mountain lion
Veteran Member
I just installed the Darkside upgraded SMIC w/ 2'' piping kit on my BEW which still has the KP39 turbo installed (vnt17 coming soon). Running an RC1 tune.
The intercooler is roughly 50% bigger than the original + added volume from the new 2'' piping. My IAT decreased about 10-15 F degrees now going down the highway and it cools down extremely fast.
What I've noticed on my scangauge II is that the boot pressure reading is now higher at idle and on cruise control @70mph by about .7-1.0 PSI. I used to boost about 1.3-1.6 with the factory IC/pipes @70mph. Now I'm seeing about 2.0-2.6. Idle is also up around 1.3 psi from around .8 psi.
I'm trying to make sense of why this is happening. I've actually noticed in the past boost would be higher when it's really cold out, but not by this much.
Is it as simple as the OEM piping was probably leaking at a few joints and causing pressure loss? The old interconnects definitely wept some oil, so it wasn't air tight sealed. The new system is sealed up extremely well. Or is it the system is just more efficient at moving air so I'm seeing higher pressures at the MAP sensor.
Where I'm more confused is I would think that if the ecu is calling for X specified boost, then it should get very close to that number. Even if there were leaks before the MAP sensor on the stock setup, the turbo would just work harder to pump more air out to compensate. With that considered, I'm not sure why the PSI would go up. The ecu map calls for x pressure and adjusts the VNT actuator until it reaches that, no? Regardless of leaks or efficiency, it should be at the target boost psi?
I have some old vcds logs measuring rpm, boost, duty cycle etc. Haven't grabbed a new log yet to compare the values. Unfortunately, the logs are mostly WOT pulls and not cruising.
I'm not overboosting at WOT and the engine definitely is pulling faster and feels less restricted. No boost leaks that I have found either.
On another note, the Darkside kit arrived in 1 day from the UK, installed effortlessly and perfectly. Super happy with fit, finish and performance!
The intercooler is roughly 50% bigger than the original + added volume from the new 2'' piping. My IAT decreased about 10-15 F degrees now going down the highway and it cools down extremely fast.
What I've noticed on my scangauge II is that the boot pressure reading is now higher at idle and on cruise control @70mph by about .7-1.0 PSI. I used to boost about 1.3-1.6 with the factory IC/pipes @70mph. Now I'm seeing about 2.0-2.6. Idle is also up around 1.3 psi from around .8 psi.
I'm trying to make sense of why this is happening. I've actually noticed in the past boost would be higher when it's really cold out, but not by this much.
Is it as simple as the OEM piping was probably leaking at a few joints and causing pressure loss? The old interconnects definitely wept some oil, so it wasn't air tight sealed. The new system is sealed up extremely well. Or is it the system is just more efficient at moving air so I'm seeing higher pressures at the MAP sensor.
Where I'm more confused is I would think that if the ecu is calling for X specified boost, then it should get very close to that number. Even if there were leaks before the MAP sensor on the stock setup, the turbo would just work harder to pump more air out to compensate. With that considered, I'm not sure why the PSI would go up. The ecu map calls for x pressure and adjusts the VNT actuator until it reaches that, no? Regardless of leaks or efficiency, it should be at the target boost psi?
I have some old vcds logs measuring rpm, boost, duty cycle etc. Haven't grabbed a new log yet to compare the values. Unfortunately, the logs are mostly WOT pulls and not cruising.
I'm not overboosting at WOT and the engine definitely is pulling faster and feels less restricted. No boost leaks that I have found either.
On another note, the Darkside kit arrived in 1 day from the UK, installed effortlessly and perfectly. Super happy with fit, finish and performance!
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