Administrator/Moderator
I am running this identical post simulataneously in the Performance and ECU forums. If you object to the multiple postings please remove this one.
Thanks


According to my reading, the J&S Safeguard will not protect against "hot spot" detonation, overboost or bad gas (low octane). It would appear that the only detonation the company claims the unit can protect against is the "lean condition" variety. As a result of the reading I have two questions:

1. How can any microphone based unit discriminate between the cause of the knock? It would be logical that while hot spot and overboost might cause high intensity "spike" types of detonation that the retardation of the spark could not affect in time to protect, the "lean condition" and "low octane" detonations would be similar in duration and should allow the unit to retard the spark sufficiently to provide protection.

and

2. Given the fact that my NipponDenso upgrade drop in fuel pump provides plenty of fuel to the stock primaries and 1300cc secondaries, what if any advantage is there to purchasing and installing the J&S unit.

BTW even though I have not yet replaced the infamous Apexi wastegate, to control the possibility of overboost I am running both a Profec B set to 12 and 14 psiand a pop-off valve set to 15 psi.

I have no problem spending the money to protect my engine, I just want to know that the money I spend WILL protect the engine and turbo

My other specs are in the sig.

 

the problem with the j&s unit is that it only works on the leading spark plugs. and it had enough range where it can retard the leading timing until it fires after the trailing which is bad.

mike

 

My car will be tuned by Crispeed, and he has one on his TII Race Car, and he insists that every street car that leaves his shop runs a J & S Knock Safeguard sensor. He claims it has saved many, many motors, as well as his own several times.

Even guys like Abel run them on their "Race" cars.

To me, that is insurance you just can't beat. It's not cheap, but it is MUCH cheaper than a rebuild.

By the way, I have mine already, but I am looking for the display, anybody have one for sale?

 

it occured to me to get one for the 20b because i've got no split anyways. do they make just the knock display?

mike

 

Knock display and AF is readily available at well known Indiana and Texas performance parts dealers. Last time I looked it ran about $160-$190

 

Do you have a link, phone number, etc..?

 

I've had one for several years, and it is true that it won't protect you when something goes very wrong. But, its greatest value to me has been as instrumentation. It will display knock that you don't hear while driving. That can help you know when to back off the gas when things are getting too hot, or give you a clue when something else is starting to become a problem.

But, mine has been falsing a lot since I went single turbo, so the instrumentation value has gone out the window. The falsing also retards the ignition (of course) and probably increases the EGTs to the detriment of the wastegate and perhaps the turbo. To be clear, the falsing is most likely the result of something screwed up with my setup rather than a problem with the J&S unit itself. But it has made the J&S a liability for me rather than an asset. I need to fix the setup to stop the falsing or remove the J&S.

Another danger is that it will retard the ignition so far that the leading fires after the trailing, which seems to be universally viewed as a very bad thing. You should be safe, though, as long as you run the J&S on 10 degree max retard and more than 10 degrees of split.

Overall, I like the J&S and plan to keep it if I can get my setup worked out so that it doesn't false. Otherwise I'll have to remove it.

Jeff48, smart move on running the pop-off valve. I wish I had one installed when my wastegate failed. I imagine that it isn't all the uncommon for less drastic failures like the wastegate signal hose coming disconnected, and the pop-off valve would protect you in those instances as well.

-Max

 

Max

As always, thanks for the insights. The idea of setting the retard limiter to ten degrees and verifying a minimum 10 degree split should address the timing issue.

As to the matter of falses, I would be interested in what you think the change to a single could have done to cause those false readings. I wonder if it could be a function of the overall increase in background noise generated by the single setup transmitting through the modified exhaust plumbing and back to the manifold where the microphone actually interprets the noises as low level knock. If that is the case, I'm not certain what could be done to reduce that noise level.


I should be finding out this week about whether the IHI modification you helped me with (cutting the damaged areas on the turbine) was successful or whether a new single is in my future. I will let you know in a pm next week or so.


BTW I have been hot for a pop-off valve ever since I put a RP turbo-back on my 2nd gen and panicked when it experienced boost spikes to 13 psi. Because it is installed, I am pretty confident my engine explosion was a tuning error or bad gas (most probable here in Southern Illinois) and not a boost related catastrophe. (although I would love to blame the hardware).

 

Holy ****! I was glad to read this because I've had the same problem since I installed my XS T04E kit. The thing would just light up like a Christmas tree after 4k rpm. What did help was I re tightened the part that screws into the block & made sure the nut holding down the mic was really tight.

Max, when you find out what's happening, let us know.

 

I've got an exhaust leak in my WG dump tube and I need to check the tightness of the sensor mount, as Sidestick pointed out. It could be a bunch of things, I just need to start fixing things and see what happens.

-Max

 

correct most falsing ive seen on these units is due to a small exahust leak near the turbine flange/manifold/wastgate area...everybody should retorque all there nuts and bolts after a week when going single...seen this problem all the time

 

Thanks Poweraxel, I'll check those, too.

-Max

 

Thanks to everyone for the input, I just bought a used unit from the forum and will be installing it on the brand new engine going in this weekend.

Max---Like you said---even if I manage to set the car up perfectly and avoid excessive detonation, I figure the instrumentation value is worth the price. On the plus side, you never know when you are going to get crap gas on a 100 degree day, this should help keep me honest.

Poweraxel---Thanks for the words of experience. I will check the torque regularly.

 

Anybody got a link to a copy of the manual for these online somewhere? I neglected to get mine from my mech after he installed it...

 

It's a glorified and expensive knock display.&nbsp If I had known better, I would've just gotten a $150 MSD knock sensor display for 1/3rd the price.

The retard function does not work very well on a stock rotary ignition.&nbsp Anyone who claims the retard function saves engines is full of it.


-Ted

 

Crispeed's car. Note the lower right - J&S. It was enough to convince me.