What are the cons if any of running a 38mm wastegate over upgrading to a 44mm or 46mm wastegate with 650+hp? Debating if it's really going to be necessary to upgrade from what we'v already got.

 

im not a pro or have all the answers, but i do know that you will have boost creep

i have a 1bar(14.7psi) 38mm wastegate and it creeps to 20psi, cant keep up with the air flow

i will be upgrading my wastegate or increasing the spring on my new build

 

From what I understand there is no downside IF the 38 can support the system and boost level. Turbo size and boost level determine which size gate is needed more than HP. If you have that additional information I am sure some people around here can offer some data.

 

That's POSSIBLE, but it depends upon the placement of the wastegate in relation to the collector of the manifold, the turbo size used, amount of boost used in relation to the turbo, etc. So in boostek9's case, He may have a boost creep, but the manifold may be the issue, the turbine housing size i relation to the wastegate placement, or even turbo size.

What people forget is that Bigger wastegates aren't necessarily needed when making bigger power. When you're using a large turbo with big power, you're not releasing as much exhaust gases into the dumptube because you're using the turbo in its efficiency range. Larger gates are used for Bigger turbochargers that are UNDER the turbo's efficiency range. This means that A T67 running only 12-14psi would need a larger wastegate 44mm because the turbo has to bleed off a lot of excess pressure to run the desired amount of boost.

So.. quick rule of thumb.

Big turbo + Big Boost (most of the time) = smaller wastegate or even twin wastegates if divided by the collector

Big turbo (35R size and >) + lower boost level = Larger wastegate

Small turbo + high boost = 38mm gate (typically)

Small turbo lower boost = 38mm gate

So, check your manifold, turbo, and pressure you tend to use it for. "Street/strip" People need to generally go slightly larger because they are using BIG turbos for both the track and the street on a regular basis.

 

topmount Manifold was built by me, just havnt welded the wg flange yet cause we were undeecided which one to run, and as far as turbo we will be running it's a precision sc6265. So what you're saying is the tial 38 will be fine?

 

Run the 44, odds of getting boost creep with a single 38 and that turbo are pretty good.

 

How much boost you plan on running?