Custom sidepipes - Phase I

RedBarchetta · #1 (**permalink**) 02-06-2005, 10:02 PM

Ever since I opened my big mouth and started sqawking about some custom mufflers I was having made for my Superformance, I've been getting hammered with quite a few inquiries.

The new mufflers were completed a few weeks ago, but timing, some serious out-of-country travel (business related), and a mid-March car show that I've already signed up for has saddled me on finishing this project until late March.

So I figured I'd at least show you some preliminary photos of the mufflers. They were made by Stainless Specialties in Sebastian, FL, to my specifications. Let's keep in mind that the stock Superformance muffler is a 4" case (approx. 21" length) with a 3.5" inlet/oulet, but with a puny 2" inner perforated core surrounded by steel wool. A real performance choker, and some have reported HP losses in the 40-50 range alone due to these restrictive pipes.

What I've decided to so was maintain the external appearance of the stockers but with a radically different core. Here you can see the raw unfinished mufflers next to a ceramic coated stocker.

I had these custom units cut one inch longer to 22", and then had the ends domed down to 3.5" (to match the entry/exit points. I intend to use the same collector and tail pipe. I had the muffler extended one inch, as I will lose some material on either end when we make the cuts to fab it in. The overall length of the pipe will then be maintained.

The cores on these stainless mufflers are a full 3" perforated tube surrounded by a ceramic mat. Notice that a baseball can be rolled right through them!

My objectives with this modification are two-fold: I want more performance and I want a louder, more aggressive exhaust note. It is my estimation that I will achieve both with this set-up.

Oh, yeah, the cost. Each muffler ran $160 plus shipping.

Stay tuned for Phase II in 5-6 weeks, when I have Alex Mickelson of American Roadster do the fabrication work.

-Dean

hp/weight · #2 (**permalink**) 02-07-2005, 09:56 AM

Dean,
First of all, thanks for taking on this project. I'm assuming based on the name of the company(Stainless Specialties) that these are made from stainless steel. Will you be ceramic coating them? Would this company and enough club members here be interested in some sort of group buy if they work well for you?

Does anyone know if the stock BDR pipes suffer from this same restriction? TIA

RedBarchetta · #3 (**permalink**) 02-07-2005, 10:00 AM

TIA, yes, I will be re-ceramic coating the entire sidepipe assembly once it's done. I never intended to have them polished, as the rest of the sidepipe assembly (coated steel) will be re-used.

As for Stainless Specialties, yes, they build all sorts of custom exhausts out of stainless. I probably ended up choosing them because they offered custom work. I only received references for 2-3 shops, so my choices were somewhat limited. I do not have any affiliation with S-S, so any "press" they get here is purely based on my experience.

scottj · #4 (**permalink**) 02-07-2005, 01:23 PM

Quote:

Originally posted by RedBarchetta

My objectives with this modification are two-fold: I want more performance and I want a louder, more aggressive exhaust note. It is my estimation that I will achieve both with this set-up.

-Dean

Those mufflers are identical to the set I made for my car. Prior to these I had tried about everything, including the Lobak auger style muffler. For a high HP application the 3" perf cores are a BIG improvement in torque and throttle response. Expect the noise level to be nearly the same as an open pipe of the same length. By comparision, the Lobaks have very lazy throttle response and are much quieter.
Scott

RedBarchetta · #5 (**permalink**) 02-07-2005, 02:20 PM

Scott, thanks for the confirmation and personal testimony.

Some of the chances that one takes going the custom route is in the final results. I realize that I might error on the side of "too loud", but we would have never sent men to the moon if we continued to believe it was just a big brick of cheese.

How many jet changes (up) did you have to go through (I'm expecting a lean condition after I do this swap)?

-Dean

scottj · #6 (**permalink**) 02-07-2005, 03:43 PM

Dean,

Here is alot more than you asked for but, to simply answer that I didn't make jetting changes wouldn't make sense.

Keep in mind that my whole combination is designed for open exhaust.

I did't make any jet changes and here is the reason why: with the 3" perf core or open pipes the fuel curve is perfect and throttle response is great. When I want the car quiet I put the Lobaks on. With the Lobaks and the increased back pressure the correct fuel and air ratio is still entering the motor but, a couple of bad things happen. Because of the combination of cam overlap and the back pressure the intake charge is now diluted by exhaust. The intake charge dilution by the exhaust slows the burn, making the throttle response very lazy and because the exhaust isn't helping to pull fresh charge in during the cam overlap the carb now feels too big, again killing throttle response. That is not something I can correct with jetting, it's just one of the evils of excessive back pressure and a big cam.

There are ways around it. Here is something I do that works: with the Lobaks I'll advance the timing 6 degrees (I run the distributor lock out). This gets back most of the throttle response that the Lobaks lose. For easy driving (which is the only time I would use the Lobaks) this works very well but, with the timing that advanced I'll now hurt the motor if I start doggin it hard. So, I run a retard box on a toggle switch that knocks the timing back to where it belongs and now I can get on it hard. This is the same principle as vacume advance only with the driver control and reliability of the electronic age.

