Blackpool Mobile Mechanics Finding the right mechanic

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September 28, 2012 by hotwheels662


Introduction

Using mathematical formula we have been asked to design a high performance engine and create a running model in GT-Power. The model will then be analyses through GT-Post to determine potential faults or problems with the design, finally the engine should be optimized and any improvements discussed. Your decisions should be viable with a written commentary of why you carried out the changes to the original model.

Technical drawings either hand-drawn or using Auto desk software should be included within the design process. Any race rules or regulations the engine is per-determined by should also be referenced.

  • Use industry standard CAE software package to design a fully functional internal combustion engine.
  • Use industry standard CAE software package to test a fully functional internal combustion engine.
  • Analyse simulation test data to identify system features and potential manufacture problems.
  •  

 

Engine Specification

 

Included below is a table listing specifications of the Zetec engine.

Bore 84.82mm
Stroke 86.07mm
Valve Lift Int 10mm
Valve Lift Exh 9.55mm
Cam Duration Int 258
Cam Duration Exh 250
ConRod Length 175mm
Compression Ratio 9.6/1
Firing order 1.3.2.4
RPM Limit 6750RPM
BHP 130BHP @ 5300RPM
Torque 135tq @ 4500RPM

Using these basic measurements a number of different formulas will be calculated to find.

  • Mps
  • Piston area
  • Port area
  • Valve radius
  • Valve area
  • Valve lift
  • Bore stroke ratio
  • Piston speed
  • Ideal intake and exhaust length.
  • Intake duct diameter

Formulae

MPS = (stroke x 2) x RPM Limit / stroke

(86.07 x 2) x 6750 / 6750

(172.14) x 6750 = 1161945 / 86.07 = 13500

 

Piston Area

The zetec engine has a bore of 84.82mm the formula for the piston area is as followed, this is just a simple formula to find the area of a circle using the given radius.

84.82 / 2 = 42.41mm

1798.6081 x 3.142 = 5651.2266502mm2

 

Port Area

 

The port area is the theoretical area in mm2 that is required to allow the engine to induct and expel sufficient charge during the induction/exhaust strokes. The formula is as followed for a cylinder head featuring a single port

Pa=piston area

Pa x 0.3 = port area

5651.2266502 x 0.3 = 1695.36799506

The zetec engine features a Siamese port this is when a single inlet runner supplies charge through 2 valves.

Pa x 0.3 / 2 = 847.68399753

The end value on a Siamese port is half the value of a single port this is because the amount of charge that has to flow though each valve is half so the port area does need to be as large.

 

 

 

Valve size

 

When designing an engine valve size needs to be taken into consideration, if the valves are too small or to large the engine performance will greatly suffer. There is a formula to find a rough valve size for a engine, all though this should be used as a base figure to work around to find a optimum valve size which works best with the configuration on engine.

The formula to find the optimum valve size is as followed.

Bore=84.82mm

Pa = piston area (5651.2266502)

Pa x 0.3 / 2 if Siamese port

x 2 to find diameter as this is only the radius

= 16.42 x 2 = 32.84

32.84mm is the valve diameter for a Siamese inlet valve, to find the valve diameter of a exhaust port just x the final answer of the equation by 0.85

32.84 x 0.85 = 27.914mm for the exhaust valve diameter.

Valve lift

The following formula is used to find the amount of valve lift (in mm) required by the engine to prevent the valve restricting the flow of charge entering and exiting the cylinder.

Bore = 84.82

x (1.57 for exhaust lift use 1.31) = 14.45mm inlet valve at max lift

12.06mm exhaust valve at max lift

Lift array

Valve reference diameter ÷ valve lift in mm this needs to be worked out in 1 mm increments starting at 1mm and ending at max lift (14.45 for inlet and 12.06 for exhaust) this needs to be worked out for the inlet as well as the exhaust as the valve reference diameter will be different and max lift.

