So I have installed a VNT15 onto my CR 1.6 This build has taken me countless hours of research, and talking to many people. In the end I decided that I had so many questions that could, or should have been easily answered, and I felt that I should help those wanting to do the same thing. With all the pictures no longer available its hard to understand and figure everything out right? So I will upload pics as I keep going, and go into best detail that I can for all you!
To begin, there are different styles of VNT turbos, Borg Warner has their own style, which is a pressure actuated VNT. Garrett has the vacuum actuated turbo. The stock VNT15 off of an ALH is the Garrett style turbo charger. Further more, everyone that has posted about the VNT15 seems to have their own idea on how they work, and almost none of them are correct on how they truly work. The VNT turbo charger is essentially a variable A/R turbo. If you don't know what A/R is, i recommend looking up Engineering Explained, and watching all of his stuff on youtube as far as turbos go, and VNT
Now when the VNT15 has absolutely NO VACUUM the vanes are completely open. On other forums and posts I could not get a straight answer. So remember that if you are planning on doing this. 0% Vacuum = vanes open
Open vanes are for high capacity, low velocity, meaning you need to be running in the higher rev range to get your turbo to spool. All that needs to happen to make the turbo spin faster is to apply vacuum on the VNT actuator. about 17inhg will fully close the turbo vanes. The hardest part of this build is the boost controller, how does one have an adjustable vacuum.
People have completely bypassed the VNT actuator by removing it, and replacing everything with a mechanical linkage set up. I said screw that, too much work, and it looks kind of crummy. Some people did it really really well, where as others, it just looked awful. too many moving parts, if one thing fails then boom your engine are turbo could be toast.
Kerma TDI has this part that is sold called the "Dawes Device" which is a manual boost controller for the VNT 15. its about 70 bucks, and its now made by a company called 3BarRacing. I recommend getting that, I will draw later as to why the Dawes Device works, and why it can work really really well.
Most people are in tune with their cars, and can tell when something has gone wrong, and what I like about keeping the turbo stock with the vacuum actuator is I can simply shut it off. All you have to do is run a 12v vacuum pump (They are like 30 bucks on amazon), a switch (if you want a kill switch for the turbo), the Dawes device, and boost line!
Again I'll post more about how everything works this week. If you guys have ANY questions at all, please feel free to ask me
I know a couple people that are running the dawes device, and they say its the next best thing if youre not running an ALH PCM and all the electronic stuff that comes with the original car.