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
E36 compact M3 CSL style...
01-13-2015 10:53 AM
Last post by madfronter
Yesterday 09:03 PM
69 Comments, 22,438 Views
Part out from former...
12-08-2016 08:09 AM
Last post by 95///M3
Yesterday 08:26 PM
4 Comments, 940 Views
alternator rebuild
09-28-2006 04:58 PM
Last post by paul somlo
Yesterday 07:17 PM
4 Comments, 694 Views
Front Sport struts and...
Yesterday 06:54 PM
Last post by ZEK
Yesterday 06:54 PM
0 Comments, 74 Views
1995 332ti Suwanee
12-13-2016 01:48 PM
Last post by dahamler
Yesterday 01:05 AM
3 Comments, 1,762 Views
Suspension bits
01-12-2017 09:17 PM
Last post by mtgoatboy
Yesterday 12:16 AM
7 Comments, 551 Views
Last 6 digits of the VIN...
01-16-2017 09:17 PM
Last post by Dr Shuffles
01-17-2017 05:53 PM
4 Comments, 241 Views
FS: 1998 Black BMW 318ti...
10-29-2016 07:52 AM
Last post by austinindian
01-17-2017 03:52 PM
6 Comments, 1,978 Views
Hi all from Northville...
01-14-2017 09:23 PM
Last post by Mr2race
01-17-2017 01:22 PM
3 Comments, 256 Views
Panic!
01-16-2017 09:52 PM
Last post by paul somlo
01-17-2017 09:36 AM
1 Comments, 247 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, 11:10 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 09:45 AM.


.
Powered by site supporters
vBulletin Version 3.8.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright ©1999 - 2017, 318ti.org

Tutorial powered by GARS 2.1.8m ©2005-2006
© vBadvanced CMPS v3.2.2
[page compression: 62.68 k/74.36 k (15.71%)]

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