Help me size a wategate
 

I know there is a bunch of stuff on this, but hear me out.

87 S4 TII with a stock port engine. The turbo I have is a BW S362sxe with a 1.0AR. I plan on running 15 lbs of boost.

Now from what I have read, either duals or a large 50-60mm wastegate is the play. I am pretty sure I am only going to go with Tial also. Should this work with no boost creep?

I dont really want to run duals, as the manifold I have is made for a single. The unfortunate part is the manifold is undivided, but the BW turbo is divided. Should I just shell out the money and buy 2 40s and a new manifold (Hint, I dont want to).

Any opinions are welcomed!

Or buy a new exhaust housing.

Sorry no idea on the gate sizes. Maybe play around with Matchbot and see what comes up

no point running dual WG with an open manifold unless you just want to be different and add complication, and Matchbot won’t really indicate sizing either imo due to the various factors involved.

A single 50 should be fine, but worst case you might need to add some backpressure downstream in the exhaust system depending on how well the WG bias might be.

typically with an open manifold you might consider tapering the center divider in the twin-scroll turbine housing entrance as the flow hitting that flat face and resulting turbulence will effectively make the two openings smaller wrt flow efficiency. On the other hand leaving it alone might add bias to the WG. 🤔

it won’t have any issue hitting 15 psig, so yeah maybe leave the housing divider as-is.

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A single 44 will be fine. On an old set up on an FD, we had an s366 at 15lbs using a Tial 44 and boost was perfectly controlled within 0.1 bar with a 3 port mac valve and profec 2. Couldn't tell you what spring was in it though but it sounded like it started to open around 13lbs.

Same car is now running a sxe362 and has the same level of stability and control with the same gate on a greddy 60mm single gate manifold.

Just get the bigger one that fits and job done

Wow, Thanks everyone for the replies, this may be a dumb question, but should I just go and buy a cheap divided manifold? Like CX racing cheap? Its maybe better than my current manifold which is XS-Power, that came in a box of a bunch of parts.

As a temporary solution you can but it would be a waste of time and money. Hold off and buy a quality manifold once

There is no point in spending extra money to replace one cheap manifold with a different cheap manifold. Run what you have and save up for a quality piece.