So how much did you put down on these numerous 11psi runs? The culprit has to be something out of wack. Ive always beaten the hell out of my car with my HKS T04E daily driving boosting no less than 1 bar everyday and never cracked a front or rear plate, and im using a thin rear S5 plate.

We didn't do any power runs on the lower boost. This was the first pull of the day.

The last motor put down 374/306 @ 14psi on a mustang dyno. I think that I was getting mid to upper 300's @11psi.

crossfireing on the coils?
 

Is there a possibility that you are crossfiring on the Ignition coils?

Kenn

I guess it could be a possibility, but I don't see how. Magnecores are some of the best, and the insulation surrounding the wire is 10mm thick!
None of the plug wires are touching each other.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/unsure-tdc-724942/ check this thread out about finding TDC. I've never tried it but it's something to consider if you don't trust the timing marks.

For what it's worth, PM Smoken' about his problem with setting timing on an aftermarket pulley. He built a motor and used some kind of aftermarket pulley and it turned out the timing was retarded way far on it. The car ran decently but never built compression on one of the rotors. Turns out a bearing had failed somehow due to the timing being off.

And I disagree that a few degrees of timing being off wouldn't cause a problem. You can get on your Haltech and advance or retard the timing in vacuum probably like 5 degrees in either way and it wouldn't make a huge difference in driveability, but that 5 degrees under boost could really risk detonation. Especially if your trailing split somehow gets messed up and you run negative split or something. I'm not saying that's what happened (I don't even know if split problems are really possible in this case), but I'm still really suspicious of your timing.

Thanks. I'll definitely look more into the issue, it's the main suspect at this point.

I follow your reasoning, but how could the same setup run fine up to 20 psi on the last motor? Why did it let go at only 11psi this time? Difference in ECU's, tuning, ignition setup?

comitatus, sorry i havent been keeping up with your thread.

the first thing that came to my mind when seeing your latest mis-hap is that maybe you had one of the random 16000rpm spikes that people sometimes have on those FC CASs...

i actually might be up at ludwigs to swap out haltechs because my e8 ignition drivers are turning off when running direct fire (waste spark runs perfectly fine though... dunno)
too bad i missed you!

No worries, man.

I thought the 16K spike was an issue with the Haltech E6X and not the CAS itself?

That's pretty crazy about your IGN driver going bad. Hopefully you'll get it resolved.

I was running in Direct Fire, and I was seriously impressed on how smooth it felt. Definitely is a nice feature.

Have you formed an opinion of the coils yet?

it might just be an e6 thing. i know my e6k did it a few years ago.

Didn't really get to test them out, but for what it's worth. They were working GREAT till that point.

We were running the recommended low charge time of 3.0ms, and everything was VERY smooth with no misses, stutters, etc.

Car started from cold start every time, first time.

I really wish we could have tested them out in higher boost levels. :(


Gotcha. If it were an CAS thing, I think I would have switch to an Internal Reluctor a LONG time ago. I don't like taking chances...but still never seems to work well for me.

i would have cranked those nice coils up to about 5ms, but that's just me. 3ms seems quite low.


i'd do some searching about this. i've known several people who have had the random 16000rpm jumps, but none of them on the e8 series yet -maybe just because it's new? maybe not. definitely something to look into though, when you're cracking irons due to misfires.

Sorry to hear about what happened. I would've been really pissed off as well. By the way, where did you get your intake, or did you custom make it? And how did you custom make it?

Personally, I would put that cas on an oscilliscope to analyze the signal at several points in the rpm range. all you have to do is rig up something with a variable speed drill and plug the 2 separate pickups in and see what happens. Honestly I am thinking that it is tack speed weirdness with the pickups. I could be far off base though. But hey, thats a good way to check on it though.
Give it some time to simmer in the back of your mind. I'm sure something will rear its ugly head. Show this problem who's boss.
Get her running again, it would be sad if you gave up now.


dpf22

Solutions:

#1. Continue to use small dowel pin TII plates Mandatory 3 to 4 extra dowel pins on the spark plug side on the block
1A. (Better option) full Stud kit... the complete block

#2. Upgrade to a front and rear TII side plates with the THICKER dowel pin area
2a. Extra dowels or studkit

#3 Upgrade to Cosmo RE side plates and UIM/LIM
3a. Extra Dowels or full stud kit

Lastly (and I consider this a must) BUY ALL NEW DOWEL pins... trash those used ones..

First post for a proper long time, but thought the work you've done is brilliant - do not give up!! Totally inspired by this

as for the cracking, to have lost 3 housings to the same problem, and you've changed basically everything to do with fuelling and ignition and air and housings does suggest something else is wrong... Is there any possibility that one of the plates could be out slightly, putting the additional load on the engine that wasn't there previously? As you've replaced everything else (inc injectors?), I'd be tempted to look at the items that haven't changed - esp the engine components.

Agree 100% :)

Thanks for your input. It's definitely appreciated.

