Exhaust gas velocity

[PanzerSD]

Would lengthening the distance from the manifold to the turbocharger (or equal length custom headers help increase the vlocity of the exhaust gasses before they reach the impeller?

It would slow it down.

[Matt L]

Given equal discharges from the engine and equal turbochargers, the velocity is directly related to the heat of the exhaust. More distance means more heat loss and lower velocity. Also lower exhaust energy at the turbine, which is no coincidence.

To increase the exhaust energy, insulate your manifold to keep the heat from escaping.

Originally Posted by Matt L

To increase the exhaust energy, insulate your manifold to keep the heat from escaping.

Thats a good way to crack the manifold too.

[Matt L]

Originally Posted by ForcedInduction

Thats a good way to crack the manifold too.

Yes it is. I was about to add the text, "If the manifold can take it," but didn't.

[Mustang_man298]

Originally Posted by Matt L

Given equal discharges from the engine and equal turbochargers, the velocity is directly related to the heat of the exhaust. More distance means more heat loss and lower velocity. Also lower exhaust energy at the turbine, which is no coincidence.

To increase the exhaust energy, insulate your manifold to keep the heat from escaping.

I do agree with the cooling causing a loss, also, a longer pipe creates more backpressure in the system, which hinders power. I don't know about heat wrapping a pipe going into a turbo, those bearings are sensitive as it is to heat being the harsh environment they are already in.
Now, I could possibly see some benefit in a creatively designed venturi type setup, use an oversized pipe off the engine and reduce it to normal size just entering the turbo, gas flows faster thru the smaller opening to maintain equal flow. Starting with an oversize pipe to a normal size also prevents creating excessive restriction.

[Matt L]

The only venturi shape that does any good is that which is in the turbine. Putting a small but fast stream into the turbine will not help.

Originally Posted by Matt L

The only venturi shape that does any good is that which is in the turbine. Putting a small but fast stream into the turbine will not help.

Are you sure? That's what happens every time my turbo's vanes are closed, low volume but high velocity.

[Matt L]

Originally Posted by ForcedInduction

Are you sure? That's what happens every time my turbo's vanes are closed, low volume but high velocity.

That's a good point. I'm a lot less sure now.

But your vanes will open under high-volume use, which is what you want. Restricting the exhaust under all conditions can't really be good, can it?

No, it will cause high exhaust pressure which will reduce engine power from higher pumping losses.

There is one good way to increase the velocity on the T3. Change the turbine housing from the stock 0.48 A/R to a 0.36 A/R housing used on some VW 1.6L diesels.

[PanzerSD]

I just thought that by allowing the exhaust gasses to move further before they hit the impeller would allow the gases also to gain momentum by having another ignition cycle pushing it along...I'm not an engineer

and there would be no restrictions so gasses wouldn't really build up much

[Cervan]

Originally Posted by PanzerSD

I just thought that by allowing the exhaust gasses to move further before they hit the impeller would allow the gases also to gain momentum by having another ignition cycle pushing it along...I'm not an engineer

and there would be no restrictions so gasses wouldn't really build up much

you could compound turbos and solve the turbo spool up time problem.

Probably the best way to maintain exhaust velocity would be to attach 5 tiny turbos directly to the exhaust port.

[PanzerSD]

Originally Posted by ForcedInduction

Probably the best way to maintain exhaust velocity would be to attach 5 tiny turbos directly to the exhaust port.

If one were to actually DO that would the benefit be power or efficiency?
not taking into account the cost of actually doing it.
Also that would be the most wicked noise 5 turbos spooling up!

[Matt L]

Or six of them, in my case. That's a tiny unit. I like it.