I had my injectors replaced, and, while being tuned on the dyno, the motor blew an apex seal. Can anyone tell anything about what happened from the attached dyno chart?

 

If I am reading it right it looks like you were way lean for turbo rotary territory. However, there are a lot of other factors involved and with the info you provided no one is going to be able to tell you much.

If the mods in your sig are correct and you were running anything more than 8 psi you obviously have some issues with the setup. The power is very low but I dont know boost pressure.

 

If I'm reading this correctly, the first pull was around 13. It didn't sound like it was under full throttle.. The second pull looks richer, and I guess those sqiggly lines show when it blew. The last time I had it dyno'd it made 360ish with the cat installed, 400 with a mid-pipe

 

Gotcha, didnt see the AFR for the second pull. Not too far out on that end. Not much a dyno chart can really tell anyone. What apex seals?

 

probably timing related, depending how quickly it spooled. if he was running anywhere near stock timing maps then it is too aggressive for the 35R in the lower RPM range.

 

"What apex seals?" They were stock Mazda, I think.

 

to elaborate, if it happened during the oddity on the sheet then that is close to your peak torque range, where timing really comes into play.

 

Weird.. Power is way to low.... on both runs... AFR's w/ the midpipe on,higher horsepower run, should not be anywhere near 13 afr's.

 

The pull was with the cat at 10psi. The last time, at 14psi, it made 100 more HP, and 60 more torque.

 

the dyno chart is not set up in such a way that you could draw many conclusions from it.

Ask the dyno operators to email your the .drf run files. Then post them up here in a zip file. The .drf files can be read in the Dynojet WinPEP7 software, available for free on the Dynojet website. You also should upload the .dat map files from your Power FC, and any data logs generated during the tuning.

 

I'll see what I can do. In the meantime, I was told the cause was my Racelogic unit, which cut power to the secondaries, making it go lean. The afr's don't seem to show that, do they? And, Racelogic (who responded almost immediately) says the unit can't cut power to one injector...it cuts power to both.

 

If your sig is accurate, you have a 9 yr old reman in the car correct? Probably three piece seals as well. At levels approaching and over 400 rwhp a slight ping can be all it takes. Sorry to hear.

 

Yes, a 9 year old reman with less than 25,000 miles on it. Oh, and water injection. I saw the torn down motor, no carbon anywhere.

 

It blew with water injection? That's surprising. Going with a street port and different apex seals this time around?

 

"It blew with water injection? That's surprising."
Yeah. Back in 2003, I bought the Aquamist unit. As I remember, using their info on how much water to inject, I replaced the Aquamist pump with a Shurflo, added an accumulator, and ran 3 Aquamist jets, 2 post turbo and 1 pre-turbo. The motor got plenty of water.
Don't buy the "bullet-proof" story.

 

Your a/f is the reason it blew. That is over 13 and will blow a motor eveytime. Anything over 12 and you are pushing it.

 

water injection isn't really a safeguard, it just allows you to run more boost before again hitting the knock threshhold, you still can't run it any leaner than you would with just the pump gas.

 

So, since the a/f is pretty steady,no sudden spikes, did the Racelogic unit have anything to do with it?

 

Maybe I should add that I WAS running 850 primaries and 1300 secondaries. They were changed out to 550 primaries and 2000 secondaries. This was the tuning run.

 

I'm not convinced the A/F meter signal was displaying correctly, not yet at least. Where was the sensor positioned in the exhaust stream? Did you have an onboard A/F meter? Also, the rpm window shown in the image for post #1 is very narrow which can obscure the big picture.

Did you have the Racelogic hooked to all 4 injectors? It says on their website that it alternates which cylinder it cuts. Well since there are 4 injectors and 2 rotors, I would think that you need to wire each rotor together so that it is, functionally speaking, treated like a 2 cylinder engine. Did you or whoever installed it talk to Racelogic for a while before you set it up? There are enough settings here that something could have gone wrong.

 

"Where was the sensor positioned in the exhaust stream?"
He uses a sensor stuck in the exhaust pipe. I have a gauge on the dash. (I forget whose, but it's a good one. The sensor is in the exhaust manifold.)
"Did you or whoever installed it talk to Racelogic for a while before you set it up"
The same shop installed the Racelogic. There was concern over how it worked, but he was satisfied that their system couldn't result in a lean condition. My understanding was it cut both the primaries AND the secondaries.
Nevertheless, the dyno a/f readings don't show a sudden change.
Actually, I was told there was continuity from the Racelogic to the injectors, and continuity from the Apexi to the Racelogic, but no continuity across the Racelogic processor. Racelogic says the primaries wouldn't work under that scenario.
I drove the car for a couple of miles, no boost, before it went on the dyno. It ran perfectly.

 

If your on-board gauge is installed in the exhaust manifold, preturbo, it would read falsely rich under boost due to high exhaust pressure. Are you sure you didn't mean that it was installed downstream of the turbo (in the downpipe)? Tailpipe widebands have a tendency to read lean.

Depends how it's hooked up and/or how it's set up in the software.

That may or may not mean something. The dyno A/F sensor is in the tailpipe. It is subject to sampling rate limitations as well as smoothing/filtering which could hide such an event.

They probably just followed the instructions



See any potential problems here?

I'm not really sure what this means in this context...

If they followed the instructions without thinking it through, they wired it up like a basic 4 cylinder with normal sequential fuel injection. And therein lies a potential problem. By default the Racelogic will cut individual injectors according to the schedule inside the computer. The more calculated wheel slip, the more injectors will be cut.





But here's the deal: with a 2 rotor engine running staged injection, if you randomly cut 1 injector you are not going to fuel cut a whole rotor. You are going to cut a random primary or secondary injector depending on how they have the thing wired up and how they have the software configured. See those little x's above? Those are the random injectors being cut if the system was essentially configured like a regular old Honda 4 cylinder.

If the Racelogic doesn't calculate a slip ratio above 5% (the default threshold in the software) and the secondary injectors haven't come online I see little risk for anything to go wrong.


Anyway, this is all speculation. Now you need to hook the laptop up to your Racelogic and see what settings they have configured it for. I doubt they were doing any logging during the dyno runs so honestly we'll probably never know for sure if the traction control intervened and did anything. I'm skeptical that this shop understands the peculiarities of sequential fuel injection on a rotary engine and then accounted for it in their configuration of this traction control system.

IMO aftermarket traction control systems are extremely primitive and not worth it. The traction/stability system on a 7-8 year old Rx-8 is 20 years ahead of this box you bought. If you want traction control buy a car that was already engineered for it. I could go on and on about the differences between this box and an OEM system.