351W .30 over bore = ?

Mstng2

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Jun 27, 2002
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Hey here one for the engineers out there and High perfomance engine guys/gals! I am going to put the displacement of the engine on the side of my cowl scoop when it's finished. It's a 351W bored .30 over. Does anyone know or can calculate the actual displacement of the engine for me?? I'm guessing around 368 or so but would like to be specific and have custom graphics made for it.
THanks in advance! :nice:
 
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3.5 stroke x 4.030 bore rounds up to 357 cubic inches. (unless you remove all floating points, of course, which is against standard mathematical rules)

You actually gain more cubic inches from boring a motor with a longer stroke than you do by boring a motor with a shorter stroke, but it's not usually a big difference.

If you increase the bore of a motor by .030" which has a 2" stroke, you will only gain 3 cubic inches of displacement. While boring a motor by .030" which has a 5" stroke will yield an increase of 7 cubic inches. (rounded up, when applicable)
Of course, that difference, while remaining proportionately similar, becomes far more apparent(and valuable from a performance perspective) when you further increase overbore:
2" stroke x +.100" = +11 cubic inches.
5" stroke x +.100" = +25 cubic inches.

By the way, why not take a jab at the imports and put 1.9L (x3) on the cowl?
 
http://www.edelbrock.com/automotive/math.html


Formula for CID (cubic inch displacement)
CID = NUMBER OF CYLINDERS x SWEPT VOLUME


Note: CID = N x 0.7854 x bore x bore x stroke (all in inches)

Example: What is CID of a V8 with a “30 over”, 4 inch bore and 3.48 inch stroke?

CID = 8 x 0.7854 x 4.030 x 4.030 x 3.48 = 355 cu. inches


or you could use Volume = Pi X r(squared) X H




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



http://www.edelbrock.com/automotive/math.html