GaryK

Just wanted to throw this out there. For those that are planning to use the J&S Safeguard, I'm also recommending that you use their monitor or devise your own. If you have the means to do this, I think it may prove to be very useful.

Why would you want yet another gauge to look at? Well, the J&S does its job very well, and can prevent catastrophic failure that might normally occur otherwise. For example, you have a fuel problem...fuel delivery, bad gas, whatever, or it could be a multitude of other things. When properly set up, the J&S should not be constantly retarding based on knock. This is a measure taken when something begins to get out of the normal range of operation. By having the monitor within view, you get a visual indicator of what the J&S is seeing and doing. If you see that it is constantly detecting knock, then it would be wise to then look for a problem before continuing to run your car hard. Your other gauges may or may not have alerted you to a problem, but persistent knock detected by the J&S tells you that something needs attention.

Without the monitor, the problem is that you don't get a visual indicator of what the J&S is doing. There is a light on the box itself that can tell you something, but normally the box is mounted somewhere behind a panel. If there is a serious problem, the J&S would be pulling a good bit of timing, and if your butt dyno is tuned well enough you might feel the decrease in power due to the timing retard. But why rely on that and take a chance?

Although I have just installed the J&S on my own car, I don't have the monitor yet. I think I will build my own to integrate into my existing gauge panel as I don't have room for an entire standard size gauge. My experience in the past does tell me that the monitor is an important piece to have. In particular, I used this on a 3rd gen rx7 and it was just invalueable. It was easy to see the J&S in action when I got a bad tank of gas, and as a result I could avoid pushing my luck in that situation since I saw what was happening.

Just my thoughts and opinions...

MardiGrasMax

iTrader: (8)

I agree 100%, a very valuable tuning aid.

Dr Bonz

iTrader: (1)

Gary: Now that you have the J&S on your Z, can you give us any driving impressions? Do you "feel" it in any way? Do you feel less power? More power? I mean does driving the car feel different in any way (good or bad) now that you have the J&S up and running?

Thanks.

GaryK

I haven't had a chance to really tune the timing retard yet. I can say that even with the unit set for no boost retard and just 6 deg rpm retard, I hardly ever see any knock and I have the sensitivity turned way up on the J&S. This is the way I currently have it set up.

For those that aren't familiar, the "rpm retard" feature on this unit is used to offset the aggressive factory timing curve at high rpms. The rpm retard starts at 5250 rpm and is at the full amount you set when it reaches 6250 rpm. However, the timing is not retarded under light throttle, when the engine is not seeing boost. The J&S must see at least 2 psi boost before it does any rpm retard, and the amount of retard at any given rpm is proportional as the boost varies between 2 and 4 psi.

I do think mine will need just a little more timing retard. I'll probably set it up for a small amount of boost retard. I need to sit down and figure out what combination of settings to run in order to shape the timing curve the way I want it. Whenever I have a chance to do more testing, and feel comfortable with my settings I'll let you guys know what I'm running.

For a few pulls I did try using a lot more retard than I am now. I've run as much as 1 deg per psi boost, and I didn't feel much difference, if any, even with that much timing retard. But we all know the butt dyno isn't very accurate. With my current settings, I don't feel that the performance is hurt at all. Midrange torque and throttle response seem to be as good as ever, and top end power is great too.

jesseenglish

I'm glad the RPM based retard is working appropriately. I was thinking about doing pretty much the same thing. 1 degree per PSI & 6 degree RPM retard. Until I get an EGT, I really won't know what effect it's gonna have, but I think it's probably pretty safe.

Enron Exec

Can the J&S retard enough timing to help prevent damage in an ATI 350 that hits its stock rev limiter?

jesseenglish

I think the question you're asking is can it retard enough to help prevent damage in a lean condition. The answer is no. Lean conditions and detonation from advanced timing are two separate issues entirely. A lean condition will still damage your engine because basically it acts like a blowtorch on the top of your piston. Timing retard just moves the time when the spark plug actually fires that fuel mixture up.

There is no real concrete evidence however that hitting the rev limiter creates a lean condition because we don't know if the rev limiter cuts fuel entirely or just partially cuts fuel. If it cuts fuel entirely, then there is no fuel to burn, thus no lean condition.

If I can fully trust my wideband O2 gauge then it cuts fuel entirely, but that's still not absolutely known. I can't believe that Nissan would allow a potentially dangerous A/F ratio on their car though.