Ever since we ran our exhaust replacement story in the fall, we’ve been asked (and have started debating) why exhaust headers are such a good thing, given the price, installation difficulties, and maintenance they require.
So let’s talk about that.
First a quick progress update: If you are a Blast Cars reader, and you’ve followed The Shop Truck’s progress, you know that we have a long way to go in restoring our 1987 Dodge Power Ram W150 pickup truck. Right now, the truck is in the shop getting its camshaft and lifters replaced, which we’ll discuss later this month.
Your car’s engine works by mixing air and fuel with an electrical spark in combustion chambers. The resulting small explosions in the chambers cause pistons to move up and down in a specific order, which turns the crankshaft and a series of gears eventually leading to the wheels spinning.
The air comes in through the air take or air cleaner, which removes dirt and dust from the air, because you don’t want that getting into your engine. (This is where Cold Air Intakes and companies like K&N come into play. They try to get the air flowing as quickly and as unobstructedly as possible without allowing dirt inside.)
Once the engine has used the air and burned the fuel to make magic, the waste leaves the engine via the exhaust system. On most cars, the exhaust system starts with an exhaust manifold:
Exhaust manifolds connect to the engine and direct all the exhaust gases outward, through the catalytic converters, mufflers, and tailpipes.
On the plus side, exhaust manifolds are cheap (at least for the company that makes them), durable, and are made by your OEM company, so they fit perfectly and don’t require adjustments or much, if any, maintenance.
On the negative side, exhaust manifolds are cast iron, so they are extremely heavy and love to rust. They also rob engine performance by creating what’s called back pressure in your exhaust system. Back pressure is really just an air traffic jam in your exhaust system, and if you look at the manifold you’ll see why. The air from each cylinder is fed to a central pipe, but there’s only one pipe to collect the gases. With thousands of tiny explosions happening every minute, an inefficient manifold is one of the main sources of performance robbing back pressure.
This is why hot rodders and tuners love exhaust headers. Take a look:
As you can clearly see, headers, like these Hooker Competition Headers, have a dedicated pipe for each cylinder, allowing air to travel into the exhaust system more freely. This reduces back pressure, thus increasing engine performance. Some people will tell you that installing headers is one of the easiest and cheapest things you can do to add performance.
On the plus side headers increase performance and are much, much lighter than manifolds.
On the negative side, cheaper headers (“store brand” products especially) are often poorly made and fit poorly to your engine. Lighter metals will also tend to warp under the high heat generated by your engine, causing more problems with fit. Headers also require tightening/adjusting periodically, and inexpensive headers will also tend to blow gaskets — not an expensive fix, but a pain in the ass nonetheless.
As an added problem, headers are illegal in some states, like California, because they reduce the effectiveness of your catalytic converters.
So what do we do?
Well The Shop Truck is considered an antique in Massachusetts, so headers are legal, and catalytic converters are not required anyway in vehicles of a certain age.
We have another problem with our 80s beast: It has that pesky A.I.R. system that blows fresh air through the exhaust in an attempt to reduce emissions. If I want to install headers, I have to remove the system and plug the air holes in all eight cylinders. By all accounts, this is a $500 job by itself.
What would you do if you were in my shoes? Leave the manifolds? Yell YOLO and rip the A.I.R. and manifolds out? Let me know what you think below.