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    Producing Quality Computer Tools for Racers and Engine Builders since 1986






Exhaust System

What is our definition of the Exhaust System?

For the purpose of this definition, we are talking about how our Engine Analyzer programs use Exhaust System specifications. This means everything from the exhaust valve to the tail pipe.

Our Engine Analyzer programs perform Engine Simulation so you can change specifications of an engine without actually purchasing the parts and putting your engine on a dyno.

The exhaust system effects the engine's performance in 2 ways:

First, the exhaust system is a restriction on the air flow (in this case, hot exhaust flow) through the engine.  Therefore, anything which can reduce this restriction generally helps performance.  That is why race motors typically have no mufflers.

Second, by designing the exhaust system correctly, you can take advantage of the pressure pulses which "bounce" back and forth in the exhaust system.  When the exhaust valve first opens, there can be 500-1000 psi in the cylinder, which produces a very high pressure pulse in the exhaust port.  (This is the loud "cracks" you hear in race motors with open headers.)  This pulse travels down the exhaust runner and gets reflected as a suction pulse back up the runner to the exhaust valve.  If this suction pulse arrives at the exhaust valve as it is closing, it can suck out any remaining exhaust in the cylinder, which helps filling the cylinder on its next intake stroke.  How these pulses work to help or hurt performance depend on the exhaust runner length, diameter, engine RPM, cam timing and much more.


Exhaust Ports

Not only does our Engine Analyzer programs allow you to change the exhaust valve size and lift but Engine Analyzer v3.4 allows you to choose Flow Efficiency Percent from a table or calculate Flow Efficiency from flow bench data (up to 3 flow data points). Engine Analyzer Plus v3.4 builds on the options from Engine Analyzer basic by allowing you to input a flow curve with up to 8 valve lifts. And Engine Analyzer Pro v3.9 allows you to input up to 12 valve lifts.

Exhaust System

Our Engine simulation programs allow you to change the Exhaust Manifold(s)/Header(s) and the flow rate of the catalytic converter(s) and muffler(s) to estimate changes in performance.  This is done as our Engine Analyzer programs use algorithms that simulate the Wave Tuning for the Exhaust Tract.

Programs that take Exhaust System Specs into account

We have 3 programs that take the exhaust system into account when conducting Engine Simulation:   Engine Analyzer v3.4, Engine Analyzer Plus v3.4, and Engine Analyzer Pro v3.9.

Our Port Flow Analyzer v3.5 program can be used to figure out the Flow Capability and Flow Efficiency of the exhaust valve and port.

We have another program which lets you record data about the exhaust system, the Engine Log Book v1.1.