Dual e shaft position sensors ?
 

Has anyone fitted/mod the RX8 with dual e shaft position sensors? I'll design my own code to handle the 2nd sensor, but I'm just wondering if anyone has created the brackets or modded the case to handle 2? The 2nd one would be for backup failure purposes.

I don't believe I've seen anything about that before. What is the scenario that you are looking at needing a second one? I've seen very few cases that even believe it might be a failure. I can't recall any failure's I've actually seen posted about.

Why? The failure is quite rare...and when it stops working the spark and fuel are cut. The ECU is quite good at interpreting the sensor signal...and knows when it isn't correct

Who doesn't like using both hands? Dual shaft sensors? Get it? Meh, troll out....

nice Slash, I found it's for airplane pourposes. That should make it much easier since you don't have quite as much space constraints.

Things like this are common on pro level race cars and airplanes for obvious reasons.

I don't think I've ever seen a dual sensor mount though.

Correct. I did some searching and asking around on the aviation forums, thought I'd check on here too in-case someone had something. I know the chances are slim of failure of the actual sensor, but I'm not willing to take that chance. Dual redundancy is key. (Which is why I love the Rotary so much over the conventional pistons)

With this logic, you may as well have an extra air intake and an extra set of coils hooked up, just in case :p:

Extra coils is common on aircraft,

We need a "WTF" forum

Is this for an air craft or renesis?

We had the crank position sensor fail mid-race at a Chump Car event. This was on a Neon. The car wouldn't rev over 4000.

We lost positions, but we pitted and replaced it. Kinda hard to do that with an aircraft, which is what this gentleman is building. So when someone says:

"when it stops working the spark and fuel are cut. The ECU is quite good at interpreting the sensor signal...and knows when it isn't correct"

That's not good news at 15,000ft :\


To the OP: I'm not sure I can help with solving the problem, but one related thought: I tinker with drones and one issue we have is with dual sensors (say compasses/accelerometers) the program gets confused when the sensors disagree, as it doesn't know which one is correct. In our case we end up running 3 of the same sensor. So I imagine you'd need to run the second one as standby and have an emergency switchover procedure if the primary fails, rather than take input from both simultaneously. I could be stating the obvious, but just a thought.

It's for a renesis, that is going to be placed in an aircraft.

And if you note he said nothing about aircraft before dan made that note.

Ah ok. Carry on then :smoker:

It would just be a straight fail-over. Not using both sensors at the same time. Ofcourse with the eshaft sensor, it will have to be programmed differently as it will be reading at a different clock position. The flight avionics uses 3 of everything for sensors.

Thanks guys, looks like I'll come up with my own bracket down the road.

ps. We do have an extra air intake in aviation. One is filtered and one is ram air once we get nice and high. The rotary already has backup injectors & coils, which is why we love them. We can limp to the closet airport on 1 rotor, or the primary, or the secondary, etc... The redundancy it already built it compared to any other automotive engine.

If you're going with a P Port than you are going to have to have a custom air intake, and install there injectors there aren't you?

Do you plan on using the OMP with it locked into a set position? Just curious.

If I was trying to build a bracket for the second sensor. I would try putting it 180 Deg out from the first for simplicity in timing.

For p-port it doesnt make much sense to even start with a Renesis engine to begin with, that's an added reliability issue in itself considering you can buy all the parts off the shelf for a full aluminum 13B p-port

Building your own ECU too, seems like you're hell bent on risk taking far beyond trying to double up on one of the most reliable parts on a Renesis engine

Where the hell are you two getting this from? Is there like another thread or something? OP has not mentioned anything about doing a peripheral port.

Yes there is another thread. about making a custom ECU.

Yes custom slide throttle and the injectors will go in the intake runners. Picture attached is not my engine, same design though. OMP is plugged and pre-mix is the only way to go.


Ok so to answer this thread, there is no bracket. Thanks everyone.

https://www.rx8club.com/series-i-eng...-seals-259056/



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lol....lets reinvent the wheel.

It a simple 23 year old position sensor (also exact same part used on FD RX-7 and some Mazda piston engines) I see zero benefit in trying to code in with two units with OBDII?

OP perhaps you are confusing the fact that the FD RX-7 does have two (same as RX-8) e shaft sensors?

Did you even bother reading this thread before posting?

Did you?..

And the answer to OP is no.
And there is still no point in adding/designing/adapting another e sensor, making two for RX-8... even for 'back up', they don't fail.

Your point is?

Ash,

I have to disagree with you. Your general statement of "they don't fail".

There isn't a part made today that does not fail. Eventually EVERY part will fail if given enough time.

I do however agree with redundant systems. The AH-64D has similar redundancies. How can you argue with the most technilogically advanced helicopter on the planet?

Yes I know, I know the RX8 doesn't fly. My point remains the same.

Travis

I agree M8, but the sales stats on these are really very low when you consider the number of models this exact particular sensor does over the past 23 years in 15 different Mazda Models.

Yeah, we might as well duplicate everything electrical in a parallel as a back up.(way overboard and just a nonsense for a road car) ;)

What an ignorant statement. They do fail. If they didn't, why do they get sold at all? Stop contradicting yourself.

It's an aircraft, we're not talking about road car applications. Why WOULDN'T you want two of everything in something like that. If an ESS fails on a road car, you coast to a stop, if it fails in an aircraft you could die.


Even pro level endurance race cars have two of almost every critical sensor on the engine. They even common to have two starters or two alternators...

MY reference was to the RX-7 which uses TWO, OK.

I could not care less what it is used for, I am not going to sit back and argue with you, or am I going to let you talk to other members in the manner you are..

Molson, is there any reason you couldn't just run a second position plate/sensor combo on the back end of the engine, and just failover to that one? You wouldn't have to do anything coding wise other than detecting the failure and changing the input. It would even work with a stock ECU if you end up going that way.

Legot, thank you for a positive post. Not sure what all that other noise is about. We are thinking about adding a generator/ 2nd alternator on the flywheel end (PSRU gear reduction unit to bring the high RPM's of the engine down to propeller RPM's). I'll keep that in the back of my mind we could add a sensor there, thank you for the positive comment.

I feel bad for asking a simple question. I know I didn't give the full details of why I'm asking, didn't think it mattered. Just a simple, has anyone made a bracket to run 2 sensors.... lol...

Yes it's for aviation, yes it's for backup, and yes the sensor has a 99.99% success rate. What about the wiring, what about the ECU components, resistors do fail, wiring does fail, crimps do fail, capacitors do fail, anything 'can' fail. I want a backup, end of story.

I'll be creating an ECU that's for specific for aviation purposes then the stock ECU/MS/etc.

There is no bracket currently out there. End of thread.

Here is the best "image" I can show you of this Sensor side by side in 'a' FD RX-7..


https://cimg0.ibsrv.net/gimg/www.rx8...e8bf893299.jpg


I repeat the FD RX-7 is the only Rotary (any Mazda) which uses two of the exact same Sensors as Renesis RX-8 which uses the one in a car.

Mazda OEM E-position Sensor p/n N3A1-18-221A.

I suggest you ask the guys over at rx7club.com about any bracket as they are not available/made as a genuine spare part from Mazda,
you are going to have to fabricate two straps and mount them to another plate to fix on engine timing cover from what I can see/remember.
For aviation use.

BTW: Can I suggest next time when you start a thread here, to be complete in OP (original post) on what you are exactly asking?, like for aviation purposes?
That way you will not get the replies which does not suit your needs...and prevent other members for going around in circles and irrelevance, and going off track, this is a car forum. :)

I think this one has gone far enough.

Thread moved/closed.