So my friend came to my house last night and i was checkin out his car. He has a divided manifold with a divided s372R on it, but only a single WG. He said that he doesn't think the WG elbow has a divider flange all the way up to the piston of the WG. So that means exhaust gasses can flow between the paired sections of the manifold, correct? Will this hurt spool/power, and should he have a divider all the way up to the WG piston? Thanks guys!

 

I doubt your friend will see slower spool or anything like that. Is it ideal? no i don't think so.

I would more concerned with boost creep then spool. Unless this is a 60mm gate i would find it hard to control boost on that big turbo.

I wouldn't lose sleep over the tube not being 100% divided.

 

It's a pretty big gate, i'm not sure what size it is. but it's not really a street car, it's just a car that can be driven on the street if he wants i guess, so i don't think creep is an issue for him.

 

He won't reap all the benifits of a divided manifold if it's not fully divided. It will greatly reduce the power of the pulses, but they will still be striking open valves during overlap. The manifold maker probably thought that if the outlet port of the WG was 'mixed', the inlet could be too. Some people don't see that once the exhaust pases the WG valve, the huge pressure difference means it wants to go out the outlet, not back to the other divided section. This is why a single, fully divided gate on a divided manifold works fine, like on the stock evo turbos.

Long story short, it will perform better than a regular manifold, but not nearly as well as a fully divided manifold.

 

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I ran a single 60mm last year with a divider all the way to the valve on my car and I needed to move the wastegate a little this off season and figured I would try it without a divider and I saw NO difference in spool or transient spool time on my personal car. I have more data then anyone could imagine on my turbo and it deff didnt make even a minute difference.

 

Well lets think about it: theory says that the exhaust gas would take the path of least resistance. Which is on the other side of the turbine in most cases. The only time cross-cylinder contamination would happen would be when the wg valve opens. By that time you have already used alot of the benefits of the twin scroll as far as spool goes.

I can still see why you would want to use two gates though, because some other engineers have shown a slight bump in performance with running two gates. Whether this is from a lack of pulse-collisions or not.

I was going to go with a single gate when I was running the F38, but since I switched to twin V38 they are much more compact and fit much better. So I went with two gates.