that, the FD3S was produced/sold. These are vastly different vehicles with very different powertrains, so which do you have?

If you have an FC3S Turbo II transmission, you would simply use a Turbo II speedometer cable.

If you have an FD transmission, I believe you'd need to swap the FC3S Turbo II transmission tail housing on to the FD transmission to use a factory style speedometer cable. This also allows you to mount the FD transmission in the stock location of the FC transmission tunnel. Aside from that, I personally used a GPS "Speedbox" converter. This connects a Ford style speedometer cable to a digital signal box that is wired to a GPS unit. Pretty easy to use and set-up.

https://speedhut.com/accessories/sen...eed-converter/

For the FC, select the Ford clip-on style cable they offer. It's a very tight fit but it works. Ideally, you'd shave a little bit of material off the speedometer input on the back of the FC gauge cluster to make install easier.

 

weird, what kind of coolant temps were you running?

 

Low. Coolant temps never exceeded 195 degrees and were typically around 175-180. I think a big contributor to the apex seals warping were the spark plugs. Stock 9's in leading and AR3932X in trailing clearly left a spark plug mountain, indicating they were too hot for this application. I need to go at least 1-2 heat ranges colder.

Once again, no idea why the rear rotor had lower compression yet. I'll have to do a lot more measuring as there's nothing super obvious.

 

Purchased a new S5 turbo front iron and started doing some research on sealant for the ports in the irons. Looks like there is various information on which version of devcon to use. There's obviously the plastic steel/plastic aluminum listed on RB's website with varying reports across the forums of how people have used it. There's also Devcon Aluminum Liquid 10720 that's been recommended. I like the idea of the liquid to help prevent any air pockets from being trapped in the putty.

Any thoughts?