There’s a lot to think about with wastegates. Here’s a collection of some observations and thoughts about available options.
Size: so these things come in a lot of different sizes. Typically, the smaller the gate, the faster it is to react and the easier it is to control boost. A lot of setups can get away with a 38mm wastegate. The setups that run very large turbos without a lot of boost need more gate. Manifolds with more questionable gate routing also typically need more gate (sometimes in number of gates) to achieve boost targets.
Mounting, 2-bolt, v-band, 3-bolt or 4 bolt. Why are there so many variants!? I don’t know. I think some of these (3 and 4 bolt) are legacy and JDM manufacturers love making that stuff. 2 bolt and v-band make up the bulk of what people use in the real world. Some v-bands are low-quality and have various issues. If using bolts, use nice hardware with copper lock nuts, otherwise this is likely to rattle out.
So knockoff wastegates are very cheap. Nice ones aren’t. The knock off TiAL and Turbosmart mostly function effectively, but they aren’t perfect.
Cheap gates typically have the issue of all their hardware rattling out. The fast moving stuff does fall all the way out, but all of it seems to loosen up. Rebuilding the whole thing with red loctite is a functional option. Buying a product that isn’t the outcome of some blatant copyright infringement also works.
TiAL, Turbosmart and Precision wastegates don’t rattle apart. These are some of the biggest players in the game. Precision’s entry is a bit of a late entrant. But it works, doesn’t rattle apart. I’m sure there are some other good wastegates that hold together without loctite, but don’t expect them to be cheap.
There are some exciting gates on the market too, Turbosmart and TiAL have some uniqe gates compared to the tradition of the form factor seen in the three gates above. The TiAL aircooled gate is awesome. But it’s substantially taller than a their standard 38mm vband gate. Keep in mind fitment constraints if considering something like this.
The Turbosmart electronic gates are also very exciting. Keep in mind these need a controller capable of dealing with them.
Gates that skip full mention bc there’s something wrong with them in price: HKS, Greddy. Turbonetics gate is a rebranded Precision. Synapse uses an alternative to a traditional diaphragm and there are mixed results with boost control outcomes.
Just as important as the wastegate are the lines attached to it. Wastegate line failures typically lead to overboosting, sometimes by massive figures, and all the failures that can come from that. Aside from just keeping your wastegate lines away from heat, one very effective strategy is to use the air-brake based pushlock system that Synapse appropriates for their ‘Boost-Connect’ product line. They have an entire section dedicated to heat-capable products which are perfect for using for boost control.