Guest Anonymous Posted December 19, 2000 Share Posted December 19, 2000 Scottie et. al. how much boost did you run with your sds stufF? ie. did you use the 2 or 3 bar map sensor? sds says the 3 bar "is not reccomended for street use", how bad is it really? I don't want to be limited to 1 bar of boost, that would kinda suck. They scare me when they say stuff like that! ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted December 20, 2000 Share Posted December 20, 2000 I ran a 2-bar sensor and ran 17# boost. The 2-bar sensor does not stop you from running more than 15# boost, however, the ECU will continue to use the last values programmed in if the boost exceeds 15#. When I bought mine, I had no thoughts of running higher than 15# , so I ended up just making the last manifold pressure related value a little larger. Patrick has the 3-bar sensor and ran 19#. The primary difference you will notice is that when tuning, the 3-bar maps involving manifold pressure will have a little less granularity. Sort of like looking at 2 tachs that have a 270* sweep but one goes to 6K and another goes to 10K. ------------------ Scottie 71 240GN-Z http://www.mindspring.com/~vscott911/gnz.html Quote Link to comment Share on other sites More sharing options...
TimZ Posted December 20, 2000 Share Posted December 20, 2000 I use the 3bar sensor with the TECII, and have no problems. I don't know why the SDS would be any different in this respect. There are a couple of things that you need to keep in mind when using the 2bar sensor... First, while you can 'trick' the ECU into delivering enough fuel above 2bar Manifold Absolute Pressure as Scotty mentioned, what you are doing in this case is essentially letting it run really rich at the point where the sensor pegs. Then, as the boost increases beyond that point, your mixture will get progressively leaner. Hopefully, the boost will stop increasing before the mixture goes too lean. The main problem here is that there is no margin for error if you overboost - you can't command extra fuel at that point, since the ECU doesn't know it's happening. Second, a MAP sensor senses absolute pressure - it doesn't know what boost or vacuum means, everything looks like pressure to it. The range of a 2 bar sensor is 2 bar, which is not the same as 2 atmospheres (1bar = 14.5psi, 1atm = 14.7psi). Since boost pressure is always measured relative to the ambient atmospheric pressure, the amount of useable boost range of the 2 bar sensor is 2bar (29psi) minus whatever your local atmospheric pressure reads on the sensor. For instance, if your local atmospheric pressure is 1 atm (14.7psi), then an ideal 2 bar sensor will peg at 29-14.7 = 14.3psi of boost (i.e., _not_ the 15psi that everybody assumes). Now, if your sensor reads higher than 1 atm at ambient, you will have even less boost range available - my 3bar sensor generally reads 1.2bar (17.4psi)ambient here in Detroit. If it were a 2 bar sensor, this would only leave me with a useable boost range of 11.6psi. I guess what I'm trying to get across here is just because you have a 2bar sensor, don't assume that it will measure boost pressures to 15psi. It could easily peg closer to 14psi, or less. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 20, 2000 Share Posted December 20, 2000 So this patrick guy... how does his car run? It scares me when the manufacturer reccomends to not use a 3 bar sensor - they should know what they're dong, and I assume they reccomended against it for a reason! ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted December 21, 2000 Share Posted December 21, 2000 Morgan - if I had to guess it would be because of th ereduced granularity. I tried swapping to a 3bar on my DFI setup once - the granularity went down noticably and I had a much tougher time tuning it. I ended up going back to the 2bar sensor. YMMV but I'd guess that this is what their concern is (shrug). Quote Link to comment Share on other sites More sharing options...
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