| Message |
Apparently, it has to do with displacement. We are displacing more Cubic Inches with the over bore... since the combustion chamber hasnt changed, we are effectively increasing the amount of air being compressed in the compression chamber.
When we deck the heads, we decrease the combustion chamber volume. the smaller the combustion chamber, the higher the compression ratio... and vices versus.I should have known this.
I apologize for spready false and misleading information.
after googling, i found this (a good visual guide to see how things increase.;
| Shiner-Block Overboring Comparison |
| Overbore |
Bore (mm) |
Bore (in) |
Total CI |
Total cc |
% Larger |
CR |
Wall thickness |
| 0.000" |
91.11 |
3.587 |
181.41 |
2972.3 |
0.00 |
8.00 |
0.288-0.300" |
| 0.010" |
91.36 |
3.597 |
182.42 |
2989.4 |
0.58 |
8.04 |
0.278-0.290" |
| 0.020" |
91.62 |
3.607 |
183.44 |
3006.0 |
1.14 |
8.08 |
0.268-0.280" |
| 0.030" |
91.87 |
3.617 |
184.46 |
3022.7 |
1.70 |
8.12 |
0.258-0.270 |
| 0.040" |
92.13 |
3.627 |
185.48 |
3039.5 |
2.26 |
8.16 |
0.248-0.260" |
| 0.050" |
92.38 |
3.637 |
186.50 |
3056.3 |
2.82 |
8.20 |
0.238-0.250" |
| 0.060" |
92.63 |
3.647 |
187.53 |
3073.1 |
3.39 |
8.24 |
0.228-0.240" |
| 0.070" |
92.89 |
3.657 |
188.56 |
3090.0 |
3.96 |
8.28 |
0.218-0.230" |
| 0.075" |
93.01 |
3.662 |
189.08 |
3098.4 |
4.24 |
8.30 |
0.213-0.225" |
| 0.080" |
93.14 |
3.667 |
189.59 |
3106.9 |
4.53 |
8.32 |
0.208-0.220" |
| 0.090" |
93.40 |
3.677 |
190.63 |
3123.9 |
5.10 |
8.36 |
0.198-0.210" |
| 0.100" |
93.65 |
3.687 |
191.67 |
3140.9 |
5.67 |
8.40 |
0.188-0.200" |
Petz #3
|
 |
