ever run into issues with knock sensors being too sensitive?
09-29-2011, 04:14 PM
#1
Race Director
Thread Starter
ever run into issues with knock sensors being too sensitive?
I thought id ask this here because this forum has more activity.
Is the lsx setup with twin knock sensors and knock retard, likd an lt1?
I'm tuning a car and had some issues where the knock sensors would retard timing 5 degrees or so around 5100 rpm (from datalog) and that would cause it to lose about 35 rwhp and rwtq on the dyno.
I didn't hear any knock (just engine roar). I replayed the videos I made and didn't hear anything unusual either.
I pulled some spark plugs and didn't notice anything weird about them.
Also I want to add that it was cool weather and timing wasn't super high either. I have my timing starting out high and falling down as rpms (and boost) increase.
Its on a stock bottom end car w meh/water inj p1sc pushing 10 psi boost.....
Is the lsx setup with twin knock sensors and knock retard, likd an lt1?
I'm tuning a car and had some issues where the knock sensors would retard timing 5 degrees or so around 5100 rpm (from datalog) and that would cause it to lose about 35 rwhp and rwtq on the dyno.
I didn't hear any knock (just engine roar). I replayed the videos I made and didn't hear anything unusual either.
I pulled some spark plugs and didn't notice anything weird about them.
Also I want to add that it was cool weather and timing wasn't super high either. I have my timing starting out high and falling down as rpms (and boost) increase.
Its on a stock bottom end car w meh/water inj p1sc pushing 10 psi boost.....
09-29-2011, 04:37 PM
#2
Safety Car
I never had any issue with my stock LS1 @ 10 lbs, 11.5 AFR, lots of meth, and 18 deg on top. I added a cam/ springs and had to turn down the sensitivity due to valve train noise.
09-29-2011, 08:14 PM
#4
Tech Contributor
Are you registering knock or just getting timing yanked out? If it's that latter, better look into burst knock tables instead.
Cars will often puff smoke when they knock on the dyno. It takes some good light and a good magnifier to properly read a plug. Pay particular attention to #'s 5&7
Cars will often puff smoke when they knock on the dyno. It takes some good light and a good magnifier to properly read a plug. Pay particular attention to #'s 5&7
09-29-2011, 08:48 PM
#5
Melting Slicks
Yep. Ya can't just pull em, look at em and say "they look OK". You need a plug reading tool. Trace signs of detonation are very small and hard to see with the naked eye.
09-30-2011, 01:05 PM
#6
Race Director
Thread Starter
I did get real knock one time on the road when my meth system failed.
I accelerated hard out of a tollbooth and got it in 2nd gear
There was some popping noises and puffs of black smoke.
It occurred at 5100 rpm, 10 psi boost,
I had a datalog hooked up and it showed knock counts w 12 degrees of retard at that event.
Amazingly it didn't do any damage to the stock bottom end.
Now, I've rigged a failsafe so that if meth fails it won't detonate!
I accelerated hard out of a tollbooth and got it in 2nd gear
There was some popping noises and puffs of black smoke.
It occurred at 5100 rpm, 10 psi boost,
I had a datalog hooked up and it showed knock counts w 12 degrees of retard at that event.
Amazingly it didn't do any damage to the stock bottom end.
Now, I've rigged a failsafe so that if meth fails it won't detonate!
