Fordmods Logo

Adv duration 

 

Page 1 of 1 [ 9 posts ] 

 
 Post subject: Adv duration
Posted: Sat Apr 15, 2006 3:00 am 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

How do you calculate / convert the duration @ .050 lift to Advertised Duration?

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sat Apr 15, 2006 3:17 am 
Getting Side Ways
Offline
User avatar

Posts: 3115

Joined: 20th Dec 2004

Ride: Falcon

Location: Adelaide
SA, Australia

AFAIK there is no conversion

If the lobes have steep ramp angles, the 50 thou duration will be closer to the duration, opposite for shallower ramp angles

 

_________________

Stoke me a clipper, I'll be back for Christmas

Top
 Profile  
 
 
Posted: Sat Apr 15, 2006 11:36 am 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

So how is the adv. duration calculated from cam specs?

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sat Apr 15, 2006 4:55 pm 
Getting Side Ways
Offline
User avatar

Posts: 3115

Joined: 20th Dec 2004

Ride: Falcon

Location: Adelaide
SA, Australia

Advertised duration is just the duration of valve lift above some value. SAE specify advertised duration as lift above 6 thou but apparently this is fudged by lots of cam grinders. Duration at 50 thou lift is a better indication as it cancels out a lot of factors that might make the cam seem bigger or smaller than it really is.

 

_________________

Stoke me a clipper, I'll be back for Christmas

Top
 Profile  
 
 
Posted: Sat Apr 15, 2006 5:07 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

I prefer to use the duration @ 0.050 lift myself, however, its amazing how many people refer to the adv. duration when discussing cam specs so I thought I'd find out what its all about.

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sun Apr 16, 2006 8:10 pm 
Tyre Shredder
Offline

Posts: 311

Joined: 3rd Jan 2006

Location: tauranga
New Zealand

advertised duration is the figure that the valve opens say 10 deg before to the figure it closes say 10 deg abdc which would be 200 deg adv , dur at 50 thou is the measurement at 50 thou opening to 50 thou b4 closing ,some cams differ, if difference is less between adv and 50 thou means valves open quicker like haveing longer duration more power better acceleration without neg side of longer duration that is the benefit of roller cams which are able to open valves quickly (ramp up quick)
Top
 Profile  
 
 
Posted: Sun Apr 16, 2006 8:54 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

fairy v8 wrote:
means valves open quicker like haveing longer duration more power better acceleration without neg side of longer duration that is the benefit of roller cams which are able to open valves quickly (ramp up quick)

Yep, this is one of the reasons why I love the roller cam. One of the down sides though, is the expense of them.

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
 Post subject: adv, duration
Posted: Sun Apr 16, 2006 11:12 pm 
Getting Side Ways
Offline

Age: 66

Posts: 2548

Joined: 18th Mar 2006

Ride: EF-XR8chaser

Location: wollongong
NSW, Australia

Vic wrote:
fairy v8 wrote:
means valves open quicker like haveing longer duration more power better acceleration without neg side of longer duration that is the benefit of roller cams which are able to open valves quickly (ramp up quick)

Yep, this is one of the reasons why I love the roller cam. One of the down sides though, is the expense of them.
it could be worse ----flat lifters------plenty of wear!!!

 

_________________

R.I.P HANS HARTMAN

Top
 Profile  
 
 
 Post subject: adv, duration
Posted: Sun Apr 16, 2006 11:14 pm 
Getting Side Ways
Offline

Age: 66

Posts: 2548

Joined: 18th Mar 2006

Ride: EF-XR8chaser

Location: wollongong
NSW, Australia

Vic wrote:
fairy v8 wrote:
means valves open quicker like haveing longer duration more power better acceleration without neg side of longer duration that is the benefit of roller cams which are able to open valves quickly (ramp up quick)

Yep, this is one of the reasons why I love the roller cam. One of the down sides though, is the expense of them.
it could be worse ----flat lifters------plenty of wear!!!

 

_________________

R.I.P HANS HARTMAN

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 1  [ 9 posts ] 

Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Fri Dec 15, 2017 4:21 am All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names