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I'm going to do a compression test to my car tonight! What should the compression be for my 03 GT?
 

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stock is 9.85 I believe
 

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stock is 9.85 I believe
thats compression ratio lol

he wants to know the PSI for compression check. I believe it is supposed to be greater than 160 PSI and each cylinder has to be within 10 psi of each other per bank. I'll try to remember to look up the spec tonight when i get home.
 

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thats compression ratio lol

he wants to know the PSI for compression check. I believe it is supposed to be greater than 160 PSI and each cylinder has to be within 10 psi of each other per bank. I'll try to remember to look up the spec tonight when i get home.
oops lol:eek:
 

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Just looked at my ford service manual...it states that the lowest pressure level must be atleast 75% of the highest pressure level. Hope this pastes ok...

Maximum Pressure Minimum Pressure Maximum Pressure Minimum Pressure Maximum Pressure Minimum Pressure Maximum Pressure Minimum Pressure 924 kPa (134 psi) 696 kPa (101 psi) 1131 kPa (164 psi) 848 kPa (123 psi) 1338 kPa (194 psi) 1000 kPa (146 psi) 1544 kPa (224 psi) 1158 kPa (168 psi) 938 kPa (136 psi) 703 kPa (102 psi) 1145 kPa (166 psi) 855 kPa (124 psi) 1351 kPa (196 psi) 1014 kPa (147 psi) 1558 kPa (226 psi) 1165 kPa (169 psi) 952 kPa (138 psi) 717 kPa (104 psi) 1158 kPa (168 psi) 869 kPa (126 psi) 1365 kPa (198 psi) 1020 kPa (148 psi) 1572 kPa (228 psi) 1179 kPa (171 psi) 965 kPa (140 psi) 724 kPa (106 psi) 1172 kPa (170 psi) 876 kPa (127 psi) 1379 kPa (200 psi) 1034 kPa (150 psi) 1586 kPa (230 psi) 1186 kPa (172 psi) 979 kPa (142 psi) 738 kPa (107 psi) 1186 kPa (172 psi) 889 kPa (129 psi) 1303 kPa (202 psi) 1041 kPa (151 psi) 1600 kPa (232 psi) 1200 kPa (174 psi) 933 kPa (144 psi) 745 kPa (109 psi) 1200 kPa (174 psi) 903 kPa (131 psi) 1407 kPa (204 psi) 1055 kPa (153 psi) 1055 kPa (153 psi) 1207 kPa (175 psi) 1007 kPa (146 psi) 758 kPa (110 psi) 1214 kPa (176 psi) 910 kPa (132 psi) 1420 kPa (206 psi) 1062 kPa (154 psi) 1627 kPa (154 psi) 1220 kPa (177 psi) 1020 kPa (148 psi) 765 kPa (111 psi) 1227 kPa (178 psi) 917 kPa (133 psi) 1434 kPa (208 psi) 1075 kPa (156 psi) 1641 kPa (238 psi) 1227 kPa (178 psi) 1034 kPa (150 psi) 779 kPa (113 psi) 1241 kPa (180 psi) 931 kPa (135 psi) 1448 kPa (210 psi) 1083 kPa (157 psi) 1655 kPa (240 psi) 1241 kPa (180 psi) 1048 kPa (152 psi) 786 kPa (114 psi) 1255 kPa (182 psi) 936 kPa (136 psi) 1462 kPa (212 psi) 1089 kPa (158 psi) 1669 kPa (242 psi) 1248 kPa (181 psi) 1062 kPa (154 psi) 793 kPa (115 psi) 1269 kPa (184 psi) 952 kPa (138 psi) 1476 kPa (214 psi) 1103 kPa (160 psi) 1682 kPa (244 psi) 1262 kPa (183 psi) 1076 kPa (156 psi) 807 kPa (117 psi) 1282 kPa (186 psi) 965 kPa (140 psi) 1489 kPa (216 psi) 1117 kPa (162 psi) 1696 kPa (246 psi) 1269 kPa (184 psi) 1089 kPa (158 psi) 814 kPa (118 psi) 1296 kPa (188 psi) 972 kPa (141 psi) 1503 kPa (218 psi) 1124 kPa (163 psi) 1710 kPa (248 psi) 1202 kPa (186 psi) 1103 kPa (160 psi) 827 kPa (120 psi) 1310 kPa (190 psi) 979 kPa (142 psi) 1517 kPa (220 psi) 1138 kPa (165 psi) 1724 kPa (250 psi) 1289 kPa (187 psi) 1110 kPa (161 psi) 834 kPa (121 psi) 1324 kPa (192 psi) 993 kPa (144 psi) 1631 kPa (222 psi) 1145 kPa (166 psi) — —
 

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Just looked at my ford service manual...it states that the lowest pressure level must be atleast 75% of the highest pressure level. Hope this pastes ok...

Ok it didnt paste correctly and dont have excel or word on this computer. Here are some examples...

134 PSI max needs a minimum of 101 PSI...in other words cylinder 5 could have the most pressure at 134 psi...the lowest pressure any other cylinder could then have would be 101 PSI.

Heres some more numbers...

Max Min
144 109
154 115
164 123
174 131
184 138
194 136
204 153
214 160
224 168


This is how ford says to do the test

Compression Test—Compression Gauge Check
  1. Make sure the oil in the crankcase is of the correct viscosity and at the correct level and that the battery (10655) is correctly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position, then remove all the spark plugs (12405).
  1. Set the throttle plates in the wide-open position.
  1. Install a compression gauge such as the Compression Tester in the No. 1 cylinder.
  1. Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position, and using the auxiliary starter switch, crank the engine a minimum of five compression strokes and record the highest reading. Note the approximate number of compression strokes required to obtain the highest reading.
  1. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
Compression Test—Test Results
The indicated compression pressures are considered within specification if the lowest reading cylinder is at least 75 percent of the highest reading.

If any cylinder fails, squirt a tablespoon full of oil into the questionable cylinder then repeat test.
 

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i just did a compression test my numbers were all around 130-135 is that normal..
 
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