Nistune Forums

Don't really need a picture - I can tell you.

Take an el-cheapo condenser mic insert from your local electronics store (or eBay):

http://cgi.ebay.com.au/10-pcs-6mm-Mini- ... 2c58b3a7e9

I then connect about 2m of shielded cable to the mic and mounted it in a piece of aluminium tubing about 16mm OD x 100mm long using epoxy. Ally tube was then wrapped in 4mm sponge rubber and then I put heatshrink around that. Making it around 30mm dia. Oh, what the hell I'll take a photo!
I then wrap that again in a piece of cloth - which further insulates it from noise and makes it sit better on the engine. Most engines I can just kinda stuff it in a gap under the inlet manifold and it'll stay there.

The ally tube allows makes the mic more focussed. So you point it at the block and it listens to the sound from there rather than all the surrounding racket from the engine bay. That's the idea anyway.

You could use any mic and get creative with the mounting - just try to insulate it from extraneous noise and definitely don't connect it to the engine head/block and you should get a usable decent result.

PL

PL wrote:Don't really need a picture - I can tell you.

Take an el-cheapo condenser mic insert from your local electronics store (or eBay):

http://cgi.ebay.com.au/10-pcs-6mm-Mini- ... 2c58b3a7e9

I then connect about 2m of shielded cable to the mic and mounted it in a piece of aluminium tubing about 16mm OD x 100mm long using epoxy. Ally tube was then wrapped in 4mm sponge rubber and then I put heatshrink around that. Making it around 30mm dia. Oh, what the hell I'll take a photo!

I then wrap that again in a piece of cloth - which further insulates it from noise and makes it sit better on the engine. Most engines I can just kinda stuff it in a gap under the inlet manifold and it'll stay there.

The ally tube allows makes the mic more focussed. So you point it at the block and it listens to the sound from there rather than all the surrounding racket from the engine bay. That's the idea anyway.

You could use any mic and get creative with the mounting - just try to insulate it from extraneous noise and definitely don't connect it to the engine head/block and you should get a usable decent result.

PL

This will only tell if you have pretty serious knock though yeah? not the faint beginnings?

Yeah, it comes down to that personal thing in the end - how good your ears/brain are at picking knock. I'm getting pretty deaf too (what??!!!) but I can still pick the beginnings of knock. But sometimes you do wonder if it's knock or just engine noise. Adding a bit more timing usually tells you pretty quickly. I always use audible knock combined with watching torque figures to get an idea of how close to the knock threshold I am.

Gotta admit though - it's easier to pick knock on low boost (under 20psi) engines. And I also find it a lot easier on iron block engines. I find SR20's running high boost to be quite difficult to pick. They just sound so "metallic".

I'd dearly love a system that would reliably tell me when the faint beginnings of knock are happening.

PL

you should seriously put together some of those into kits and sell them. would be happy to promote them.

Too many products!

I'd need to find some suitable headphones first, then try and work out if I could fit the circuitry in them or use an external box and then try to work out a suitable mic housing that didn't look like it was made in a shed. All fiddly time consuming stuff. Unfortunately it's the asthetics that are hard to do.

I've gotta tidy my crusty prototype some time and make myself something nicer like I did for Simon, so I'll keep you in mind Trent.

I'm currently using ex-military headphones cos they keep the noise out so well. But they're big bulky things that make people laugh at you! They stop laughing pretty quickly when they realise how effective they are though!

PL

Andrew that file you posted two pages ago shows ECR33 AFM. Thought you were still using the ER34 AFM. Would be good to get the injection multiplier for that one (if you havent upgraded injectors yet)