Honda-Tech - Honda Forum Discussion

Notices
Tech / Misc Tech topics that don't seem to go elsewhere.

Oversized pistons, what in MM does .xx mean??

   
Old 01-21-2002, 08:39 PM
  #1  
B18C-EJ1
Guest
 
Posts: n/a
Default Oversized pistons, what in MM does .xx mean??
I'm trying to get the exact size of my pistons.

So what is each one in mm?

10 over?
20 over?
25 over?

You get the idea. Is there a formula I could use?

Thanks
 
Reply Like
Old 01-21-2002, 08:51 PM
  #2  
Honda-Tech Member
 
earl's Avatar
 
Join Date: Jun 2001
Location: Irvine, CA, usa
Posts: 8,120
Likes: 0
Received 1 Like on 1 Post
Default Re: Oversized pistons, what in MM does .xx mean?? (B18C-EJ1)
1 mm = .03939 inches
10 over = .010 inches larger
81 mm x .03939 = 3.19059 diameter in inches
earl is offline  
Reply Like
Old 01-21-2002, 09:15 PM
  #3  
vhd
Junior Member
 
vhd's Avatar
 
Join Date: Jul 2001
Location: bay area, california
Posts: 214
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Oversized pistons, what in MM does .xx mean?? (B18C-EJ1)
you can also use this formula to change mm to inches or vice versa

X (mm) divided by 25.4 = X (in inches).....i.e. 81.5mm divided by 25.4 = 3.209"

or

X (inches) times 25.4 = X (in mm).......i.e. 3.209" times 25.4 = 81.5mm
vhd is offline  
Reply Like
Old 01-21-2002, 09:45 PM
  #4  
B18C-EJ1
Guest
 
Posts: n/a
Default Re: Oversized pistons, what in MM does .xx mean?? (vhd)
So, If I used 25 over pistons, they are 81.64mm?

Is that right?

81mm = 3.189
25over = 3.214

3.214= 81.64mm

I'm rounding to .xx digits.
 
Reply Like
Old 01-21-2002, 10:00 PM
  #5  
sgT
Honda-Tech Member
 
sgT's Avatar
 
Join Date: Apr 2000
Location: WI
Posts: 8,757
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Oversized pistons, what in MM does .xx mean?? (B18C-EJ1)
Most people that refer to 25 over mean .25mm overbore.
sgT is offline  
Reply Like
Old 01-21-2002, 11:44 PM
  #6  
B18C-EJ1
Guest
 
Posts: n/a
Default Re: Oversized pistons, what in MM does .xx mean?? (sgT)
So that would make it 81.25mm?
 
Reply Like
Old 01-22-2002, 09:17 PM
  #7  
vhd
Junior Member
 
vhd's Avatar
 
Join Date: Jul 2001
Location: bay area, california
Posts: 214
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Oversized pistons, what in MM does .xx mean?? (B18C-EJ1)
you had it right, your bore would be 3.214" or 81.63mm with the .025"/.635mm over
vhd is offline  
Reply Like

Trending Topics

Old 01-22-2002, 09:48 PM
  #8  
Honda-Tech Member
 
earl's Avatar
 
Join Date: Jun 2001
Location: Irvine, CA, usa
Posts: 8,120
Likes: 0
Received 1 Like on 1 Post
Default Re: Oversized pistons, what in MM does .xx mean?? (B18C-EJ1)
Simply stated, .5 mm overbore equals .020 inches overbore
earl is offline  
Reply Like
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
81.5 mm pistons
honda_ef9
All Motor / Naturally Aspirated
1
03-22-2007 03:49 PM
Piston size? before and after hone . . .
Dent Free
Tech / Misc
2
06-14-2004 02:29 PM
What does .20 over means when talking about pistons....
mz3bo
Tech / Misc
6
04-27-2003 10:15 PM
83mm v/s 81mm pistons?
Benny Z
Forced Induction
18
12-20-2002 03:35 AM
differences between standard bore and .25 overbore pistons?
JDMvtecDRAGSTA
Honda Civic / Del Sol (1992 - 2000)
2
07-02-2002 01:17 AM
Tags
Back to Subforum
Tech / Misc
View Next Unread
Anyone kind enough to give me torque specs on suspension bolts.


Thread Tools
Search this Thread
Search this Thread:

Advanced Search

Advanced Search
Quick Reply: Oversized pistons, what in MM does .xx mean??


Reply Closed Thread Share

All times are GMT -8. The time now is 07:21 AM.