318ti.org forum

Go Back   318ti.org forum > Technical, Maintenance and Modifications > Knowledge Base

Notices

Knowledge Base How to articles and things explained.

.
» Recent Threads
Happy Birthday ...
Today 05:00 AM
Last post by 1996 328ti
Today 05:00 AM
0 Comments, 94 Views
1998 BMW 318ti - 5...
04-09-2018 10:02 PM
Last post by savagepix
Today 01:06 AM
8 Comments, 943 Views
1999 BMW 318ti with M...
04-04-2018 05:00 AM
Last post by BRADESTAR
Yesterday 08:50 AM
6 Comments, 1,277 Views
Steering wheel won't...
04-14-2018 02:34 PM
Last post by Bobert1035
04-17-2018 07:03 PM
1 Comments, 309 Views
Feeler: DASC, Dinan...
04-15-2018 01:50 AM
Last post by 740isport
04-17-2018 05:46 PM
3 Comments, 632 Views
1995 ti total loss; free...
03-13-2018 12:01 AM
Last post by Bobert1035
04-17-2018 05:05 PM
3 Comments, 976 Views
for sale grey door cards...
04-17-2018 02:29 PM
Last post by derek502
04-17-2018 02:29 PM
0 Comments, 148 Views
Good deal on parts for...
03-21-2018 11:42 PM
Last post by dsamuel565
04-17-2018 07:40 AM
4 Comments, 923 Views
Wtb aftermarket exhaust
04-17-2018 05:33 AM
Last post by Platanos
04-17-2018 05:33 AM
0 Comments, 155 Views
Miscellaneous Parts for...
02-13-2018 09:56 PM
Last post by Earl
04-16-2018 10:07 PM
31 Comments, 5,248 Views
Comment Share/Bookmark
 
Tutorial Tools Display Modes
Fun with math: determine engine displacement
Fun with math: determine engine displacement
Published by J!m
02-09-2006
Default Fun with math: determine engine displacement

Determine displacement (D) of your engine…

Formula:
D=π/4 (B)2 x S x N

Where D= displacement
B=bore
S=stroke
N=number of cylinders

Example: six cylinder engine with a 3.5 inch bore and a 3.75 inch stroke.

D = π/4 (3.5)2 x 3.75 x 6 = 216.4753688 Cubic Inches (or just 216.5 rounded)

That's great for inches, but what about liters?

For metric units (liters) we must convert measurements to mm (or record them directly in mm), then convert cubic mm to cubic centimeters (if you want to know the CC's of the engine) then finally to liters if you want to know that.

There are exactly 25.400 mm in each inch. If you remember that, the rest is easy…

There are 1000 cubic millimeters in a cubic centimeter

There are 1000 cubic centimeters in a liter.

Therefore (using the same engine above, converting inches to mm):

D = π/4 (88.9)2 x 95.25 x 6 = 3547395.723 cubic millimeters
/ 1000 = 3547.395723 cubic centimeters
/ 1000 = 3.547395723 liters, or rounded, this is a 3.5 liter engine.

The above equation is fun if you have already or plan to over-bore your 'metric' engine. Even if you over-bore in inches (typically 0.010", 0.020", 0.030", 0.040" or 0.060" at most US engine shops) you can convert these numbers easily to mm, and plug them into your equation where the base numbers (numbers in engine manual or blueprint) are in mm. Simply multiply any inch measurements buy 25.4 to get mm.

Example, for a 0.020" over-bore, we simply add 0.508mm to our bore size (in the example above, that's 88.9mm) to get a revised bore size (89.408mm in the example) and a new displacement of 3588.053221cc or (rounded) 3.6 liters.

Wasn't that easy?
Tutorial Tools

  #1  
By demonicdelsol on 06-24-2011, 10:10 PM
Default sir

you can also do it this way....
(pi)3.14159265x bore radius squared x number of cylinders. also on metric (mm) you have to convert to cm when you do it this way. so if your bore stroke is 86x86 on a honda k20, it would be

pi(4.3squared x 8.6) x 4 = 1998.2.... 1liter = 1000cc, honda rounds up. 2.0L
Reply With Quote
Comment

Bookmarks


Currently Active Users Viewing This Tutorial: 1 (0 members and 1 guests)
 
Tutorial Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT +1. The time now is 06:11 PM.


.
Powered by site supporters
vBulletin Version 3.8.8
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright ©1999 - 2018, 318ti.org

Tutorial powered by GARS 2.1.8m ©2005-2006
© vBadvanced CMPS v3.2.2
[page compression: 62.51 k/74.20 k (15.76%)]

318ti.org does not warrant or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information or products discussed.