Removed Cat and Resonator lose power?

[k3nny]

hey guys.. just looking for an opinion... i recently took out the whole exhaust system from the headers on.. it was a 2inch pipe and now its a 2 and 1/4inch pipe.Also theres no cat now and just 1 hi-flow resonator. Im thinking of removing the resonator and just running the pipes straight. Will i be losing power? I thought maybe not as the pipe diameter only increased from 2inch to 2 and 1/4 inch. I know that even if there was a gain, or a loss to be had, it will be minimal but nevertheless, im just wondering. Thanks! PS: Bearing in mind that i also have a cold air intake now, not sure that it would make a diff or not..

 

[musclehedz]

Originally posted by k3nny@Jun 16 2005, 12:30 AM
hey guys..

just looking for an opinion... i recently took out the whole exhaust system from the headers on..

it was a 2inch pipe and now its a 2 and 1/4inch pipe.

Also theres no cat now and just 1 hi-flow resonator.

Im thinking of removing the resonator and just running the pipes straight.

Will i be losing power?

I thought maybe not as the pipe diameter only increased from 2inch to 2 and 1/4 inch.

I know that even if there was a gain, or a loss to be had, it will be minimal but nevertheless, im just wondering.

Thanks!

PS: Bearing in mind that i also have a cold air intake now, not sure that it would make a diff or not..

Some low end power will be lost. You should be gaining a tad bit of top end power. Just a tad little bit. Downside is more noise?

 

[bazet]

the mods had been done to many proton road cars hence contributing to more noise on public road.


But on BMW, I never seen it. So how's the sound ? Too loud or ok for 6 cylinders engine ?

Tell me more on your modifications ..

what car ?
waht mods has been done ?

 

[musclehedz]

Originally posted by bazet@Jun 16 2005, 10:26 AM
the mods had been done to many proton road cars hence contributing to more noise on public road.


But on BMW, I never seen it. So how's the sound ? Too loud or ok for 6 cylinders engine ?

Tell me more on your modifications ..

what car ?
waht mods has been done ?

If you put large pipes and only 1 rear big sport silencer...it will sound like an R34..very nice and bassy rumble but the downside is...its blardy loud and boomy. Believe me, you will put back the original pipes and fittings after 2 weeks or usage. It's too boomy. I tried it yesterday just for the fun of it

 

[bazet]

I'm using M20 B20 with original header.

I'm thinking of using nice stainless steel from the header

6 - 2 - 1

and ended by a APEXI N1 muffler

the current setup is like having 3 big boxes underneath my car...and started to rust.

The E34 exhaust clearance is so small..so the only choice is using muffler like the attached pics.......

R34 rumble..that's nice

 

[musclehedz]

Originally posted by bazet@Jun 16 2005, 10:34 AM
I'm using M20 B20 with original header.

I'm thinking of using nice stainless steel from the header

6 - 2 - 1

and ended by a APEXI N1 muffler

the current setup is like having 3 big boxes underneath my car...and started to rust.

The E34 exhaust clearance is so small..so the only choice is using muffler like the attached pics.......

R34 rumble..that's nice

fooo..6 cylinder straight thru and rear apexi muffler...r34 sound if your engine is 2.8cc and above. JPJ road block garuntee to get stopped. N1 muffler is too small if yoru engine is 2.5 and above..the sound will be too loud and you won't get that very deep bassy rumble sound. big engine + big pipe + 1 big rear muffler = r34 bass rumble

 

[bazet]

he he...ok ....just forget it....

 

[musclehedz]

Originally posted by k3nny@Jun 16 2005, 12:30 AM
hey guys..

just looking for an opinion... i recently took out the whole exhaust system from the headers on..

it was a 2inch pipe and now its a 2 and 1/4inch pipe.

Also theres no cat now and just 1 hi-flow resonator.

Im thinking of removing the resonator and just running the pipes straight.

Will i be losing power?

I thought maybe not as the pipe diameter only increased from 2inch to 2 and 1/4 inch.

I know that even if there was a gain, or a loss to be had, it will be minimal but nevertheless, im just wondering.

Thanks!

PS: Bearing in mind that i also have a cold air intake now, not sure that it would make a diff or not..

You got CAI, so meaning you have a more free flow breathing in system, now u need a more free flow exhaust system to complement it as well. You can bolt on those proper R&D full systems like AC, Sebring and alike which should get you a balance of performance and not to mention not LOUD. Those Ahkow/AhChi Sungai Buloh R&D system don't cut it.

Correct me if I'm wrong...bigger pipes = gas cools faster = less velocity = gas exits slowly = cockup, if you use bigger pipes, it would be a tad bit beneficial to have them thermally wrapped but do not wrap the headers, it will shorten the lifespan of the header a lot and will end up cracking them.

As for the high-speed resonators..its doesn't really make a difference unless you are always top-ending the engine everytime u go out. Its much more beneficial to use a high-flow mid silencer instead.

 

[supergripen]

agree..all these local setups actually will increase unwanted noise and u'll get very negligible increases in top end power but u loose out low down which is where we spend most time in..
i've done it to my prev car(e36) and its not worth the headache from the booms anr rumbles..better to go for reputable euro brands..

 

[musclehedz]

Originally posted by supergripen@Jun 16 2005, 10:59 AM
agree..all these local setups actually will increase unwanted noise and u'll get very negligible increases in top end power but u loose out low down which is where we spend most time in..
i've done it to my prev car(e36) and its not worth the headache from the booms anr rumbles..better to go for reputable euro brands..

Couldn't agree more.

Ah Kow R&D System are best if one is joining an ICE competition to see who is louder..Ah Kow system sure win, Alpine F1 Status with 4xKicker Solo-X also no fight :rofl:

 

[supergripen]

Originally posted by musclehedz+Jun 16 2005, 11:01 AM-->QUOTE (musclehedz @ Jun 16 2005, 11:01 AM)

 

[k3nny]

Im using a Sebring Twin DTM Straight flow muffler.

I bought the muffler.. no pipework. Its custom pipework..

Previously, it was just the muffler installed onto the stock pipework meaning there was 1 cat and 1 resonator there.

It was very drony in the low rpm ranges but going higher up after 3500rpms or so, the engine screams like a sick puppy getting raped but the exhaust, no sound.


Then i did the custom pipework, where the headers merged into 1, onwards, the pipe is now 2 and 1/4inch diameter single pipe.

No more CAT, and no more stock S-flow resonator. Just a single hi-flow resonator and then my muffler.

Now in the lower rev ranges, the car is very quiet.. like 1500rpm - 3500rpm, not as noisy as before, but when i go past 3500rpm, the exhaust and the car alike sounds like a totally different car from the sick puppy before..

Really like it.. but still too quiet for me. So i was contemplating removing the resonator as well and just run the pipes straight...

As im heading down to the plex this weekend to try my luck on the quarter mile, i also want to make sure this doesnt cause me to lose power.. if any at all was gained la..


PS: im driving a 318i with a 2.0 valvetronic.

My mods.. hmmm

Custom cold air intake with K&N filter routed down to the M-TechII bumper next to the foglight.

Above mentioned exhaust.

www.powerchip.com.au - tuned to 98 octane