Custom piping recommendations? [Archive]

SmoothOperator

09-01-2002, 12:34 PM

This was originally posted by David K. on another thread. Hope it helps...

Mandrel bending is the prefered way to build a performance exhaust system, because it doesn't kink or reduce in diameter thru the curves. Crush bent merely refers to the cheaper, more common bending done by most exhaust shops. In mandrel bending, an insert or "mandrel" is inserted into the pipe; it's kinda like a universal joint. It fits tightly inside the exhaust tubing and can bend in any direction. So when the exhaust is bent, the mandrel inside the tubing maintains the pipe diameter, even thru bends and corners.

With crush bending, a pipe will lose size thru the curves. For example, a 2.5" exhaust may neck down to 2.25" thru the bends; mandrel bending maintains that full 2.5" even thru the curves.

CleanBlackSi02

09-01-2002, 12:46 PM

Thanks for pasting that excellent description! Any recommendations?

David K.

09-01-2002, 08:13 PM

Glad you liked my explanation:D!!! I've got a 2.25" crush- bent system on my car; sounds great. A little deeper than stock, but still real smooth without being too loud or droaning. I don't have a resonator on it either. I recommend one of two things: Find an exhaust shop that can order mandrel bends or does it themselves, OR, call MBRP . I emailed them the other day and they told me I could order their mid-pipe, which is mandrel bent stainless steel w/ a resonator. Also, a company called Motionmania.net is supposed to be offering a 2.5" mid pipe w/ resonator soon.

CleanBlackSi02

09-01-2002, 09:36 PM

Originally posted by David K.
Glad you liked my explanation:D!!! I've got a 2.25" crush- bent system on my car; sounds great. A little deeper than stock, but still real smooth without being too loud or droaning. I don't have a resonator on it either. I recommend one of two things: Find an exhaust shop that can order mandrel bends or does it themselves, OR, call MBRP . I emailed them the other day and they told me I could order their mid-pipe, which is mandrel bent stainless steel w/ a resonator. Also, a company called Motionmania.net is supposed to be offering a 2.5" mid pipe w/ resonator soon.

MBRP?

David K.

09-01-2002, 10:27 PM

Sorry

MBRP is an exhaust company in Canada. They are the company that some guys were tring to get a group buy together on their cat-back systems. There is a thread about it somewhere on this site.

DrPimpSiR

09-02-2002, 05:44 AM

Hey Clean,
I'm the guy that started the MBRP group-buy, but sorry to say it's over. The deadline was Aug 30.
Here is the thread:
http://www.ephatch.com/forum/showthread.php?s=&threadid=1518

wu343

09-02-2002, 09:34 AM

Why not just keep the cat-back? Are you not getting very good power gain?

DrPimpSiR

09-02-2002, 01:12 PM

Originally posted by CleanBlackSi02
I've decided to sell my Thermal exhaust and get some custom piping. Any recommendations as far as sizing, style, materials, etc, etc? I know miamijdm made some impressive gains with 2.25" mandrel bent piping. What exactly is mandrel bent? Any info will be appreciated! Thanks!
I'm sure that the Thermal system is mandrel bent. If you don't like the sound, just use their mid-pipe and put the factory end/muffler back on.

CleanBlackSi02

09-03-2002, 09:59 PM

Originally posted by DrPimpSiR

I'm sure that the Thermal system is mandrel bent. If you don't like the sound, just use their mid-pipe and put the factory end/muffler back on.

Good point! However...the Thermal is 2.5" while the stock is 2.25" to the muffler, if I'm correct. How would that work?

David K.

09-04-2002, 09:48 AM

Any exhaust can link the two pipes together. It's only .25" difference. I think they will probably flair the factory 2.25" inlet so that it will match your 2.5". I'm wanting to go to 2.5" myself, so if you decide not to go this route, pm me; I'd be intrested in your Thermal mid-pipe.

CleanBlackSi02

09-04-2002, 11:38 PM

Originally posted by David K.
Any exhaust can link the two pipes together. It's only .25" difference. I think they will probably flair the factory 2.25" inlet so that it will match your 2.5". I'm wanting to go to 2.5" myself, so if you decide not to go this route, pm me; I'd be intrested in your Thermal mid-pipe.

How would that affect backpressure and the like? Thanks for all of the great info BTW!

66elwood99

09-05-2002, 08:33 AM

Originally posted by DrPimpSiR
Hey Clean,
I'm the guy that started the MBRP group-buy, but sorry to say it's over. The deadline was Aug 30.
Here is the thread:
http://www.ephatch.com/forum/showthread.php?s=&threadid=1518

Clean I had called after the deadline and explained that I was unable to call before and they were great about it and offered me the group price, I called on Tuesday the 4th , give it a shot!

