Here is some information about the composition of this manifold.
Physical Properties
The density of 304 stainless steel, or the mass per unit volume, is .29 pounds per cubic inch or 8,060 kilograms per cubic meter. It has a specific heat, which measures heat absorption, of 503 Joules per kilogram kelvin. It has a melting point of 2,550 degrees Fahrenheit or 1,400 degrees Celsius.
Then compare against this document.
Turbocharger for an exhaust temperature of 1050°C
The turbocharger is also becoming more and more accepted in connection with the gasoline engine. The advanced charging technique will cause the percentage of turbocharged vehicles to steadily increase. The exhaust temperatures of future turbocharged gasoline engines will increase. The air ratio ? at the rated output point is currently about ?=0.75–0.85 since a portion of the fuel is used to cool the inside of the engine. If the air ratio is increased to a value between ?=0.9-1.0, then a potential fuel savings of up to 20% can be attained. However, this leads to an increase in the exhaust temperature of up to 1050°C/1992 F and places new demands on the turbocharger, among other things
This for the T321:
PHYSICAL PROPERTIES
Melting Point
Density 2550-2635° F
1398-1446° C
You also have this:
Why it might be chosen instead of 321
Grade 310
The temperature of the operating environment is up to about 1100°C - too high for 321 or 321H.
Finally this:
The advantage and disadvantage of cast steel.
One of the advantages of cast steel is the design flexibility, the designer of the casting have the greatest freedom of design choices, especially the complex shape and hollow cross-section parts.
Cast steel has the metallurgy manufacturing flexibility and strongest variability, you can choose a different chemical composition and control, adapted to the various requirements of different projects. By different heat treatment choice in the larger context of the mechanical properties and performance, and good weldability and workability.
Cast steel is a kind of isotropic material and can be made into the overall structural strength steel castings, thereby improving the reliability of the project. Coupled with the design and weight the advantages of short delivery time, price and economy has a competitive advantage.
The weight range of steel castings is larger. Little weight can be only a few dozen grams of molten mold precision castings, and the weight of large steel castings up to several tons, dozens of tons or hundreds of tons.
Steel castings can be used for a variety of working conditions, and its mechanical properties superior to any other casting alloys, and a variety of high-alloy steel for special purposes. To withstand high tensile stress or dynamic load of components, it is important pressure vessel castings in low or high temperature by the large and important part load key parts, in principle, should give priority to steel castings.
However, the cast steel has comparatively bad shake-suction, wear resistance, mobility and the casting performance are compared bad with cast iron, moreover, the costs are higher than normal cast iron.
Therefore, for cast iron vs cast steel, they have their own advantages and disadvantages, you should choose it according to your application and their physical properties.