Ex. manifold with plenum chamber ???

[sorens2]

Hi guys

I wan´t to try to make an exhaust manifold with a plemun chamber.
Well, where the 5 (4) runners run directly into a tube (plenum) and on the other side on this an outlet for the turbo. This is instead of the traditional with 5 tubes into a collector.

Any comments.
Bad project on a Audi 1.8 T

Søren S2

[Audi_CQ]

Why?

Isn't such a setup best on large engines running at steady speeds, like large boats?

Cheers,
Roger

[Lee]

You will take too much energy out of the gas flow (well convert it to heat anyway). Best design is to have 5 equal length pipes meeting at a single collector/turbo flange. Keep the bend radii large to conserve gas momentum.

Incidentally, most tubular manifolds I have seen have really poor wastegate port designs. Looks like most have added it as an after-thought.

[91_S2]

I think the plenum on an intake manifold is there to equalize the pressure and flows into the 5 runners.

In the EM I don't see where equilizing pressures and flows has a benefit. What you want is to maximize the kinetic energy impinging on the turbine wheel. I would think you do that by using the shortest, straightest path from the exhaust port to the turbine inlet.

What I really like about your idea is that it shows you are thinking outside the envelope.

[audiman]

Well, thats the best picture i have ever seen!! My manifold looks like the WG was an after thought, and with some turbos its hard to get the wastegate to vent enough gas. My car wont boost lower than 1.55bar

[91_S2]

My car wont boost lower than 1.55bar

Tom,

It's hard to tell whether you are complaining or bragging ;-)

[4WheelDrifter]

I agree with Lee. Most wastegate designs I have seen are far from ideal. That even includes some Formula 1 engines and rally cars such as the S1. They do seem to be an afterthought. It sounds as if anyone who has seen Tom or Doug’s exhaust manifolds and wastegates, realise how important a smooth and free flowing design is. When cars like this are on full boost, a lot of gas passes through them. So they shouldn’t be an afterthought. A good example of exhaust manifold and wastegate integration I could find is on this Ford Focus WRC. I was very impressed. Although it shows what a p!ss take WRC is these days. But that’s another rant!

[sorens2]

It´s just that I know that some Audi teams in the 80´s greated a twin-turbo 5 cylinder using this design. I have made my own in the usual design, but this project was to make it an easy solution. It´s a lot of work to weld a manifold "the right way".
I have just seen an Alfa with a 1.5 L 4 cyl. with turbo producing 370 hp with max torque @ 4500
The design of the manifold was the worst I have ever seen, a bit like this plenum type, but working.

Søren S2

[4WheelDrifter]

The turbo relies on energy and heat to drive it. So the less loss between conbustion chamber and turbine, the better. Although this may require hard work as you say.

[Audi Parts Guru]

You will take too much energy out of the gas flow (well convert it to heat anyway). Best design is to have 5 equal length pipes meeting at a single collector/turbo flange. Keep the bend radii large to conserve gas momentum.

I think that this is the best setup that you should go for, anything else and you'll end up with inferior results

[CR500Dom]

I agree with Lee. Most wastegate designs I have seen are far from ideal. That even includes some Formula 1 engines and rally cars such as the S1. They do seem to be an afterthought. It sounds as if anyone who has seen Tom or Doug’s exhaust manifolds and wastegates, realise how important a smooth and free flowing design is. When cars like this are on full boost, a lot of gas passes through them. So they shouldn’t be an afterthought. A good example of exhaust manifold and wastegate integration I could find is on this Ford Focus WRC. I was very impressed. Although it shows what a p!ss take WRC is these days. But that’s another rant!

Erm not strictly true
Wastegate is there to relieve pressure only.
They are Clever but not to flow a lot of gas through, just to relieve pressure quickly.
And they dont impinge or upset the flow throught the main Collector either.
That picture does not represent "Current" WRC,

A well designed Cast Iron Manifold is best for Turbos.
You loose a tremendous amount of heat through a Tubular manifold, which is not good, Thats why they are Ceramic coated on WRC cars, to try and keep the heat in the pipe.
They are Lighter and quicker to make with very little tooling needed, so manufacturing is relatively flexible as the development requires through the season.
Cast iron is better though, if the design is right as it retains more heat and keeps the gas velocity up, Its also far less prone to movement and fatigue (Not a problem on a Race car)

HTH
Dom

[sorens2]

Then I guess I have to design to plenum type just to show you guys that it is possible then...

Søren S2