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#1
12-20-2002, 02:23 PM
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SRP's pontiac 455 piston has a compression hieght of 1.48 inches. This puts the piston .034 in the hole. I think this piston is useless because you have to cut the deck so much to get 0 deck height. How much do you usually have to take off to true the decks? Am I missing something here?
10.244 - 6.625 - 2.105 - 1.48 = 0.034 block height - rod length - bore/2 - pistion comp. height = piston to deck clearance |
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#2
12-20-2002, 02:23 PM
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SRP's pontiac 455 piston has a compression hieght of 1.48 inches. This puts the piston .034 in the hole. I think this piston is useless because you have to cut the deck so much to get 0 deck height. How much do you usually have to take off to true the decks? Am I missing something here?
10.244 - 6.625 - 2.105 - 1.48 = 0.034 block height - rod length - bore/2 - pistion comp. height = piston to deck clearance |
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#3
12-20-2002, 03:22 PM
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Never did all the math but they have not been that far in the holes on the last couple of engines built here. Can't remember exactly how much was removed for zero deck, but it was not over .020"?.....cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#4
12-20-2002, 06:10 PM
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Seems the TRW are pretty close to that. Don't have my chart handy now though.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#5
12-20-2002, 08:48 PM
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[img]/infopop/emoticons/icon_biggrin.gif[/img]
Charlie
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Charlie |
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#6
12-20-2002, 08:50 PM
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Try this again
Charlie
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Charlie |
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#7
12-20-2002, 08:52 PM
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Try this again
About Compression Ratio Formula for CR CR = COMPRESSION RATIO = CYL. VOLUME @ BDC ÷ CYLINDER VOLUME @ TDC = 1 + (SWEPT VOLUME ÷ VOL @ TDC) = 1+ (0.7854 x BORE x BORE x STROKE) ÷ (CCV + HGV + PDV) CCV = Combustion Chamber Volume, in cubic inches Note: if volume is given in cc’s then ÷ 16.4 to get cubic inches. HGV = Head Gasket Volume, in cubic inches, = Head gasket compressed thickness x 0.7854 x bore x bore PDV = (Piston Deck Volume) + (Piston Dome Effective Volume) = (0.7854 x bore x bore x deck to piston distance) + (volume of piston depressions - volume of piston bumps) Example: What is CR of the engine in #9 if heads have 72 cc chamber, head gasket is compressed to 0.040 inch and flat top pistons give 0.025 deck clearance at TDC? CCV = 72 ÷ 16.4 = 4.39 cubic inches HGV = 0.040 x 0.7854 x 4.030 x 4.030 = 0.51 c.i. PDV = 0.025 x 0.7854 x 4.030 x 4.030+ 0- 0 = 0.32 c.i. CR = 1+ (0.7854 x 4.030 x 4.030 x 3.48 ÷ (4.39 + 0.51+ 0.32)) = 1+ (44.39 ÷ 5.22) = 9.5 CR Charlie
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Charlie |
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#8
12-20-2002, 08:55 PM
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Hope this works:
http://www.edelbrock.com/automotive/index.html Just scroll down half a page and they got the formula for CR. Charlie
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Charlie |
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#9
12-20-2002, 08:56 PM
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Sorry, computer illeriate.
Charlie
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Charlie |
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#10
12-21-2002, 06:01 AM
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Never had one that far in the hole. But I never owned a block that tall either. They were all around 10.220 range or so.
Furthest in the hole was .015 and depending on application that's fine. Build it fast, build it right, build a Pontiac. http://PontiacDude.cc |
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