Stainless back box = less power

[16vMK2 to 172Sport]

Morning all,

As the title, this is the reality of a recent problem I have; my latest (and forced) mod was to get a custom Powerflow back box made after the standard one fell off - i'd like to understand why and how I might rectify the problem.

To outline a bit of modification history....

Bought the car standard 3 years ago and in the first 2 years carried out the following:

Panel filter and C.A.F

Fast road Cat-cams
C.N.C matched inlets
Re-map
The above carried out by K-tec

De-cat
Replacement stainless centre section (after the standard fell off)
Above carried out by Powerflow - rear section remained standard.

After all of the above she really was running sweet, clean crisp & smooth power delivery, picking up from 3000rpm and went a bit mental beyond 5000rpm. Saw of Civic Type-Rs, kept up with R26's and the like.

Now my standard back box fell off I got Powerflow to make me a replacement - this was always my intention when the time came. However, now there is a really noticable flat spot between 3-4000rpm, and it has just lost it's 'mentalness' beyond 5000rpm. Its deeply sadening as it feels now as though all my well spent cash before has been wasted! :dead:

Can anyone enlighten as to why this has happened? I'm assuming it's likely due to a loss of back pressure, but 'sports exhausts' are supposed to improve performance after all! :S

What would you guys suggest to regain the lost performance? Obviously i could source a standard exhaust - however, I'm guessing very expensive and will need replacing in 3 years!

I also thought about reintroducing the cat with the hope of increasing the back pressure.... but this might have a negative effect??

Any help appreciated!

 

[R-Sport.]

Morning all,

As the title, this is the reality of a recent problem I have; my latest (and forced) mod was to get a custom Powerflow back box made after the standard one fell off - i'd like to understand why and how I might rectify the problem.

To outline a bit of modification history....

Bought the car standard 3 years ago and in the first 2 years carried out the following:

Panel filter and C.A.F

Fast road Cat-cams
C.N.C matched inlets
Re-map
The above carried out by K-tec

De-cat
Replacement stainless centre section (after the standard fell off)
Above carried out by Powerflow - rear section remained standard.

After all of the above she really was running sweet, clean crisp & smooth power delivery, picking up from 3000rpm and went a bit mental beyond 5000rpm. Saw of Civic Type-Rs, kept up with R26's and the like.

Now my standard back box fell off I got Powerflow to make me a replacement - this was always my intention when the time came. However, now there is a really noticable flat spot between 3-4000rpm, and it has just lost it's 'mentalness' beyond 5000rpm. Its deeply sadening as it feels now as though all my well spent cash before has been wasted! :dead:

Can anyone enlighten as to why this has happened? I'm assuming it's likely due to a loss of back pressure, but 'sports exhausts' are supposed to improve performance after all! :S

What would you guys suggest to regain the lost performance? Obviously i could source a standard exhaust - however, I'm guessing very expensive and will need replacing in 3 years!

I also thought about reintroducing the cat with the hope of increasing the back pressure.... but this might have a negative effect??

Any help appreciated!

Your mapping is probably now wrong-

Steve

 

[aucky]

Redline say back pressure is a myth.
Its loss of exahaust gas velocity thats the problem..

 

[l1clio]

Probably the Powerflow back box.

I've heard Powerflow just stock a load of various size universal back boxes.

Then they just pick one that's the closest size to the original and weld on the pipes and brackets to fit the car. Don't think they take into account gas flow?

I'm sure Yozza, Scorpion, Janspeed etc. spend lots of time & money testing there exhausts.

Please correct me if I'm wrong.

 

[16vMK2 to 172Sport]

Where do I stand when it comes to Powerflow, do I have any right to make a fuss and complain/ask for a new one?

 

[jack_davey]

^I doubt it you get what you pay for with them!
You've gone to the effort of spending good money on good mods like the inlet matching and cams, surely these should be accompanied with a decent exhaust like miltek/yozza/janspeed/piper?

 

[16vMK2 to 172Sport]

^I doubt it you get what you pay for with them!
You've gone to the effort of spending good money on good mods like the inlet matching and cams, surely these should be accompanied with a decent exhaust like miltek/yozza/janspeed/piper?

