Intake manifolds for a Turbo engine. For more airflow, a higher flowing carb, intake, heads (ports and valves) and exhaust system is beneficial. Supercharging will increase power on a stock engine, but increasing the airflow capability of the engine will bring your blown engine to its full potential.
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Overview
A15 Turbo using factory Twin Hitachi sidedraft manifold
Stock manifold with carburetor hat -- see #Top-hatted Carburetor
Log Manifolds
Log manifolds can either be fed by an EFI throttle body or by a sidedraft carburetor.
clyon's A-series Turbo Manifolds
This kind of stock manifold-runner is limited in horsepower. The turbo can force more air through it (for more HP) but the air temp will escalate, limiting the power to be made.
Tuned Runner Length
For scavenge effect at 5000 RPM, the runners should be 20" long!
Stock Manifold
Blow-through systems can use the stock Intake Manifold.
Stock manifold with carburetor hat
Stock manifold with EFI throttle body
Top-hatted Carburetor
Feeding the carburetor via a top hat was a popular OEM method. phunkdotaspok say the stock Hitachi can handle 10 psi with a good top-gasket seal. In an NA application, a warped top is not a problem, as there is no pressure in the float chamber. This only becomes important in boosted application.
Blow-through system feeding carb top-hat
Weber 32/36 Carburetor with custom top hat
downdraft Dellorto carburetor on custom manifold
Boxed Carburetor
Boxing the carb allows a more or less stock carb to be used, the outside pressure balancing the inside pressure. Special non-crushable fuel floats are needed.