Quote:
Originally Posted by civicdrivr
Question though - I'm not well versed when it comes to turbos, what's the difference between internally and externally wastegated turbos? Which is better?
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OEM Turbochargers are, in general, internally wastegated to bleed off boost pressure into the exhaust. It is easier to package that way, and is quieter.
External wastegates became popular because many aftermarket turbochargers simply use an OEM or off the shelf exhaust housing, and the internal wastegate wasn't large enough to keep up with the higher boost of larger compressor wheels that were fit. It would overpower the small wastegates, and boost creep would come into play. The solution was to simply move that to an external wastegate setup.
There is, of course, another solution - make a larger exhaust housing with larger wastegate. However, that solution requires somebody to actually cast and mill the housings themselves. To toot our own horn, and to be also totally blunt about it, we are one of the few that make our own exhaust and compressor housings. Thus we haven't gone down the external wastegate path - if there were boost creep issues, we'd engineer that issue out on the exhaust housings. That's why our AVO380's are running just fine at 30psi on diesel racing trucks on an internal wastegate setup.
But lets be realistic here - a 12:1 compression 2.0-liter engine isn't going to run 30psi, other than on very exotic builds. 5-10psi is likely the limit on a "street" build that's both daily driver friendly and reliable. At those psi/boost levels internal vs. external wastegating is not much of an issue.