Inlet lift array

Lift in mm ÷ 32.84 Lift array
1mm 0.030450669914738124238733252131547
2mm 0.060901339829476248477466504263094
3mm 0.091352009744214372716199756394641
4mm 0.12180267965895249695493300852619
5mm 0.15225334957369062119366626065773
6mm 0.18270401948842874543239951278928
7mm 0.21315468940316686967113276492083
8mm 0.24360535931790499390986601705238
9mm 0.27405602923264311814859926918392
10mm 0.30450669914738124238733252131547
11mm 0.33495736906211936662606577344702
12mm 0.36540803897685749086479902557856
13mm 0.39585870889159561510353227771011
14mm 0.42630937880633373934226552984166
14.45mm 0.44001218026796589524969549330085

 

Exhaust lift array

Lift in mm ÷ 27.91mm Lift array
1mm 0.035829
2mm 0.071659
3mm 0.107488
4mm 0.143318
5mm 0.179147
6mm 0.214977
7mm 0.250806
8mm 0.286636
9mm 0.322465
10mm 0.358295
11mm 0.394124
12mm 0.429953
12.06mm 0.432103

 

 

 

Intake and exhaust system lengths

Intake system

L= length from valve to atmosphere

N= desired rpm for max power

Theata t= amount in degrees (80-90 ideal inlet duration for max pulse in degrees 120for exhaust)

C= speed of sound (343 for inlet and 518 for exhaust)

L =

L =

L =

Ideal inlet length from valve to atmosphere = 485.91mm for maximum power at 5000rpm

L =

L =

L =

Ideal exhaust length from valve to atmosphere = 1036mm for maximum power at 5000rpm

Exhaust flow split calculation

Now that the exhaust valve diameter  and piston areas have been found the diameters of the flow splits can be worked out, a flow split is when two exhaust runners join to become one and the collector is know as the flow split.

Gt suite uses a number based system to link all the parts added to the engine in regards to flow splits numbers 1 and 2 will be the entry and number 3 the exit, it is crucial that the parts are numbered in this manor or a simple error may cause complications further on in the simulation.

 

 

 

 

 

 

 

 

 

Camshaft profiles

As the measurements of the zetec camshafts were not available in degree increments, they were measured using a engineers bench, 2 engineers squares a dti (depth measurement device) gauge and the engines camshafts.

The engineer’s squares were placed on the level work surface supporting each end of the camshaft on there mounting journals; a degree wheel was then affixed to one end of the camshaft. The dti gauge was then set up and zeroed on one of the camshafts lobes to ensure a true reading. The camshaft was then rotated in degree increments and the amount of camshaft lift documented in mm.

 

 

Intake duct diameter

 

 

 

 

                       

00mm = 5808.80 x 0.2 = 1742.64

1742.64÷ 2 = 871.32  = 29.5mm

10mm = 5808.80 x 0.2 = 1161.76

1161.76 ÷ 2 = 580.88  = 24.1mm

20mm = 5808.80 x 0.2 = 1161.76

1161.76 ÷ 2 = 580.88  = 24.1mm

30mm = 5808.80 x 0.2 = 1161.76

1161.76 ÷ 2 = 580.88  = 24.1mm

40mm = 5808.80 x 0.2 = 1161.76

1161.76 ÷ 2 = 580.88  = 24.1mm

50mm = 5808.80 x 0.23 = 1336.024

1336.024÷ 2 = 668.012 = 25.8mm

60mm = 5808.80 x 0.24 = 1394.112

1394.112 = 37.3 mm

70mm = 5808.80 x 0.25 = 1452.2

1452.2 = 38.8mm

80mm = 5808.80 x 0.25 = 1510.288

1510.288 = 38.1mm

90mm = 5808.80 x 0.25 = 1510.288

1510.288 = 38.1mm

100mm = 5808.80 x 0.25 = 1510.288

1510.288 = 38.1mm

110mm = 5808.80 x 0.25 = 1510.288

1510.288 = 38.1mm

120mm = 5808.80 x 0.27 = 1568.376

1568.376 = 39.6mm

130mm = 5808.80 x 0.3 = 1742.64

1742.64 = 41.7mm

140mm = 5808.80 x 0.35 = 2033.08

2033.08 = 45mm

150mm = 5808.80 x 0.4 = 2323.52

2323.52 = 48.2mm

160mm = 5808.80 x 0.45 = 2613.96

2613.96 = 51.1mm

170mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

180mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

190mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

200mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

210mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

220mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

230mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

240mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

250mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

260mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

270mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

280mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

290mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

300mm = 5808.80 x 0.5 = 2904.4

2904.4 = 53.8mm

 

 

 

 

 

 

Length from inlet valve Duct diameter
0mm 29.5mm
10mm 24.1mm
20mm 24.1mm
30mm 24.1mm
40mm 24.1mm
50mm 25.8mm
60mm 37.3 mm
70mm 38.8mm
80mm 38.1mm
90mm 38.1mm
100mm 38.1mm
110mm 38.1mm
120mm 39.6mm
130mm 41.7mm
140mm 45mm
150mm 48.2mm
160mm 51.1mm
170mm 53.8mm
180mm 53.8mm
190mm 53.8mm
200mm 53.8mm
210mm 53.8mm
220mm 53.8mm
230mm 53.8mm
240mm 53.8mm
250mm 53.8mm
260mm 53.8mm
270mm 53.8mm
280mm 53.8mm
290mm 53.8mm
300mm 53.8mm

 

Piston Area

 

Piston area A =

3.142 X (bore / 2)2

3.142 X (86/2)2

3.142 x (43)2 = 5808.80

All the required formula has been transposed to find the optimum values for a SI performance engine.

Before any engine could be created we needed to replicate air (atmospheric pressure), this was done by selecting the EndEnviroment Template from the GT-Power libary and changing the preset data. The pressure was set to 1 bar which is atmospheric pressure and temperature set to 300K (Kelvin’s) there temperature of air is always changed but we are using 300 as a preset because the accuracy of the results over different ambient air temps is not required.

Next the composition had to be chosen this replicated the fluid composition of the inlet environment the input field was double clicked to bring up the value selector box,

The completed end environment template is placed on the workspace on the left hand side as GT POWER  simulates a model engine from left to right, inlet air on left, and expelled exhaust on the right.

Intake manifold

The inlet manifold needed to be completed next using various measurements and pictures to relate to the configuration of runners and flow splits. Intake runners and flow splits are needed to transfer end environment to inlet port. The pipe round template is selected from the template library this was then renamed int runner, the attributes in the main folder where then filled with the data obtained from measuring of the standard Zetec inlet. The diagram below left, show an illustration with diameters of intake runners, lengths and the dimensions and areas of the inlet plenum.

Figure ?? above, illustration of a Ford Zetec inlet manifold and its dimensions

Figure ?? above. Ford Zetec EFI inlet manifold

Figure ?? to left
pipe round template renamed intrunner and filled with attributes and measurements  from a standard Zetec inlet.

A flowsplit is now needed to link the 4 intake runners to create a plenum (a chamber with equalized atmospheric pressure)

The flow split is drawn on paper first to find the measurements needed to create the flow split, there is 1 input from the throttle butterfly and 4 outputs for the intrunners to feed each cylinder with charge.

The Zetec features a 1-4 flow split this is where the plenum delivers air flow to 4 intake runners using only a single collector.

The drawing now needs to be measured using a compass to find the angle each port is in relation to the x y and z axis.

Axis

Angle In Degree’s
X 0 180 90 45 135
Y 90 90 90 90 90
z 90 90 0 135 135

The flow split template is selected from the template library. The boundary data tab is then selected and the form is filled with the following data which was previously obtained from the drawing.

The part is also renames man-fs

[Type a quote from the document or the summary of an interesting point. You can position the text box anywhere in the document. Use the Drawing Tools tab to change the formatting of the pull quote text box.]

It is wise to then view the flow split in 3d to check the data entered is correct and that all the ports are in the correct location in relation to the x,y,z axis.

[Type a quote from the document or the summary of an interesting point. You can position the text box anywhere in the document. Use the Drawing Tools tab to change the formatting of the pull quote text box.]

The man-fs is then placed on the workspace and linked to the intrunner’s when doing this, it is crucial that the parts and linked in the correct order using the number forms, for example our 3d model of the flowsplit the largest port number 3 is connected to the throttle butterfly and must be the third component to be linked. It is also important that the components are linked in the correct direction as GT-Power engine simulations runs from left to right.

Intake ports and valves

The next component created were the inlet ports, these consist of a pipe round and a flow split due to the design utilising Siamese ports, the pipe round template was then renamed [intport] with a diameter of 66mm and a length of 80mm this single port then splits into 2 separate ports known as Siamese ports, a flowsplit was created and renamed siemese-sfs and filled with the following criteria.

Above Figure?? A screen print captured in GT Power

Inlet valves were now needed in order to complete the induction side of the cylinder head,

The valveCamCon template was the selected from the component library and dragged onto the workspace this was then renamed intvalve and filled with the following criteria obtained from prior measurements of the Zetec cylinder head

Int valve diameter 32mm
Exh valve diameter 28mm
Valve Lift Int 9.4mm
Valve Lift Exh 9.55mm
Cam Duration Int 258
Cam Duration Exh 250
Valve lash 0.1mm

The camshaft profile was then created using measurements previously obtained from measuring camshaft lift over 360 degrees.

this data was then used to create a lift array on GT-Suite, the data was entered into the table, because we have seat theata=0 at max lift any measurement before max lift is in – degree and after max lift +degree and max lift as 0degree’s, the reason the measurements had to be entered into the table in this way is to allow GT to used max lift as a reference point for altering and defining camshaft timing.

The flow array tab was then selected as reference array had to be created using this simple mathematical equation, Array of valve lift or valve lift divided by Valve Reference Diameter, as specified in Flow Coefficient Lift Unit: must be monotonic and start at zero.

The following data was then entered.

0mm 0
1mm 0.0312
2mm 0.0625
3mm 0.09375
4mm 0.125
5mm 0.15625
6mm 0.1875
7mm 0.21875
8mm 0.25
9mm 0.28125
9.4mm 0.3125

This step was repeated using different data to complete the exhaust camshaft.

Cylinders and crank train

The engine cylinders and pistons were then created, the EngCylinder template was then selected from the template library and dragged into the workspace, The EngCylinder is somewhat unique, because the majority of the input to the object comes in the form of reference objects.The engine performance gt-suite tutorial was then followed to complete the cylinder.

“Cylinder Initial State Object

The cylinder initial state can be the same as the initial state of the intake runner and intake port. For the Initial State Object attribute use Value Selector, select “initial” under ‘In GTM file’ below FluidInitialState, and press the OK button.

Cylinder Wall Temperature Object

For the next attribute, ‘Wall Temperature Object’, use Value Selector and select ‘EngCylTWall’ under ‘In Template Library’. This object is a simple cylinder wall temperature object used to define three constant imposed wall temperatures, one for the head, one for the piston, and one for the cylinder/liner. Defining three constant temperatures is sufficient for most engine performance and acoustic analysis simulations. The three numbers entered are typical values for most engines at full load. Fill in the values below and press OK to complete the reference object.

Cylinder Heat Transfer Object Tutorial 1 Gamma Technologies, Inc. © 2010 10

For the attribute, ‘Heat Transfer Object’, use Value Selector and select ‘EngCylHeatTr’ under ‘In Template Library’. This object is used to describe the in-cylinder heat transfer characteristics between the gas and the combustion chamber walls. Double-click on ‘EngCylHeatTr’ to create a new object. Name the object “htr”, fill in the following values, and select OK when finished. Use SI or DICI values depending on which type of engine you are building. The Woschni heat transfer model is the industry standard, because it is easy to use and gives good estimates of in-cylinder heat transfer.

Two of the less intuitive attributes are Head/Bore Area Ratio and Piston/Bore Area Ratio. The Head/Bore Area Ratio compares the surface area of the head to the bore area. The Piston/Bore Area Ratio compares the surface area of the piston to the bore area. This is a simple way of accounting for heat transfer from a concave head, flat piston combination in an SI application, and a flat head, bowl piston combination in a DICI application, without explicitly defining the detailed geometry. Another attribute to explain is the radiation multiplier. For SI engines radiation is typically not a factor, and so the recommended value is ign, which equals 0, meaning radiation will not be included in the heat transfer analysis. Conversely, for diesel engines radiation is important because the soot particles actually radiate. Therefore the recommended value for diesel engines is 1.

Cylinder Combustion Object

For the attribute, ‘Combustion Object’, use Value Selector and select either ‘EngCylCombSIWiebe’ or ‘EngCylCombDIWiebe’ under ‘In Template Library’ depending on if you are building the SI or DICI engine, respectively. The combustion burn rate will be modeled with a Wiebe curve. Please consult the chapter on Combustion in the Engine Performance User Manual for more information on the combustion models and how they are used. Type in the following values in Main folder (Options and Advanced folder remain unchanged) and select OK when finished. The figure below shows how the EngCylinder will look when finished. The Advanced folder is pre-filled and will remain unchanged. Press OK to complete the cylinder.”(figure??)

The crankshaft was then created this defines the engine type, cylinder arrangement and firing order, EngineCrankTrain template was then selected and dragged into the workspace, this was then renamed “cranktrain” the following values were then entered.

For engine speed a value of [RPM] was entered in GT-Power Parameters are created in GT-POWER by placing square brackets around an object value name in an attribute. This promotes the value to a different location called Case Setup, parameterized variables allow a value to be changed easily from case to case. This can be seen on page?????? Were case setup is discussed.

“Engine Friction Object

The friction reference object must now be defined. Use Value Selector in the ‘Engine Friction Object or FMEP’ object value box. Select ‘EngFrictionCF’ under ‘In Template Library’, name the object “friction”, and fill in the values as shown in the figure below. CF stands for Chen-Flynn model, which is a common engine friction model. This friction includes and accounts for all friction from the cranktrain, pistons, and valvetrain.” (figure??)

(left figure ??)

The cylinder geometry tab was then selected. The following Bore stroke and Con rod length were set to manufactures specifications for the 2.0 Zetec engine. The compression ratio was also added to create a realistic simulation of the engine.

Exhaust System

And exhaust system in now require by the engine in order to create a realistic simulation, similar to the inlet manifold the exhaust system consists of pipe rounds and flow splits.

A drawing was made from measurements obtained measuring a Zetec exhaust system.

The exhaust ports measured 56mm diameter, the exhaust runners measure 150mm from cylinder head mating surface to the exhaust down pipe port measuring 60mm diameter.

The exhaust down pipe has a length of 1000mm. this gives a total length of 1190mm

For the purpose of this simulation a full exhaust system is not necessary in order to obtain sufficient results,

Figure ??

The drawing was then split up into pipe rounds and flowsplit to allow for the exhaust manifold to be created in GT-Power, the following boundary data was entered to create the 4-1 exhaust flowsplit.

Link ID Number 1 2 3 4 5
Part Name exhport-1 exhport-2 exhpipe-1 exhport-3 exhport-4
Adjacent Part Diameter 56.0 56.0 60.0 56.0 56.0
Angle wrt X-axis 0 180 90 45 135
Angle wrt Y-axis 90 90 90 90 90
Angle wrt Z-axis 90 90 0 135 135
Characteristic Length mm 40 40 40 40 40
Expansion Diameter mm 56 56 60 56 56

Fuel injector

Fuel injector’s are required in order to deliver fuel to the air mixture, the fuel injector is controlled by the ECM unit, the ECM unit knows the required amount of fuel needed by the engine by the use of a AMF (air mass flow meter), the AMF measure the density and quantity of the air. In GT-Power fuel delivery quantity is distinguished by selecting a component of the inlet tract in which an Air Mass reading will be taken.

The InjAfSecConn template is selected from the template library and copied into the work space,

The injector delivery rate was set at 6 as a base, the injector delivery rate in which fuel is injected the higher the figure the faster the fuel can be injected,

Fuel Ratio Specification was then set to air-to-fuel this allows GT-Power to alter the amount of fuel injected in proportion to the quantity of air.

Fuel Ratio this is the quantity of fuel in proportion to air, for example a ratio of 5.1 would be 1 part fuel to 5 parts air.

RLT for air mass flow rate sensor this is the part in which the air mass reading will be taken the pipe-to-man-1 has been selected this is the pipe linking the throttle body to the inlet manifold.

Number of Injectors per Sensor this is the number of injectors used by the engine

The timing-general tab was then selected.

Part giving Angle (def=attached cylinder) this is the part in which the injection angle is defined.

Injection Timing Angle this is the point in cycle when the fuel injection will occur.

Injection Timing Flag this defined whether the Injection Timing Angle is the start of injection or end of injection,

Injection Location (pipes only) this is the location of the injector 0.0 represents the inlet end of the pipe, and 1.0 the outlet end.

Injected Fluid Temperature the Temperature of the injected fluid.

Fluid Object the name of the reference object defining the properties of the fluid to be injected.

Vaporized Fluid Fraction the mass fraction of the injected liquid that will vaporize immediately after injection.

The values entered for the Zetec fuel injector can be found below.

Figure ??

[Type a quote from the document or the summary of an interesting point. You can position the text box anywhere in the document. Use the Drawing Tools tab to change the formatting of the pull quote text box.]

Connecting components

Now all components have been created they can now be placed on the workspace and connected together, this is done from left to right,

Figure ?? above is the complete zetec engine built in GT-Power

All components are now linked the next step is to run the engine simulation,


 

Case Setup

In order to obtain sufficient result from the engine being run a case setup needs to be assigned ,Case setup allows different parameters previously set by the user (any value in closed square brackets e.g. [RPM]) to be replaced by different values set in the case setup dialogue box.

When the engine crank train was created a value of [rpm] was entered for engine speed, this has created a RPM tab in the case setup, this allows us to create different cases for different rpm sites, 7 cases were assigned in 1000rpm intervals from 1000 idle speed to a max engine speed of 7000rpm,

Figure ??

With the case setup now complete the simulations can be run, once the simulation is finished the results can be analysed in GT-Post.

Running simulation

When running engine simulations GT-Power will bring up a black dialogue box containing all the information being processed to obtain engine performance results, it is wise to watch for any errors or restricted time-steps as this will show you which components are hindering engine performance, or any errors causing power loss.

Figure ???

 

Figure?????

Once the simulation has completed text similar to the above should be displayed, press any key to continue, the engine can now be viewed in GT-Power.

GT-Post

The power and torque were then viewed as a graph

Max BHP = 133.686

Max Torque = 149.925 at 4000rpm

The production model 2.0 zetec engine in standard form produces 136 BHP and 150 N-m or torque so the results obtained from the computerised simulation are highly accurate.

Because the engine being produced

            Parameters that will be optimised;

  • Inlet manifold
  • Exhaust system
  • Cylinder capacity (bore)
  • Valve size
  • Fuel delivery rate and ratio
  • Inlet cam timing

Changes to inlet cam timing

Altering cam timing will effect when power is created and how much, in theory by advancing cam timing low range power will decrease but mid to high rpm will increase, this is due to the fact that the charge can be induced earlier allowing more charge to enter the cylinder at higher rpm.

