Where can I buy the spring for the flipped vaccum can. Same as Libbydiesel used and was used by Rock3tman in his mTDI build and he writes " He also selected a new spring with characteristics so that it linearly opens the vanes from closed to fully open at approximately 20 psi). I built the rest"
Libby?
Thanks for help,
Bo Gunnar
It has been several years since doing that. I did a lot of measuring and calculating for spring rate, coil size, etc... If memory serves, the springs that I found worked best I bought from mcmaster with the correct spring diameter and rate for my goals. They were long length and I cut them to the correct length for my desired preload and max pressure. It's been long enough that I no longer remember and no longer have written down further details than that.
Rock3tman here..
I bought a new VNT-15 actuator from Hans VW (Chinese made, but I didn't care as it was to be cut apart and modified anyway) for $49.00 - - much less than a new one from
Garrett/Honeywell.
The actuator was cut apart by grinding off the crimp on the perimeter, the new spring was put in on the other side, the vacuum nipple was cutoff and replaced with short
6mm threaded rod section welded/brazed onto actuator, a small boost port tube was installed with epoxy on the actuator to input the post-turbo boost pressure into the actuator and, finally, the actuator was refastened on the perimeter with 8 very small bolts, washers, and locknuts. Whew!
To help you with spring selection: from 0 - 20 psi, the actuator changes in length by about 12 - 15mm. My adjustable linkage translates that to full motion at the VNT-15 vane arm from fully closed to fully open. To calculate spring strength, take area of membrane in actuator and multiply by the boost pressure you intend to use, over the distance from 0 to 12-15 mm.
Hope this helps, Rock3tman
Thanks both of you for reply. Another question. Can I use a wire to pull the can and vnt lever to max boost (open vnt)? It would simplyfie my build. I have no idea at all what forces are coming out of vnt lever - size and direction.
Pics of my mock-up.
Closed
Open
Which turbo do you have? My only experience is with a Garrett GT1749V, sometimes called a VNT-15 (previously GT 15 V). This was stock on an ALH I believe.
The vane actuator should move about 3/8-1/2" travel, from fully closed to open. Again you want to get a spring from McMaster-Carr that matches your boost range (I'm
using a max of 20 psi as measured at the stock IDI TD intake manifold elbow brass port barb).
Itīs a 2052. I have to rethink. With wire vnt vanes doesnīt get the "massage" (forced open - closed movement) that Libby has pointed out many times.
I will copy your design of linkage.
I think I was looking for one with 1/8" spring wire.
On my VNT15 the original spring was around 3/16",.. pretty beafy spring.
vntboostcaninside by
vwfatmobile, on Flickr
Looks like I ran 2 of them last time. I have the diameters written down somewhere.