Im sorry to read about the loss and money wasted, but its a learning curve correct ?

If you abandonan now you will accept defeat !.

Why dont you start from another core motor, say a S5 or a RE , there affordable enough, and as your doing the work wont cost as much to port and check specs.

Maybe its the motor ( center iron, oil passages , etc who knows )

start with another complete motor ( cheap jspec maybe from japantola ) and rebuild that.

Well either way hope you get it going again !

 

My car is a true S5 TII, and thats what this core motor is, plus many upgrades, including the thicker rear plate.

I don't think it's accepting defeat, as I wouldn't be done forever, only done for a certain period of time. Life can change in an instant, and recently mine has taken a few turns so I'm still trying to decide the best thing for me to do. The timing couldn't be worse for all of this to happen.

 

Luke asked me to wade in here with some input on the failure. Wish I had answers but it's really a mystery to me as well and open to much conjecture.

What we can rule out are coolant and oil temperature issues. Prior to the oil filter pedestal checking out we did nearly two straight hours of steady state tuning up to 6psi as high as 6000 rpm without real temp issues. Sure holding positive manifold pressure in steady state would cause the temps to rise but not outside the realm of other cars we've worked with. In fact the proportion of tuning time to cool down time was quite good. Outside of steady state tuning at relatively high loads and rpm there is not a temperature issue with the car. At least that is documented by the array of Defi gauges Luke has install or with the Haltech coolant temp sensor. I understand localized heating of the combustion chamber but we loaded the car much harder (and hotter) in steady state than we were doing an 11 psi pull without issue.

The tune at that point was not lean. Composite a/f ratio was in the 11 - 11.5:1 range across the rev range. At 11 psi I wanted to see about 11.2 at peak torque tapering to 11.5 above and below. EGT probes were recording temp variations between the two rotors at less than 100*F. So it wasn't a case of one rotor running lean. Again, we did steady state to 6 psi just a week prior with these same results.

My immediate thought was the timing marks on the pulley. After all this is one of the only hard parts that's been on board for all three failures. Being off only 3-5 degrees would be enough to cause an issue. I have no experience with this manufacturer but I have personally received a bad pulley from a different very reputable manufacturer. So it does happen. That's the easy convenient thing to hope for but who would get that lucky?

We datalogged one pull to about 6200 rpm the night before on the road. On my small screen laptop, viewing the log trace through the Haltech software, the rpm trace looked smooth without any hiccups. There are no RPM spikes to indicate a trigger issue and as Luke has said the car never indicated an issue with the trigger. Unfortunately, I've experienced that issue enough to identify it. However, after the failure, I looked at the trace in numerical format in a spreadsheet and found the following anomaly. A clip of the spreadsheet is posted below. Notice when the throttle is lifted the RPM trace drops by about 400 rpm only to recover back to the pre-drop throttle level. I'm guessing this is due to the gear lash in the CAS drive. Jump off the throttle and the CAS lags behind for a split second before meshing with the drive gear again and resuming accurate readings. This all take place in about a 2/10 second time period or over the course of about 20 engine cycles at 6000 rpm. The dangerous thing here is that the EMS requires an accurate RPM reading to determine event timing. If the RPM reading is off the timing will be off. Bad times. Is this what has been causing his failures? Hard to pin this on the CAS because others have used it successfully and I've used in in a number of cars without issue. However, this (at least to me) is hard evidence of what others have talked about before. Using the CAS will induce slop in the timing events. I've recommended to Luke a crank trigger for the future.



Now, the failure itself. Up to the point of the failure we hadn't experienced any ignition problems. I'd driven the car on a very gross tune and the ignition had no problems lighting a 10:1 mixture at 11 psi on the way to the first dyno session. We hadn't experienced any sort of miss or cause for concern. However, when the engine failed there was a miss. Not a big one. I've felt much, much worse but there was a miss. As these things happen in a bang-bang sort of way I can't be certain if the miss was the failure event or if the miss preceded the failure. Going out on a limb and saying the miss preceded the failure it's easy to assume that the CAS slop, triggered by the rapid deceleration of the engine from the miss, could lead to a seriously ill timed spark event. Again, only a theory.

Another theory I threw out was an overboost condition. Luke's 2nd failure had an overboost condition logged at the time of failure. Luke runs twin Tial wastegates. Tial is high quality stuff and it's hard to imagine they'd be problematic but it happened before. Without a datalog of the time of failure it's impossible to say if it happened this time. The prior overboost event only showed itself for less than one second on the datalog. Something you would most likely never see watching a boost gauge. The data trace from the night before the engine let go does shows very uniform boost.

I like the suggestion of checking all plates for squareness. Makes sense that a center iron putting everything in a bind could lead to failure even without a miss-fire or detonation.

In the end I'm as stumped as everyone. I can see breaking at 20+ psi, even multiple times. But these things don't happen at 11 psi with a conservative tune. I'm urging Luke to stay with it as well. For his sake and for the sake of myself and other just being curious about what has led to the failures.

 

Chris, thanks for the great explanation! I appreciate it.

 

Thanks for the rundown Mr. Ludwig. Much good info there and indications of how bad the stock cas really can be.


dpf22

 

While I don't mean to invalidate your suggestions B, these won't solve the issue. The issue is external to the engine. These engines can take all the abuse in the world under normal conditions. If they knock while under high RPM's and heavy loads, then they run the risk of breaking. The issue here isn't making an allegedly bulletproof block; it's finding what's causing the knock. Sure, it may hold together better with four more dowel pins, but it's still knocking for some reason.

