V6 exhaust manifold, for spooling up faster the turbos.

Hello, I try to design the perfect manifold, to have enough back pressure and exhaust pulse.

Plenum

(3) (6)

(2) (5)

(1) (4)

Radiator

Firing order 1-4, 3-6, 2-5.

I’m converting it to Bi-Turbo, also I projected wet sleeves, pistons, short rods… I have it.

My headache, I can’t find the perfect shape (diameter, shape, length of each tunnel, blah blah) so that the turbine spins optimally. Only 3 cyl for each turbo, the exhaust manifold is located outside.

greetings from Romania. 3.0 tfsi project.

Honestly this is actually an incredibly complex topic and goes well beyond the scope of our 3D modelling course. There's plenty of literature out there on exhaust manifold design if you do want to go down that particular rabbit hole. That being said, my personal experience is that manifold design is more critical on an NA engine than a turbo engine.

The tips I'd offer for a turbo manifold that will spool well would be to keep the manifold as short as practical and en sure a proper 3-1 merge collector into the turbine housing. The other place people go wrong is to use runners that are too large. Again there's a bit of science behind runner diameter however a good place to start is with the diameter of the exhaust port. You may not be able to exactly match this with the avaialble off the shelf materials so if anything I'd use the next bigger size to ensure there's no step-down at the exhaust port.

Can you tell me the books and where I can find good studies for this?

First thing is, you won't get a "perfect" design, just "good enough" - even the F1 boys and girls have different solutions for this. Some biased towards gas velocity, some pressure.

As Andre said, a good place to start would be the port, in conjunction, maybe, with the diameter recommended for a N/A engine. Short runners will reduce heat loss, and I'd be curious if using the runner length for a N/A engine to the collector would help scavenging of the exhaust - it should help because, even though the average pressure is higher, the pressure waves should still be at least as important for the scavenging?

In practice, though, you're either going to have to make a call, or spend some time with different designs to see exactly what works best with your particular combination.

You may also find a significant difference with the charge cooler, it's not just the matrix, but the end cap designs that are important for getting an even, low restriction, transition.

Here are some books on exhaust system design.

https://www.amazon.com/Scientific-Exhaust-Systems-Engineering-Performance/dp/0837603099

https://www.amazon.com/Performance-Exhaust-Systems-Fabricate-Install/dp/1613254458/