I am thinking of switching to a SD tune for the new setup. Right now I am maxing the MAF at around 5000 rpm in second gear only on 6#. I am going to run it with the current pully setup till I decide on a new tranny and get it installed but then will be going up to what I believe will be around 16#. Right now it would be a no brainer to go to a 2-bar OS but how about when I pump it up above 15? The truck is a daily driver so I like the idea of a higher MAP resolution with the 2 bar sensor for the non-boost majority of driving. I just dont want to upgrade to a 3-bar unless I absolutely have to. What's you guy's thoughts on the subject?

 

2 or 3 bar is definately a smart move. But anything above 15psi is hard to do on pump gas unless your intercooler is very efficient and using meth inj. but if you have a 2 bar and you push over 15psi it will be just like you are now with fueing under boost, you have the same amount of fuel at 5000rpms whether you are at 6psi or 2psi. Basically if you are going to run 17psi boost with a 2 bar for example you will tune the fuel in the 210kpa region for 17psi but it will also be the same amount of fuel at 15psi in the same rpm cell.
But, with a supercharger the boost is pretty linear with rpms, unlike a turbo, so tuning is easier and you should be ok with running a little more than 14.7psi with the 2 bar and never know the difference.
But on the other hand does the 3 bar really cost more? I don't think so.

 

No, initially the 3-bar does not cost more that the 2-bar but if I were to upgrade from a 2 to a 3 bar down the road, it would be twice as much. The problem with the 3-bar sensor is that it shares the same 0-5V signal as the 1 and 2-bar MAPs thus reducing the resolution on MAP transitions. Since the majority of my driving is not in boost I dont want to loose any more resolution than I have too in the 0-100 KPa range. Not to mention I don't know how long it will take to get everything set up so I can up the boost to the 15+ lb region. Maybe by then I will have another DD and I wont have to worry about non-boost regions of the VE as much.

 

I never had any drivability or tuning issues when I was running a 3 bar. After I went back NA I still had the 3 bar on there for a couple months. I went back to 1 bar just because.
But, a 2 bar will probably be fine for what you are going to do.

 

Not trying to hi-jack your thread, but do they make a 2-3 bar to replace the stock one or do you have to rig something up?

 

They make a 2 bar that's a direct fit, but no 3 bar. Just make sure when/if you buy a 3 bar you get a connector with it. Then just cut your factory plug off and wire in the new one.

Oh BTW, I have no driveability issues with my 3 bar. It drives better than when I was N/A with a MAF.

 

Then jsut run a vaccum hose to the unit? or do they have one that fits where the old unit was?

 

It's old style. you run a vacuum hose to it.

 

will the hose stay put? and where do you put the sensor, just lay it there?Any pics will be helpful

 

I would not go three bar. How often are you really going to be above 15 psi? Once twice a day for a few seconds on the street? It's not worth it to to loose resilution down low (where you will drive it 99.8% of the time) to be able to "see" those last two pounds...