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haha. Hopefully I didn’t offend you but that’s how I feel about LS swaps. The great thing though is that it’s your car so do whatever makes you happy. Given the engine woes I’ve had, maybe swapping was the better option for me 🤷♂️😆
and I would say not ruin the car so much as the soul. The wankel, for better or worse, is the soul of an RX7 (in my very biased opinion)
Effin legend . Don't backpedal. Tell us how you really feel. Hate I missed that convo...
Well...the mysterious sound in the rear has been solved! It wasn't super simple, but it was cheap. I took my FD to a friend's house and got the car on quick jacks (I need a set of these). After telling him what we had already ruled out (the diff and rotors), he got under the car and i started turning the rear wheels. He noticed the issue immediately. The anti-vibration spacer between the diff and drive shaft along with the dust shield for the rear diff pinion seal was just spining freely. Our best guess is that depending on the position of those two, they would rub against each other and the drive pinion seal. The spacer literally separated from the rubber as you can see rubber is still on the part it was attached to.
I called @seckerich who told me the spacer can be removed and not put back so I junked that. My local dealer got me the drive pinion seal in 2 days for $24. They are $23 at Atkins Rotary so the dealer's price was more than fair especially since I didnt have to pay shipping costs. We had to take off the drive shaft to replace and fix the issue but now we're back in business.
While I haven't messed much with my AC yet, I noticed that when I turn the AC on, my cooling fans weren't turning on. After getting some remote help from @Molotovman, we determined that my grounds at Ground Point #2 (front bar behind the bumper support on passenger side) was wonky. The plastic rectangle piece was slightly cracked, brittle, and a little malformed. If i wiggled it, my wipers might stop working and my fans would sometimes come on. I just ran a new ground wire from the fan connector plug direct to a chassis ground and now I'm back in business.
Lastly, I ran a post-DGRR compression test because you know I have compression PTSD now. The motor now has 1200+ miles on it (double how long my previous motors went). The number across rotor 2 is still consistent but that one side seal on rotor 1 isn't getting better. It's actually gotten worse but I'm not sure it matters in the big picture. I did put an analog boost gauge on and at idle I'm pulling -18mmHG of vacuum which for a ported motor I'm told is really good. I attached a screenshot of my compression test tracking sheet.
Next up, I'm going back to the dyno in 2 weeks for Nelson to clean up the tune (it needs some drivability work) and also to see what kind of power we're putting down. I have a 2-day track event at VIR at the end of June and Nelson is out of the country for most of next month so gotta knock this out ASAP.
Thats awesome you got the a/c squared away along with the scraping sound in the driveline. I know we had this discussion at dgrr about the rest of the world being hung up on compression #s. I'm still fully in the camp of good vacuum and if it hot starts you're fine, and I really do hesitate to say it, but, 75psi on one face is concerning. The others are fine. I had similar #s before my 1st rebuild on one face of one rotor and it was a broken corner seal. Need to keep a close eye on that.
Thats awesome you got the a/c squared away along with the scraping sound in the driveline.
AC isnt fixed yet. The compressor still doesn’t turn on. It’s gotta be the thermal switch. My guess is without fans running, it got really hot. It was fine on the drive up to DGRR but it was wet and raining. My guess is when it got warmer on day 2, things went bonkers. The vMount flows enough that my thermostat rarely has to open up so I suspect the AC was struggling since no fans were running period.
As for the 75 psi face…yeh..im Uber paranoid about it. If gets even worse, I legit don’t know if I can stomach having to pay Bryan or anyone else to pull the motor, crack it open, and fix it (again). That likely will be the end of the road for this car. I mentioned this to Bryan when I picked up the car and he said it was fine so if it’s not and this gets worse, I’m 100% done with him. Let’s hope it doesnt get to that. Does make me a little nervous to take to dyno though…
^then you have a mildly ported motor at best. Probably cleaned up intake port runners with minimal port timing change and stock exhaust ports.
Not necessarily a bad thing.
Yes. Bryan says its a mild street port motor. So would you be worried about that one side seal that is clearly not getting better? @seckerich told me that the dyno might actually free it up.
good luck expecting integrity for most companies post covid, just lucky he isn't still waiting for the engine he paid for 2+ years ago per the shameful IRP no-refund-done-went full-scumbag-crook thread
Yes. Bryan says it's a mild street port motor. So would you be worried about that one side seal that is clearly not getting better? @seckerich told me that the dyno might actually free it up.
