Compression test
From Crankshaft Coalition Wiki
(→Dynamic compression ratio: fix link) |
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==To check compression:== | ==To check compression:== | ||
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'''Disable spark and fuel''' | '''Disable spark and fuel''' | ||
| + | Ideally, warm up the engine first. Piston and rings are designed to provide optimum sealing at operating temperature. | ||
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On a vehicle with a electric fuel pump pull the fuel pump relay, let engine idle until it stalls out. For mechanical fuel pump, I think using a vise grip and 2 thin blocks of wood (to avoid crimping the soft line) on the rubber fuel line will work. This prevents fire hazard. | On a vehicle with a electric fuel pump pull the fuel pump relay, let engine idle until it stalls out. For mechanical fuel pump, I think using a vise grip and 2 thin blocks of wood (to avoid crimping the soft line) on the rubber fuel line will work. This prevents fire hazard. | ||
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*[http://www.uempistons.com/calc.php?action=comp2 KB/Silvolite DCR calculator] | *[http://www.uempistons.com/calc.php?action=comp2 KB/Silvolite DCR calculator] | ||
*[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator] | *[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator] | ||
| − | + | Some dynamic compression rtatio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point figure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate. | |
| − | + | If the intake valve closing (IVC) point isn't known, it can be calculated: | |
# Divide the intake duration by 2 | # Divide the intake duration by 2 | ||
# Add the results to the lobe separation angle (LSA) | # Add the results to the lobe separation angle (LSA) | ||
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