Lost power after exhaust set up

[Izso]

Veloc - my take on this is this :

Last time I had my power band shifted up like you was when the flow of the exhaust was too 'smooth' or 'slow'. I had to add restrictions like a S-flow muffler to normalise it. So to me it sounds like you might have the same issue. 4AGE being a 1.6L, I'm thinking the 2.3" piping probably is too large. Like what most of the sifus said here, I think your issue is the large piping. I don't see a problem with adding the additional mid-box, but this is just my personal opinion.

What is the piping size from header right to the back? The mid-boxes are the same size as well or step up/down piping sizes?

 

[Veloc]

Veloc - my take on this is this :

Last time I had my power band shifted up like you was when the flow of the exhaust was too 'smooth' or 'slow'. I had to add restrictions like a S-flow muffler to normalise it. So to me it sounds like you might have the same issue. 4AGE being a 1.6L, I'm thinking the 2.3" piping probably is too large. Like what most of the sifus said here, I think your issue is the large piping. I don't see a problem with adding the additional mid-box, but this is just my personal opinion.

What is the piping size from header right to the back? The mid-boxes are the same size as well or step up/down piping sizes?

Yes bro after some thinking, I came to the same conclusion too. Piping. Mid boxes are same size. But slightly bigger shouldn't be a problem right? Since it will taper off back tot he same piping size shortly.

The header piping at the "1" section (after the 4-2 section) is only about 2". And the most noticeable part is the squashed design like in the picture. Then, catback onwards I am using 2.1" piping which works beautifully for me all this while. I didn't change that part. All I did was change the "1" section to 2.3" and without squash, and added another midbox to minus the drone..

 

[vr2turbo]

Looks like you need to trail and error to get the best fit......

 

[Izso]

Big taper down to small will cause some scavenging loss I think. Better to have all same size la.

 

[Veloc]

Big taper down to small will cause some scavenging loss I think. Better to have all same size la.

Really? I thought big to small is actually good coz it speed up the exhaust gasses?

 

[vr2turbo]

Really? I thought big to small is actually good coz it speed up the exhaust gasses?

Big to small not bottle neck meh?

 

[Izso]

Back pressure la.. it's restrictive.

 

[vr2turbo]

Back pressure la.. it's restrictive.

Restrictive same like bottleneck but mention back pressure sometimes we need a little back pressure for low end....

 

[Veloc]

Big to small not bottle neck meh?

Back pressure la.. it's restrictive.

Restrictive same like bottleneck but mention back pressure sometimes we need a little back pressure for low end....

I have come across so many different theories and advices. Some say small to big.

Some say big and gradually go smaller as the exhaust approach the back. Because as the exhaust gasses travel, it cools down and loses velocity. So by going, the gasses are force to speed up, hence maintaining velocity. This helps in maintaining scavenging.

I would say NA exhaust tune is one of the hardest and most expensive systems to learn in terms of theory and trial and error besides suspension.

 

[vr2turbo]

So far I have not heard from big to small. Most have them of equal size all the way. Only heard from one of my turbo friend with modded engine, from 2.5" all the way the near rear end go to 3". Even my turbo is 2.5" all the way. NA depending on CC can be from 2" to 2.2"......:rolleyes:

 

[marv3]

So far I have not heard from big to small. Most have them of equal size all the way. Only heard from one of my turbo friend with modded engine, from 2.5" all the way the near rear end go to 3". Even my turbo is 2.5" all the way. NA depending on CC can be from 2" to 2.2"......:rolleyes:

I think is pretty common now for turbos to go from big to small. I have seen a turbo car went from 3" at downpipe, to 2.75" middle piping and 2.5" muffler...... 3">2.75">2.5".....

But i myself use 2.5" all the way la....and the muffler is called a Loop Flow....Not S-Flow....Something the exhaust shop fella came up with.....

 

[Izso]

My understanding of physics is big to small will increase the velocity of the air but increased friction will increase pressure so you're effectively increase back pressure. No meh? Bournelli's law

 

[marv3]

My understanding of physics is big to small will increase the velocity of the air but increased friction will increase pressure so you're effectively increase back pressure. No meh? Bournelli's law

Tak tau wor. Dont understand also why he wants the back pressure in TC cars. More low to mid end? But anyways, its not the first TC car i heard of that does from big to small. As for me, just straight 2.5"....

 

[vr2turbo]

Maybe depends on what type of turbo also.....hahhaha

 

[^pomen_GTR^]

I think is pretty common now for turbos to go from big to small. I have seen a turbo car went from 3" at downpipe, to 2.75" middle piping and 2.5" muffler...... 3">2.75">2.5".....

But i myself use 2.5" all the way la....and the muffler is called a Loop Flow....Not S-Flow....Something the exhaust shop fella came up with.....

thats usually to cover up some lost midrange due to big turbo (turbo lag)...


but if it was me...i will prefer the best spool turbo option....(not a fan of big power and loosing torque at bottom end)

 

[marv3]

thats usually to cover up some lost midrange due to big turbo (turbo lag)...


but if it was me...i will prefer the best spool turbo option....(not a fan of big power and loosing torque at bottom end)

I see....

To me....I like smooth.....as linear as possible....easier to handle and drive....

 

[Shinjite]

I would say it's the extra mid box and the bigger piping size (I would say a 2" inner diameter will do) that you have changed to fix the original piping bend
You don't need more than one mid box to be honest, additional restriction.

For me, extractor -> midbox/bullet -> muffler, that's it :D

 

[Veloc]

I would say it's the extra mid box and the bigger piping size (I would say a 2" inner diameter will do) that you have changed to fix the original piping bend
You don't need more than one mid box to be honest, additional restriction.

For me, extractor -> midbox/bullet -> muffler, that's it :D

If I want more silence, but cannot use two midbox, how about using just one midbox but bigger? Will it be better or the same?

 

[KenDiriwan]

If I want more silence, but cannot use two midbox, how about using just one midbox but bigger? Will it be better or the same?

Guess what? This is current set i am using, more quiet than previous 2SET of different s-flow.

This is Greddy Power Extreme GS, sounded almost as HKS Silent Hi Power. Yet doesn't impact my fuel consumption and better power output.

 

[vr2turbo]

The one you polished, so still using this one?