Engine Designer Docs

Engine Designer is a convenient tool for engine builders to explore the performance potential of various engine design parameters.

Getting Started

To get a quick understanding of how to use Engine Designer to configure an engine design:

Click the Calculator button near the upper left corner of the screen.

The default values for a 350 cubic inch racing engine are loaded if any of the data fields are empty.

 Notice in the System Notes window, that you have been notified of any empty field that was filled; in this case all of the fields were empty, so they all were filled.

Click the Calculator button near the upper left corner of the screen again, now the notifications of automatically filled fields are cleared and only design related notices will appear in the System Notes window.

The following notice appears in the System Notes window:

"The Intake Port Choke Flow is 98.9 % of the Throat Flow; if possible, try to increase the Intake Port Choke Area."

This notice points out that the flow through the Choke area of the intake port is a limiting factor in the current design.

Notice the current performance results in the Results area in the lower right part of the screen.

Change Choke Width to 1.2 and then Click the Calculator button again.

Notice the System Notes window is now empty and the engine performance is improved.

Colored Data Fields

Notice the data fields are different colors; While, Light Purple, Silver, and Light Yellow. If you do not see these colors and have normal color vision, check the Background Color settings on your Desk Top settings as this has been reported to hide some field coloring.

If you need a quick reminder of the purpose of the field colors; hover your mouse over the four color icons near the upper left corner of the screen, a pop-up message will give you a reminder.

White

White fields require user input, the values in the white fields do influence performance reported in the Results area.

Silver

Silver fields do not accept user input, they report the results of calculations. In some cases the results are simple math calculations such as Displacement; other silver fields such as HP and VE are solved through more complex converging solver based processes.

Light Purple

The light purple fields do not accept user input. These fields provide suggestions based on collections of formula that have proven to accurately predict a safe or optimum value for a combination of physics based rules and real performance data records. 

Light Yellow

Yellow fields require user input, however this data is not used to calculate Horsepower Torque or Volumetric Efficiency. These fields will influence other silver (calculation) and light purple (suggestion) fields.

Data Fields

Environment

Fuel: Specifies the fuel used

Short Block

Layout: Specifies whether the block configuration is in-line "L" or "V" as in V8.

Cylinders: Specifies the quantity of cylinders

Bore: Specifies the Bore Diameter

Stroke: Specifies the Stroke (piston travel)

Rod Length: The center to center distance of the connecting rod

Rod / Stroke: Returns the Calculated Rod Length to Stroke Ratio

Displacement: Returns the Displacement of all cylinders

Piston Max: Returns the maximum piston velocity based on a suggested RPM limit. (See RPM Limit)

RPM Limit: Returns a suggested maximum engine speed

Cylinder Head

Valve Layout: Specifies the number of valves and the angle of wedge chambers.
Note: Valve angle does not currently effect power estimates but is used to validate that a planned valve to bore size is reasonable.

Compression Ratio: Standard Usage

CR Dynamic: Returns the calculated dynamic compression ratio considering valve timing and volumetric efficiency.

Camshaft

Cam Type: Specifies the follower type

Duration In @ 0.050: Specifies the duration of intake valve opening above 0.050 lift

Valve Lift In: Returns a suggested intake valve lift

Lobe Center In: Returns a suggested intake lobe center

Duration Ex @ 0.050: Specifies the duration of exhaust valve opening above 0.050 lift

Valve Lift Ex: Returns a suggested exhaust valve lift

Lobe Center Ex: Returns a suggested exhaust lobe center

Intake Port

Valve Dia In: Specifies the Intake Valve Diameter

Valve Stem Dia In: Specifies the Intake Valve Stem Diameter

Throat Dia: Specifies the Throat Diameter near the Intake Seat

Throat CSA: Returns the calculated cross section at the throat.

Throat Velocity 28": Specifies the average speed of air flowing through the throat at max lift.
Note: this value generally is between 300 and 315 for high performance engines with well developed ports. 

Port Flow CFM: Returns the calculated intake port flow.

Port Has Choke: Specifies whether or not the port has a restricted area upstream from the valve seat such as a most push rod engines have near the intake port opening.