#1 - Understood. I've known this, but was always told that it wouldn't be necessary, as it's all in the tuning. (I think I've proved that wrong).
1A - Regular Stud kit, or the Oversized, where the block has to be milled?

#2 - Rear has been upgraded to the later/thicker S5 TII plate. Front was supposedly the same when I purchased this time, but when I received it, discovered that it was not. Apparently the front plate is harder to find...

#3 - Didn't know that this was possible, or probably would have went this way a long time ago.

Do dowel pins go bad? I've never heard about this theory, but I'm very interested to learn about it.


Wow, Thanks for the kind words! Hopefully the inspiration that I've had by pursuing this project will filter down to others, but hopefully they'll have better results.

I guess it could be a possibility, but I don't see how I received 2 bad plates. Both were within spec and in GREAT shape.
Yes, injectors are all brand new, Seimen Deka 720 primary and Bosch 1680cc secondary.

Items that haven't changed thus far would just be mostly shortblock pieces (internal/external), and the pulley.

# 1a. Yes.. if you buy the Guru oversized 12mm Stud kit, your complete block needs to be machined.. All the sideplates, and both rotor housings.. Cost about $1000.00 including the machine work. You will never crack a sideplate again..

The Stock Diameter Kit= waste of time.. You are better of simply adding dowel pins instead..

#2a. Yes, hard to find used...but If you buy a NEW front sideplate you will get the thicker dowel pin plate

#3a. Cosmo RE block upgrade would probally be best.. The stock ports are already 30% larger than S4/S5 TII ports, the sideplate are newer/stronger/larger dowel pin casting, the ports on the intake manifold are larger... Lee Toscano has just proved the stock ports can make 700 plus HP without porting.. and his motor is only pinned..his motor does not have the 12mm studkit.

get your hands on a set or Cosmo RE plates, UIM/LIM/TB/Elbow/ cosmo re oil pan, and a set of mounts... use all your other stuff , add some extra dowel pins ( machine work required) and be done with it... No more cracking sideplates...

I think those are great suggestions Japan2la, but any insight on the issue?

No stock iron should crack at that boost level/revs. If he goes to all the work of putting together a stronger motor and this issue is still present, something will give even if its not the iron.

Personally I have no clue on what the problem is, I'm battling a similar situation myself.

I think I know the issue.. HEAT and or lean condition

What caused the Heat/lean condition???? Not sure

Heat causes the rotor housing to expand. This causes the small dowel sideplates to crack at the dowel pin (weakest area). Aluminum expands at a much faster rate than the sideplate whic barely expand due to heat..

Mazda had this same problem on stock motors, reason why they redesigned the casting to be thicker around the dowel pin. If an all stock S4/S5 TII motor can crack front or rear small dowel pin plates as soon as you put more heat ( larger turbo) the problem is increased.. I know a guy who cracked the Thickside plate 20B iron on low boost and only 437HP on an A series motor ( small dowel pin).. Same problem.. Heat.. as a 20b is hardly being pushed at 437HP..

Simple and plain.. the thicker sideplate dowel pin plates can handle more stress and for more insurance extra dowel pins or a studkit can add extra protection..

Yo! Answer my PM's!

less than parallel surfaces can cause some of these issues. So you might check how "true" these plates are. It could simply be an unparallel center iron causing this crap. ArchBish was hinting at this. Give it some thought. I don't remember seeing that you had either of those machined, but it could hold water either case.


dpf22

It's just really weird to me how uneven the quality of some of the irons can be, even among the supposedly stronger later series blocks. I know a couple people who have cracked an iron multiple times and then some people never seem to have problems. That's why it's hard to say for sure if it's a tuning problem, a random freak accident (Haltech flaking out on you for whatever reason), or weak parts.

This is my issue 100%. I have take care of "possible causes" of the stutter/haltech/boost control, etc...in the past builds. Sure, those could have been part of the problem, but evidently, the issue still remains for whatever reason.


The thicker rear plate that I found has definitely proven to be beneficial, so this "fix" to cracking plates is accurate. Although, it just spreads to the next weakest link. Purchasing a NEW plate is definitely a good idea, since it would have the later/thicker dowel land.

Cracking plates is definitely a HUGE concern of mine. Figuring out the cause of why is MORE of a concern than the result.

I can understand how heat or a lean condition could have caused it, but I am pretty positive there was no lean condition present. 3 widebands within .1-.2 of each other would have confirmed this.

If heat definitely caused it, then there is no way around the issue. Since it was the first run on the dyno, general "over-time" cooling problems (heatsoak, etc) was not an issue. Why didn't it let go the night before on the road when we did the same run multiple times?


It definitely makes sense, and I see where you are coming from. The middle iron came from the original motor. I had a "pro" rebuild my motor the first time and I was told that everything was in spec. Of course, that is assuming everything was checked in that fashion. I can only trust, since I was not there and didn't do it myself. I would have gladly had any surfaces machined or lapped from being out of spec if it would have been recommended to me.