# B17 Crank into LS

#### 22crazy

##### Senior Member
is there a way to calculate the displacement using the stroke, bore, rod lenght? oh yah what about putting in a b17 crank into an ls...would that help to rev higher...and what are the draw backs

Yes, if you know bore and stroke you can calculate displacement.
Displacement in cc's (divide by 1000 to get liters) = r^2 * 3.14159 * stroke (in centimeters) * 4
r = 1/2 the bore in mm * 10
Yes, you can run a B17 crank in an LS engine, you lose displacement.

Originally posted by lsvtec@Feb 2 2003, 10:33 PM
r^2 * 3.14159 * stroke (in centimeters) * 4
r = 1/2 the bore in mm * 10

simpler way to say it- pi(r^2)s*cylinders=displacement
convert to cm (for mm to cm, move decimal one to the left), r=.5*bore, s=stroke

if you are using custom rods or something (shorter rods) deck height-.5s-rod=x
replace the s with the x in the formula above and add that to the answer you got.

ex: b18c block, b18c rods, b17 cranks;
3.14(4.05^2)8.14=419.4cc per cylinder, 1677.6cc total
18.15-(8.14*.5)-13.79=.29cm; 3.14(4.05^2).29=14.94cc per cylinder, 59.76cc gained

p.s. because of the extra space the compression ratio will be lower also.

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