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Q: timing curves...stand alone systems...

298 Views 5 Replies 4 Participants Last post by  steves280
Hey everyone, I have a couple questions and checked the archives, but didnt find what I was looking for. I have an SDS system thet I've been running on my 240ZT for about 6 mos now. I had it on a dyno and tuned. When i had the car on the dyno, I didnt have the knock sensor hooked up yet, but I didnt hear any knock at these settings. im at 30 degrees advance after 3000rpm with timing retard starting at 6 psi and gradually increasing to 14deg. retard at 13psi.
The other day at the track I noticed that my knock sensor was picking up knock after approx 8psi. so I started to retard the timing more to fix the issue, but after retarding it quite a bit, the sensor was still picking up knock. Now im not sure if I set the knock sensativity to high, but it seems odd that its still picking up knock. I noticed that at the high boost/lower rpm (like around 4000) it wasnt picking up knock which should indicate a good setting since the engine is loaded more. but at about 5000 and above it was picking it up at the same boost levels, which leads me to believe that the sensor is picking up engine noise and sensing it as knock. right now I have the unit set so that it doesnt pick up knock after 5500 RPM. should I lower that value to 4500? What do you guys have for your settings on the inline 6 motors?
Also can you guys list some of your timing curves, or where I should be aiming for on this setup? I know there will be other variables, im just looking for baseline settings up to 1 bar boost. thanks.

heres my setup. 82 280zxt motor stock everything with nismo head gasket. T3 turbo, spearco intercooler, 370cc injectors, stock fuel press regulator. 2.5" straight exhaust running 91 octane pump gas. also according to my readings the engine is getting plenty of fuel.
thanks for any help.
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check for "steves280 sds" in the search....he set up maps for 14 psi. sensitivity might be too much on the sensor...i forget what the manual said to set it at.
You are picking up engine noise and also have the timing WAY too retarded. You have it set for 16 degrees total timing under boost which is at least 15 degrees too much retard. I've run ZXT's at 42 -total- at 3000, 20 degrees at idle (both at zero boost) another 8 degrees at full vacuum (total of 50 dgrees) and 10 degrees of retard (which end up at 32 degrees) at 14PSI with no pinging using the fuel map below for 440cc min injectors and 93 pump gas


given you have 370's of course you'd have to refigure for that but should give you an idea on what I used. I've been warned that these engines are mechanically noisy and give false knock sensor readings so I've never bothered using them.
thanks guys. Steve...just the info I needed. I appreciate it. So you dont use a knock sensor at all? I was thinking about unhooking it, but I wasnt sure on that. anyway thanks again.
My stock turbo engine doesn't detonate with 30 degrees of timing at 8 psi of boost and 25 degrees at 15 psi of boost.
No knock sensor. These engines are noisy and again if it's tuned right, you don't need one. One of the keys to having a "spunky" turbo is LOTS of off boost timing.
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