CleanBlackSi02

09-08-2002, 04:31 PM

JSIR

09-08-2002, 05:49 PM

in most cases people re-use the stock flanges, thus the exhaust shop just cuts them off and welds new pipe onto the stock flanges. The pipe hole is larger than the hole that goes through the flange, so there is a step there particularly if you go 2.5". The hole in the flange is somewhere around 2 inches give or take .25". The flange off the cat is closer to 1.75", the rear flange is around 2 inches.

I've been seriously considering a 2 inch mandrel bent mid pipe recently, I wont' know until I discuss it further with my exhaust guy. To date I've tried 2.25" and 2.5" crush bent pipes and I think I've given up some bottom end torque. I intend to keep using the stock muffler, and the rear muffler has 2 inch piping (50mm). The holes in the stock flanges are 2 inches or less, so I don't see the benefit of going with a mid pipe that is any larger than 2 inches in theory unless you go with a bigger muffler. So that may be my next choice when I decide to get a quality mid-pipe. To date I've just been messing with cheaper pipes for testing purposes.

The stock mid-pipe is 1.66" (42mm) in diameter, and it actually necks down to 1.5" in some locations including the resonator. The pipe is slightly crush bent as well so it necks down in curves very close to 1.5". The muffler piping is 50mm (2 inches). So even going to a full 2 inch mandrel bent pipe would be a decent upgrade in terms of flow. Many of the guys using custom mid-pipes seem to be going with 2.25" mandrel piping.

CleanBlackSi02

09-08-2002, 06:11 PM

Well, that makes me think that 2.5" from the Thermal would not be good at all.....Hmmmmm....anyone else?

chunky

09-08-2002, 06:16 PM

Originally posted by JSIR
in most cases people re-use the stock flanges, thus the exhaust shop just cuts them off and welds new pipe onto the stock flanges. The pipe hole is larger than the hole that goes through the flange, so there is a step there particularly if you go 2.5". The hole in the flange is somewhere around 2 inches give or take .25". The flange off the cat is closer to 1.75", the rear flange is around 2 inches.

I've been seriously considering a 2 inch mandrel bent mid pipe recently, I wont' know until I discuss it further with my exhaust guy. To date I've tried 2.25" and 2.5" crush bent pipes and I think I've given up some bottom end torque. I intend to keep using the stock muffler, and the rear muffler has 2 inch piping (50mm). The holes in the stock flanges are 2 inches or less, so I don't see the benefit of going with a mid pipe that is any larger than 2 inches in theory unless you go with a bigger muffler. So that may be my next choice when I decide to get a quality mid-pipe. To date I've just been messing with cheaper pipes for testing purposes.

The stock mid-pipe is 1.66" (42mm) in diameter, and it actually necks down to 1.5" in some locations including the resonator. The pipe is slightly crush bent as well so it necks down in curves very close to 1.5". The muffler piping is 50mm (2 inches). So even going to a full 2 inch mandrel bent pipe would be a decent upgrade in terms of flow. Many of the guys using custom mid-pipes seem to be going with 2.25" mandrel piping.

I did my own measurments, and the inside diameters of the pipes are 2" from the cat back to the resonator. It drops to 1.5" through the resonator, but the pipe attached to the muffler is 2.25" internal diameter. I meant to take some pictures with the ruler over the pipe openings, but I was out of film that day =\

maybe next time.

CleanBlackSi02

09-08-2002, 06:36 PM

chunky

09-08-2002, 07:48 PM

Originally posted by CleanBlackSi02

My main question was, will I have more loss that gain if I just use the piping from my Thermal exhaust and weld the stock muffler on....or will it not be very advantageous?

My opinion on this matter is that if your motor is virtually stock, you won't benefit from anything much larger than 2". At most, i'd go 2.25"

Anything larger, and you will likely see a loss of low end and midrange torque b/c flow velocities will begin to drop at lower rpm, and only a modest gain in top end exhaust flow resulting in a slight bump in peak #'s, but it's not worth the tradeoff in midrange IMO.

So, no, I wouldn't use the thermal exhaust. 2.5" is too big for a stock motor. However, i'd keep it around b/c eventually you'll have forced induction, or bump the compression and need the wider pipe diameter.

The stock muffler also seems to flow pretty well - the main bottlenecks in the exhaust system are the exhaust manifold and the silencer canister.

JSIR

09-08-2002, 07:50 PM

Originally posted by chunky

I did my own measurments, and the inside diameters of the pipes are 2" from the cat back to the resonator. It drops to 1.5" through the resonator, but the pipe attached to the muffler is 2.25" internal diameter. I meant to take some pictures with the ruler over the pipe openings, but I was out of film that day =\

maybe next time.

no that can't be right, the outside diameter of the piping is 42mm (metric piping), which is 1.66 inches max., thus internal diameter is even smaller and far away from 2 inches. I've got the midpipe sitting in my garage without the flanges so its easy to measure.

The piping is flared a bit at the flanges but the diameter of the majority of the pipe is a maximum of 1.66 inches outside diameter. In the bends it goes down to 1.59 inches (40mm) or less outside diameter. I'm using an electronic caliper to measure so its pretty accurate. Inside diameter is just a bit over 1.5 inches. The main piping on the stock muffler is 50mm or 2 inches outside diameter, the pipe that attaches to the flange may flare out to 2.25" for a short bit, but the main muffler piping is the smaller of the two so it would determine the actual flow.

chunky

09-08-2002, 08:38 PM

Originally posted by JSIR

no that can't be right, the outside diameter of the piping is 42mm (metric piping), which is 1.66 inches max., thus internal diameter is even smaller and far away from 2 inches. I've got the midpipe sitting in my garage without the flanges so its easy to measure.

The piping is flared a bit at the flanges but the diameter of the majority of the pipe is a maximum of 1.66 inches outside diameter. In the bends it goes down to 1.59 inches (40mm) or less outside diameter. I'm using an electronic caliper to measure so its pretty accurate. Inside diameter is just a bit over 1.5 inches. The main piping on the stock muffler is 50mm or 2 inches outside diameter, the pipe that attaches to the flange may flare out to 2.25" for a short bit, but the main muffler piping is the smaller of the two so it would determine the actual flow.

odd, I'll have to take some pics next time. I double checked my measurements, and yes I also observed that the pipes widened at the flange (the flange going into the muffler is almost 3" wide)

anyhow, dropping the ehxaust is cake if the car is cool, I'll get some pics taken soon.

CleanBlackSi02

10-29-2002, 03:51 PM

Any new insight? I'm seriously thinking about just getting the stock muffler welded onto my Thermal 2.5" piping. Just getting tired of the constant deepness. I've heard 2.5" is better for the K series, but then I hear otherwise! Help!

ssvr6

10-29-2002, 04:37 PM

I thought that DC was making a 2.25 because the 2.5 showed a loss of power?

I PM'd you info on a shop.

Steve

TezGari

10-29-2002, 04:57 PM

Hey guys,

I want to go custom piping to. I think its a pretty good price and it does thejob well.

PoRT

10-29-2002, 05:21 PM

just say F*ck it and run a straight pipe all the way out. no cats.. no muffler.. hell yeah

ssvr6

10-29-2002, 06:05 PM

No cat, no muffler, no hearing....:o

Steve

CleanBlackSi02

10-29-2002, 09:10 PM

Originally posted by ssvr6
I thought that DC was making a 2.25 because the 2.5 showed a loss of power?

I PM'd you info on a shop.

Steve
In the issue of Honda Tuning with the Yokohama Si, it had the DC prototype and they said that they were going with 2.5"...they tried 2.0 and 2.25, but the "k series is a whole new beast" or something to that effect... Thanks for the shop info. I'll check it out.

02SilverSiHB

10-30-2002, 05:31 AM

Originally posted by CleanBlackSi02

In the issue of Honda Tuning with the Yokohama Si, it had the DC prototype and they said that they were going with 2.5"...they tried 2.0 and 2.25, but the "k series is a whole new beast" or something to that effect... Thanks for the shop info. I'll check it out.
yeah, I remember they (DC) also said 2.5 didn't work out at first till, they did something else...maybe resonator? I don't know. Dyno's the only say to show. 2.5 sounds too much, but then again, this is a whole new car

TezGari

10-30-2002, 07:44 AM

I think we should write a letter to someone who knows alot about the K20's in the EP's. It's a new engine and a new liter 2.0.
If we could just email an expert on exhuast or K20's and get an answer........ ;)

Or have 3 stock EP's Dyno thier car one with, 2.5, 2.25 and straight 2.5 and 2.25 going all the way back, no cat no nothing. OR how about no exhuast? j/k

But really if you guys wana see power increase or decrease i say dyno test. Im gona put my Mid pipe upgrade on soon, but i wana see whats the best way to go.

