I'm in need of a wastegate. I'm going to use a 14b (TD05H) on a D16z6 and shoot for 200whp. Maybe 8 psi or so? I need an external wastegate. I read this:

Wastegate sizing-
One of the more popular misconceptions about wastegate sizing is; the more powerful the engine, the bigger the wastegate is needed. This guide indicates the right size of wastegate:

big turbo/low boost = bigger wastegate
big turbo/high boost = smaller wastegate
small turbo/high boost = smaller wastegate
small turbo/low boost = bigger wastegate

How much of this is true? My friend said a small WG would be ideal for me. He said a 38mm should be good. What do you guys say?

 

where did you find this info?

 

That is correct information. WHich is rare these days. TiAL can testify to this information.

 

learned somthing new , howcome people who have creep issues with 44's upgrade to dual 44's then ? dont take that wrong haha i like learning new things

 

Because of poor manifold design. Well kinda. The manifold is flowing too much of the exhaust gas to the turbo and not enough flow to the wastegate to regulate boost.

 

Hmm...someone that did research and has a clue. That's rare these days. The Tial 38mm should work just fine for your setup

 

I tried explaining that idea on the Subaru forum and they would have none of it! Glad other people understand how it works.

 

my work here is almost complete!

yes, an MV-S gate would be perfect for your car

 

Good info - I found this interesting (running internal gate currently so it doesn't have any effect on my setup) and searched a bit only to find the same info on other sites.

I was under the misconception that a larger gate would expell more exhaust so you would want a larger gate at high boost. My thoughts are obviously backwards to how it should be done.

Can anyone shed some detail for how this works?
What goes wrong with a large gate at high boost?

 

you want less gas to go into the wastegate at higher boost. using a bigger gate would require more cycling of the wastegate to keep constant pressure.

 

The position of the wg is more important than size im my opinon.... you can have a huge waste gate stight off cyl 1 but it will not work as well as a small one on the collector of the manifold. I have a tial 38 on a lower 8 psi setup and it never creeps. the goal is to keep even pressure across all cylinders. I think it is actually dangerous to run a wg off one single cylinder before the collector because that cylinder will go lean in comparison to the other ones.

 

wikipedia

 

Basic principles of manifold design. That is why a ram horn is better than a log manifold. Each cylinder approximately has a similar distance to the collector thus they are more efficient. Its also a good idea to have your manifolds wraped becasue you want to keep the exhaust gas as hot as possible until it hits the turbine. It should help with your spool time and also under hood temps.

Work=(Enthalpy inlet)-(enthalpy exhaust) and that is aproximatly
1.004(Temp inlet- temp exhaust) of the turbine 1.004 is the cp of air but is not a good approx at this temp because air is essential diatomic and translational energy becomes a factor.

assuming that the turbine is adiabatic for air and I was neglecting changes in kenetic energy also.

wow that was a tangent. sorry