Knock Test" How bad can it affect Engine?
05-12-2018, 09:59 AM
#1
Senior Member
Thread Starter
Knock Test" How bad can it affect Engine?
Found this Knock test ran in a MB ..With all 3 Levels of Gasoline and Premium had the less Knock.....*Question to the Experts* How much damage or effect can knocking really do with these levels on a daily basis ? Please no exagerations..or Captain Obviuos' pls..
Link... https://m.youtube.com/watch?v=iWl4h-HmExI
Link... https://m.youtube.com/watch?v=iWl4h-HmExI
05-12-2018, 06:05 PM
#3
Senior Member
Thread Starter
05-13-2018, 12:15 AM
#4
Super Member
I doubt very much you will find anyone here that has had such severe predetonation on their cars to cause piston damage.
havent heard much of that in general since the advent of electronic engine controls and knock sensors.
havent heard much of that in general since the advent of electronic engine controls and knock sensors.
05-15-2018, 02:23 AM
#5
Member
Best way to know if your motor is knocking (by detonating) is by reading the plugs. To do it right, you really need to do a full load shut down and have a 10x flashlight magnifier to really see what you are looking at. That's not practical on a street driver, but something I got pretty good at back in the day. My best builds were in the 170 - 190 hp/L range.
Tuning, I remember seeing deto show up during dyno testing as black spots (like pepper spots) or shiny silver spots (aluminum spotting) on the white plug insulator. As it got worse, small deposits of aluminum start appearing on the insulator. After that it's a very rapid down hill to busted insulators and mechanical failure. Better fuel helps to a point, but just as often it starts because of too much ignition advance, lean mixtures, a poorly designed combustion chamber / squish area, or too much exhaust backpressure.
If your experimenting with running regular gas, don't trust the built in knock sensors and ignition controls, or just concerned about collateral engine damage, pull a few plugs after a tank or two and be safe. Compare them with some of the photos shown in on-line articles about spark plug reading. If you are seeing insulator spotting, possibly another solution (besides going back to premium) would be to contact one of the more respected Merc tuning companies. Let them know what you are trying to do, how much load you usually put the motor under (how aggressive you drive, if you haul extra weight or trailers, etc.), and how your plugs look. Maybe they would put in a more appropriate timing curve into your ECU for you.
But with all the electronic wizardry and sensors on the motor, I'd be surprised if you find much signs of deto running regular, Especially if you're not a thrash driver.
Tuning, I remember seeing deto show up during dyno testing as black spots (like pepper spots) or shiny silver spots (aluminum spotting) on the white plug insulator. As it got worse, small deposits of aluminum start appearing on the insulator. After that it's a very rapid down hill to busted insulators and mechanical failure. Better fuel helps to a point, but just as often it starts because of too much ignition advance, lean mixtures, a poorly designed combustion chamber / squish area, or too much exhaust backpressure.
If your experimenting with running regular gas, don't trust the built in knock sensors and ignition controls, or just concerned about collateral engine damage, pull a few plugs after a tank or two and be safe. Compare them with some of the photos shown in on-line articles about spark plug reading. If you are seeing insulator spotting, possibly another solution (besides going back to premium) would be to contact one of the more respected Merc tuning companies. Let them know what you are trying to do, how much load you usually put the motor under (how aggressive you drive, if you haul extra weight or trailers, etc.), and how your plugs look. Maybe they would put in a more appropriate timing curve into your ECU for you.
But with all the electronic wizardry and sensors on the motor, I'd be surprised if you find much signs of deto running regular, Especially if you're not a thrash driver.
Last edited by Lioninstreet; 05-15-2018 at 02:34 AM.
05-15-2018, 10:18 AM
#6
Senior Member
Thread Starter
Nice..thanks for the advice @Lioninstreet
Best way to know if your motor is knocking (by detonating) is by reading the plugs. To do it right, you really need to do a full load shut down and have a 10x flashlight magnifier to really see what you are looking at. That's not practical on a street driver, but something I got pretty good at back in the day. My best builds were in the 170 - 190 hp/L range.
Tuning, I remember seeing deto show up during dyno testing as black spots (like pepper spots) or shiny silver spots (aluminum spotting) on the white plug insulator. As it got worse, small deposits of aluminum start appearing on the insulator. After that it's a very rapid down hill to busted insulators and mechanical failure. Better fuel helps to a point, but just as often it starts because of too much ignition advance, lean mixtures, a poorly designed combustion chamber / squish area, or too much exhaust backpressure.
If your experimenting with running regular gas, don't trust the built in knock sensors and ignition controls, or just concerned about collateral engine damage, pull a few plugs after a tank or two and be safe. Compare them with some of the photos shown in on-line articles about spark plug reading. If you are seeing insulator spotting, possibly another solution (besides going back to premium) would be to contact one of the more respected Merc tuning companies. Let them know what you are trying to do, how much load you usually put the motor under (how aggressive you drive, if you haul extra weight or trailers, etc.), and how your plugs look. Maybe they would put in a more appropriate timing curve into your ECU for you.
But with all the electronic wizardry and sensors on the motor, I'd be surprised if you find much signs of deto running regular, Especially if you're not a thrash driver.
Tuning, I remember seeing deto show up during dyno testing as black spots (like pepper spots) or shiny silver spots (aluminum spotting) on the white plug insulator. As it got worse, small deposits of aluminum start appearing on the insulator. After that it's a very rapid down hill to busted insulators and mechanical failure. Better fuel helps to a point, but just as often it starts because of too much ignition advance, lean mixtures, a poorly designed combustion chamber / squish area, or too much exhaust backpressure.
If your experimenting with running regular gas, don't trust the built in knock sensors and ignition controls, or just concerned about collateral engine damage, pull a few plugs after a tank or two and be safe. Compare them with some of the photos shown in on-line articles about spark plug reading. If you are seeing insulator spotting, possibly another solution (besides going back to premium) would be to contact one of the more respected Merc tuning companies. Let them know what you are trying to do, how much load you usually put the motor under (how aggressive you drive, if you haul extra weight or trailers, etc.), and how your plugs look. Maybe they would put in a more appropriate timing curve into your ECU for you.
But with all the electronic wizardry and sensors on the motor, I'd be surprised if you find much signs of deto running regular, Especially if you're not a thrash driver.