Any one wana be part of the experiment? Or i can be, just send me $5 buks per a person to pay for my Dyno and Midpiping! j/k;)

Talk later.

CleanBlackSi02

10-30-2002, 11:53 AM

From a Honda Tuning (June/July) article about the K series...talking about the K20a2:

"The engineer in charge of the K series engines, Jehan Tetangco, told us the RSX proved to be a tricky customer. Naturally, DC fell back on its prior knowledge of Honda engines, fitting a 2.25-inch B-pipe to the car. It promptly lost power. A 2-3/8-inch pipe lost even more power. After going backwards and fitting a 2-inch pipe, which pushed power back up to just less than stock levels, he finally reached for the B series power handbook and threw it away. Clearly, this K was a completely different animal.

After much experimentation, Tetangco finally discovered a combination that worked. According to DC Sports, its Twin Canister System axle-back system and a 2.5-inch B-pipe resulted in a solid 6 hp gain and an average 3 hp gain from 3000 rpm to redline."

Here's the link for more info: http://www.hondatuningmagazine.com/tech/0209ht_family/index.html

Granted, it's the Type S, but to my knowledge our stock piping is very similar...

myeverlovinsir

10-30-2002, 03:34 PM

It seems that this engine is a strange beast, when I and others
have tried to open up the mid pipe to 2.5" I lost much of the bottom
end. I immediately went back to 2.25". I would seem if you are
running stock intake and headers the best combo is the stock midpipe.
When you add new headers and intake, 2.5" is still too big.
If you are going to make mods to the midpipe alone don't expect to gain,
instead expect to loose. I noticed from using the larger midpipe,
and having the new intake and header, the power gains
became evident. If you are deciding on adding a blower, then I
would expect to see even better gains with the larger midpipe
compared to the stock.

I recommend going to 2" first and see what you get(mandrel bent), assuming you have made mods to the intake and header.
A 2.25" crush bent would get the same results as the bends neck down close to 2" anyway. hth

TezGari

10-30-2002, 11:35 PM

Geez...So confusing, see guys just sponsor me for the dyno! j/k

really tho, it seems to me that running Headers and intake and the 2.25 is the way to go. And if your going to force induction 2.5 is better. IMOP
i think the 2.25 is best for people who are leaving thier engines away from force induction. But any one wana correct me, please do.

"Whether you like it or not, Honda is not making the B (series motors) anymore. Smart tuners are going to get cracking on the new K as soon as they can. Those that don't, will undoubtedly be left behind."

A quote from the Honda tunnning website.

He is true, we are all leading the frontier of the K20's!!!

CleanBlackSi02

11-01-2002, 03:57 PM

Well...since nobody seems to agree on one thing, I think I'm going to go ahead and get my stock muffler welded onto my Thermal R&D catback. Once I get my header I will head towards a dyno and we'll see how things turn out. I didn't feel any power loss when I installed the full catback, so why should I feel one with the stock muffler and same piping? My appointment is Tuesday. I can't wait to rid myself of the droning sound that muffler makes on the highway.

myeverlovinsir

11-01-2002, 04:07 PM

CleanBlackSi02, good luck and you are right, there is no silver bullet
or good answer that all will agree with. It will always come down
to what has been tried and proven. All I can offer is the setups I have
tried and gotten good results from. Keep us up on what you get
from your setup on the dyno. cheers.;)

P.S. Here is what mine sounds like now. exhaust sounds (http://www.imagestation.com/video/play.html?id=4247116793)

CleanBlackSi02

11-07-2002, 01:05 PM

I know I posted this in another thread, but...

-I got the mid-pipe made and installed today. I was waiting at the shop and it took forever! He had to make a new piece for his mandrel machine to get the bends 2.25".

-I'm back to the stock muffler and no resonator on the new mid-pipe. It sounds almost as deep as my Thermal at low RPM's but really screams in the middle of the powerband. It sounds pretty high pitched, but I THINK I like it better. I HOPE I do. It has more of a traditional Honda sound now. If you liked the B16, you'd probably like the sound of my car now. Before it was deeeeep. I don't wanna say bumble bee...but you know. Hey, if F1 racers and Ferrari's can sound like that, so can I.

-I felt a slightly better throttle response in the daytime heat today. We shall see how it is in the evening. I'm going to record myself launching and driving by so I can have a better sense of how it really sounds. So far, so good.

- My Thermal exhaust is still for sale and I should have some pics up for anyone that's interested. Sounds great...looks great. ;)