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Head Work for your 32 Valve Porsche® 928


Porting: Usually, porting a set of heads is up to the skill of the tool operator as each intake and exhaust port is hand-milled to open them up. In many cases, this is the only way it can be done. But no matter how expert the operator, making the intake and exhaust ports match from cylinder-to-cylinder is just about impossible. And with that irregularity, you are building in variables from cylinder to cylinder that will negatively affect the engines smoothness, power, and longevity under high loads.

To correct this and improve on the hand-ported performance head, 928 Motorsports LLC has developed and uses a CNC milling program on a 5-axis mill for optimizing the Porsche 928 heads. This digital milling process guarantees not only maximum flow, but repeatability from cylinder-to-cylinder.

Now, with 5-axis CNC machining, we can confirm that each cylinder and its ports are an exact match across the head - giving you greater engine output as well as smoothness and increased safety from detonation in high-output engines.

Valves: We can also replace the stock 36mm intake valves with our Hi-Flow 39.5mm valves. The stock valve seats are removed, and new larger valve seat reliefs are milled into the head and the seats pressed in.

Our Hi-Flow valves and seats are available in both Titanium and Stainless Steel. For more information on our valves, visit the Valve Page Here.

Flow bench analysis before-and-after our CNC porting and Hi-Flow valve installation shows that you can expect the following gains:

Intake
Valve Lift

Stock
CFM's

Ported Heads
CFM's

 

+ or -

 

Exhaust
Valve Lift

Stock
CFM's

Ported Heads
CFM's

 

+ or -

0.150

142.50

158.90

16.40

0.150

124.80

153.26

28.46

0.200

187.10

204.93

17.83

0.200

169.00

194.50

27.72

0.250

225.70

244.13

18.43

0.250

190.80

218.52

27.72

0.300

248.29

273.83

25.54

0.300

210.50

234.78

24.28

0.350

261.30

291.06

29.76

0.350

220.10

245.63

25.53

0.400

267.30

311.50

44.20

0.400

223.30

252.01

29.44

0.450

267.30

323.96

56.66

0.450

226.40

255.84

29.44

0.500

297.00

329.30

32.30

0.500

229.60

259.99

30.39

0.550

297.00

333.75

36.75

0.550

229.60

260.94

31.34

Comparison: The 928 Motorsports LLC modified Porsche 928 heads compared to Small Block Chevy Brodix GB2000/2001 racing heads (IRL, NASCAR):

Intake
Valve Lift

Brodix Race Heads
CFM's

928MS Ported Heads
CFM's

 

+ or -

Exhaust
Valve Lift

Brodix Race Heads
CFM's

928MS Ported Heads
CFM's

+ or -

0.200

157.00

204.93

47.93

0.200

109.00

194.50

85.50

0.300

238.00

273.83

35.83

0.300

152.00

234.78

82.78

0.400

302.00

311.50

9.5

0.400

205.00

252.01

47.01

0.500

353.00

329.30

23.7

0.500

232.00

259.99

27.99

NOTE: maximum valve lift on the 928 with the most aggressive cams possible is only .442 on the intake, .398 on the exhaust. See Camshaft Details Here

CNC Porting and Polishing:
32 v heads: $1800  per pair. Price includes surface milling, and seat milling for over-sized valve seats.

Multi-angle Valve jobs: (2-angle valve job on exhaust valves, 3-angles on intake valves)
32v heads $650 per pair

Other charges may apply as needed, such as: valve stem replacement, etc. Prices do not include parts.

 
   
       

Phone: (920) 485-0928
Email: info@928motorsports.com

© 928 Motorsports, LLC - All Rights Reserved
Horicon, Wisconsin USA

928Motorsports.com - Performance Parts for your Porsche® 928