Parts Catalog Accessories Catalog Tech Info Tech Forums
 
  Search our site:    
 Cart  | Project List | Order Status | Help    
  We salute a legendary member of the community.
Thank you for selflessly sharing your wisdom with us...
Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > Porsche 911 Technical Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
too many projects 1983 sc
 
56 nomad's Avatar
 
Join Date: Nov 2008
Location: los angeles
Posts: 543
Garage
exhaust valves open?

hello,
I know many of you know this info by heart...i do not so i am hoping i can get pointed in the right direction.
will someone tell me where i can find information about the 911 valve train....more specifically i would like to know which exhaust valves are partially open as the engine rotates in the cylinders. i want to better understand the compression of the intake and exhaust cycle.
looking for some light reading.
regards, ben
Old 10-18-2011, 07:12 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #1 (permalink)
Registered User
 
Tim L's Avatar
 
Join Date: Jul 2001
Location: Hamden, CT, USA
Posts: 427
HowStuffWorks "Internal Combustion"
__________________
Tim Lynn
84 911 Carrera
PCA E Stock #278
Old 10-18-2011, 07:29 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #2 (permalink)
too many projects 1983 sc
 
56 nomad's Avatar
 
Join Date: Nov 2008
Location: los angeles
Posts: 543
Garage
Quote:
Originally Posted by Tim L View Post
Tim,
thanks for responding ...let me ask the question another way ( same way?) as i understand how the internal combustion engine works but am trying to get a handle on the sequence of the cycle (combustion and ehaust). for example at tdc number 1 cylinder both valves are closed before combustion...in cylinder 6 (after 1 fires) exhaust closed intake beginning to open (drawing in fuel and air for combustion stroke etc. etc.
in the other cylinders which exhaust valves are beginning to open or are closed etc.
hope i made it clearer and not more confusing, ben
Old 10-18-2011, 08:21 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #3 (permalink)
Registered User
 
Tim L's Avatar
 
Join Date: Jul 2001
Location: Hamden, CT, USA
Posts: 427
it's the same in all cylinders it just happens in the sequence of the firing order of the engine in question. in a 6 cylinder there are two cylinders at top dead center at a time one is in compression and one is in exhaust then at 120 degrees of crank rotation the next two are up.... the firing sequence will tell you the order
__________________
Tim Lynn
84 911 Carrera
PCA E Stock #278
Old 10-18-2011, 08:52 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #4 (permalink)
Max Sluiter
 
Flieger's Avatar
 
Join Date: Mar 2006
Location: So Cal
Posts: 18,455
Garage
Do you want the valve timing for an individual cylinder- like the overlap? That info is in Porsche 911 Story by Paul Fere. The firing order is 1-6-2-4-3-5 I think.
__________________
911S
1971 chassis, 2.7RS spec MFI engine, suspension mods, lightened

Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance
http://www.flickr.com/photos/max_911_fahrer/
Old 10-18-2011, 09:05 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #5 (permalink)
Registered User
 
T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 5,536
the only way i can think to answer it is starting with #1TDC, starting its power/down stroke after combustion.
you would also have to know what the cam timing of the motor you are talking about, IE when the valves open and close, if you wanted to be exact as far has how open/closed is a valve.

since one cylinder fires every 120 degrees of crank rotation,
#1 is TDC, the spark plug has fired, combustion has/is taken place and the piston is starting its power stroke, both valves closed.
#6 would be at 240 degrees, both valves are closed and it is on its compression stroke.
#2 would be at 120 degrees, and on the intake stroke with the intake valve open.
#4 would be at TDC, valve overlap (which is where cam timing is set), and it has just completed its exhaust stroke and begining its intake stroke. with most cams, both valve are slightly open with the exhaust closing and the intake opening.
#3 is at 240 degrees and on the exhaust stroke. exhaust open.
#5 is at 120 degrees nearing the bottom of its power stroke, both valves closed.

hope this helps.
start at TDC and work CCW in firing order.
__________________
86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ [__] RUNNING: [__] NOT RUNNING:
2000 MERCEDES E320 WAGON [____] WRECKED:[__]RUNNING:
99 GRAND CHEROKEE 160K:: [__] RUNNING: [__] NOT RUNNING:
02 HONDA ACCORD[__] RUNNING: [__] NOT RUNNING::
Old 10-18-2011, 09:06 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #6 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
too many projects 1983 sc
 
56 nomad's Avatar
 
Join Date: Nov 2008
Location: los angeles
Posts: 543
Garage
Quote:
Originally Posted by T77911S View Post
the only way i can think to answer it is starting with #1TDC, starting its power/down stroke after combustion.
you would also have to know what the cam timing of the motor you are talking about, IE when the valves open and close, if you wanted to be exact as far has how open/closed is a valve.

since one cylinder fires every 120 degrees of crank rotation,
#1 is TDC, the spark plug has fired, combustion has/is taken place and the piston is starting its power stroke, both valves closed.
#6 would be at 240 degrees, both valves are closed and it is on its compression stroke.
#2 would be at 120 degrees, and on the intake stroke with the intake valve open.
#4 would be at TDC, valve overlap (which is where cam timing is set), and it has just completed its exhaust stroke and begining its intake stroke. with most cams, both valve are slightly open with the exhaust closing and the intake opening.
#3 is at 240 degrees and on the exhaust stroke. exhaust open.
#5 is at 120 degrees nearing the bottom of its power stroke, both valves closed.

hope this helps.
start at TDC and work CCW in firing order.
T77,
exactly what i was looking for....i guess i could have figured it out, thanks for helping me save my few remaining grey cells! let's close the thread.
thanks again and regards , ben
Old 10-18-2011, 11:05 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #7 (permalink)
Registered User
 
HawgRyder's Avatar
 
Join Date: Feb 2002
Location: Langley, BC Canada
Posts: 2,796
Garage
Send a message via ICQ to HawgRyder
Internal Combustion Engine.....Suck...Squeeze...Bang...Blow.
And there you have it.
Bob
__________________
Bob Hutson
Old 10-18-2011, 01:07 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #8 (permalink)
Registered User
 
db_cooper's Avatar
 
Join Date: Nov 2007
Location: Decatur, Ga.
Posts: 708
Garage
Combustion Chamber - YouTube

Whats missing from the video is the scavenge stroke..
Old 10-18-2011, 01:28 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #9 (permalink)
Old 10-18-2011, 01:28 PM
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:21 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.