Displacement Question
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Master Ho
If a 350 CID is overbored .080, what's the new displacement, in cubic inches? TIA.
Master Ho
Master Ho
can they go that much?
Safety Car
Joined: Mar 2005
Posts: 4,255
Likes: 82
From: Brampton Ont.
I was always told that if you go 30 over, the cylinder walls start getting to thin and your prone to overheating. Enhancement may have to be made to the cooling system to compensate. If you looking for ways to increase your cubic inch displacement to gain horsepower........there are other ways to achieve that.
Drifting
Joined: Mar 2003
Posts: 1,608
Likes: 3
From: Canberra AUSTRALIA
St. Jude Donor '05-'06
Originally Posted by Master Ho
If a 350 CID is overbored .080, what's the new displacement, in cubic inches? TIA.
Master Ho
Master Ho
PI = 3.14159265359
Its all about area x stroke. You make the area bigger but the stroke is the same unless you get a stroker crank.
SB 350 has 8 cylinders with a 3.48" Stroke with a 4" Bore
D= 4" = 2R
R = 2"
CI = 8 x Stroke x Area
= 8 x 3.48" x 2" x 2" x PI
= 349.85 CI
= 350 CI
With a 0.030" over you get a 4.030" Bore and hence:
R = 2.015"
CI = 8 x 3.48" x 2.015" x 2.015" x PI
= 355.11 CI
= 355CI
With a 0.060" over you get a 4.060" Bore and hence:
R = 2.030"
CI = 8 x 3.48" x 2.030" x 2.030" x PI
= 360.421 CI
= 360CI
With a 0.080" over you get a 4.080" Bore and hence:
R = 2.040"
CI = 8 x 3.48" x 2.040" x 2.040" x PI
= 363.9816CI
= 364CI :o
Now what happens if you stroke that 0.080 with a SB400 crank (3.75")
You get:
CI = 8 x 3.75" x 2.040" x 2.040" x PI
= 392.22 CI
= 392CI
Counting, Counting, Always Counting (sinister laugh) as cookie monster enters on stage right........
Drifting
Joined: Mar 2003
Posts: 1,608
Likes: 3
From: Canberra AUSTRALIA
St. Jude Donor '05-'06
Originally Posted by Maymyvetteliveforevr
I was always told that if you go 30 over, the cylinder walls start getting to thin and your prone to overheating. Enhancement may have to be made to the cooling system to compensate. If you looking for ways to increase your cubic inch displacement to gain horsepower........there are other ways to achieve that.
Like you said though the more you cut out, the closer you get to the water jacket. I have seen books where that is filled with concrete (serious stuff there) so that the water jacket doesn't allow the block to flex.
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Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Originally Posted by Gordonm
At .080 on a SB the walls are so thin they would not hold up at all. .060 is pushing it. If you are loking for extra cubes stroke it.