What exactly is a wastegate? Sounds like something that would release air pressure or something, but not sure.
Its a device mounted on the turbo that allows a certain amount of boost to be built before it opens up and bleeds off pressure. Allowing only a preset PSI to be reached everytime a hard pull is made.
Usually not from the factory, but you can get adjustable wastegates after market and you can sometimes modify the factory models (though often without much "fine control").
Many people with modded diesels just remove the wastegate activation system, so it is shut all the time, although this can be problematic down the road because of constant overboost situations.
Yeah, when people start messing with the WG on relatively stock motors, you start hearing about blown head gaskets and such pretty often. Mostly an issue for the Cummins guys after they o-ring the head or something and they want run up the boost. But small increases are often safe, and the DMax (not sure about the PSD?) has show that some pretty decent increases are usually relatively safe (notice all the qualifiers?) even on a stock motor, but it is chancy, especially if your doing it the "home mod" way rather than something like a Banks Big Head with a fine control screw.
O-ringing the head or block would allow for more boost with less concern about head gasket issues. At least that is what is gonna allow me to run 65psi of boost on the 5.9 after I get the block o-ringed.
Agreed, that's exactly what I meant. I'm guessing you misunderstood my use of "issue" (probably a bad choice of words), or maybe your just agreeing? What I intended by "issue" is that the the WG is something Cummins guys want to muck with or disable after an o-ring/stud mod, but most of the rest of us should be very careful when considering changes to the WG.
Ohhhhhhh, gotcha. I misread it I guess. Yea, for relatively stock blocks, heads, and headgaskets, increasing boost beyond a very reasonable amount is definitely asking for trouble.
A WG is more to keep a turbo from overspeeding rather than keeping it from overboosting. Back in the earlier days of turbocharging diesels, turbos were large, inefficient, and spun relatively slowly. These large, slow spinning turbos resulted in lots of lag before spool up which hurt performance a lot on engines that only have maybe a 2-3000 rpm power range. The solution was to use smaller turbos that spooled up much quicker, but also pushed a large amount of air due to advances in shape and materials. The downside of this was the turbos could easily overspeed, thus, wastegates were added to keep the speed down to a safe level. So, on diesel engines, wastegates are employed so that a small, responsive turbo can be used while keeping the turbo in its efficiency range and keep it from flying apart. waytogo
Wastegates dump exhaust out of the turbine housing and have nothing to do with the compressor side.......by controlling the flow of exhaust to the turbine with the wastegate, you can control it's speed. When running at higher boost levels, wastegates often are not as effective at controlling boost quickly enough, so blow off valves are used on the compressor side, usually down stream from the compressor itself, to quickly limit peak boost or spikes or surges. When running reasonable levels of timing, CTD head gaskets are typically good for 50-55 psi of boost.....My 94 peaks at 46 psi without any problems.
This is correct, I don't think I said anywhere about the compressor having anything to do with the WG :dunno:
