Fordmods Logo

oversized exhaust? loss of power 

 

Page 2 of 2 [ 19 posts ] Go to page Previous  1, 2

 
 Post subject: Re: oversized exhaust? loss of power
Posted: Tue Dec 03, 2013 8:10 am 
Getting Side Ways
Offline

Age: 29

Posts: 2563

Joined: 19th Feb 2007

Gallery: 21 images

Ride: 98 EL Futura

Power: 199 rwkw

Location: Lilydale
VIC, Australia

fiend wrote:
Sure I just said that? Ah well.


Ah yep i had this page just sitting there for a while and hadn't refreshed it

 

_________________

EL Futura: CVE head, Wolf V500, ICE Ignition and Coil, 36lb injectors, Walbro 255lb, Paci comps, 3" exhaust, T5, Harrop Truetrac with 3.9s. Now with 198.9rwkw, (~185rwkw and 13.80 @99.1mph) with more power to come

Top
 Profile  
 
 
 Post subject: Re: oversized exhaust? loss of power
Posted: Tue Dec 03, 2013 11:20 am 
Moderator
Offline

Posts: 14513

Joined: 7th Nov 2004

Ride: ford falcon au3 xr8

Location: a shit suburb in sydney
NSW, Australia

wrongwaynorris wrote:
WARMACHINE wrote:
The reason why the car feels slow to get going is because it is a ford falcon, it weights near on 2 tonne with people in it...

The exhaust is fine theres nothing wrong with it, myths about exhaust being too big are just that.


Wrong , ever heard of back pressure ? Companies like Caterpillar spend millions of dollars on computer programs to calculate things such as back pressure and dew point . Exhaust size is critical .



your comparing a large capacity low revving high torque diesel engine that needs as much torque as possible at lower rpms to a smaller higher revving efi petrol engine..
look at high performance or race cars, there is next to no back pressure..
so as long as the engine in question has reasonable headers and matching size cat the rest of the system is either or neither imo... having a to small exhaust can hinder the max output of an engine, but within reason a larger than required exhaust isn't going to kill power out put...
I had 2 1/2 and a 3" system on my au i6 and other than the noise difference it made no difference in how the car performed....
Top
 Profile  
 
 
 Post subject: Re: oversized exhaust? loss of power
Posted: Tue Dec 03, 2013 2:11 pm 
Getting Side Ways
Offline
User avatar

Age: 25

Posts: 4599

Joined: 30th Aug 2010

Ride: BF XR6,

Location: NEWCASTLE
NSW, Australia

Jmm said they gained 4rwkw on a ba going from their 2.5 to a 3 inch exhaust.that was on an unopened engine.

 

_________________

BF XR6
xr8 snorkel,typhoon lower snorkel,territory intake pipe,20% underdrive kit,pacemaker extractors,high flow cat,xforce exhaust,t56 conversion hd turbo clutch/ flywheel,m86 3.45 lsd,custom tune187.1rwkw as an auto

Top
 Profile  
 
 
 Post subject: Re: oversized exhaust? loss of power
Posted: Tue Dec 03, 2013 3:41 pm 
Getting Side Ways
Offline
User avatar

Posts: 1427

Joined: 21st May 2005

Location: Melbourne
VIC, Australia

Back pressure is the most evil word ever. It is a by product, not a target.

A choke can be a benefit in a designed exhaust system, but it is far from the simply being "back pressure"
A choke is normally used in a merge collector to speed up the flow through it, and restrict the back flow.


An example I use is if you have your manifold exit in to a pipe 1m in diameter that has a cap on the end with a very small hole to simulate the 'back pressure' of say a 2" pipe. The results would be very different to actually using a 2" pipe.
What this demonstrates is that there's more to it than just size.
Some exhaust builders actually use something similar to this example, called a wave termination box. this lets the header act they way they planned while still being able to attach to an exhaust system.

With the right header, you can have any size exhaust system you want. (as long as it's not a restriction)

 

_________________

EL Fairmont Ghia - Manual - Supercharged
- The Car
- The Headlights

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 2 of 2  [ 19 posts ]  Go to page Previous  1, 2

Who is online

Users browsing this forum: No registered users and 13 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 Sun Dec 17, 2017 4:04 pm All times are UTC + 11 hours

 

 

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