Suggestions for knock sensor location?

[MazdaRX8/6]

I want to use a knock sensor with my Haltech ECU. There doesn't seem to be a good place to put one. I'm using a hydraulic cam, but the consensus seems to be that you should avoid the side of the engine where the lifters are. I saw somewhere that someone mounted the sensor under the upper motor mount bolt on the driver's side. That seems lower than ideal. It occurred to me to make a special plug to replace the center core plug on the driver's side. I also thoght about using epoxy to put a bolt pad on the side there.

Any suggestions?

 

[Killer6]

Pic of the particular sensor You are using???

 

[MadScientistMat]

There isn't a great one, but theoretically on the cylinder head or threaded into the side of the block under the exhaust would be best.

But don't go into aftermarket knock sensing with high expectations. OEMs blow up a half dozen engines on the dyno while using five figure amounts of instrumentation to get the level of knock sensor tuning they have.

 

[MazdaRX8/6]

Something like this.

Pic of the particular sensor You are using???

 

[slantsixdan]

H'mmm. How 'bout one of the existing bolt bosses on the cylinder head, facing the sky, between the valve cover and manifolds? The engine-lift bosses, I mean.

 

[MazdaRX8/6]

I'm told that it needs to be near the cylinders away from any valve train noise.

 

[mopar head]

My dumb logic would think they`d be located beside a crank main.

 

[MazdaRX8/6]

My dumb logic would think they`d be located beside a crank main.

My guess is that if there is going to be detonation it will be at the top of the stroke and make the piston rattle against the cylinder wall. My 1992 small block chevy has the knock sensor screwed into a water drain hole, but on the slant the water drain hole is next to the camshaft.

 

[Killer6]

Something like this.


View attachment 1716482678

OK, that's like a Subey one,....flat/flush mount & a screw. Valvetrain & exhaust noise can both trigger false knock sigs., hard to avoid both,.....You could just drill the block anywhere mid-high & spot-face it, then tap it. As long as You're clear of exh. pipes & excess heat, it should function fine. Mopar's 2.2/2.5's put them on top of the intake plenum, but a cracked EGR pipe was setting off the one on My lightly modded turboI, I ran it for years w/o the sensor hooked up until I found a good pipe & time to swap it in.

 

[MazdaRX8/6]

I hope to not have ehxaust noise with Dutra Duals and I am running hydraulic lifters. I am seriously considering making a mount in that center freeze plug hole.

 

[TT5.9mag]

I’d drill and tap the block on the opposite side of the lifters. Thread a stud in and seal it. Use the stud to secure the knock sensor. You’ll likely still have to tune around valvetrain noise.

 

[RustyRatRod]

H'mmm. How 'bout one of the existing bolt bosses on the cylinder head, facing the sky, between the valve cover and manifolds? The engine-lift bosses, I mean.

That was EXACTLY what I was going to recommend. I think it would work fine.

 

[RustyRatRod]

I'm told that it needs to be near the cylinders away from any valve train noise.

A LOT of GM engines have them screwed right into the bottom of the intake valley RIGHT in the middle of valve train noise. That's not the frequency knock sensors are designed to pick up anyway. But by all means, go to all the trouble in the world to put it where you want to. lol

 

[TT5.9mag]

A LOT of GM engines have them screwed right into the bottom of the intake valley RIGHT in the middle of valve train noise. That's not the frequency knock sensors are designed to pick up anyway. But by all means, go to all the trouble in the world to put it where you want to. lol

They also have years and years and years and thousands and thousands and thousands of dollars of research and development to know which frequency they’re looking for. And which frequencies to ignore.
And also those knock sensors in the lifter valley of the LS engines, rusted like crazy and caused all kinds of problems.

 

[RustyRatRod]

They also have years and years and years and thousands and thousands and thousands of dollars of research and development to know which frequency they’re looking for. And which frequencies to ignore.
And also those knock sensors in the lifter valley of the LS engines, rusted like crazy and caused all kinds of problems.

There are disadvantages to everything if you look hard enough. That's simple enough to overcome with some oil based high temp paint.