Injecting my two cents into the conversation - I would be concerned as this is not normal. Something is incorrect, and as TwinCharged says, a brand new motor should be the responsibility of the builder - period. Bryan is a good guy, but he needs to own this issue.
Could the dyno free up the side seal? Perhaps, but it might also break it, and then what do you do? If it were me, I'd skip the dyno, take the car back to Bryan's shop, and demand he makes things right.
At this point, you are much too kind - I've been down this path more than once and have learned that being nice is fine, but you also have to be assertive in making others take action to correct their issues. This is a mechanical issue that is clearly related to the engine build so there is no blame to deflect to others. But if you dyno the car, then that adds in the additional complication of "it's the tuner's fault."
Sucks for sure, but you have come so far, why not have this simple issue resolved by the guy who built the engine?
Yeah. I would not go on the dyno with this in question. If a seal is going to come unstuck, normal driving around town produces enough movement and heat to accomplish that (it is inside a rotating engine spinning at thousands of RPM and in the combustion chamber exposed to EGT after all).
I looked at all my compression test results and the face that's making lower compression (due to the side seal) is on avg about 13psi lower than the highest number on that rotor. The delta hasn't changed that much so much as the higher numbers from when I first got the motor have come down about 3-5psi.
At this point, I'm gonna run it. If it goes, so does the car. Bryan says he stands behind the motor and that he'd have zero issues putting it on a dyno tomorrow with the current numbers. I talked to another builder (who wants to remain anonymous) who told me the same thing. Both said starting compression at 250pm isn't a good measure of running compression. If the car starts hot/cold fine (and it does fire right up) and the vacuum at idle is good, send it. Was also told the seal likely isn't stuck so much as there might be a little extra clearance and I'm just getting some blowby/leak but when the car is running, that psi delta isn't going to make a lick of difference.
I looked at all my compression test results and the face that's making lower compression (due to the side seal) is on avg about 13psi lower than the highest number on that rotor. The delta hasn't changed that much so much as the higher numbers from when I first got the motor have come down about 3-5psi.
At this point, I'm gonna run it. If it goes, so does the car. Bryan says he stands behind the motor and that he'd have zero issues putting it on a dyno tomorrow with the current numbers. I talked to another builder (who wants to remain anonymous) who told me the same thing. Both said starting compression at 250pm isn't a good measure of running compression. If the car starts hot/cold fine (and it does fire right up) and the vacuum at idle is good, send it. Was also told the seal likely isn't stuck so much as there might be a little extra clearance and I'm just getting some blowby/leak but when the car is running, that psi delta isn't going to make a lick of difference.
Fingers crossed for you, my friend. If that were my motor, I'd take it back to Kilo, and I am confident he'd pull it and fix the issue. That is what is meant by "standing by his motor" not, "Well there is an issue, but I think I - Bryan - am okay living with the problem even though the impact is on you."
Last edited by David Hayes; May 20, 2023 at 07:38 AM.
Something to consider. As you may know I also warped/wore down two sets of apex seals. I noticed that with quick spool/boost assist on, the 8374 and its variants have incredible transient spool. As a matter of fact, I found it to be TOO quick. Throttle modulation was terrible and more importantly dialing in transient throttle fueling becomes very difficult and unpredictable even with quality ECU software such as Haltech.
In my own journey figuring out what went wrong with my motors, I elected to leave boost assist OFF and noticed tighter AFR's during the various transient scenarios.
Cheers
Good to know. Im not running an EFR (but I should have knowing what I know now). My issue was definitely because my rotors were jacked. I'm pretty confident my apex seals won't be an issue now that we found the underlying cause.
Good news. Nothing went boom on the Dyno. The car made solid power: 376WHP and 311TQ at 14psi. The car was solid the entire time except...
After the tune was done, I wanted to do one more pull without AI and one with to see the delta. On the very last pull, we got to 7.3k RPM and we tripped one of Nelson's engine protections. The ECU showed a "couldn't find home error" which Nelson said basically means the CAS "lost a tooth" (figuratively). At that point, we decided not to press our luck. We cleared the error and during my entire 40 min drive home, the error didn't come back.
