ok so i just noticed that the rear rotor housing has a spot for a knock sensor.. so my quetion is could i run 2 knock sensors and just splice it in to the existing wire for knock sensor #1. i would like to do this because i have an extra knock sensor and for the added security since there is nothing to detect knock on the rear rotor.. and the rear rotor is the one that normally goes out. let me know what you think

 

Knock sensors work on piezoelectric crystals. When hit, they will generate a tiny electric signal. Since the entire block is metal, any knock felt on the block will transmit the signal to the knock sensor regardless of location. And remember, sound travels faster through more dense materials. Yes, it is possible, but it won't do you any good.

 

the RX7 stock knock sensors have no gaurantee of saving the engine anyways, in fact they do next to nothing except retard your timing after your motor is already running on one rotor.

but after thinking about it, tying 2 together may generate a strong enough signal to actually fire up the knock box when an actual knock does occur... hmmm. the stock knock retard system was horrible and was way too slow to react when even moderate knocks did occur because the knock sensors were too unreliable and inaccurate.

 

so karack... in your opinion do you think that adding a second knock sensor "might" improve the knock signal to the factory knock system. and it "might" give me some added security. and it should not adversely effect my car in any way.

 

It may, but it most likely will not. In either case, the work required to do this really is too much for something like that. You would have to rebuild your engine because only the rear housing has a threaded hole for the sensor, and then use a rear housing in place of the front one. So there's the cost of rebuilding the engine versus the chance that it's really not going to do anything anyway.

 

actually there is already a threaded hole above the rear trailing plug for a knock sensor. it would be as easy as screwing one in to the empty hole and splicing it in

 

the knock box was engineered to detect the signal from only one knock sensor. so the idea of having a stronger knock is irrelevant. what i think would happen is that it's going to increase how often the knock box is going to retard the timing, 2 sensors = twice the chance of detecting a knock. this is of course if both sensors have the same sensitivity, and not one going off all the time before the other detects anything.

 

and the knock sensor in the car is in the front housing

 

yah thats kinda what i was going for. not so much looking for a stronger signal but a more accurate one. from what my employer was telling me ( he was and is the only rotary mechanic in my city) the 2nd gens blow rear rotors with the knock sensor being on the front and the RX8s tend to blow the front with the knock sensor on the rear. he owns a Turbo rx8 that he has done all the work on. but anyways we were thinking that it was kinda odd that rotaries seem to be more likely to blow the rotor that has no knock sensor. ergo have a knock sensor on both may help

 

Yea, on the rear housing. If I'm not mistaken, there isn't one on the front housing. At least I've never noticed one.

Am I mistaken on my memory? I thought the knock sensor hole was in the rear housing, below the oil filter pedestal. Can someone else verify?

 

S4 had the knock sensor on the center iron facing the front of the engine, S5 had it threaded into the front rotor housings above the trailing plug along with the S6, both rotor housings are threaded for a knock sensor because it wasn't worthwhile to make castings of 2 different rotor housings.

i have no idea if adding the second knock sensor will help or make the knock box too sensitive. referring to my original argument though, that the knock box is a very ignorant system and very crude. as far as i'm concerned it probably wouldn't save a motor regardless of however you try to tweak it to perform better.

 

with ever motor i've ever built, i've put the knock sensor on the rear and still the rear is usually the first to go, even on race motors, that don't have a sensor it's still usually the rear that goes. it's clearly nothing to do with the sensor. last year as i changed fuel system, (feeds the secondary rail from the rear, then the leading from the front) to see if it make any difference, haven't blown the motor yet so i'll let you know which goes first.

a capable ECU with a good tune is a far better solution then a second knock sensor, even water meth has better results.