Debating which knock sensing route to go down. Quite important as I know full well I am going to have a problem at some point and I know I am not going to be able to hear it!

The Duratec already has a knock sensor but I need some way of getting the signal from it.

Running an MS1 ecu, so could use knocksense which will allow me to automatically retard ignition when knock is detected. That said, I have heard they can be a pain to set up and give a lot of false triggers. However this could be down to individual set ups.

The other option seems to be a Phormula system, which come highly rated all around, but are expensive (£220) and will not automatically retard the ignition.

What should I do?

Or are there some more options I havent considered?

The KS4 does have e 0-5V output, so you could use that to hook it up to the MS1. However, I would not like to rely on one of these things, as sensing high speed knock (which is the sort that really kills engines) is going to be near impossible with these devices due to the high amount of engine background noise. OEM knock sensing solutions get around this by only monitoring during the combustion period which makes things slightly easier.

If it is only for mapping (try to set the engine at borderline detonation or BLD and then retard the timing 3 degrees), hook a knock sensor up to a small amplifier driving a pair of headphones. Your brain makes a better knockdetector then one of these boxes anyway....

Thanks for that.

Sadly headphones dont mix with wearing a helmet very well. I know David Jenkins did just as you say, hooked up a small amplifier to his knock sensor and did it that way. Though I could try small in ear types and see what that tells me. Not that I know what I am listening for!

I was of the impression that as rpm increases knock is less likely because there is both less time for it to happen and because the velocity of the gas in the combustion chamber is so high that knock is less of an issue? I was more worried about knock in the cruising rpm range (1500-3000rpm) but is this not the case?

Just trying to give my engine the best chance of long term survival

quote:

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Originally posted by flak monkey
Thanks for that.

I was of the impression that as rpm increases knock is less likely because there is both less time for it to happen and because the velocity of the gas in the combustion chamber is so high that knock is less of an issue? I was more worried about knock in the cruising rpm range (1500-3000rpm) but is this not the case?

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some more info here: http://autospeed.com/cms/article.html?&A=0348

Excellent, thank you very much.

I may try the amp and headphones route first, will try and find some more sound files so I know what I am listening for!

get it setup on 95ron then run it on 97ron to be safe.

when i had my engine tuned/setup the guy tuning it had been doing engines 20-30 years and could hear knock by ear!!

Following the instructions on the autospeed site looks like a good starting point. Managed to find a suitable amplifier, will have to have a play and see what I can get out of it.

Don't panic when you do listen to your engine - it will sound like a tin of spanners being shaken, even when it it's running properly!

I have a not-very-good WAV file that gives a clue about the sound that knock makes, but I'm not sure that I can post it here...

Oh - I can!

The knock is the nasty rasp near the end of the recording.

[Edited on 13/12/09 by David Jenkins]

Thanks David Could you point me in the right direction for a microphone transformer as mentioned on your website? Found this on the maplin site:

http://www.maplin.co.uk/Module.aspx?ModuleNo=12151

Is that the right sort of thing?

Will see how I get on once the engine is up and running, and no doubt there will be a load of questions.

Got myself the locost solution, cheap ampy thing off ebay to do the thing in the autospeed link above.

Also been speaking to Phormula, and their systems have variable sensitivity over the rpm range. Looks like the KS4 would be useful as a monitoring system after setting it all up with the locost solution.