Adding a Turbo

But Richard didn't blow his up for the hour he had it on the dyno or whatever.

It makes me wonder, though, how gonzo cheap could you go with the relatively-stock junkyard motor?

Slap a few thick head gaskets on it to drop compression dramatically so your timing could still be reasonably advanced. Don't use aftercoolers. Save a few more bucks.

 

No, you have to look at his material. He isn't careless, and it obviously takes some time and effort, but 1000hp is more easily achieved with turbocharging than with any other means, and puts less stress on the engine to NET 1000hp than supercharging does.

 

Turbocharging, due to the fact that it just wastegates-off less exhaust to make more airflow happen through the compressor, can tolerate very badly-designed exhaust systems and still make power.

However, bad exhaust design still costs wasted power and efficiency, as do poorly-designed cheap turbos.


What an exhaust turbine thrives on is two things, given the same density of the gas at no additional pressure: Exhaust stream heat (not temperature) and exhaust stream SPEED.

What crummy exhaust flow does to a turbo system is threefold:
A) below wastegate-activation threshold, it slows turbo response, adding turbo lag
B) AT your wastegate setpoint, it bleeds off exhaust at a lower power level because it is not comparing boost versus exhaust backpressure, it's just measuring intake air pressure
C) bad scavenging, so reduced cylinder fill by the intake air charge.

Some of the dynamics of the exhaust flow are altered by the higher backpressures than on a non-turbocharged exhaust.

The higher pressure raises the resonant frequency of the exhaust pulse, even as the speed of sound is higher at lower altitudes and greater pressures. This causes it to be the case that for the same "tuning RPM" you need longer exhaust primary tubes to find peak efficiency.

What the older F1 engines used on their 10,000+RPM engines was extremely long exhaust primary tubes leading to the turbocharger. This is on engines where a short primary tube is supposedly better, due to their high RPM.

So, even though we "get away with" ridiculously badly-designed exhaust plumbing on turbo cars, it isn't free. Power and efficiency are being sacrificed, most often for budget and packaging.

Industrial diesel engines have among the worst exhaust manifold designs on Earth. A log with one hole per cylinder. It is hard to imagine a worse design, and as Richard Holdener's video proves, a less-efficient design, even though the Holley cast manifolds were a bit more free-flowing than the "knotty log" design of many diesel engines.

In short, you can get away with worse exhaust plumbing on a turbo car and still kludge your way to power, but for maximum power and efficiency, well-designed headers are better than cheap manifolds.