Not all exhaust manifolds are created equal.  In fact, they aren’t even close.  There seems to be some confusion in the industry as to which manifold is the best and where they are manufactured.   I can tell you this:  If it doesn’t say “Made in the USA”, it’s not made here and is usually made in China.  It is illegal to say “Made in the USA” if it’s not made here.  So if you have purchased an exhaust manifold that doesn’t say that, then you were taken advantage of.  The rest of this article is going to tell you how we build our exhaust manifolds and may get a little technical.

We start out by flowing a standard OEM-made overseas factory manifold on a Saenz S-600 flow bench.  Next, we flow the head to see how much air flows from it to see if the stock manifold is sufficient.  Usually it’s not enough flow for 500hp, so we design the new manifold on a computer using a computer-animated flow bench to match the flow coming from the head.  The computer allows us to simulate the cylinder pulses and measure the velocity of the exhaust.  This is why our manifolds allow the turbocharger to respond quicker to the movement of the throttle.  Once we have established a design, we then print the exhaust manifold on a 3D printer that makes a functional part out of plastic, which we use on the flow bench to confirm our findings on the computer.  Now it’s off to the foundry to make the first mold and pour the first casting.  After the cast iron has cooled down, it has to be machined and re-tested on the flow bench.  Any changes that need to be made are done at this time.  These Made in the USA manifolds are made of a high-silica moly that has the correct metal properties to ensure strength and proper elongation so the exhaust manifold can expand and contract and still hold their shape without cracking, leakage at the joints, or breaking of the mounting bolts.  Now the manifolds are ready for the heat-treating process, which lines up the molecules in the high-silica moly cast iron.  The overseas manifolds are NOT heat-treated and that is why they break bolts and studs.  After heat-treating, the manifolds are machined and then hand-ported to guarantee the exhaust is turbulence-free.  This also allows the turbo to respond quicker to the input from your right foot.  Once again, the exhaust manifold is installed on the flow bench to make sure we obtain the correct velocity and 20% or more flow than a stock manifold.  At 20% increased flow, the exhaust gas temperature will be 125 degrees lower and the fuel mileage and horsepower will increase by 5%.  The final step is the ceramic coating, which is buffed to a shine.   We are the only exhaust manifold manufacturer that can make these claims.  Remember to look for the “Made in the USA” logo on the center section of the manifold.

After 25 manifolds have been poured, a test bar of the cast iron is poured and the metal properties are checked.  A log of all of the batches of cast iron has been kept since we made our first exhaust manifold.  Nobody else in the entire world does this.  The following is a list of all of the manifolds we manufacture in the manner:

Caterpillar:  3406E, C-15, and ACERT for Peterbilt, Kenworth, Freightliner, International, and Western Star.
Cummins:  ISX EGR and EGR REPAIR for ALL trucks.  Coming Soon:  1998-2002 ISX and N-14.
Detroit:  12.7 and 14.1 liter Non-EGR and EGR for ALL trucks.
Australia ONLY:  C-13 CAT and C-15 CAT (cabover only).

 If you don’t see your manifold in this list, then we have to purchase the stock manifold, hand port it, flow test it, ceramic coat and buff it to a shine.  YES, it will flow 20% more exhaust and will also lower the EGT by 125 degrees and on the MBE 4000 Mercedes Engine, a 50 horsepower gain will be realized (most others gain 35hp).

When calling to check availability and/or price, please be sure to have the CENTER SECTION CASTING NUMBER of YOUR STOCK MANIFOLD.  This is the only foolproof way of making sure that we send you the manifold, which will hold your turbocharger at the angle that permits it to fit under your hood.  If you can’t find it, you can call your truck dealership or engine manufacturer with your VIN# or engine serial# and they can tell you your CENTER SECTION CASTING NUMBER.  This will usually be a 7 or 8-digit number. 

Written by:  Bruce C. Mallinson, Pittsburgh Power Inc., 3600 South Noah Dr., Saxonburg, PA  16056. Email: bruce@pittsburghpower.com.  Phone 724-360-4080.