Really didn't think it would make that much of a difference between one manufacturer or the other. I just chose powerflow as I was able to get each section done as and when they needed replacing, effectively spreading the costs

 

[16vMK2 to 172Sport]

so what do we reckon is the problem then... exhuast or mapping as someone suggested?

Possible ways to regain the exhaust gas velocity? exhaust recommendations?

 

[Kam.]

Probably the Powerflow back box.

I've heard Powerflow just stock a load of various size universal back boxes.

Then they just pick one that's the closest size to the original and weld on the pipes and brackets to fit the car. Don't think they take into account gas flow?

Yup, from all accounts they don't use mandrel bends either. It is easier to loose power from making an exhaust than to gain it so always best to go for one from a decent manufacturer such as Piper or Supersprint as they do all the calculations and test everything on dyno's..

 

[16vMK2 to 172Sport]

Yup, from all accounts they don't use mandrel bends either. It is easier to loose power from making an exhaust than to gain it so always best to go for one from a decent manufacturer such as Piper or Supersprint as they do all the calculations and test everything on dyno's..

Tis true about the non-mandrel bends. Thought i've read on here that Piper are pants....:S Yozza or BTB seem to be what everyone raves about. I'm stuck in this dilema of would a different exhaust system actually make a difference and give me back my low end torque which i've lost? and what ever the answer to the first question, is it worth spending/wasting £300-400 on a different system? No doubt i'll re-coup next to nothing for my powerflow system....

 

[ForceIndia]

My piper 172 system was poo. Currently using a yoz stealth, my god it's awesome. Quiet as standard, slightly louder when booting it. I've got a race backbox for trackdays etc, 10min job to swap. Best of both worlds!

 

[Gaz_]

Might go this way with mine when i get it back. Currently running standard, but when its hot it ticks and cracks like f**k, sounds w**k!

 

[tom_carey]

I have a powerflow cat back and sports cat and have the same flat spot! Ive been told by lots of people how crap these exhausts really are! The universal backboxes are only 1 of many things that would most likely effect this. If you look at the size of the backbox they put on compared to the size of your old one your soon realise!

 

[16vMK2 to 172Sport]

I have a powerflow cat back and sports cat and have the same flat spot! Ive been told by lots of people how crap these exhausts really are! The universal backboxes are only 1 of many things that would most likely effect this. If you look at the size of the backbox they put on compared to the size of your old one your soon realise!

and I bet non-powerflow customers don't speak of this flat spot either! I'm hopefully getting in on the yozza group buy so hopefully it will a) give me back some power and b) not be quite as loud!

 

[Fred@BTM]

accompanied with a decent exhaust like miltek/yozza/janspeed/piper?

i only see one decent one listed

and yes we did do a fair bit of ye olde dyno testing, track testing, sound testing yada yada including a stint at Mira believe it or not!

 

[16vMK2 to 172Sport]

Fred, was all that testing just for the sports/racing systems? I'm looking to get the stealth system.... hopefully giving me back my lost power while not being as loud as my current powerflow system!

 

[tom_carey]

and I bet non-powerflow customers don't speak of this flat spot either! I'm hopefully getting in on the yozza group buy so hopefully it will a) give me back some power and b) not be quite as loud!

Mines loud as hell too!

 

[16vMK2 to 172Sport]

thanks for all the brilliant advice!

 

[16vMK2 to 172Sport]

BTB exhuast arrived, had to modify to fit (kindly subsidised by BTB ) as the centre section was an inch too long. Now its fitted... OH MY GOD!!! The difference in performace is NIGHT AND DAY!! Literally! It even feels faster then when I had the OEM back box on. I never appreciated the difference a decent exhuast makes, feels as though i got an extra 15-20bhp/lb.ft in the mid-range.... and dont get me started on the highly addictive noise it makes :evil:

 

[M055360]

I've heard Powerflow just stock a load of various size universal back boxes.

exactly i've always thought this, there not designed for the car for optimal performance. two mates had powerflows put on their nova's and the quality was shocking they had to go back a few times cause they'd come loose and rattle like mad.

a tip welded onto a universal backbox :dead: