Volkswagen VR6 12 valve Intake Manifold Research and Development

 

  Ported VW MK3 intake manifold

VW VR6 MK3 Intake Manifold Development

This is the first VR6 intakes we've tested. Fact is this is the first non 4 cylinder intake manifolds we've tested. Good news is the air flow needs for a cylinder don't change no matter how many cylinders there are.

All air flow tests were performed on the same day, with the same flow bench setup and piping for each manifold. The purpose of the flow tests is to determine the relative air flow per runner and how they compare with each other. So far all intakes we've tested from the factory have not had equal flow between each runner.

 

 Flow tests were perfomed on the vr6 head with the intake at max lift of .475".  Tests were run in three different configurations. Fisrt test with just the head with proper radius for testing intake ports.  Secondly the head with the stage 3 ported MK3 VR6 intake manifold upper and lower sections, then finally the stock intake manifols upper and lower sections.  The motivation for the tests is to see what restriction the stock intake puts on the head flow and measure the realitive flow difference the ported intake provides.  If the ported intake flows well when not connedted to the head but shows no improvement when flow tested with the head then its not likely to make more power.  

 VR6 head + Complete scientific rabbit stage 3 ported intake manifold - shows close to 10% flow improvement vs stock through the head. VR6 with a cam similar to the TT 276 will create aproxamatly 10% more power through the power range.

 

VW MK3 VR6 flow tests, cfm

 

Raw Data From Tests

NOTE: Upper Section Only

VR6 Scientific Rabbit Super High Flow Intake Manifold Flow test results ( low numbers indicate better air flow)

Port #

1

2

3

4

5

6

Manometer in H2o

6

8

6

8

6

8

 

 

 

 

 

 

 

  

 

NOTE: Upper Section Only

VR6 EIP High Flow Intake Manifold Flow test results ( low numbers indicate better air flow)

Port #

1

2

3

4

5

6

Manometer in H2o

8.5

10

8.5

9.5

8.5

10

 

 

 

 

 

 

 

 

 

NOTE: Upper Section Only

VR6 Stock Intake Manifold

Port #

1

2

3

4

5

6

Manometer in H2o

9

10.5

8.75

10

8.75

10.25

 

 

The odd numbered ports feed the rear intake ports, and travel through 2/3 of the width of the VR head. Seems that since there is still some 7” worth of runners still in the head for the odd ports so its clear that the intake manifold runners need to flow more air to feed the rear port.

 

EIP did a nice job with the intake manifold, all the odd ports flow the same, but #4 was off quite a bit from #2 and #6. I suspect this is because of the spark plug wire holes.

For the intake to make more power the intake needs to best tested on head. The less the intake restrics flow through the head ports the more power the engine will make.

 

VR6 Head Flow tests vs Stock Intake Manifold vs Ported intake

 

Stick VR6 Head Flow tests with bell mouth at head port surface

Port #

1

2

3

4

5

6

Head @ .475" lift

Manometer in H2o

11.25

11.25

11.25

11.25

11.25

11.25

 

Stock VR6 Head Flow with Complete Stock Intake Manifold

Port #

1

2

3

4

5

6

Head + Complete Stock intake manifold @ .475" lift

Manometer in H2o

13

13

13

13

13

13

 

VR6 head + Complete ported intake manifold - shows close to 10% flow improvement through the head. VR6 with a cam similar to the TT 276 will create aproxamatly 10% more power through the power range.

Stock VR6 Head Flow with Complete Ported Intake Manifold

Port #

1

2

3

4

5

6

Head + Complete Ported intake manifold @ .475" lift

Manometer in H2o

12

12

12

12

12

12

  

Other Testing Notes:

The throttle body is 65mm diameter, the neck down section of the throttle body mount to the plenum opening is roughly the same area as the 65mm throttle body.

 

Lets see what PipeMax MaxRace software says we need to make more than 300 BHP.

170.476 Cubic Inches @ 8000 RPM with 115.0 % Volumetric Efficiency PerCent

Required Intake  Flow between  198.7 CFM  and  209.5 CFM  at 28 Inches
Required Exhaust Flow between  155.2 CFM  and  168.2 CFM  at 28 Inches

600 RPM/Sec Dyno Test    Lowest        Low        Average        Best
Peak HorsePower              323.6        336.9        343.5        350.2
Peak Torque Lbs-Ft           231.7        241.2        245.9        250.7

HorsePower per CID        1.898        1.976        2.015        2.054
Torque per Cubic Inch     1.359        1.415        1.443        1.471

BMEP in psi               204.9        213.3        217.6        221.8
Carb CFM at 1.5 in Hg.    454        505        530        556

Target EGT= 1274 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
Octane (R+M)/2  Method  = 100.4 to 101.0  Octane required range
Air Standard Efficiency = 62.22586 % for 11.000:1 Compression Ratio

Peak HorsePower calculated from Cylinder Head Flow CFM only
600 RPM/Sec Dyno Test    Lowest        Average        Best Potential
Head Flow Peak HP =     328.0        354.7        381.5

               ----- Engine Design Specifications -----
    ( English  Units )                   ( per each Valve Sq.Inch area )
Engine Size CID      = 170.476        Intake Valve Net Area    = 1.773
CID per Cylinder     = 28.413        Intake Valve Dia. Area   = 1.851
Rod/Stroke Ratio     = 1.816        Intake Valve Stem Area   = 0.078
Bore/Stroke Ratio    = 0.897        Exhaust Valve Net Area   = 1.247
Int Valve/Bore Ratio = 0.481        Exhaust Valve Dia. Area  = 1.325
Exh Valve/Bore Ratio = 0.407        Exhaust Valve Stem Area  = 0.078
Exh/Int Valve Ratio  = 0.846        Exh/Int Valve Area Ratio = 0.716
Intake Valve L/D Ratio= .293        Exhaust Valve L/D Ratio= .346
CFM/Sq.Inch = 107.4 to 113.2        CFM/Sq.Inch =117.1 to 126.9
Curtain Area -to- Valve Area Convergence  Intake Valve Lift inch= .384
Curtain Area -to- Valve Area Convergence Exhaust Valve Lift inch= .325

Intake Valve Margin CC's        Exhaust Valve Margin CC's
1.00 CC = 0.0330            1.00 CC = 0.0460
0.50 CC = 0.0165            0.50 CC = 0.0230
0.25 CC = 0.0082            0.25 CC = 0.0115
0.10 CC = 0.0033            0.10 CC = 0.0046

             -------  Piston Motion Data  -------
Average Piston Speed         (FPM)= 4740.00 in Feet Per Minute
Maximum Piston Speed         (FPM)= 7723.91 occurs at 75.587 Degrees ATDC
Piston Depth at 75.587 degree ATDC= 1.5688 inches  Cylinder Volume= 205.5 CC
Maximum TDC Rod Tension     GForce= 4120.75 G's
Maximum BDC Rod Compression GForce= 2341.52 G's

             -------  Current Camshaft Specs @ .050  -------

IntOpen= 20.00    IntClose= 60.00        ExhOpen= 58.00    ExhClose= 26.00
Intake Duration @ .050  = 260.00    Exhaust Duration @ .050 = 264.00
Intake CenterLine   = 110.00        Exhaust CenterLine  = 106.00
Compression Duration= 120.00        Power Duration      = 122.00
OverLap Duration = 46.00        Lobe Center Angle (LCA)= 108.00
Camshaft Retarded = 2.00degrees

-Recommended Camshaft Valve Lift-
         Minimum  Normal  Maximum
Intake  = 0.593   0.639   0.703
Exhaust = 0.525   0.566   0.622
Max-effort  Intake Lift = 0.736
Max-effort Exhaust Lift = 0.652
Minimum  Intake Valve Lift to prevent Choke = .639 Lift  @  8000 RPM
Minimum Exhaust Valve Lift to prevent Choke = .566 Lift  @  8000 RPM

- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 28.843 (usually this Length is never used)
2nd Harmonic= 16.370 (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 11.429 (ProStock or Comp SheetMetal Intake)
4th Harmonic= 8.995 (Single-plane Intakes , less Torque)

5th Harmonic= 7.298 (Torque is reduced, even though Tuned Length)
6th Harmonic= 6.140 (Torque is reduced, even though Tuned Length)
7th Harmonic= 5.299 (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 4.661 (Torque is greatly reduced, even though Tuned Length)
    Note> 2nd and 3rd Harmonics typically create the most Peak Torque
          4th Harmonic is used to package Induction System underneath Hood

Plenum Runner Minimum Recommended Entry Area = 2.119 to 2.384 Sq.Inch
Plenum Runner Average Recommended Entry Area = 2.437 Sq.Inch
Plenum Runner Maximum Recommended Entry Area = 2.489 to 2.946 Sq.Inch

Minimum Plenum Volume CC = 521.5  [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 31.8  [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 2793.6  [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 170.5  [typically for Tunnel Ram Intakes]

        -------  Operating RPM Ranges of various Components  -------

Camshaft Intake Lobe RPM = 6494        Exhaust Lobe RPM = 5841
Camshaft's Intake and Exhaust Lobes operating RPM range = 4331 to 6331
         Note=> Lobe RPMs are only BallPark estimations

Minimum  Intake Valve Lift to prevent Choke = .639 Lift  @  8000 RPM
Minimum Exhaust Valve Lift to prevent Choke = .566 Lift  @  8000 RPM

Current  (Intake  Valve Curtain Area -VS- Time)  Choke  RPM = 5634 RPM
Current  (Exhaust Valve Curtain Area -VS- Time)  Choke  RPM = 6366 RPM

Intake Valve Area + Curtain Area operating RPM Range = 4081 to 6081 RPM

Intake Valve Diameter RPM Range = 3634 to 5634

Intake Flow CFM @28in RPM Range = 6179 to 8179
 ___________________________________________________________________________

  Best estimate RPM operating range from all Components =  5870 to 7870

 Note=>The BEST Engine Combo will have all Component's RPM Ranges coinciding
 ___________________________________________________________________________

 ---  Cross-Sectional Areas at various  Intake Port Velocities (@ 28 in.) ---
220 FPS at Intake Valve Curtain Area= 2.170 sq.in.  at .450 Lift
258 FPS at Intake Valve OD Area and at Convergence Lift = .384
318 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 1.499 sq.in. at 8000 RPM
350 FPS Velocity CSA= 1.361 sq.in. at 8000 RPM Port Sonic-Choke with HP Loss
330 FPS Velocity CSA= 1.445 sq.in. at 8000 RPM Port Sonic-Choke with HP Loss
311 FPS Velocity CSA= 1.533 sq.in. at 8000 RPM Smallest Useable Port CSA
300 FPS Velocity CSA= 1.590 sq.in. at 8000 RPM Recommended Smallest Port CSA
285 FPS Velocity CSA= 1.673 sq.in. at 8000 RPM Recommended Smallest Port CSA
260 FPS Velocity CSA= 1.834 sq.in. at 8000 RPM Recommended Port CSA
250 FPS Velocity CSA= 1.908 sq.in. at 8000 RPM Recommended Port CSA

240 FPS Velocity CSA= 1.987 sq.in. at 8000 RPM Largest Intake Port Entry CSA
220 FPS Velocity CSA= 2.168 sq.in. at 8000 RPM Largest Intake Port Entry CSA
210 FPS Velocity CSA= 2.271 sq.in. at 8000 RPM Torque Loss + Reversion
200 FPS Velocity CSA= 2.384 sq.in. at 8000 RPM Torque Loss + Reversion

 ---  Cross-Sectional Areas at various Exhaust Port Velocities (@ 28 in.) ---
211 FPS at Exhaust Valve Curtain Area= 1.836 sq.in.  at .450 Lift
293 FPS at Exhaust Valve OD Area and at Convergence Lift = .325
361 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 1.073 sq.in. at 8000 RPM
435 FPS Velocity CSA= 0.892 sq.in. at 8000 RPM Sonic Choke at Throat Area
350 FPS Velocity CSA= 1.108 sq.in. at 8000 RPM Port Sonic-Choke with HP Loss
330 FPS Velocity CSA= 1.176 sq.in. at 8000 RPM Port Sonic-Choke with HP Loss
311 FPS Velocity CSA= 1.248 sq.in. at 8000 RPM Smallest Useable Port CSA
300 FPS Velocity CSA= 1.294 sq.in. at 8000 RPM Recommended Smallest Port CSA
285 FPS Velocity CSA= 1.362 sq.in. at 8000 RPM Recommended Smallest Port CSA
250 FPS Velocity CSA= 1.552 sq.in. at 8000 RPM Recommended Port CSA
240 FPS Velocity CSA= 1.617 sq.in. at 8000 RPM Recommended Port CSA
225 FPS Velocity CSA= 1.725 sq.in. at 8000 RPM Largest Exhaust Port Exit CSA
210 FPS Velocity CSA= 1.848 sq.in. at 8000 RPM Largest Exhaust Port Exit CSA
190 FPS Velocity CSA= 2.042 sq.in. at 8000 RPM Torque Loss + Reversion
180 FPS Velocity CSA= 2.156 sq.in. at 8000 RPM Torque Loss + Reversion

            ----  Some Useful Formulas are: ----
Average_CSA = Port_Volume_CC / (Port_CenterLine_Length * 16.387)

Port_Volume_CC = Average_CSA * Port_CenterLine_Length * 16.387

Port_CenterLine_Length = Port_Volume_CC / ( Average_CSA *16.387 )

FPS = ( Flow_CFM * 2.4 ) / Average_CSA

Flow_CFM = Average_CSA * FPS * .4166667

Average_CSA = ( Flow_CFM * 2.4) / FPS

Valve    Intake    Exhaust    Curtain Area    300 FPS Velocity        Minimum Head
Lift    Choke    Choke    Square Inches    Cross-Sect Area         Flow @ 28 In
inches    RPM    RPM    Intake    Exhaust    Intake    Exhaust         Int     Exh
.050    626    707    0.241    0.204    0.124    0.101        15.5    12.3
.075    939    1061    0.362    0.306    0.187    0.152        23.3    18.5
.100    1252    1415    0.482    0.408    0.249    0.202        31.1    24.6
.125    1565    1768    0.603    0.510    0.311    0.253        38.9    30.8
.150    1878    2122    0.723    0.612    0.373    0.304        46.6    36.9
.175    2191    2476    0.844    0.714    0.435    0.354        54.4    43.1
.200    2504    2829    0.964    0.816    0.498    0.405        62.2    49.2
.225    2817    3183    1.085    0.918    0.560    0.455        70.0    55.4
.250    3130    3537    1.206    1.020    0.622    0.506        77.7    61.5
.275    3443    3890    1.326    1.122    0.684    0.557        85.5    67.7
.300    3756    4244    1.447    1.224    0.746    0.607        93.3    73.8
.325    4069    4598    1.567    1.326    0.809    0.658        101.1    80.0
.350    4382    4951    1.688    1.428    0.871    0.709        108.8    86.2
.375    4695    5305    1.808    1.530    0.933    0.759        116.6    92.3
.400    5008    5659    1.929    1.632    0.995    0.810        124.4    98.5

Valve    Intake    Exhaust    Curtain Area    300 FPS Velocity        Minimum Head
Lift    Choke    Choke    Square Inches    Cross-Sect Area         Flow @ 28 In
inches    RPM    RPM    Intake    Exhaust    Intake    Exhaust         Int     Exh
.425    5321    6012    2.050    1.734    1.057    0.860        132.2    104.6
.450    5634    6366    2.170    1.836    1.120    0.911        139.9    110.8
.475    5947    6720    2.291    1.938    1.182    0.962        147.7    116.9
.500    6260    7073    2.411    2.040    1.244    1.012        155.5    123.1
.525    6573    7427    2.532    2.142    1.306    1.063        163.3    129.2
.550    6886    7781    2.652    2.245    1.368    1.113        171.0    135.4
.575    7199    8134    2.773    2.347    1.430    1.164        178.8    141.5
.600    7512    8488    2.893    2.449    1.493    1.215        186.6    147.7
.625    7825    8842    3.014    2.551    1.555    1.265        194.4    153.8
.650    8138    9195    3.135    2.653    1.617    1.316        202.1    160.0
.675    8451    9549    3.255    2.755    1.679    1.366        209.9    166.1
.700    8764    9903    3.376    2.857    1.741    1.417        217.7    172.3
.725    9077    10256    3.496    2.959    1.804    1.468        225.5    178.5
.750    9390    10610    3.617    3.061    1.866    1.518        233.2    184.6
.775    9703    10964    3.737    3.163    1.928    1.569        241.0    190.8