When I got back from DGRR, I saw this error when I logged into the Haltech. We had no idea how long that error was there since it could have possibly been right when the motor first started or even a leftover from the last engine. I cleared it and it didn't show itself at all in any driving I did leading up to today. Nelson didn't love the error and was actually concerned but because it didn't do it at all today but we weren't in a "you cant drive the car" panic. At this point, it's intermittent. If my trigger wheel was bent, we would have seen issues all day long. At this point, I think the easiest option is to replace the CAS. Atkins Rotary sells them for $147 each (ouch) but I see them on Rock Auto anywhere from $14 - $80 depending on the brand. Thoughts on OEM vs Generic? I may also replace the OEM wheel just for my own sanity assuming it's not outrageously priced but I just don't see that being bad.
For now, Nelson said I can drive the car spiritedly at full boost but he limited me to 7k rpm. Since we had no issues with the motor otherwise, we got to do drivability tuning and man did it make a huge difference on the way home.
I would not chance my engine to an aftermarket sensor. I would ONLY replace it with an OEM unit. This doesn't feel like a place to save a few bucks.
I don't disagree. I think I get stuck because it's not a specialized part and likely not made by Mazda. There is a lot of markup in an OEM part. It's essentially a magnet but I emailed Ray Crowe for his price. The RX8 uses the same exact part as does the Protege. For the price of (2) OEM + whatever the wheel costs, I could move to Full Function Trigger kit with a Hall Effect sensor. Nelson did say he likes the OEM setup because there are two sensors, essentially one to verify the other.
I don't disagree. I think I get stuck because it's not a specialized part and likely not made by Mazda. There is a lot of markup in an OEM part. It's essentially a magnet but I emailed Ray Crowe for his price. The RX8 uses the same exact part as does the Protege. For the price of (2) OEM + whatever the wheel costs, I could move to Full Function Trigger kit with a Hall Effect sensor. Nelson did say he likes the OEM setup because there are two sensors, essentially one to verify the other.
On the CAS sensors, splurge for the OEM ones. They are most likely NOT made by Mazda, probably made by Denso, NGK, Mitsu or some other big Japanese automotive electronics company, but they will be made to Mazda's OEM quality control standards. The cheap no-name replacements you get from Rock Auto are an unknown risk in that regard.
When I did my build and was building out the wiring harness, I thought long & hard about switching to the FFE Hall effect trigger kit. Ultimately my conversations with the application engineers at Link (I'm running a Link G4+ Fury ECU) convinced me that the switch to a Hall sensor, at least for my Link ECU, was an unnecessary expense. The Link ECU handles the variable reluctance (VR) type sensors very well, and is very happy using the OEM CAS & trigger wheels. So I wired my setup to use them - milspec twisted pair shielded wiring, proper grounding and routed my harness as far away as possible from the spark plug wires to avoid potential EMI issues.
Nelson is partially correct in his statement regarding the OEM CAS with the 2 VR sensors - they are "better" in a sense than a single sensor setup (either Hall or VR sensors), but they don't actually "verify" one another like a redundant sensor would, since they are sensing different teeth on the trigger wheel. One is tracking the rotational angle of the E-shaft at any instant in time (12 teeth on the OEM wheel), the other detects the start of the 4-stroke combustion cycle (one or two teeth on the wheel, IIRC). The reason an OEM dual sensor setup like this can be considered "better" than a single sensor setup (e.g., FFE 36-1 trigger wheel w/Hall or VR sensor) is because the ECU is burdened with less computational overhead to figure out actual crank angle relative to the start of the 4 stroke cycle. With the single sensor setup, the ECU needs to reliably detect the missing tooth (i.e., 36-1 wheel or similar) on every E-shaft rotation without fail and the software does the rest - add in some noise, poor wiring, etc, and that task can become problematic. With a 2 sensor setup like OEM, your 2nd sensor is dedicated hardware that provides the "synch" signal, so your ECU doesn't have to compute/guess at it.
Originally Posted by Djseto
I also need to check my wiring. This could be as simple as a wire crossing my CAS wires and causing some EM interference or maybe a loose ground.
I forget what ECU you're running (Haltech?) but if it has a "trigger scope" display/logging feature built in to the ECU/tuning software, you can use that to diagnose any potential issues with CAS wiring and its functionality. In the Link, it works pretty much like hooking up an oscilloscope to your CAS sensors - you get a nice log of output voltage vs. time for each CAS sensor, so you can clearly see if there are any timing errors and/or amplitude hiccups in the trace.
