Boost Tuning ?'s
Thread Starter
Staging Lane
Joined: Apr 2003
Posts: 52
Likes: 0
From: texas
Boost Tuning ?'s Lets say I have a centrifugal supercharger making "X" number lbs of boost and the PCM has been tuned to for the correct air/fuel ratio. Now, if I add a smaller supercharger pulley, and my boost is now "X+2" lbs, then the air/fuel ratio is now incorrect. Now the big question. Will a Predator programmer or a MAFT be able to tune/correct the air/fuel ratio? Each say they can richen the mix by 15% or lean the mix by 15%. So, how many % change (richer) would the air/fuel mix have to be to compensate for an additional 2 lbs of boost?
Thanks!
Thanks!
Re: Boost Tuning ?'s At 6 psi of boost, you have 6/14.7 or about 40% more air. I don't know much about the predator, but I would think you need something a little more dynamic.
-Geoff
-Geoff
Re: Boost Tuning ?'s If your using your MAF correctly, you shouldn't have to change a thing. That's the beauty of a MAF system.
Assumming you haven't maxed out your MAF, or screwed with the MAF curve, and have enough fuel system your A/F shouldn't change with the added air.
It's not like a speed density computer, ie FAST, DFI, etc, where you need to dial in the MAP vs RPM efficiency tables when you up the boost.
Assumming you haven't maxed out your MAF, or screwed with the MAF curve, and have enough fuel system your A/F shouldn't change with the added air.
It's not like a speed density computer, ie FAST, DFI, etc, where you need to dial in the MAP vs RPM efficiency tables when you up the boost.
Thread Starter
Staging Lane
Joined: Apr 2003
Posts: 52
Likes: 0
From: texas
Re: Boost Tuning ?'s The MAF is stock and in the stock location (attached to the air filter housing). The blower intake tube hooks up to the MAF.
With the old pulley (5 psi) the truck ran like normal until you punched it, then it ran like a bat out of hell. With the new smaller pulley (7 psi) truck runs like a dog (bogs, sluggish, unresponsive) under normal non boost conditions. To make it run OK you have to hit at least 2 psi boost. Then it starts pinging (lightly) until 5 psi, then pings like a hail storm up to the 7 psi max (5,200 rpms). Also, my track times are at least 0.100 sec better with the old pulley.
Powerdyne stated that the stock fuel system is good up to 8 psi boost and the FMU with the kit is calibrated a 12:1.
To me it feels like too much timing or too lean. With the extra air (cfs) I tend to think the mix is too lean.
What are your feelings?
With the old pulley (5 psi) the truck ran like normal until you punched it, then it ran like a bat out of hell. With the new smaller pulley (7 psi) truck runs like a dog (bogs, sluggish, unresponsive) under normal non boost conditions. To make it run OK you have to hit at least 2 psi boost. Then it starts pinging (lightly) until 5 psi, then pings like a hail storm up to the 7 psi max (5,200 rpms). Also, my track times are at least 0.100 sec better with the old pulley.
Powerdyne stated that the stock fuel system is good up to 8 psi boost and the FMU with the kit is calibrated a 12:1.
To me it feels like too much timing or too lean. With the extra air (cfs) I tend to think the mix is too lean.
What are your feelings?
