Dynamic compression

Old 10-11-2010, 08:18 PM
  #1  
superstreeter
Senior Member
SENIOR BUILDER
Thread Starter
 
Join Date: Sep 2007
Location: Div VI
Posts: 122
Default Dynamic compression

How many engine builders really look at dynamic compression, when building an engine to run on pump gas, I want to use all the compression I can without getting knock,Ive used the calculators online, and Camshaft #s can really make a difference here with ABDC #s, how important is dynamic when building around a cam ? compression can change quite a bit from one cam to another..I`ve heard If I stay in the 7.75 to 8.0 to 1 range, this is best, so if I go with 10-1 static, cam selection gets tuff, or do I find a Cam and build the compression to match it ???
superstreeter is offline  
Old 10-12-2010, 06:26 PM
  #2  
superstreeter
Senior Member
SENIOR BUILDER
Thread Starter
 
Join Date: Sep 2007
Location: Div VI
Posts: 122
Default

Wow... no takers ? lol. I guess no one uses "Dynamic" ?
superstreeter is offline  
Old 10-12-2010, 09:24 PM
  #3  
kwkracing
Senior Member
RACING JUNKIE
 
Join Date: Dec 2004
Location: austin texas
Posts: 729
Default

The guys that know all the ins and outs of adjusting the compression as per the cam openings and overlaps are not going to freely give advise. I wish i knew more on this subject as well.
kwkracing is offline  
Old 10-12-2010, 10:18 PM
  #4  
cepx111
Senior Member
RACING JUNKIE
 
Join Date: May 2006
Posts: 2,044
Default

You might try Yellowbullet
cepx111 is offline  
Old 10-13-2010, 06:04 AM
  #5  
oldandtired
Senior Member
RACING JUNKIE
 
oldandtired's Avatar
 
Join Date: Dec 2008
Location: Sugar Hill, GA
Posts: 1,370
Default

Originally Posted by kwkracing
The guys that know all the ins and outs of adjusting the compression as per the cam openings and overlaps are not going to freely give advise. I wish i knew more on this subject as well.
Very difficult to measure, as even advancing / retarding the cam timing makes big changes in dynamic compression.

What we are talking about is the "capture" of the compression and the efficiency that the pistions movement has on drawing in the charge and expelling the spent gasses. Every aspect has a part in the process, timing, rod length, octane, plug heat range, intake plentum size, runner size, header size and length, etc.
oldandtired is offline  
Old 10-13-2010, 02:52 PM
  #6  
markdunlap
Senior Member
DYNO OPERATOR
 
Join Date: Jan 2004
Location: central Illinois
Posts: 459
Default Dynamic

Since you mentioned cam phasing, you may be able to select the optimum intake lobe centerline, in an asembled engine, by finding the highest cranking compression of different positions.
markdunlap is offline  
Old 10-13-2010, 04:49 PM
  #7  
superstreeter
Senior Member
SENIOR BUILDER
Thread Starter
 
Join Date: Sep 2007
Location: Div VI
Posts: 122
Default

couldnt that be done on a calculator ? or not ? lol
superstreeter is offline  
Old 10-13-2010, 09:13 PM
  #8  
jmarksdragster
Senior Member
RACING JUNKIE
 
jmarksdragster's Avatar
 
Join Date: Jul 2007
Location: Florida
Posts: 635
Default

http://www.yellowbullet.com/forum/sh...d.php?t=287013

Ignore the ranting of a lunatic over there.
jmarksdragster is offline  
Old 10-13-2010, 10:14 PM
  #9  
cepx111
Senior Member
RACING JUNKIE
 
Join Date: May 2006
Posts: 2,044
Default

Originally Posted by jmarksdragster

Ignore the ranting of a lunatic over there.
LMFAO :lol: :lol: ol~ Ed is a trip
cepx111 is offline  
Old 10-14-2010, 05:13 AM
  #10  
TheRabbit
Senior Member
RACING JUNKIE
 
TheRabbit's Avatar
 
Join Date: Jan 2007
Location: Augusta, Ga.
Posts: 2,295
Default

Originally Posted by superstreeter
Wow... no takers ? lol. I guess no one uses "Dynamic" ?
Well I'm not even gonna try to give an answer and show just how stupid I am. All I could do is call my motor builder (SVRE) and ask him. I'm sure he'd rattle off what you need to know or how to figure it, but I'd just get it all messed up by the time I tried to repeat it.
TheRabbit is offline  

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service