Displacement Question
Thread Starter
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MUST GO FASTER!!!!
Joined: Aug 2020
Posts: 1,538
Likes: 356
From: Arizona
Displacement Question
This is more less inconsequencial, but i was telling someone i ran into at the auto parts store about my engine and told them about the rebuld, showed them pictures, and the such
When i mentioned it was bored 030 over, they asked, oh, what is the new displacement, and well, its a good question....
using ford numbers i found for the stock engine i came up with the following, any of you know if its accurate?
I used this calculator here: https://performancetrends.com/Calcul...splacement.php
Stock Bore: 3.552
Stock Stroke: 4.165
Cylinders: 10
Comes up at 412.72 Cubic inches for a stock motor which is 2 and change off Fords spec of 415 CI, but then on another site someone mentioned the extra 2.28 cubes come because of the dished pistons which makes sense to me.
So using the same math i added the 030 to the bore number and did the following math on the same calculator
Bore: 3.582
Stroke: 4.165
Cylinders: 10
And according to this calculator my new displacement is 419.72, but then add in the 2.28 for the dished pistons, so a new total of 422 cubic inches?
Is this correct?
When i mentioned it was bored 030 over, they asked, oh, what is the new displacement, and well, its a good question....
using ford numbers i found for the stock engine i came up with the following, any of you know if its accurate?
I used this calculator here: https://performancetrends.com/Calcul...splacement.php
Stock Bore: 3.552
Stock Stroke: 4.165
Cylinders: 10
Comes up at 412.72 Cubic inches for a stock motor which is 2 and change off Fords spec of 415 CI, but then on another site someone mentioned the extra 2.28 cubes come because of the dished pistons which makes sense to me.
So using the same math i added the 030 to the bore number and did the following math on the same calculator
Bore: 3.582
Stroke: 4.165
Cylinders: 10
And according to this calculator my new displacement is 419.72, but then add in the 2.28 for the dished pistons, so a new total of 422 cubic inches?
Is this correct?
Super Moderator
Joined: Apr 2004
Posts: 34,527
Likes: 2,831
No. The dish or pop up or flat of the piston has nothing to do with displacement. It's volume of a cylinder x the number of cylinders. Straight geometry. "Advertised " displacement might be rounded, based on an inaccurate conversion from metric to inches or simply made up to sound better. 427s were actually 425s, and there are others.
More Turbo
Joined: Sep 2015
Posts: 640
Likes: 282
From: Texas
This kind of imaginative "rounding up" happens everywhere. The same way .44 magnum mics out at .429. Honesty would mean calling it the .43 magnum but who would buy that?
it's even worse in motorcycles where 1000cc's is really 963 because reasons.
it's even worse in motorcycles where 1000cc's is really 963 because reasons.
Thread Starter
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MUST GO FASTER!!!!
Joined: Aug 2020
Posts: 1,538
Likes: 356
From: Arizona
since no one knows, until a better answer comes along, im just going to split the difference and say its 420 CI
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Super Moderator
Joined: Apr 2004
Posts: 34,527
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The caluclator above agrees with other calculators and at .030 over you end up with 419.72. 420 is close enough.
https://www.omnicalculator.com/math/cylinder-volume
https://www.omnicalculator.com/math/cylinder-volume
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