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patina patina is offline
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Join Date: Mar 2012
Location: NC
Posts: 1,230
Originally Posted by Tippy View Post
Been pondering this for ages. Det cans* are said to be better than electronic detonation detection equipment, reading from a bunch of tuners.

We always fear detonation, and thought how perfect it would be to use det cans during racing, so you know when to back off throttle (and possibly timing later), and to save your eardrums from your M&K Outlaw muffler.

Sure, there is J&S Safeguard and other EFI systems that use true knock sensors, but there seems be a lot of error with these systems and it is hotly debated "tuning" these is black magic. Some say it's simple, some say it takes a team of engineers to figure out the frequency band the software should be identifying detonation by. I'm neutral, just stating what I read...

Which again, leads to det cans. A lot of folks I've read claim there is no false-positives with these. When you hear "marbles in a can", it is detonation. No valvetrain noise, no piston slap, or any other mechanical sound will falsely believed to be detonation.

The problem is, how do you use a helmet with them?

Any thoughts?

Next time I get mine back together, I am tuning it with them. Next best thing to a dyno....

*Det cans are simply ear muffs with nipples threaded into each ear piece. A copper tube is rolled onto itself a few time and compressed tight as you can (vise would be best I'd imagine or a press), then a bolt hole is drilled through it. From this copper tube, you hook hoses from it to the ear muffs using a "Y" or "T" connection.

Key here is that it is AIR TIGHT.

The copper tube is then bolted to the block somewhere similar to where a knock sensor would be mounted.

When detonation occurs, the sound will travel to the ear muffs just like the principle of a stethoscope.
With all of modern technology at your fingertips you would choose to ear trumpet knock? Seriously?
'78 930 #441
'87 951
Old 10-30-2017, 07:31 PM
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