External gates usually have a wider range of adjustability. For instance, range on an external may be from 10 lbs. to 30 lbs. of boost, whereas the internal may only cover 12-22lbs.
You only need an external wastegate if the exhaust housing that you need to run does not come with an internal gate. There are a LOT of people making a lot of power with internal gates.
The external gate is a thing of the past now that the internal gates have larger pucks.
External gates are much better for bleeding down boost. HP has nothing to do with what gate you need. Not sure why people reference wastegates off HP. You can run 2000hp with a deltagate as long as your not trying to bleed off any boost....
In theory, according to Corky Bell in "Maximum Boost", the external gate will always have an advantage since the internal gate causes turbulence right at the turbine wheel where the exhaust is bled off, and more turbulence right after the turbine where the flows recombine. This assumes the external gate is installed well before the turbo and the bypass flow plumbed back in well past the turbo. Course, he never quite gives a HP difference example on this theoretical difference .
Originally posted by JZ 97 SS 1500 External gates are much better for bleeding down boost. HP has nothing to do with what gate you need. Not sure why people reference wastegates off HP. You can run 2000hp with a deltagate as long as your not trying to bleed off any boost....