I've read enough to give me a headache for the evening and searched without a solid answer. Getting ready to fab up a couple of manifolds for the H22. Both top mounts. One for a twin scroll .94 housing and an undivided 1.10 housing.

Trying to decide on primary diameter. 1.5" schedule 10 seems small but 2" schedule 10 seems large.

Looking for 600whp at or below 9500 rpms.

Currently made 450@17psi on an undivided manifold and and a TS .94 housing.

I'm open to any and all opinions. Hell flaming is fine too...

 

there's cars out there making 1000+whp with 1.5" sch 10

 

What ever size mates up to the exhaust port once oval shape is the best size. It's 1 7/8" tube but I have no idea what it is in schedule pipe size beings I've never use pipe for my manifolds.

 

While I'm sure this is true, how efficient is it. There are also cars making 800+ HP on stock cams, we both know there is a large deficiency here.

I'm not necessarily stuck on schd pipe but 321 is expensive...

I'm just curious if anyone has ran 2" on larger displacement Hondas...

 

1.5" schedule 10 is the nominal size. Actual size is about the same as a 1 7/8" tube. A lot more than hp# plays into runner diameter, even fuel type and runner length play a big deal as well as the obvious things like cam, turbine wheel/housing. General concensus is that 1 7/8 is actually too big of a runner for what you are doing but it's an acceptable loss due to convenience and still obviously performs adequately.

 

1 7/8 is actually almost .200 larger ID than 1.5 pipe.

I'm definitely not a fluid/thermal dynamics engineer... but I do understand exhaust velocity/heat transfer/ turbine and post turbine size all has to be taken into account.

My primary length will be roughly 16-18" in length all as equal as possible.

Anything else that could or should be taken into account?

 

i believe the ID of 1.5" schedule 10 pipe is 1.68". just heavy stuff, we never use it.

 

1 7/8 tube ID is 1.745 for .065 w/t and 1.685 for .095 w/t...so it's definitely not .200...depending on wall thickness it could be smaller than 1.5 schedule 10 pipe (.120+ w/t) the most common is .065 wall and it's only ~.060 bigger.

 

You will have no problem with 600whp on 1.5"

I use 1.25" for applications up to 400hp on a 4 cylinder.