I've been struggling with the GTI lately. My indecision has plagued the car with balancing between a daily driver and track machine. But now I'm faced with a crossroads that is rather immediate in need: my IS38 is damaged.
Unlike most IS38 failures, I actually found this failure by chance. Crappy hose clamps led to multiple blown charge pipes, and blown charge pipes led to oil findings. Oil findings lead to a turbo inspection and ...
The weird part is -- no shaft play. Both thrust and lateral movement are negligible. Unlike most IS38 failures, I've been fortunate enough to keep my rotating assembly in check. I attribute this mostly to the very conservative tunes I've been running which maintain 30% or greater WG duty cycle. For reference, here in Colorado my peak boost is about 19.5psi and tapers to just 15. It's not much -- but enough for me to hit almost 130 on the back straight High Plains Raceway.
The real dilemma is what to do next. Obviously the MK7 community is no stranger to turbo failure, and as a result there's been a quite a few options for replacements. EQT's Vortex turbo, the Vargas VTT turbo, BOSS kits, EFR kits, Iroz kits... the list goes on. Of course, almost all of these options start close to $2000, and 500+whp capable kits in excess of $3000.
I'm not going to give you a run down of the entire turbo market, but I will segment some things at a high level. Lower end options are going to use journal bearings. There's nothing wrong with JB turbos, they just don't spool quite as well as their ball-bearing counterparts. It's my understanding that some of the early hybrids re-used the journal bearing CHRA's from the IS38 -- if this is the case just stay away. The next step up is ball bearing turbos. You'll start to find these from companies like DBV2. The cost is more, but so is the performance. And then of course there's full-frame units like the EFR, which aren't really vehicle specific but made to fit the VW with a kit.
I'd like to premise by saying, a big turbo FWD hatch is a little silly to begin with. Traction issues and turbo lag make it kind of a pointless package. The IS38 I have actually did great in my opinion... the damage is likely due to a foreign object. My dilemma is that the GTI will be used for track, so it needs something reliable. Will I get as lucky with a second used IS38?
Being budget conscious, one consideration is a turbo rebuild. A proper rebuild would bring the turbo back to a new condition in terms of all wear items, but at a much reduced cost. The big advantage of this approach is cost, and the big cost of this approach is the time. The turbo must be removed, shipped out, serviced, shipped back, and finally reinstalled. Overall, it's likely a month of downtime. Nevertheless, with a spare car in my possession it's a possibility.
I contacted up G-Pop Shop, a turbo shop out of Arkansas. A while back they were fairly popular on the forums and Facebook pages, but in recent months it's been radio silence. I'd heard mixed things from various sources but wanted to call first hand to inquire. The phone call did not go as planned.
"Hello, G Pop Shop"
"Yes, I'm looking to get a quote for a turbo rebuild."
"Sure! What kind of car and turbo is it?"
"It's a IS38 turbo off of a Golf R". There's a pause here. "I believe your familiar with these units?"
"Yup. We don't service those any more."
I was stunned. The shop wasn't servicing these? Why? G-Pop continued on to explain that these units just fail. New ones even fail. Originally they believe it to be a balancing issue. However, after addressing this units continued to fail. Ultimately, they feel IS38's have an inherent design flaw. G-Pop offered that it was likely due to lubrication, but couldn't confirm it. Bottom line, they weren't servicing IS38 turbos anymore.
The call solidified a lot of rumors, and meant I would likely be spending a lot more money... but it also piqued my enthusiast interest. Perhaps a reason to upgrade after all. I proceeded to ask the owner about his opinion on TD06 cores, as it's used in some hybrid units. The reaction was overwhelmingly positive. Not only did he say that the TD06 core was great, he said that at one time G-Pop suggested partner that a TD06 hybrid was in fact the way to go.
Which leads me back to the crossroads: a ball-bearing hybrid turbo or an IS38 replacement. The GTI has years of track abuse to come, but does 400whp really make sense for a FWD car? Only if we have a limited slip diff, some grippy R-comps, and get spool by 3500. Oh wait...