Choke Height: Specifies the height of the port in the choke area

Choke Width: Specifies the width of the choke area.

Choke Radius: Specifies the corner radius of the port in the choke area.

Choke CSA: Returns the calculated area at the choke area.

Choke Velocity: Specifies the average velocity of air through the choke area.
Note: This value will be 350 or less in most pushrod engines.

Choke CFM: Returns the calculated CFM of the choke area.
Note:If the Choke CFM is less than the Port CFM the smaller value is used for Port CFM.

Intake Manifold

Type: Specifies the manifold configuration.

Flow with Runner%: Specifies the percent that the cylinder head flow increases or decreases when flowed with the manifold attached.

Runner Turn: Specifies the amount that the runner (excluding the turn in the valve area) turns in degrees.

Fuel Dist Rating: Specifies the quality of the fuel distribution, For example an EFI is a 10 and a typical crossram would be a 0.

Manifold Air Temp: Specifies the manifold Air Temperature. This value is used to calculate the optimum length of the runner. At this release, this value does not effect power calculations.

Optimum Length: Returns the reccommended optimum length for the complete intake tract.

Total Throttle CFM: Specifies the actual throttle CFM at 1.5 hg.

Vacuum: Returns the calculated manifold vacuum at peak HP

Throttle VE: Returns the Volumetric Efficiency of the throttle. A value lower than 95 suggests a larger throttle is needed.

Runner Max CSA: Returns a suggested maximum cross section area for the runner at its opening to the plenum.

Plenum Helmholtz: Returns the calculated Helmholtz Resonator volume for the plenum.

Minimum: Returns the suggested minimum plenum volume.

Maximum: Returns the suggested maximum plenum volume.

Taper Included: Specifies the runner taper from the valve seat or choke area (if it has one) to the runner opening.
Note: This value does not effect the performance values in this version. Reasonable values in this area around 4 degrees included.
This value does effect the calculated areas and volumes for the manifold.

Manifold Design Parameters:

Length: Returns the calculated length for an intake tract including the cylinder head port and manifold of the particular design specified in the rows below.

Max CSA: Returns the calculated runner opening area

Volume: Returns the estimated intake tract volume.

Plenum Helmholtz: Returns the plenum volume for a Helmholtz based design.

Helmholtz: Returns on this row provide the calculated values for a manifold designed to capitalize on Helmholtz Resonator theory.
Note: The available literature on this approach is not particularly complete or precise, consider this design theory to be experimental rather than proven.

2nd~5th Harmonic: Returns on these rows provide the calculated values for a manifold designed to capitalize on harmonic resonance. 2nd harmonic designs generally return the best performance followed by 3rd. The benefits of the 4th and 5th harmonics is minimal.

Exhaust Port

Note: None of the exhaust port values effect the the performance results. They are used to calculate reccommended dimensions.

Valve Stem Dia: Specifies the valve stem diameter

Percent Intake Flow: Specifies the percentage that the exhaust port flows relative to the intake. In this version, this value does not effect performance estimates. Values of 70 to 75% are commonly used in this field. Reference benchmark heads used in engines similar to your application as a guide for this value.

Bench Flow @28: Returns the calculated exhaust port flow.

Throat Velocity: Specifies the velocity in the exhaust port. 435 is commonly used in this field.

Throat CSA: Returns the calculated area at the valve seat. This does consider the valve stem.

Throat Dia:  Returns a reccommended throat diameter.

Valve Dia: Returns a reccommended valve diameter.

Exit Velocity: Specifies the air speed at the port exit.

Header

Exhaust Temp: Specifies the exhaust temperature. This value is used to calculate the optimum length of the header.

Inside Diameter: Returns the reccommended inside diameter of the header tube.

Port Length: Specifies the length of the exhaust port. This dimension is used as part of the head length calculation.

Tube Length:  Returns the reccommended header tube length.

Collector Dia: Returns the reccommended header collecotor diameter.

Weather Correction

Note these fields do effect the performance reported in the Results section.

Results

Max HP: Returns the calculated maximum Horsepower

RPM of Max HP: Returns the calculated RPM of Maximum Horsepower

VE at Max HP: Returns the Volumetric Efficiency at Maximum Horsepower