Build Turbo Kits

Learn How To Build Turbo Kits

Chapter 5 - Turbocharger Manifolds etc. - The Hot Side

The Hot Side

The hot side of a turbocharger system refers to any headers, manifolds, tubing and flanges that feed the turbine side of the turbocharger, and the exhaust system exiting the turbocharger.

Headers/Manifold

Headers for turbocharger systems range from stock manifolds to custom tubular style manifolds and everything in between. Let’s take a look at the pros and cons of different types of headers and manifolds available for turbocharger systems.

Stock Manifolds

Stock manifolds offer a low cost solution to turbocharging your vehicle. Most well enough to provide turbochargers with enough energy to create a lot of horsepower. No extra cost is involved when using the stock headers, and labor is reduced because they do not have to be removed and replaced during a turbocharger installation.

The down side of using the stock manifolds is that they may exit the rear of the engine, or route away from prime turbocharger mounting locations. Unless you are installing a rear mounted system, tubing will need to bend up to 180 degrees to reach the turbocharger(s) near the front of the engine. The bends will cause restrictions, and ground clearance problems, not to mention a few feet of pipe will exist between the headers and turbocharger. In some applications, the tubing will need to be routed under the K-member, reducing ground clearance.

Hot side tubing for stock manifolds. Not the 180° bends in the tubing.

Photo courtesy of Nick Nagrodsky aka ddnspider.

See more of Nick’s Trans Am build at http://my.fit.edu/~nnagrods/mp/

Log Style Manifold

A log manifold has all exhaust ports exiting into a single pipe. The pipe has a turbo flange attached to it where the turbocharger bolts on. On a single turbocharger system, the log manifold is bolted onto one head, while a stock header is bolted to the other. A crossover pipe connects the stock header to the log manifold so that both banks feed the turbo. Two log manifolds are used in a twin turbocharger system.

Turbocharger log style manifold.

A log style manifold, like stock manifolds can produce a lot of horsepower. They are generally cheaper than tubular style manifolds, but do not flow as well. One of the major drawbacks of the log style manifold is that a lot of back pressure is built up due to all exhaust ports feeding into the single channel. This is why the log style manifold is more prone to cracking than true headers.

Tubular Headers

For big horsepower. And great looks to boot, tubular headers are by far the best route to go if money is no object. Tubular headers will support almost unlimited horsepower. Custom tubular headers are built to fit your application and generally have no fitment issues. Most kit manufacturers provide tubular headers with their kits.

The only drawback to tubular style headers is the cost. The headers are usually hand fabricated from stainless steel. If you are building a high horsepower application, tubular headers are worth the price.

Custom tubular headers and downpipe. Photo courtesy of 1INSANEGTO.

Downpipe

The downpipe connects to the turbine housing at the exducer. The downpipe merges into the exhaust system and into to the catalytic converter(s) and muffler(s) if installed.

There are different types of turbine flanges that connect the downpipe to the housing. The most popular being the V-band type. The V-band includes a clamp and a flange. The flange is welded onto the downpipe, then clamped onto the turbine housing.

Some turbochargers have a bolt on type housing. The downpipe welds to the discharge flange, and the flange is bolted onto the turbine housing. Both types are shown in the pictures below.

Downpipe bolted to a turbocharger.