Fordmods Logo

Head to exhaust match 

 

Page 1 of 1 [ 13 posts ] 

 
 Post subject: Head to exhaust match
Posted: Sat Jul 02, 2005 7:44 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

I've been thinking recently about my Pacemaker headers which have a primary size of 1 5/8" ( 44mm ) and what the exhaust port size of the GT40P is and whether they will match properly. Does anyone know? Will the exhaust port be smaller than the header primary?

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sat Jul 02, 2005 8:32 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 1440

Joined: 7th Nov 2004

Ride: 320kw BA XR8

Location: Adelaide
SA, Australia

The exhaust ports will be a fair bit smaller, and thats the way it is suppose to be, you dont match the port sizes on the exhaust.
Top
 Profile  
 
 
Posted: Sat Jul 02, 2005 9:18 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

But doesn't going from a smaller exhaust port into a larger diammeter primary give some torque loss? That the suddenly larger opening robs the engine of torque?

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sat Jul 02, 2005 9:59 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 1440

Joined: 7th Nov 2004

Ride: 320kw BA XR8

Location: Adelaide
SA, Australia

Yes going too large will reduce torque but the design of the tri-y pacemakers maintains the low down torque while giving plenty of flow.
Top
 Profile  
 
 
Posted: Sat Jul 02, 2005 10:17 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

The reason I ask is that when I had Mick Webb look at my car briefly previously, we got to talking about exhausts and GT40P heads and he was saying that the primaries of my headers are too large for the heads and that it robs it of torque. The thing is I cannot remember if he was talking about my E7's or the GT40P's which was the main discussion, hence my curiosity. I was trying to learn just what exhaust port size would be too small for the Pacemaker headers I have and how to know when it is okay or a problem or even if porting would help out.
Feel free to educate me.

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sat Jul 02, 2005 10:56 pm 
Getting Side Ways
Offline

Age: 44

Posts: 661

Joined: 2nd Dec 2004

Ride: AU XR8

Location: Wollongong
NSW, Australia

What headers are you running Vic?
Top
 Profile  
 
 
Posted: Sat Jul 02, 2005 11:08 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

PH 4000.

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sun Jul 03, 2005 6:22 am 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 1440

Joined: 7th Nov 2004

Ride: 320kw BA XR8

Location: Adelaide
SA, Australia

The PH4000's are an excellent match IMO, they don't seem to loose low down torque at all. The pacemaker tri-y design probably helps the greatest here, maintaining enough backpressure to keep the low down torque but also flow enough to produce good peak power.

I will get the actual measurements of the GT40P vs Pacemaker PH4000's tomorrow as my heads are off at the moment. There is still plenty of room in the GT40P's for porting while still keeping enough exhaust port to header difference to aid in the scavenging process but IMO the PH4000 headers aren't too big and porting or smaller primaries are not needed.
Top
 Profile  
 
 
Posted: Sun Jul 03, 2005 1:27 pm 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

Appreciated.
I was certainly wondering how precise Mick Webb prefers to match headers to heads and if he was referring to my E7's or the GT40P's. I'd always assumed that GT40P's might be harder to port for matching to headers because maybe there wouldn't be enough meat on the bone so to speak to safely shave off - if I was to worry about it.

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Sun Jul 03, 2005 9:49 pm 
Getting Side Ways
Offline

Posts: 6449

Joined: 11th Nov 2004

there is more to it then just the size of the port and size of the header.

things like the length of the primary and secondary pipe.

the shape of the pipe as it come off the head.

and the miss match of port to header is also a very critical part of the deal.

the wrong miss match can be the down fall of even an otherwise perfect header
Top
 Profile  
 
 
Posted: Mon Jul 11, 2005 2:11 am 
Getting Side Ways
Offline
User avatar

Posts: 6432

Joined: 5th Nov 2004

Gallery: 6 images

EDXR8, did you have a chance to measure the exhaust ports on your GT40P's?

 

_________________

5.6L of carbon footprint.

Top
 Profile  
 
 
Posted: Mon Jul 11, 2005 2:47 am 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 1440

Joined: 7th Nov 2004

Ride: 320kw BA XR8

Location: Adelaide
SA, Australia

Nope I forgot, I am working on them tomorrow so will do it then and post the measurements.
Top
 Profile  
 
 
Posted: Wed Jul 13, 2005 12:46 am 
Stock as a Rock
Offline
User avatar

Age: 48

Posts: 117

Joined: 16th Apr 2005

Gallery: 9 images

Ride: ED Fairmont Ghia 5.0L

Location: Brisbane
QLD, Australia

My GT40P's and Paceys matched up perfectly.
Across the port was a good match. I was checking it out with calipers a while back.
The stock E7 heads would do better with 1 1/2" primaries I think.

 

_________________

ED Fairmont Ghia.
306ci, Pro-m 80 MAF & #42inj, Kirban AFPR, Walbro 255LPH intank & inline, BBK 70mm, Ported Edelbrock #60399, Ported Explorer, Crane 2031 & YT1.72, MSD 6AL, paciemaker tri-y, 2.5" cats into single 3". 3.45 lsd, Powerdyne XB1A.

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 1  [ 13 posts ] 

Who is online

Users browsing this forum: No registered users and 50 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 Mon Dec 23, 2024 2:22 pm All times are UTC + 11 hours

 

 

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