Download presentation

Presentation is loading. Please wait.

Published byDebra Ward Modified about 1 year ago

1
Applied Math Compression Ratio

2
Compression

3
Compression Ratio BDC TDC Compression ratio = BDC TDC

4
10 cu in Compression Ratio TDC Compression ratio = BDC TDC 90 cu in Compression ratio = BDC TDC 90 cu in 10 cu in BDC Compression Ration = 9 to 1

5
45 cu in + 7 cu in 45 cu in Compute 7 cu in Compression ratio = BDC TDC Swept Volume of Piston + Clearance Volume Clearance Volume Compression ratio = 7 cu in Compression ratio =7.4 to 1

6
740 cu cm + 78 cu cm Compute Compression Ratio Intro Problem Determine the compression ratio: Swept Volume = 740 cu cm Clearance Volume = 78 cu cm Compression ratio = BDC Cylinder volume + Clearance Volume TDC Clearance Volume Compression ratio = 78 cu cm =10.5 to 1

7
Changing the Piston Shape General assumption: Flat top pistons. How would the compression ratio change if dished pistons or pistons with valve relief cutouts were used instead? Valve Relief 8.6 cc

8
740 cu cm cu cm Compute Compression Ratio Piston Shape: dished Determine the compression ratio: Swept Volume = 740 cu cm Clearance Volume = 78 cu cm Compression ratio = Cylinder volume + Clearance Volume Clearance Volume Compression ratio = 86.6 cu cm = 9.5 to cc valve relief cu cm It was 10.5 to 1 before the piston change

9
Compute Compression Ratio Piston Shape: dished Conclusion: Pistons that are dished or have valve relief cutouts will lower compression ratio (if everything else stays the same).

10
Changing the Piston Shape Dome How would the compression ratio change if domed pistons are used instead? Ford 351 Cleveland Dome =12 cc

11
740 cu cm + 66 cu cm Compute Compression Ratio Piston Shape: Dome Determine the compression ratio: Swept Volume = 740 cu cm Clearance Volume = 78 cu cm Compression ratio = Cylinder volume + Clearance Volume Clearance Volume Compression ratio = 66 cu cm = 12.2 to cu cm It was 10.5 to 1 before the piston change 12 cc dome

12
Compute Compression Ratio Piston Shape: Dome Conclusion: Pistons that are domed will raise the compression ratio (if everything else stays the same).

13
Compute Compression Ratio Problem 2 Bore = 3.985” Stroke = 3.000” Clearance Volume = 4 cu in Compression ratio = Cylinder volume + Clearance Volume Clearance Volume cu in + Clearance Volume cu in + 4 cu in 4 cu in = to 1

14
1 Compute Compression Ratio Problem 3 Bore = 4.000” Stroke = 2.870” Deck Height = 0.015” Head Gasket Thickness = 0.045” Combustion Chamber = 58 cu cm Compression ratio = Cylinder volume + Clearance Volume Clearance Volume cu cm cu cm cu cm 1 cu in cu in 1 x = = cu cm

15
Clearance Volume Deck Height Compressed Gasket Thickness Volume of combustion chamber Bore = 4.000” Stroke = 2.870” Deck Height = 0.015” Head Gasket Thickness = 0.045” Combustion Chamber Volume = 58 cu cm

16
cc’ing a cylinder head Burette Plexiglass Cylinder head Pictures from Auto Math Handbook by John Lawlor Published by HP Books

17
Combustion Chamber Volume Deck Height Compressed Gasket Thickness 58 cubic centimeters

18
Combustion Chamber Volume Deck Height Compressed Gasket Thickness 58 cu cm 0.015” 4.000” 0.045” 0.045” ” 0.060” Clearance Volume = 58 cu cm cu cm cu cm cu in x cu cm

19
Bore = 4.000” Stroke = 2.870” Deck Height = 0.015” Head Gasket Thickness = 0.045” Combustion Chamber Volume = 58 cu cm Compute Compression Ratio cu cm 58 cu cm cu cm Compression ratio = Cylinder volume Clearance Volume cu cm cu cm = 9.40 to 1

20
Dished Piston Or flat top piston with valve relief cut outs Affect on Overall Clearance Volume: Domed Piston Affect on Overall Clearance Volume: Other Things to Consider Piston Shape Adds to Overall Volume Takes away from the overall volume

21
Practice Compression Ratio Worksheet

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google