J&S Electronics Ultra Safeguard Knock Timing Controller
Thread Starter
Staging Lane
Joined: May 2002
Posts: 80
Likes: 6
From: PA
J&S Electronics Ultra Safeguard Knock Timing Controller I haven't seen any discussion of this timing controller.
Since it determines individual cylinder knock timing requirements, it sounds like it would be a desirable unit.
Has anyone actually adapted one to LS1 or thought about doing it?
PS. As far as I know, LS1 does not do individual cylinder knock timing adjustments. But wasn't there talk around 92 that Corvette would have such individual cylinder control?
Since it determines individual cylinder knock timing requirements, it sounds like it would be a desirable unit.
Has anyone actually adapted one to LS1 or thought about doing it?
PS. As far as I know, LS1 does not do individual cylinder knock timing adjustments. But wasn't there talk around 92 that Corvette would have such individual cylinder control?
Thread Starter
Staging Lane
Joined: May 2002
Posts: 80
Likes: 6
From: PA
Sounds like the big deal with this box would be you would not retard all cylinders 2* if only 1 cylinder required the 2*.... or worse.
If each cylinder is tuned optimally, you have 8 seperate cylinders w/unique flow characteristics, effective compression ratios, and timing requirements.
If each cylinder is tuned optimally, you have 8 seperate cylinders w/unique flow characteristics, effective compression ratios, and timing requirements.
I talked to these guys on the phone a couple of times.
We basically decided that it was not going to help my setup any better then a good tune with Edit. My car is a '98 though, so I can control the knock sensitivity in LS1Edit...not sure if this has been implemented for the other years yet.
We basically decided that it was not going to help my setup any better then a good tune with Edit. My car is a '98 though, so I can control the knock sensitivity in LS1Edit...not sure if this has been implemented for the other years yet.
TECH Addict
Joined: Sep 2003
Posts: 2,065
Likes: 0
From: Atlanta, GA
wait are you kidding me? The ecu knows which cylinder is knocking?
my 90 vw has cylinder selective knock retard, as does every vw following. You sure the ls1 doesn't? It has two knock sensors, a cam position system, it can easily figure out which cylinder is knocking with that hardware.
wow if the pcm doesn't have cylinder selective KR then thats a real suprise to me.
my 90 vw has cylinder selective knock retard, as does every vw following. You sure the ls1 doesn't? It has two knock sensors, a cam position system, it can easily figure out which cylinder is knocking with that hardware.
wow if the pcm doesn't have cylinder selective KR then thats a real suprise to me.
Teching In
Joined: Dec 2001
Posts: 387
Likes: 0
From: Southern IN, USA
No the LSx does not have the ability to determine the amount of knock in an individual cylinder. Some phase shifting program on the output of the 2 knock sensors may be able to localise th knock, but that is not implimented. Furthermore, even if there were 8 individual and isolated knock sensors, the timing is not controlled individially for each coil, but is an average across all, as found in the timing maps in the PCM.
For sure, engineers are working on individually controlled ignition advance (per cylinder, pre power stroke) but it's not in your local production car yet.
For sure, engineers are working on individually controlled ignition advance (per cylinder, pre power stroke) but it's not in your local production car yet.
TECH Addict
Joined: Sep 2003
Posts: 2,065
Likes: 0
From: Atlanta, GA
wow that sucks. i guess gm is light years behind vw in that respect. The latest gen 1.8T's can pull 40 degrees so fast your eyes won't bat (each cylinder keeps its own ram table matrix rpmXload). This is like a ltrim/strim setup. This is why you can run 15psi on 9.5:1 on the puny motor on 87 or 93 octane and boost never is reduced, by using rapid knock select per cylinder you can extract the max power per cylinder. Also you get a little extra juice (gas) on those cylinders that are knocking as it can individually be a cause of leanout.
Well i learned something today. Lame. boosted cars have to "ride the edge" of detonation to survive,for being fully sequential/etc, i'm suprised gm didnt go the extra few lines of code to sync the two sensors to the cam timing to figure out which cylinder was knocking. thanks for the info.
Well i learned something today. Lame. boosted cars have to "ride the edge" of detonation to survive,for being fully sequential/etc, i'm suprised gm didnt go the extra few lines of code to sync the two sensors to the cam timing to figure out which cylinder was knocking. thanks for the info.
Teching In
Joined: Jul 2004
Posts: 16
Likes: 0
Our system doesn't need a cam or a crank sensor to know which cylinder is knocking. If it hears a knock, it knows that it had to come from the cylinder that just fired.
Software knows that the knocking cylinder won't fire for two more revolutions. When it comes up to fire again, software dials in the calculated amount of retard for that cylinder.
The system retards one, two, or three degrees per knock event, up to ten degrees. The decay rate is one degree every twenty revolutions. A mode switch lets you double this, for a maximum of twenty degrees knock retard, if desired.
Software knows that the knocking cylinder won't fire for two more revolutions. When it comes up to fire again, software dials in the calculated amount of retard for that cylinder.
The system retards one, two, or three degrees per knock event, up to ten degrees. The decay rate is one degree every twenty revolutions. A mode switch lets you double this, for a maximum of twenty degrees knock retard, if desired.
Trending Topics
According to the book "Corvette Fuel Injection" (Probst), the LT1, LT4, and LS1 knock sensor processing is cylinder-selective, and timing can be retarded for each cylinder independently. Assuming this is true, I doubt it would be any different between a vette and and fbody.
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