Thanks guys! You know, they say imitation is the sincerest form of flattery.
Hey I finished the intercooler install yesterday, installing everything and finishing off the boost tubes:
It was a chore to route the tubes in that location with them being properly supported and not rubbing on anything. I was concerned about the thin aeroduct chafing against something, but so far the only thing rubbing is one of the rubber-lined adel clamps on the soft hood sound absorber mat. I need to do something about it before driving a lot more, as the sound absorber is wearing where it is rubbing. The boost tubes and intercooler are holding up great though, and I have had no problems with boost tubes getting blown off.
I also changed the wastegate from .6 bar (little green spring) to the .9bar (big green spring). Check out the differences in these spring dimensions!
Against the force of the big green spring, holding the spring cover on there while starting the little bolts into their threads was not easy!
After a road test, it looks like the wastegate with the new big green spring is opening and regulating pressure pretty well at about 12psi - a pretty healthy bump over the previous 8 psi setting.
I did several tests to adjust the VNT to increase it's pressure, and I reached the end of it's threaded adjustment range. So I disassembled it and reassembled it with a threaded rod that is shorter, so I could get more VNT spring pre-load to further increase it's regulated boost pressure. I've got it set now so that it starts opening at about 5-6 psi and it opens completely at about 11 psi. I will probably experiment soon with adjusting this a bit higher.
I also adjusted the LDA as well to broaden its working pressure range. I wanted to set it to allow more fueling than stock at the high boost levels to go with the added air, but also wanted to have it minimize fuel at low boost, so that in the event of a blown boost tube, the LDA reduces fueling as much as it can to try and help save the turbo from overspinning on closed vanes. With the LDA set up this way, the car's horsepower and torque characteristic is more closely linked to its boost pressure, so there is a bit more turbo lag powering away at very low RPMs, but it's usually not for very long with the VNT.
The car rocks with added boost - really fun to drive. The way it's set up now, there is a little bit of "hyperactive boost" cruising on the freeway, etc, at around 5 psi where the vanes are nearly totally closed, the boost is very responsive to small throttle changes. But it is well regulated around 10 psi, and creeps beyond that up as RPMs increase to about 12 and then at the highest RPM where there is still max fueling the boost peaks at about 12.5psi. There is definitely more power, and more torque, despite fueling being set to make zero visible smoke detectable out the rearview mirror.
Oh by the way when I was under there removing and reinstalling the VNT can, I noticed that the compressor housing was HOT! I remember there was a heat shield on the TDI exhaust manifold on the compressor housing side of it, and I can see two mounting studs for it sticking out of the exhaust manifold, but on this car it is missing. Maybe I should try and track one of those TDI heat shields down.
Topic: VNT Rabbit tuning: intercooler + more boost (Read 25340 times)
