Exhaust system

[yewly1990]

Had done my exhaust and open pod in speedwork, not really happy with the craftsmanship, they are even terrible than wei yip.

Get to main point, I had some question here. The exhaust setting they give me was like this
it was a straight flow, and I dunno why, I`m a automatic transmission. They said i`m using open pod, so I should use straight flow.

Anyway, The exhaust system by speedwork are using stainless steel piping and extractor only, the muffler and resonator part are metal spray with some unknown heat reduce paint , it was deep tone, and quite load, I`m not really like it.

I was planning to change the mid muffler and resonator into the previous I buy from Jian Hang motorsport
, I heard this kind of longer muffler could reduce the sound more, But I was curious about the performance.

Before I go to speedwork I was using original stock 4-1 extractor, jian hang sport cat with mid muffler, and stock back muffler. And works drop in air filter intake.

After went to speekwork, the gain was 88.8hp to 99.9hp, and 104.4nm to 115nm. Speedwork was giving me 4-2-1 extractor + 1 mid muffler + 1 resonator + 1 straight flow muffler without cat, and knn open pod with heat shield.



The reason I wanna change the hotbits muffler and resonator back to jian hang because of 3 reasons.
1st reason because I prefer stainless steel, 2nd is because I hope it could decrease some noise, 3rd reason because I hope that the muffler and cat that jian hang sell me was better than hot bits, and it could give me gain.

I`m worry about the performance now, because I`m using open pod, I not sure will there have gain or lost by changing the mid muffler and resonator from hot bits to jian hang muffler and cat.
Because as speedwork told me the striaght flow exhaust they do for me is to pair the open pod that they do for me, to get a sufficient gain.
I`m also plan to change the hotbits straight muffler into s-flow in future, because my ride is auto, I not sure what Am I doing is correct or not, any suggestion from zth member please???

 

[desmond0318]

If our engine don't have those vvti or dvvt to assist our pick up when stationary, back pressure is the thing that assist our car to move easier, mean while straight flow usually saw on track car, they don't event need a muffler for better flow at high rev..

 

[yewly1990]

If our engine don't have those vvti or dvvt to assist our pick up when stationary, back pressure is the thing that assist our car to move easier, mean while straight flow usually saw on track car, they don't event need a muffler for better flow at high rev..

I not sure how the back pressure assist our car to move easier, all the exhaust shop tell me same as u, s-flow is best for auto car, since it have the best back pressure. Speedwork was the only one who tell me, 4-2-1 and straight flow are recommended for all the car to get the maximum power =\, I know 4-2-1 are very useful to city driver since we are always doing stop and go, and automatic transmission can`t raise our rpm to 8k. But I having question with the back pressure method.

As the information I get from some oversea website and some magazine, they said exhaust system should had the least restriction to the exhaust flow to get the best power gain. The more restriction means more back pressure generated, making the engine work harder to pump out the exhaust gases from cylinder. And it count as one source of pumping lost.

I get stuck between 2 theory, which one said exhaust are design to let go exhaust gases as fast as possible for all the car, and another theory which said back pressure are use to be gain more power to automatic transmission???

 

[desmond0318]

As the information I get from some oversea website and some magazine, they said exhaust system should had the least restriction to the exhaust flow to get the best power gain. The more restriction means more back pressure generated, making the engine work harder to pump out the exhaust gases from cylinder. And it count as one source of pumping lost.

I get stuck between 2 theory, which one said exhaust are design to let go exhaust gases as fast as possible for all the car, and another theory which said back pressure are use to be gain more power to automatic transmission???

Yup less retriction makes engine exhale smoother so inhale also smoother but the most restriction part is cat.con, you already removed that

Back pressure gain low end torque and FC, but too much back pressure will cause power lost at mid end and hardly reach top end.

By the way your piping have sexy bend, what size was that piping?

 

[yewly1990]

Yup less retriction makes engine exhale smoother so inhale also smoother but the most restriction part is cat.con, you already removed that

Back pressure gain low end torque and FC, but too much back pressure will cause power lost at mid end and hardly reach top end.

By the way your piping have sexy bend, what size was that piping?

I not sure with the piping, should be around 2 inci, the craftsmanship is bad, so u suggest me not to put in the cat? only the mid part muffler?

 

[DanzEterna]

hotbits exhaust systems should give u some gain better than std exhaust, but since u are running on auto tranny, open-pod air filters
are not recomended, suggest to use K&N drop in.

 

[Supra_Fanatics]

but from what i was told by Jian Hang, most stock cars are 4-1 set up. I did say the same but my car is auto. But if ori was 4-1 i guess shud be fine?

 

[Maxx]

but from what i was told by Jian Hang, most stock cars are 4-1 set up. I did say the same but my car is auto. But if ori was 4-1 i guess shud be fine?

stock usually 4-1 bcoz cast header direct to cat. con.

 

[yewly1990]

hotbits exhaust systems should give u some gain better than std exhaust, but since u are running on auto tranny, open-pod air filters
are not recomended, suggest to use K&N drop in.

But how about the set from jian hang..? Because I got 2 set mid muffler now, I was thinking to swap over the jian hang mid muffler and replace the hotbits one. I love stainless steel much more =\, just worry about the performance drop or raise.

And actually I`m already using a open pod, and the result of dyno are raise on both hp and torque.

 

[TitanRev]

Your car torque curve very quite flat from 4000 to 5500rpm...but I see a dip in torque from 2500 to 3000rpm range.

 

[yewly1990]

Your car torque curve very quite flat from 4000 to 5500rpm...but I see a dip in torque from 2500 to 3000rpm range.

Mean its good or not?? Usually I only step hard when I need speed, I got use potent booster, which can let my rpm raise up 7k only switch to next gear.
I dunno whenever change the current hotbits muffler and resonator to jian hang custom muffler will be good choice or not =\.
I saw a gain in dyno which proof open pod had gain, but not sure about knn drop in, cause speedwork din`t show me the dyno of doing knn drop in + hotbits exhaust.
I was thinking they dun wan to show or they not dare to show?? Since knn open pod can charge me up to RM900 which drop in only charge me maximum of rm3xx.

 

[stupidcar]

Post by the famous Drex tai kor.
https://www.facebook.com/notes/dréx-chan/4-2-1-4-1-which-is-better/292031897492759
Since u have a torque dip, use 4-2-1.

 

[yewly1990]

Post by the famous Drex tai kor.
https://www.facebook.com/notes/dréx-chan/4-2-1-4-1-which-is-better/292031897492759
Since u have a torque dip, use 4-2-1.

Ya, I`m using a 4-2-1, hotbits, was giving 4-2-1, maybe its open pod, that`s why low rpm does`t gain much.

I was`t have problem with extractor, I was worried about mid muffler only =\

 

[infinity.melvin]

what car is that btw?

 

[yewly1990]

what car is that btw?

A small b segment almera:slug: