Why to manufacturers make Intake Manifolds out of Plastic instead of Aluminum?

Answer 1

Dear Manifold-

They have started doing this for two reasons.

First is engine weight. They are trying to meet the new EPA Fuel Regulations where automanufacturers get $$$$ for their as many of their cars as possible meeting or beating the new 25 MPG Standards.

Reducing the weight in the vehicles means the engine does not have to work as hard to make the same amount of power go further and use less fuel.

The cost of manufacture is another angle, but a minimal one. The fact is that you can better control the casting abilities of plastic. Keep in mind that this is not just your ordinary plastic either. Most of the intake manifolds are made from a material called Zytel or Lexan.

Both of these materials are used in the manufacture of Bullet Proof Glass. These plastics are extremely hard, but flexable enough to allow them to be used in such applications as your engine's intake manifold.

It will never be used on the exhaust side of the engine, or in engines where the intake and exhaust ports are located on the same side of the cylinder head. This is because it cannot withstand the intense heat from the exhaust gasses that are coming out of the exhaust port at about 1200F degrees.

These intake manifolds are also very smooth inside allowing the air to better flow into the engine. Just for the record, this technology was not started with the common automotive type car that you are driving.

Plastic intake manifolds have been used on many racing circuits for a number of years now for the same reason. Reducing the weight on the Race Cars so they go faster more efficently.

These have been in use on the Grand Prix Circuit for about 10 years now with excellent results. I also see this technology coming to NASCAR in the very near future too.

In fact most of today's technology that is adopted by the automanufacturers is first tested and researched out on the race tracks to see how it will perform under extremely abusive conditions. That is one reason that there are so many different cars on the tracks, some of those vehicles are research cars that have equipment on them having a look at how parts are going to possibly function in the real world.

Anyhow, I hope that answers your question.

Answer 2

Personally, they are less expensive to produce eventually they warp and leak vacuum or water in the crossover passage.

All car manufactures are being murdered by this symptom. If you look at a pure performance angle, it's much easier to blow a a perfect symmetrical intake shape that's smoother inside and out. Take a look at a few that have gentle rounded sweeping intake runners to increase the distance from the throttle body to the intake valve. If you remember the old Weiand Ram Log intake manifold it had super long runners from the carburetor to the valves. It made wicked power at a relatively high RPM band. At low RPM'S it was awful. Somewhere along the line someone came up with small individual long intake runners to increase air velocity and even distribution of the air entering the combustion chamber. It's a win win situation except that the material is crappy. Soon they will come up with a better plastic.

Answer 3

Aluminum cost a lot to refine and plastic is cheaper, lighter and will not corrode.

Answer 4

cuz plastic is cheaper than aluminum and plastics wears quicker so you have to buy more they make the huge profit

Answer 5

plain and simple, costs....its cheaper but not better.