When cam timing is retarded the inlet valve opens later and closes later this allows more charge to enter the cylinder at lower rpm. As the zetec engine in question is to be used in a race series max power is wanted higher in the rev range.

Below is a graph showing standard inlet timing with max lift at 477.41995 degrees with inlet valve opening at TDC, this timing arrangement is favourable for a engine designed for economical road use as the average driver usually stays in the 1000/4000rpm range.

The inlet camshaft timing was the retarded by 12 degrees.

The graph below is the results of the change to cam timing.

Max Bhp at 7000rpm = 136.842 this is a increase of 3.156

Max torque at 4000rpm (N-m) = 170.126 there is an increase of 20.201 there is a substantial increase to max torque with a mild raise of Bhp

Increasing cylinder capacity

By increasing the displacement of the engine cylinders the cylinder capacity is increased, the effect of increase capacity allows for more charge to enter the cylinder allowing for a increase in performance

Standard bore = 84.5mm

Standard stroke = 86mm

Standard cubic capacity = 1929.38cc

The bore was then increased to 88mm retaining the standard stroke whist increasing the cubic capacity of the engine to 2092.52cc

Max BHP at 7000RPM = 150.016Bhp this is a increase of 13.174Bhp

Max torque (Nm) = 186.607 at 4000rpm this is a increase of 16.481Nm


 

Changes to valve size

By changing the size of the inlet and exhaust valves will increase or decreases the ability of the engine to induces and expel charge. By changing the valve sizes alone may not change the performance of the engine but will enhance the breathing capabilities of the engine when combined other breathing changes such as inlet/exhaust manifold design and inlet and exhaust port size

Inlet valve was increased from 32mm to 34mm

Exhaust valve was increased from 28mm to 30mm

Below is a graph showing that no change occurred when the valve sizes were increased.

Max BHP at 7000RPM = 150.016Bhp no increase occurs

Max torque (Nm) = 186.607 at 4000rpm no increase occurs

.

Changes to inlet length and inlet ports

The design of the inlet manifold has a huge effect on engine performance and how it is produced, altering the length of the inlet runners will move the power band up and down the rev range, increasing the diameter of the inlet runner will de-restrict flow but will in-turn slow down the velocity of the charge, reducing the diameter of the runners will increase the velocity of the charge whilst sacrificing flow.

Also the placement of the throttle entry will affect the delivery of air to each cylinder, the inlet manifold below (log type) features the throttle body to the right of the engine, and this will provide uneven distribution of the charge, i.e. less charge will reach the runner furthest away from the throttle body, whist the runner closest will receive the most. Even cylinder distribution can be achieved by tapering the inlet plenum (wedge shape), the charge will speed up as it enters the tapered plenum and will be at maximum velocity at the smallest end.

Figure ???

Changes made to the inlet manifold were as followed inlet length from valve to plenum was changed from 450mm to an optimised value of Ideal inlet length from valve to atmosphere = 607mm for maximum power at 4000rpm

The following formula was obtained to find the optimised inlet length

L= length from valve to atmosphere

N= desired rpm for max power

Theta t= amount in degrees (80 -90  ideal inlet duration for max pulse in degrees 120 for exhaust)

C= speed of sound (343 for inlet and 518 for exhaust)

L =

L =

L =

Max BHP at 7000RPM = 154.019Bhp this is a increase of 2.265Bhp

Max torque (Nm) = 195.053 at 4000rpm this is a increase of 8.446Nm

Compression Ratio

The compression ratio of the zetec engine of standard is 9.5 this was changed to make the compression ratio higher to 12.5 the outcome of this can be seen below. When the CR is raised, peak combustion pressures are increased. This increases the ferocity of the burn.

Read more:

Max BHP at 7000RPM = 162.85Bhp this is a increase of 8.831Bhp

Max torque (Nm) = 205.938 at 4000rpm this is a increase of 10.885Nm

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