 

[Dave999]

never say never but having a knock sensor and having one work effectively might be quite hard,
they need to be tuned to spot knock before you can hear/feel knock... i don't know how you do that..... (doesn't mean it can be done i just know my limits )

buying a TPS a MAP sensor or a oil pressure sender water temp sender you have something to measure that is right in your face, its obvious, and you can compare and contrast output..
user your mitivac multimeter or boiling water measure and check. adjust ECU ranges to fit with the sensor..

if the knock sensor was made by someone specifically for the slant 6 running your cam with your lifters i can see the benefit but if it was designed for something else i'm really sorry but i don't see how you would "tune" it to be of benefit.

some aftermarket FI kit comes with a knock sensor. i never worked out if this was just feature creep, more stuff to shout out on the packaging, to pull in more punters. or REAL...

doesn't mean there are not people out there retro fitting, making good use, but for me the dury is still out, maybe i'm just cynical old luddite.

i can't measure the harmonics in my crank and cam never mind the vibrations transmitted through the block, no kit to do it and a severe lack of Physics in my head

dave

 

[MazdaRX8/6]

Thanks guys. The guy I bought my Haltech ECU can do all the tuning. He does this full time. His recommendation was right below the head in the middle of the blick. I think I found a web inside of the block that is wide enough and thick enough to drill and tap for a small bolt.

 

[RustyRatRod]

Thanks guys. The guy I bought my Haltech ECU can do all the tuning. He does this full time. His recommendation was right below the head in the middle of the blick. I think I found a web inside of the block that is wide enough and thick enough to drill and tap for a small bolt.

View attachment 1716483247

...and mere INCHES away from the threaded boss in the cylinder head. Drill your hole. Have fun!

 

[TT5.9mag]

Thanks guys. The guy I bought my Haltech ECU can do all the tuning. He does this full time. His recommendation was right below the head in the middle of the blick. I think I found a web inside of the block that is wide enough and thick enough to drill and tap for a small bolt.

View attachment 1716483247

Your tuner is intelligent. Listen to him.

 

[RustyRatRod]

Your tuner is intelligent. Listen to him.

Yeah I'm just a retard. Well this RETARD would try an already threaded hole and see if it worked before I went possibly drilling an unneeded hole.

 

[TT5.9mag]

Yeah I'm just a retard. Well this RETARD would try an already threaded hole and see if it worked before I went possibly drilling an unneeded hole.

You’re not a retard stop it. But if you’ve never tuned an aftermarket ECU to the necessary threshold for false knock vs real knock and experienced the frustration that can come from it you should just watch. Sticking the knock sensor in a location susceptible to a bunch of other frequencies lessens the chance of actually being able to use it for its intended purpose. It WILL pick up any and every harmonic and frequency that is being produced, the sensor is stupid, it’s the ECUs job (specifically the range of frequencies that the tuner tells the ecu to look for) to filter out what not to look for as well as what to look for. And it gets exponentially harder to tune the more false crap the sensor pick up.

 

[RustyRatRod]

You’re not a retard stop it. But if you’ve never tuned an aftermarket ECU to the necessary threshold for false knock vs real knock and experienced the frustration that can come from it you should just watch. Sticking the knock sensor in a location susceptible to a bunch of other frequencies lessens the chance of actually being able to use it for its intended purpose. It WILL pick up any and every harmonic and frequency that is being produced, the sensor is stupid, it’s the ECUs job (specifically the range of frequencies that the tuner tells the ecu to look for) to filter out what not to look for as well as what to look for. And it gets exponentially harder to tune the more false crap the sensor pick up.

My point is, HE doesn't know, YOU don't know, nor do I know until he tries. I'd rather TRY an already threaded hole than drill a hole I might not need in a block. Plus, I'm unsure it will even FIT where his finger is since the intake manifold is not in place to make that determination. You can talk all the fancy talk you want. The fact is, none of us knows. It MIGHT work.

 

[TT5.9mag]

My point is, HE doesn't know, YOU don't know, nor do I know until he tries. I'd rather TRY an already threaded hole than drill a hole I might not need in a block. Plus, I'm unsure it will even FIT where his finger is since the intake manifold is not in place to make that determination. You can talk all the fancy talk you want. The fact is, none of us knows. It MIGHT work.

I beg to differ. I DO know. I’ve done it. I set up dual knock sensors on my j35 and tuned them in the AEM infinity ECU. And I went through hell trying to locate them. After a **** ton of research and 3 different locations, the best place for them is exactly where HIS tuner told him to put them. Because he’s likely done it once or twice also and suffered the same frustration I have.

 

[RustyRatRod]

I beg to differ. I DO know. I’ve done it. I set up dual knock sensors on my j35 and tuned them in the AEM infinity ECU. And I went through hell trying to locate them. After a **** ton of research and 3 different locations, the best place for them is exactly where HIS tuner told him to put them. Because he’s likely done it once or twice also and suffered the same frustration I have.

On a slant 6?

 

[TT5.9mag]

On a slant 6?

Nope. But it doesn’t need to be.