I thought id post this in here to see if i get more replys than i did in the tech q&a section.

Hi im still tring to learn about tuning/mapping and was wondering when advancing timing how do you know when to stop obviously when you hear det, but i was thinking surely you cant just advance till you hear it then back off on every load site otherwise by the time you have fully sorted the map out you will have destroyed your engine.

Dont worry i havent done any ignition mapping yet just trying to learn.
__________________

 

Depends on the application, if your engine isnt det limited at a particular point then the only way to find optimum advance is with a set of rollers really.

 

Cheers Chip

 

Mild det won't destroy a piston engine quickly

 

On cruise and light throttle i put in enough advance so that the engine feels sprightly but not over advanced (kangarooing) and in boost as mentioned above a few degrees retarded from the point of det. det will not kill your engine if you are carefull when tuning.
Just bought a KS3 knock device with knock sensor, this has been very usefull when mapping my subaru on boost, Just last night it came up with a det warning, only after did i think i may of heard something (6000 rpm very difficult to hear) i then retarded the ig timing by 3 degrees and it has not alarmed since and the car is now quicker.

 

Thanks mate how much was your ks3 and where did you get it from

 

Ive got the Ks4 in the tuning package that Phormula do, not cheap but its a nice gadget

http://phormula.co.uk/ProTuningSolution.aspx

Manaul set of det cans is all you really need, but this is certainly a nice to have.

I use the headphones from a knockbox instead though as I prefer them to the phormula ones, they're good quality but dont insulate outside noise as well as the knockbox ones.
Cheap option that also works REALLY well is in the ear headphones, I had to use some when det checking a car on track (had to wear a lid) and was amazed how well they work so I sometimes use them just cause they are so easy to carry.

On my nova I was using the 0-5v output as an input to my Autronic so I could datalog and monitor knock, that was really good, but still I think your ears HAVE to be the thing you rely on.

 

Bought it second hand from a boy on scoobynet for £160, they are on ebay for around £280 new iirc, as chip says very handy, not always easy to hear det at 1,000,000 rpm and 300 bar boost!

 

It can be a problem on some engines definately to hear, but just a case of your ears learning whats normal for that engine, with a bit of practice it becomes easier.

 

The problem is that the first signs of det are not auidiable to the human ear, hence an electronic device will always be better

 

That sort of det wont break anything anyway on a piston engine.
Might be an issue on a rotary, but not a 4 stroke.