B

 

The RPM spikes come from the conversion the internal reluctor on the Haltech does w/o good filtering (older models) when any kind of RF or EMI jumps on the CAS's trigger harness (alternator, ignition, etc.). I ran into it once in California in '05 with a car I was trying to tune -- 16krpm spikes all over the place. Removed the alternator? Gone.

B

 

Better trigger filtration on a smarter ECU compared to the E6K/X models.

B

 

He was using an E8 this time though.

That has crappy filtering also?

 

Yes, I switched to an E8 this time around.

As Chris noted earlier, we had 0 ignition issues this time around. I would consider the E8 to be far superior in that regard.

I also wrapped the CAS wiring in Aluminum tape from the connector back to the ECU, so if RF interference occurred, then it was because God himself said to.

 

The Hanson Bros. recommend puting on "the foil" also

 

Is the REW crank trigger any better? or does it share it own problems too?

I guess, I now understand why the old school distributor is so popular back home among drag racers

 

I agree with Brian on all counts except limiting rouge RPM readings to the ECU. It's been shown that poor installation is a much more prevalent cause than the ECU itself.


The issue with the inaccuracies in the datalog I posted is not related to the Haltech. It's related to the lash in the CAS drive gear. Even the most advanced ECU will see the same thing. The failure itself related to the Haltech? Dunno, could be but I would guess it's not likely since it's a different system than he had for the 2 previous failures and someone else was programming it.


The REW crank trigger would eliminate the lash in the CAS drive gear that can induce the timing inaccuracies. However, I'm still hesitant to blame the failure on the use of the CAS as it's proven reliable enough for myself and other over the years. However, for the best in timing accuracy the crank trigger is the only way to go. Mazda changed it for a reason.

 

Just tripped over this, and seems to be identical to the failure you're experiencing...

http://www.rotaryresurrection.com/2n...ron_break.html

 

I've seen that before. Thanks for the info.

That is referring to the rear plate, which cracked the first time. I found the rare S5 TII plate with the thicker dowel land, and the rear plate has been fine ever since.

Second and Third time was the front plate. I'm still leaning toward an ignition discrepancy, but if it's the ECU, then I have the worst luck with cracking 1 plate with an E6X, and 1 with an E8. I just can see 2 different ECU's failing on the same issue...back to back.

That leaves the CAS and the pulleys. Hopefully something will rear it's ugly head.

 

It's up for sale, AS IS, for a short time only...


https://www.rx7club.com/showthread.php?t=752393

 

C.Ludwig and I spent some time yesterday to pull the motor and tear it down. Everything looked fine inside, so no issues there. No flattened seals or springs, just a cracked front iron dowel land.

Ludwig rigged up a jig to check TDC using my E-shaft and pulleys. We did discover that the TDC timing mark on my Mazda Racing Pulley was a bit off. We were actually hoping that it would have been off on the advance side to give us some sort of indication that the pulley might have been the cause all along. Instead of being advanced, it ended up being off to the retarded side, 3.5 degrees to be exact.

At this point, after the tear down, the cause is still unknown but there are a couple theories in place. 1) The combination of the pulley timing marks being a few degrees off, along with the the play or "slop" in the CAS, magnifies the possibility that the ECU could see a crazy event leading to firing the plugs at the wrong time, stuttering the motor, shifting the plates, cracking the dowel land.
2) In discussing some of the wiring of the ECU, Coils, and remotely located battery, it might be a possibility that I need to re-wire some grounds in the car. I'll go into more detail on how I have it currently wired to get everyone's thoughts on this theory.

 

Please forgive the grade school drawing, but here is an example of how the ground wires are routed throughout the car.

The only (+) power wires that are shown is the 2 gauge wire running from the battery to the (+) post of the remote terminals in the engine bay, and the stock power harness/fuse block wiring which make their connections also on the remote terminals.

Any thoughts/suggestions are welcome.

 

Here is the proposed solution that is in discussion right now:

 

i dont know about others, but i ALWAYS ground everything back to the battery negative. then i add a few grounds from the block to the chassis.

 

That is what I've heard others say also. That was kinda the idea, except we were going to run a bus bar to the Negative Battery terminal and then run gauges/controllers/etc to the bus bar.

It was brought to my attention that running the grounds the way presented in the above picture will eliminate ground loops.

I still need to know where I can ground the remote negative terminal in the bay, along with the E-fan.

 

Well, I'm giving this one more shot.

Here are the plans this time around:

-New OEM front plate (thick dowel land)
-4 New OEM Dowel Pins
-Re-wire Factory Battery Harness (Starter/Alt/Fuse Block)
-Re-wire Ground System using Bus Bar
-Banzai Racing Oil Pan Brace
-Aeromotive Fuel Filter w/ -6 SS lines (replaces factory filter)
-FD Oil Pressure Regulator
-Vacuum/Boost Manifold

Also, of course, the rebuild will be done with all NEW OEM O-rings. Everything will be cleaned, inspected, clearanced during the rebuild as well.

C.Ludwig and I will be doing the rebuild and should have this thing back on the road shortly.

I'm still kicking around the idea of switching to a hall effect sensor/pickup or somehow implementing the FD Crank Signal/pickups onto my motor.

 

I think the idea of using a crank trigger wheel setup is good. It's far superior to a crank angle sensor; that's for damn sure. Good luck with the build!!

B

 

Good luck with it man, I am rooting for you!

 

How hard (with your particular setup) would it be to switch to the FD front cover to use its crank trigger?