Matt Vassallo

ear vs knock sensor

opinions and reasons

0HP930

A good knock sensor can detect detonation that can't be heard by someone in the car.

On top of that every knock sensor I have ever seen turns the timing back to stop it from happening or reducing the severity.

A good knock sensor should be a part of any good high output setup.

I have a classic J&S unit in the porsche.

Matt Vassallo

my personal method which i discovered at age 17 was to run a copper filled oil pressure mechanical gauge into the engine bay.
this device works as a stethascope for your engine.

with it you can really differentiate between ping and lifter noise, and turbo spool up, exhaust leak, etc etc etc. with my new found p.a. system for the engine block audible knock was heard.

There was a great article on knock sensors written by some aussies a few weeks ago, it went into detail showing how a knock sensor actually was worse than the well trained ear in every test for knock.

However one thing to note is that if nissans detect knock 2 times in one cycle, they will retard 4 degrees of timing. if they still detect knock after 4 degrees knocked back, then they will go to the low octane maps. if they then detect knock they will knock it back 4 more degrees.. this can be as much as 15 degrees ignition retard in order to prevent knock.

however as soon as you turn the car back on, it will try once again to start out in the high octane map with all timing in place. if it again registes knock, it will start the knock back 4 degrees cycle all over again.

i'm not sure what the hondas do for knock.

0HP930

I no longer remember the exact parameters, but this is similar to how the J&S works.

I think the total amount it could turn back the timing was as high as 20 degrees.

There is also a meter available for the J&S that will display the timing change so you know when something is not right.

Those of us with air cooled engines that vary greatly in operating temperatures and mechanical fuel injection need the protection a little more than people with water cooled motors and EFI do.

Once I install the new AIC it may once again become just a saftey device and not need to kick in unless I have been sitting in traffic for too long or the intercooler has heat soaked.

Matt Vassallo

whats it like being air cooled anyways

if you sit and idle will your engine just explode

0HP930

Well, its nice not having to carry around over a hundred pounds of additional hardware for cooling purposes.

As a cooling fluid its a lot easier to carry around four gallons of oil than it is to have a gallon of oil and other 4 gallons of water. Oil is also lighter than water.

Various racing events have proven this setup is good enough to allow the engine to put out over 600 HP for almost 24 hours straight.

My car always runs at 180 degrees unless I have the A/C and I am sitting in traffic in 100 degree weather while reingesting my hot cooling air.

Under those adverse conditions I have seen it get as hot as 250 degrees which is within the accepted upper limits for the car.

Once both of us have our projects complete I would be happy to see if the flat air cooled pancake can beat your water cooled vee.

Chances are that just your engine weighs more than my engine and tranny combined.

Matt Vassallo

how much does your engine and tranny weigh?

my tranny weighs 90 lbs, my engine weighs under 300
my car weighs 2300