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
getBMWparts.com | MARCH...
Today 05:11 PM
Last post by Evan@Tischer
Today 05:11 PM
0 Comments, 33 Views
Ideas on Spring Rates
01-20-2017 01:02 PM
Last post by joe1602
Today 01:15 PM
9 Comments, 928 Views
1996 BMW 318ti CA top on...
01-22-2017 01:55 PM
Last post by baystint
Today 11:05 AM
4 Comments, 485 Views
318ti M package with...
07-11-2015 01:19 AM
Last post by BRADESTAR
Today 05:06 AM
28 Comments, 7,124 Views
Fs: 96 ti s50 swap
10-17-2016 08:19 PM
Last post by CASTRO
Today 04:30 AM
2 Comments, 1,090 Views
FS: 1998 Black BMW 318ti...
10-29-2016 07:52 AM
Last post by sven
Today 02:58 AM
8 Comments, 3,196 Views
alternator rebuild
09-28-2006 04:58 PM
Last post by paul somlo
Yesterday 10:39 PM
15 Comments, 2,154 Views
WTB: Shift Boot
01-22-2017 06:44 PM
Last post by adamcleepatrick
Yesterday 01:06 PM
1 Comments, 595 Views
water leaks door and...
10-17-2013 08:51 PM
Last post by Coyoteh
Yesterday 10:23 AM
15 Comments, 2,679 Views
WTB / Needed: OEM Radio...
02-26-2017 08:26 PM
Last post by DGWGuitars
02-27-2017 09:14 PM
3 Comments, 243 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 08:59 PM.


.
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: 62.37 k/74.04 k (15.77%)]

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