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
Parting out 96 318ti M...
04-26-2015 02:52 AM
Last post by marleymon
Today 12:13 PM
20 Comments, 791 Views
Mike's e36 Compact Build...
02-14-2014 08:15 AM
Last post by Earl
Today 11:26 AM
228 Comments, 32,825 Views
Tackling knock sensors
04-11-2015 11:08 PM
Last post by bazar01
Today 11:17 AM
28 Comments, 1,606 Views
1996 318ti with 118k...
Today 06:42 AM
Last post by Coopster121
Today 06:42 AM
0 Comments, 12 Views
1996 318ti M-sport...
06-10-2014 02:32 PM
Last post by trevor557
Today 06:10 AM
3 Comments, 1,386 Views
Ti track pics
12-20-2009 03:35 PM
Last post by BlackBMWs
Today 02:44 AM
175 Comments, 30,084 Views
New(ish) member from...
Yesterday 11:07 PM
Last post by cuseikan
Yesterday 11:07 PM
0 Comments, 94 Views
Comprehensive Brake Info...
11-25-2008 09:25 PM
Last post by twdavis1
Yesterday 03:23 PM
81 Comments, 23,575 Views
Bremi Spark Plug Wire...
04-21-2015 02:36 PM
Last post by Jsch
Yesterday 03:20 PM
1 Comments, 258 Views
Parting out Euro Compact
08-23-2013 09:44 PM
Last post by Shellback
Yesterday 02:46 PM
204 Comments, 28,490 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 01:00 PM.


.
Powered by site supporters
vBulletin Version 3.8.8
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Copyright ©1999 - 2015, 318ti.org

Tutorial powered by GARS 2.1.8m ©2005-2006
© vBadvanced CMPS v3.2.2
[page compression: 62.81 k/74.50 k (15.69%)]

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