charged air temps and knock

jdmawd · 07-25-2002, 06:18 PM

i have been doing a LOT or research on tuning, and have yet to find. any references to charged air temps and knock sums. is their a specific temperature that the chance of knock is more prevalent or is knock not air temperature related at all. we all know how charged air temps affect intake air density, but does the density or lack their of, affect knock from the air being thinner when hot, or denser when cool? it would seem hot air, which is thinner would be more prone to knock, than cooler denser air.

rdrkt · 07-25-2002, 09:09 PM

I think the temperature of the air is the most important. I don’t think their is a reference chart or anything. I'm sure most of it has to do with your ic core’s ability to cool the air down. Obviously the colder the air the better.

NDgsx · 07-26-2002, 12:36 AM

Hotter air is more prone to preignition. Remember there are two types of "knock". Detonation and preignition. Detonation is simply from running lean or having too much timing advance. That does things like melt pistons and exhaust valves. It is audable.
Preignition is when the flame front ignites before the plug fires. So it happens while the piston is traveling upwards. The uncontrolled flame front slams into the piston. It cause all kinds of fun things like spun rod bearings, bent rods, and cracked ring lands. You can't hear it.

jdmawd · 07-26-2002, 07:15 AM

Quote:

Originally posted by NDgsx
Hotter air is more prone to preignition. Remember there are two types of "knock". Detonation and preignition. Detonation is simply from running lean or having too much timing advance. That does things like melt pistons and exhaust valves. It is audable.
Preignition is when the flame front ignites before the plug fires. So it happens while the piston is traveling upwards. The uncontrolled flame front slams into the piston. It cause all kinds of fun things like spun rod bearings, bent rods, and cracked ring lands. You can't hear it.

With that said, is there a specific temperature where preignition detonation is more prevalent. In other words, is there a specific temperature where preignition starts? On the intake side that is. Example if intake temps are around 140*F post turbo. Would i have a greater chance of detonation than at say 90-100*F post turbo?

NDgsx · 07-27-2002, 10:10 AM

I don't think there is a specific temperature where it becomes more likely. You shouldn't have anything to worry about with the irc race core a br intake though. Other cars with the same core and similar intakes have reported temps very close to ambient at the tb elbow.

jdmawd · 07-27-2002, 10:19 AM

Quote:

Originally posted by NDgsx
I don't think there is a specific temperature where it becomes more likely. You shouldn't have anything to worry about with the irc race core a br intake though. Other cars with the same core and similar intakes have reported temps very close to ambient at the tb elbow.

cool thats what i wanted to know thanks