I've got another thread going where I'm trying to set the mixture on my dual dells, but this got me thinking about a knock sensor. Does anyone here have one? I see there are some aftermarket ones like these:

http://www.dpmotorsport.com/parts/knocklink/home.htm

http://www.msdignition.com/tool_8.htm


Is there a cheaper alternative?

BTW - I tried the search, and kept getting 1000+ hits.

I didn't think knock sensors work to well on air cooled cars cause they are so much noisier then water cooled cars. On the SDS sight it illudes to that.

you know, that could be true. One of my coworkers asked how I could tell if my engine was pinging without a knock sensor.

A calibrated ear.... and the ability to read the plugs so you know it's in tune.

knock sensor is only good on a car w/ computer controlled ignition. It is used to retard the timing when detonation occurs (knocking)

964s and 993s had knock-retard sensors, and mechanical lifters. A knock-retard system is only good if you're running a computer-controlled ignition. If you wanted to, you could adapt a late 944 (post 85½) injection and ignition system to the 914. It also has a knock-retard system and is digital (and would probably cost less).

Just a light would be helpful... Think of it as an idiot light (Hey idiot, there's somethign wrong) Could use it as a tuning tool (advance timing till knock occurs or power falls off under heavy load.

BJH

I guess something like this is what I'm talking about :

http://forums.nasioc.com/forums/showthread.php?t=768081

Just a light that would flash when a knock is heard, so that I'd know something is wrong. It probably wouldn't be much good on a daily basis, but it could be neat. Any reason that something like this wouldn't work?

Knock is usually used by the engine management computer to retard ignition and to deal with poor quality gas or gas of a lower grade than intended. There's not a whole lot of point if you don't have an engine managment computer.

There is a megasquirt knock circuit available which basically turns a light on - that's what I have in my car although mine is actually hooked up to the megasquirt.

There may be other issues though - Knock sensors are basically microphones, and I don't know that they are thermally resistant enough to sit where they would need to be (probably on the cylinder body for a TIV) - plus mounting would mess with the cooling some.

I'd get a WBO2 first if I were you.... it will give you more actionable information.

I'd be kind of iffy actually putting a knock-sensing unit on a Type 4. Depending on sensativity, of course... These engines have a lot of mechanical noise...

What's a WB02?

WB02 = Wide Band O2 sensor

Air cooled engines are too noisy for a knock sensor....it can be made to work but it can also fuch you up when tuning. Not worth messing with.

Since knock sensors are actually microphones, and knock comes at a certain time (in the combustion cycle) and is of predicable pitch (due to the resonant frequencies of the combustion chamber) - I'd guess that it's theoretically possible to overcome the noise issues on a TIV - but in practice - it would take a lot of R&D. It wouldn't be easy . I think the megasquirt guys are making progress on this kind of stuff though.

A WideBand Oxygen sensor will tell you what your mixture is - i.e. lean or rich - this information can be applied to both carbs and fuel injection (although fuel injection systems can actually read the output in real time and adjust themselves to your engine).