Originally Posted by smdandb2
And when you blow it up, the repair is how much?
Thats part of the dispute/discussion here. The price to pay on replacement parts and labor.
Its funny, because I was in the VAG arena for a while. Saw lots of blown stock turbos with chips. Sure, some turbos fare better than others. But there was a fairly large amount of people replacing the stock K03s. In fact, I've done 2 on a 1.8T Passat since the guy bought it 2 years ago.
You will always have factory freaks. It happens.
We have seen turbo failures here, hell I found a thread earlier talking about premature failure running high boost on the 335s. I didnt read much into it though.
What it comes down to is, run the boost as HIGH AS YOU WANT IT. Be ready for BMW to prime their rubber penis when something fails.
I worked for APR, there were hardly any reports of blown turbos. I have also had 3 tuned 1.8Ts in the family, all with 50K+ miles of chipped "abuse." They were all fine. I have 3-4 friends with chipped 1.8Ts with mileage in the 70k+ range, they are all fine. There is not that much mention of turbos failing on vortex. There will be turbos to fail, but some will fail regardless of boost. Your guy replacing two in a year or two is doing something wrong, or maybe you are during installation. Are you replacing the feed line every time?
Regardless, APR has become a premier engineering house, and works directly with VAG/VW racing. They see fit to run those turbos that far off the map, and call them reliable. If there were a significant issue with this, it wouldn't have been done. In fact, there is not a SINGLE 1.8T tuner that lives anywhere close within the confines of the compressor map.
Finally, cost is a consideration, but with BMW stuffing the N54 in every car they make, and with aftermarket turbo solutions looming the horizon, I don't feel it will be that much of an outlay in the future to pick up some stock replacements. Hell, people already occasionally find them in perfect condition for $200 on ebay.
One other point I wanted to make, but forgot about, is that I feel the hotside is more of a bottleneck than the cold side. I think that as compressor flow nears peak mapped flow, the hotside is already a bit closer to nearing peak flow, and is negatively impacting the VE of the system. This obviously would dec the CFM the compressor would need to flow at higher PRs in relation to the math above as preturbine pressures (even post turbine pressures in cars with stock DPs) increase, especially in the 6k+ region.