Headers over a catback system?

[BigNige]

How much extra might one expect to get on a CV8?

[BO55 VXR]

Certainly +50 points on the Grin Gauge

BTW: You get my email...Suspension now @ Greens

Edited by BO55 VXR on Sunday 24th September 21:14

[BigNige]

**checks**...


Yes I did Chris, thanks and apols for not replying.

Any idea how many torques?

[ringram]

From info gathered cat back is best for power then headers. Of course both mods are required before going further down the NA or SC route.
Dual 2.5 is good for around 500 engine bhp, if you are planning more than that dual 3" is good to somewhere a little north of 700bhp. There is an excellent exhaust article here including tables and formula to zero your own application in. www.popularhotrodding.com/enginemasters/articles/hardcore/0505em_exh/index.html

[BigNige]

Tbh I don't really use the 400 I have that much and doubt many folk here honestly do ona regular basis.

It's more about bragging rights if I'm totally truthful...isn't it?

[ringram]

Well, it depends...

It could also be about maximizing efficiency? You might want to leave your car standard and optimise the configuration.. Or you might want to go for an 11.x timeslip at the track. Others might want a dyno queen that is optimised for dyno power.

An efficient engine can also be more economical.

When all is said and done it depends on what the owner wants. Personally its about fully optimising what I have while not breaking the bank too badly.

[Twin Turbo]

Surely it just depends on what sound you like.

Cat Back = 10 on the volume scale
Headers = Your ears will bleed

[Le Sarthe]

Better headers generally = better torque. Different header designs will offer better power over torque gains and vice versa as I understand it but the sound comparison is wow but you know that BigNige.

I had catback first then headers and the difference in oomph was quite considerable..

[ringram]

Actually its muffler design that has the most effect on noise. Of course you need the minimum pipe to remove power restrictions, then its down to the mufflers to handle the sound.

[biglump]

Lesarthe,

Which system did you go for i.e. Manufacturer???

[Le Sarthe]

I had an 04 VXR catback on my 04CV8 for a couple of months and was one of the first original Wortec systems which had Pacemaker Headers (still got them). Very good system loud as you like under load but quiet when cruising which was important to me as it is a daily driver.

Recently had new Wortec single tip system from Headres back (new ones soon to follow) and the noise is awesome much more V8 rumble at idle, big roar when under load but still very acceptable at cruise soon not to be daily drive so can go for it...

Done nigh on 50k miles with my kit and completely trouble free and looks as good as new when clean so quality is spot on..

[V8HSV]

BigNige said:

Tbh I don't really use the 400 I have that much and doubt many folk here honestly do ona regular basis.

It's more about bragging rights if I'm totally truthful...isn't it?

I'll own up to bragging but 570 is NOT enough for me, yes I'm a bit heavier than most (car not me) but once you get used to it you will always want more & it does all get used.

I have had the headers on for about 3 yrs & most of that time without cats & mufflers which was not quiet, now with Wortec system including the headers (no cats) and it is very acceptable, more to the point I think as the Wortec system breathes better than a chopped standard unit I'll bet I am producing more power.

Edited by V8HSV on Tuesday 26th September 08:22

[sid447]

On the older cars,

With the twin system that merged behind the diff into something like a 2.5 single then rearbox with single tail.
You would get a good honest 25hp or more as it was so restrictive.
Certainly more than you would with headers/exhaust manifolds. They changed the sound so you could hear the individual cylinders more easily.

The newer cars with the twin 2.25" systems are fairly good and I'm not sure how much changing to a good twin 2.5 would be worth.
Certainly what seems to hold though is that changing the system will have more obvious results than headers.
I did post a complete validated headers test a few years ago on LS1.com.au I'll see if I can find it...........
Here it is:

www.ls1.com.au/forum/showthread.php?t=29529&highlight=headers+test

No-one to my knowledge has done an involved systems test, but this site has some before & after graphs:-

www.surefloexhaust.com.au/frame1024x768.htm

[doleboy]

Apparently, the only Monaro that has "decent flow" headers out the factory is the 2004 VXR.

Seems the guys spent too much cash on the bonnet nostrils so had to fit a dodgy iron system on the 05 models.

[sid447]

doleboy said:

Apparently, the only Monaro that has "decent flow" headers out the factory is the 2004 VXR.

Seems the guys spent too much cash on the bonnet nostrils so had to fit a dodgy iron system on the 05 models.

Sort of,
The '02 to '04 CV8's used the same exhaust manifolds as the Commodore with the cats located under the front seat area each side of the txmsn.
The '05 on CV8's used the same as VY-II and VZ, with the cats right at the join with the system.

[hsv_rulz]

Don't forget that the VXR's, being HSV's, have completely different engine sound systems to the CV8's.

[bennno]

doleboy said:

Apparently, the only Monaro that has "decent flow" headers out the factory is the 2004 VXR.

Seems the guys spent too much cash on the bonnet nostrils so had to fit a dodgy iron system on the 05 models.

In the same way, isnt the 04 VXR also the only one with a lower ratio diff?

Bennno

[GSI_Daz]

bennno said:

In the same way, isnt the 04 VXR also the only one with a lower ratio diff?

Indeed - All have 3.45 diffs except the 04 VXR which has a 3.7