freeing up exhaust

More threads by sean sherry

sean sherry

Connoisseur
Messages
1,685
Points
59
Location
sydney
I used to be a fan of this but I fear today's cars don't respond to any interference with the back pressure.
Inlet, firing, and exhaust are now a designed continuous loop, computer controlled. Disturb one element and performance drops.
I'm very fond of a comment made to a young Gun Ho teen who wanted to modify the engine in his V Tech Honda.....what makes you think that you know more than 40,000 Honda engineers ???
 

irvine

New Member
Messages
26
Points
0
Location
Maroubra, Sydney
Fair comment, but....

Exhausts then AND now are designed both restrictive and with efficiency in mind.

Take for example the “mines” one piece titanium turbo back exhaust for the Nissan r34 grr has been shown to produce up to 100bhp over the standard exhaust system, and that’s before you go crazy on tuning.
It’s been proven even the material of the exhaust can gain bhp.

I know I’ve a lowly 280 d-jet but I’m planning a full stainless exhaust, no cat and centre box with a free flow back box. Should see a “few” bhp.

Neil.
 

c107

and 111/126
Moderator
Messages
2,279
Points
124
Location
Sydney
Fair comment, but....

Exhausts then AND now are designed both restrictive and with efficiency in mind.

Take for example the “mines” one piece titanium turbo back exhaust for the Nissan r34 grr has been shown to produce up to 100bhp over the standard exhaust system, and that’s before you go crazy on tuning.
It’s been proven even the material of the exhaust can gain bhp.

I know I’ve a lowly 280 d-jet but I’m planning a full stainless exhaust, no cat and centre box with a free flow back box. Should see a “few” bhp.

Neil.

In addition, Mercedes designed their exhaust systems to be very quiet. You obviously don't want it to drone, but the M110 sounds great above 4000 rpm. Reducing restriction should hopefully allow some more engine note at high RPM while maintaining quiet cruise.
 
OP
S

sean sherry

Connoisseur
Messages
1,685
Points
59
Location
sydney
I would hate to see the $$$$ signs for modifications to modern Cars.,noise restrictions are part of the Law. But don't tell that to Harley Owners.
Why are they not Policed ????
 
OP
S

sean sherry

Connoisseur
Messages
1,685
Points
59
Location
sydney
P.S. Ten years ago I fitted a flow free exhaust system from a leading specialist manufacturer to an SS Ute V8'. I did not notice a blind bit of difference except for on increase in noise. I can't remember if I also fitted Headers. I sold the car to a dealer and all he was interested in was that it did not have an accessory metal cover instead of the factory canvas. I learned a lesson, in that if you can't see it you can't sell it.
I also understand that Men are visually stimulated in more ways than one !!
 

motec 6.9

Prodigal Son
Messages
6,495
Points
0
Location
Cantberra
I dont know about other cars but I can confirm with dyno sheets extractors and decent exhaust makes over 20jp at the rear wheels difference with a 6.9
 

Styria

The Godfather
Moderator
Messages
8,824
Points
177
Location
Sydney
I would hate to see the $$$$ signs for modifications to modern Cars.,noise restrictions are part of the Law. But don't tell that to Harley Owners.
Why are they not Policed ????

Sean, a most valid observation. I get Harleys driving past my home on a fairly busy, although weight restricted major thoroughfare, and some of those Harleys are absolutely abominable - yes, they should just seize them and fix up the exhaust. How horrible ! Regards Styria
 

Styria

The Godfather
Moderator
Messages
8,824
Points
177
Location
Sydney
In addition, Mercedes designed their exhaust systems to be very quiet. You obviously don't want it to drone, but the M110 sounds great above 4000 rpm. Reducing restriction should hopefully allow some more engine note at high RPM while maintaining quiet cruise.

HI Bryce, you have driven my Gleaming Beauty, and you can probably vouch for the fact that she emits a fairly raucous sound - and I also think some very useful extra ponies. I would certainly be happy to take on any 6.9 and also 6.3 for that matter. I achieved this "extra horsepower" (!!) by fitting a 1973 - 350SL standard Mercedes first muffler plus a straight through
huge stainless steel second muffler. The sound is toxic, especially as you are climbing up the revs, and I reckon on at least an extra 5% to 10% of extra power. Regards Styria
 

c107

and 111/126
Moderator
Messages
2,279
Points
124
Location
Sydney
HI Bryce, you have driven my Gleaming Beauty, and you can probably vouch for the fact that she emits a fairly raucous sound - and I also think some very useful extra ponies. I would certainly be happy to take on any 6.9 and also 6.3 for that matter. I achieved this "extra horsepower" (!!) by fitting a 1973 - 350SL standard Mercedes first muffler plus a straight through
huge stainless steel second muffler. The sound is toxic, especially as you are climbing up the revs, and I reckon on at least an extra 5% to 10% of extra power. Regards Styria

I like what you have done with the exhaust on your 6.9. Its not annoying at low RPM, but if you plant your foot you get a great V8 rumble.

I did something similar with my Jag, its fairly quiet normally but if revved you get the snarl of the DOHC 6.
 

Oversize

Master
Messages
5,144
Points
181
Location
Melbourne
Standard exhausts are a huge compromise between functionality, noise, budget, economy and performance. As a ‘tuner’ you can decide which way to weigh that equation...
 

Oversize

Master
Messages
5,144
Points
181
Location
Melbourne
For best results you should undertake intake mods too...
 

Similar threads

Top