detonation detector

[joe84]

don't know if any of youse have stumbled by the autospeed article on a diy detonation detector ? http://autospeed.com/cms/article.html?&A=1353 , well since i like the idea of being able to tune myself i gave it a go just haven't used it yet.. i'm thinking i should of giving the clamp the flick and just used a peice of 3mm sheet metal with a hole in it bolted to one of the bolts on the block , where is the ideal place to listen for it ? there are a couple of lugs on the top of the block on the exhaust side, but i'm thinking it's going to melt there.. so one of the intake manifold bolts might have to do, i'll just find someone to drive and i'll start with conservative igntion timing eg 10static + 17 in the dissy , and increasing 2deg at a time, i have a timing light with the advance function so should help, any thoughts? in there test there using more modern efi cars , so i'm thinking an old pinto is going to be alot more noiser to try listening for detonation (not even sure what is going to sound like through this gadget) any thoughts apprec'd

[red_rs2000]

through my time tuning cars, especially engines with forged pistons etc (that develop alot of mechanical noise) it is very hard to use some electrinic devices as they do not have good adjustability to block out mechanical noise... A good product, but is pretty expensive is the knockbox, works really well...

A good cheap system i use alot is an old stethascope, extend the hose with a bit of EFI/fuel hose, weld a washer to a bolt clamping it in the end of the hose, and bolting this to the cylinder head. (may need to experiment to get a prime spot) but you will hear detonation like a clap of thunder over the engine noise)

Hope this helps....

[Chris Kitzen]

I've worked on the Subaru World Rally Team and at Possum Bourne Motorsport and we used a similar setup but with an off the shelf knock sensor bolted to the standard place they are fitted to on the boxers. With long leads it enables you to fine tune the car (if it has efi etc) while you drive. We did it every event to make sure the engine was safe as fuel quality usually varies slightly. From my experience with one, it will work just about anywhere you bolt it and det is easy to hear. That may depend on the quality of the electronics however. Having said that it will probably work better bolted directly to the head or block. Qantas inflight headphones work particularly well with them