First off I would like to thank the Mad Man, Adrian for motivating me to do what I did. I was initially thinking of going down the non-VGT route and just about did when I started reading about the surging issue some members were having. However, I saw the success rate and figured I would build my own creation, a LLY compressor (63.5/88mm) from a donor GMC truck and mate it to a GT3782VA middle and turbine sections , AKA Stage 1.
The first step is to clock the backing plate if you want to use the stock pipes. You could fill the back hub and re-drill the holes, offset 30*, but you should keep a large area free so the oil can circulate to provide cooling. I decided to cut and weld. The first cut is always the hardest, and as soon as the cutter hit the metal, I knew I would have to change the set up a little. The cutter was chattering too much so I had to stabilize the mounting point for a narrow cut line.
The cut was still larger than I wanted, but you have to use the tools you have at hand!
I had a seal set that made what I thought was a perfect jig. It worked extremely well except for one thing, it allowed the heat of the weld to pull the center section about 3/4mm forward. So after grinding down the weld for wheel clearance, the compressor housing was just being lightly rubbed by the comp wheel.
So what to do to raise the backing plate? I could weld it up, but then I would have to mill or turn it down after (too much work), build it up with epoxy (still have to reset the height) or shim it. I decided to shim the backing plate with some thin aluminum ( yes from an old shovel)! It was almost the correct thickness and only required a small amount of work to make it fit. I ended up epoxying it to the backing plate.
I kept all the parts stock so if I had to, I could go back without buying new old parts. I had to add a ring around the comp outlet to bring it up to 2.5". The intakes are different, so I fabricated a bellows (from a old intake tube) to attach to the outside of the original intake. To make it strong enough for the clamp, I used a 4"ring to slip inside of the tubing. With the slightly larger turbo and the 1/4" of bellows, the CCV tube needed to be shortened about 1" to fit.
As those of you that have changed a turbo in the vehicle know, it is a PITA to get to most of the bolts! I only lost the back bolt, with the socket attached to it twice. Once on removal - no big deal once the turbo was out, and once on installation - big deal, because I wanted to get my socket back! My $45 inspection camera and flexible stick magnet did a good job at finding the pieces wedged up against the up-pipe heat shields.
I also cleaned up the old turbine section and replaced the ring with the one from the donor turbo (actuator grove damage). My bearings were better, but the ring and vanes were better in the 3788. Unfortunately the vanes are about 2mm taller than those for the Ford. If you really had to, you could grind/sand them down.
I cranked the motor with the FICM fuse out to prime the oil to the turbo (about 30 seconds). Started it up to do a leak-check and then went for a test drive. It sure sounds different, but due to the weather (snowing) I couldn't do a qualitative test. As well, I think the tune I am using is limiting the boost to 23 psi. It gets to 22.9 then reads 0, then 22something, then 0.
It was doing it before the swap-out as well. It doesn't stumble like a boost leak and seems to keep pulling. I noticed it when I hooked up my monitor a few month ago. Checked all the boots, but did not pressurize the CAC system. I will probably do that this spring.
BTW, no surging!
01-30-2013, 05:08 PM
Linear Mode
