What is KR?
#2
01-14-2009, 11:59 AM
RE: What is KR?
well you almost posted in the right section actually ,htis section can help to reduce KR!!!!!
KR is Knock Retard (I'm not trying to call you an idiot, thats seriously what it stands for)
It is something in the rattling of the valves I think... but I know the only way to see how much you have is to get the engine scanned or to have one fo those laptop tuner programs....
It can be reduced by getting a more free flowing exhaust, a more free flwoing intake (CAI), and running higher octane gas.
KR is Knock Retard (I'm not trying to call you an idiot, thats seriously what it stands for)
It is something in the rattling of the valves I think... but I know the only way to see how much you have is to get the engine scanned or to have one fo those laptop tuner programs....
It can be reduced by getting a more free flowing exhaust, a more free flwoing intake (CAI), and running higher octane gas.
#3
01-14-2009, 12:17 PM
RE: What is KR?
knock retard is when the engine backs off (or retards) the timing due to engine knock or pre-detonation. there is a knock sensor on your engine block that senses irregular vibrations when the engine knocks. sometimes you can feel it if it's bad enough, but otherwise like cowboy 6622 said, you'll need a computer.
your engine may knock as a result of carbon deposits on the valves, pistons, or combustion chamber. these deposits get hot and act kinda like a spark plug when the fuel mixture is being compressed, it ignites and combusts before it's supposed to. there areother reasons it could knock, but this is just one thing that couldhappen.hope this helps.
your engine may knock as a result of carbon deposits on the valves, pistons, or combustion chamber. these deposits get hot and act kinda like a spark plug when the fuel mixture is being compressed, it ignites and combusts before it's supposed to. there areother reasons it could knock, but this is just one thing that couldhappen.hope this helps.
#6
01-15-2009, 05:09 AM
RE: What is KR?
ORIGINAL: Cowboy6622
KR is Knock Retard (I'm not trying to call you an idiot, thats seriously what it stands for)
KR is Knock Retard (I'm not trying to call you an idiot, thats seriously what it stands for)
Thanks for the replies everyone ... that explains alot. Now, hopefully, I'll understand what I'm reading.
#7
01-15-2009, 09:13 AM
RE: What is KR?
Expanding on this a little further...
It doesn't have anything to do with the valves at all- it is a result of detonation, as was said above.
What basically happens is you have two sensors screwed into your engine's block/coolantjacketsthat are basically microphones. They are designed to pick up only certain frequencies. The idea is that detonation in a cylinder produces a different vibration frequency than a normal combustion explosion- and those sensors are used to listen for any noise in those frequencies.
The way KR relates to that is, it is showing the computer's response to that detonation- which is does by removing timing advance (retarding timing)- and KR is just the value associated with how much timing is being pulled.
This is true, however since you have an 05 ss supercharged- you should already be running premium anyways.
Honestly- if an L67 is knocking bad enough that you can feel it- you've probably already chipped all the pistons. I've seen people chip pistons running as little as 5-7* of KR at WOT, and you couldn't tell at all.
The idea is that if your computer is showing KR, that means it has already pulled the timing to make the detonation go away- so you wouldn't be able to hear it by then because its gone. The only time it would even be possible to hear it is right as it happens, just before the pcm pulls timing (which is a very short window). The only thing you can feel while you have KR, is the engine will be running at reduced power- but unless you've rode in a car with the similar mods, its hard to tell how fast the car 'should' be.
All of this stuff is true- and is what the NA (non-supercharged) people worry about for causing knock. However, KR is much more relevant to your engine (the L67) when you start modding.
One of the most common ways to add power to your engine is to drop the supercharger pulley size. This forces more air into the engine (+ more fuel = more heat), and also spins the supercharger faster, lowering its efficiency (= more heat also). This extra heat makes knock a significantly bigger threat, because you can go from a 100% knock free car, to a car knocking so bad that you start chipping pistons in about 30 minutes by dropping to too small of a supercharger pulley for your mod level.
That is why before you start messing with your supercharger pulley, that you do some serious research to find out what mods are necessary to support the size pulley you want to go to.
That is also why you see it talked about a lot more with the L67. All the other NA people out there worry about carbon buildup and slowly leaking valve guides and piston rings causing KR after tens of thousands of miles. For them, its not really a big deal because there is so little knock involved, and there is relatively no danger to the engine- just slightly more sluggish performance which can be cured by just stepping up a grade of gas (since most NA people run 87). But for you, its a whole lot bigger of a deal, because if you get into modding without educating yourself, you can end up destroying your engine with a simple $50 mod.
It is something in the rattling of the valves I think...
What basically happens is you have two sensors screwed into your engine's block/coolantjacketsthat are basically microphones. They are designed to pick up only certain frequencies. The idea is that detonation in a cylinder produces a different vibration frequency than a normal combustion explosion- and those sensors are used to listen for any noise in those frequencies.
The way KR relates to that is, it is showing the computer's response to that detonation- which is does by removing timing advance (retarding timing)- and KR is just the value associated with how much timing is being pulled.
and running higher octane gas.
sometimes you can feel it if it's bad enough
The idea is that if your computer is showing KR, that means it has already pulled the timing to make the detonation go away- so you wouldn't be able to hear it by then because its gone. The only time it would even be possible to hear it is right as it happens, just before the pcm pulls timing (which is a very short window). The only thing you can feel while you have KR, is the engine will be running at reduced power- but unless you've rode in a car with the similar mods, its hard to tell how fast the car 'should' be.
your engine may knock as a result of carbon deposits on the valves, pistons, or combustion chamber.
One of the most common ways to add power to your engine is to drop the supercharger pulley size. This forces more air into the engine (+ more fuel = more heat), and also spins the supercharger faster, lowering its efficiency (= more heat also). This extra heat makes knock a significantly bigger threat, because you can go from a 100% knock free car, to a car knocking so bad that you start chipping pistons in about 30 minutes by dropping to too small of a supercharger pulley for your mod level.
That is why before you start messing with your supercharger pulley, that you do some serious research to find out what mods are necessary to support the size pulley you want to go to.
That is also why you see it talked about a lot more with the L67. All the other NA people out there worry about carbon buildup and slowly leaking valve guides and piston rings causing KR after tens of thousands of miles. For them, its not really a big deal because there is so little knock involved, and there is relatively no danger to the engine- just slightly more sluggish performance which can be cured by just stepping up a grade of gas (since most NA people run 87). But for you, its a whole lot bigger of a deal, because if you get into modding without educating yourself, you can end up destroying your engine with a simple $50 mod.
#8
01-15-2009, 10:51 AM
RE: What is KR?
Honestly, I probably won't do many mods - probably a downpipe, high-flow cat and u-bend delete. Maybe mufflers - if I find something I like. No thoughts of supercharger pulley mods. I'm pretty happy with it the way it is.
#9
01-15-2009, 11:26 AM
RE: What is KR?
If you never touch the pulley, then you never have to worry about KR as long as you use premium gas.
However, if you ever get to the point where you do want to go faster, a new s/c pulley is right at the top of the list for an L67. A 3.4/3.5" pulley along with the other basic bolt ons can kick you up to ~300ish crank hp for under $1000. That may sound like a lot of money up front, but it gets addictive- all the individual pieces are $300 or less each, and the gains are a tremendous value for the money.
However, if you ever get to the point where you do want to go faster, a new s/c pulley is right at the top of the list for an L67. A 3.4/3.5" pulley along with the other basic bolt ons can kick you up to ~300ish crank hp for under $1000. That may sound like a lot of money up front, but it gets addictive- all the individual pieces are $300 or less each, and the gains are a tremendous value for the money.
