Knock Sensor w. 3.3 CIS
 

Does anyone use knock sensors on a 965 3.3 turbo engine?

I am using the Clewett Engineering XDi2 dual plug crankfire kit, which has knock sensor retard capability. However, there seems to be a consensus that the 3.3 CIS engine is too noisy to effectively use knock sensors.

I would greatly appreciate any input.

Cheers.

You might want to read through this thread:

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/405586-knock-sensor.html

Mines not a 965 but it is an aircooled, boosted motor. I use a Bosche adapted from a 993 bridge across 4-5-6 cylinders, feeding my Adaptronic ECU.

How long have you had it and what is your experience with it?

Do you feel that it falsely retards due to noise that is not related to knock?

I have actually posted this thread after reading the one you are referring to.

Unfortunately, the other thread seems to be mainly based on hearsay rather than on factual experience. I would like to get feedback from people who either have or had it installed on their engine.

Cheers.

I posted a quote from Steve Weiner of Rennsport in that thread. Speak to the source if you consider it hearsay:

Steve Weiner
Rennsport Systems
Portland, Oregon
503.244.0990
E-mail: porsche@rennsportsystems.com

didn't he state that he uses it for tuning purposes only, but advises against keeping it on the engine?

I already have a system that can detect knock, but I don't have the sensors installed as there seems to be some controversy about the effectiveness of using them on the 3.3 engine.

This post makes it sound like closed loop knock control:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/229355-thoughts-combo-please.html#post1998268

I've had it on about 6 months, including ~15 hours on the dyno altogether. I've found power falls off before I get knocking so how we have the timing and fuel mapped it doesnt interfere very often. I originally installed it because I didnt know thats how this motor was going to behave.

Thanks for the link. I will contact Steve and get his opinion whether this would also work on a 3.3

Cheers.

Knowing what you know now, would you install it again?

Definately. I'm upping the boost to 15psi now.

Excellent. Thanks for your input.

Les Garten has a Tec III, but I don't know if he has them enabled.

I contacted Steve re knock sensor and his take is that it is not feasible on a CIS motor. Oh well...

I know for a fact that Raymo also runs one in his CIS motor. He tapped the breather cover and installed it there. He used it for tuning, I've seen his logs and we talked about it this morning.

I would like to hear more about his setup.

I was told that the kock sensor would require either MAP or MAF along with throttle position, and RPM to be truly effective.

Did he say he tried it on a CIS engine? I'm guessing he said it wouldn't work because that's a mechanical system with no sensors to read.

The SafeGuard has a processor and onboard MAP sensor, so it reads load and RPM.

Decel or light loads can cause false knock, so software ignores the knock sensor if the onboard MAP sensor sees more than five inches of vacuum.

Also, the program has a detection window to listen for knock at the appropriate time.

I'm pretty sure Steve wasn't aware of these points.

There's a lot more I would like to say about the detection algorithm, but it's proprietary. Unfortunately, saying nothing gives the impression there is nothing to brag about.

Revealing details also has drawbacks. One, it gives the competition a starting point. Second, it gives the armchair detractors an opportunity to say "Why did you do it that way, here's how I would have done it..."

It's already happened to me on another forum. The original forum where I posted the information totally ignored it, so I gave away secrets for nothing, then got hit over the head with them later by someone that posts links to knock papers, hoping someone will design what he wants.

AIEEEE! (Marvel Comics scream).

NASIOC - View Single Post - The Knock Box

John,

are you saying that it does work with CIS?

I honestly do not understand too much about this topic and how the Safeguard works. I am using CIS with a XDi2 ignition system that has knock sensing capability. Can I use the Safeguard in combination with the XDi2 and how would it work w/o throttle position, RPM, and MAP/MAF inputs?

SafeGuard reads RPM and has an onboard MAP sensor to read load.

J&S Eight Channel Interceptor

I would have to check with Electromotive to see if it's compatible with their DFU.

If not, our Vampire system will work, but it requires MSD 8870 coil spacers. These install under the coils and allow access to the coil negative signal, required by the Vampire.

J&S Vampire