Sorry to ramble
Scott

RedBarchetta · #7 (**permalink**) 02-07-2005, 04:20 PM

Scott, sounds like a very well thought out set-up! Since I won't have a another pair to swap in/out, I'll just have to re-jet accordingly. All that extra oxygen that the engine will want to inhale/exhale will have to be offset by some more fuel.

JAM1775 · #8 (**permalink**) 02-08-2005, 07:47 AM

Terrific thread guys....I am at the deciding point to go with 3" straight through mufflers or Lobaks.
...I have 2 1/2" glasspacks in my stock FFR side pipes, they are probably blown after 7K and they are noisy....but guess what, I like the sound and I still can have conversation on a highway. In researching bullet style straight through mufflers I have been advised they "create" turbulence even with louvered tubing. Lobaks , as we know are touted as reducing turbulence and increasing air velocity while scavenging the exhaust . The Lobak manufacturer advised me they also offer a Lobak with a larger center core for those motors turning higher RPMS or HP. The standard Lobak center tubes are 1.25" ( Small IMHO) while the larger tubes offered have a 1.75" center tube. The rep at RPM told me the 1.75" center core, plus the auger openings comes very close to flowing the full 4" of air in the muffler casing. I am still not sure about that claim. I am sure a 3" straight tube flows more than a 2-2.5" tube. I like Red's suggested 3" bullet tube. Thanks for that...Red. Scott...thank you for your comments because you are the first person I recall actually able to report comparable engine response to a before/after Lobak install. With regard to jetting I believe the many components unique to each motor may determine if a muffler change requires more jet. When I make the muffler change, probably to a 3" straight tube model, I will read the plugs or even put the motor on a dyno.

scottj · #9 (**permalink**) 02-08-2005, 09:30 AM

JAM,
Nothing I've seen out-performs the perforated-core straight-thru design. The straight-thru LOUVERED-core mufflers are the ones that perform poorly.

Most of the time on our dirt engines a 3-1/2" perf-core makes more torque than an open header. 3 weeks ago I saw an 820HP 418 cid Ford SC1 dirt engine pick up 5ft/lb of torque on the dyno using a Dynatech Split-Flow muffler. The shop that built the engine does allot of circle track stuff, ranging from local dirt and asphalt to super-speedway lease engine programs for Busch and Craftsman Truck. They are also the shop that did all the Dyno development for Dynatech on their Tri-Y dirt headers. I’ve seen similar gains with the Borla perf-core when that was the spec muffler for the series now known as the World Of Outlaw dirt Late Models.
I’ve also raced at tracks that required the Lobak spiral-core and that design is only used when noise requirements make it absolutely required by the track. It kills the throttle response on the track to a much greater extent than the dyno losses indicate. Everyone I know that had to use them on a dirt car ran a Y-pipe off the header and ran 2 per side.

As I said previously, my engines are built and tuned as open exhaust race engines. A high-backpressure muffler like the Lobak really took the fun out of the Cobra due to lazy throttle response. It just lacked any crispness that I knew I should have. The jetting on my engine combination is just very-slightly fat with the Lobak and not the cause of the losses felt and seen on the dyno.

I think Red has an excellent design with the louvered core. But, I can’t speak to how much benefit it is to performance on a street build when compared to the Lobak or any other design. I also can't comment on what will be required to tune for them. I just don’t have any first-hand experience testing with street-type builds.
Scott
.

hp/weight · #10 (**permalink**) 02-08-2005, 12:47 PM

Quote:

Originally posted by JAM1775 I am sure a 3" straight tube flows more than a 2-2.5" tube....

Surprisingly, (at least to me) this isn't always true. At times, particularly during lower RPM states, having too large a diameter can actually decrease the flow. It has to do with allowing the gases to cool and stagnate potentially increasing the backpressure. There's an interesting article about it here:

http://www.burnsstainless.com/TechAr...ry/theory.html

ERA Chas · #11 (**permalink**) 02-08-2005, 02:34 PM

Red,
Excellent idea and excellent choice using Stainless Specialties.
I have the original prototype set of these ceramic mat pipes built by Lou Berger. Mine are cut and flanged aft of the pipe merge and have 12" long open header collector turn-outs made by Lou for track use.
I dyno'd both configurations for back-to back- comparison on Lizzard Racing's chassis dyno.
The car made 462 WHP on open headers and 457 WHP with these side pipes. Made eight runs up to 7000 RPM for consistent results. A 5 HP loss is amazing. The original mild steel/glass-packed pipes from ERA were 53 HP worse.
I also decibel-tested at 3000 RPM. Open headers and the ceramic mat sidepipes were exactly 103 dB EACH. However the mufflers have a different tone than the raw open headers-but just as loud to the test instrument. I love 'em and it seems you will too.
Stainless Specialties makes complete sidepipe units for ERA's Contemporary's
and several other makes as well as custom work such as you have ordered.
I'm not affiliated with the business in any way other than as a customer, but much like the Weaver's and the Kirkham's for example, Stainless is a quality, family run business and good folks to deal with.

RedBarchetta · #12 (**permalink**) 02-08-2005, 03:01 PM

Chas, thanks for the testimonial. It's reassuring knowing that you and others have either dealt with similar pipe configurations or, in this case, the manufacturer, and are equally satisfied with the results. It helps justify my efforts before I realize the benefits of them. Makes me want to go out, borrow a TIG welder and get crackin'!

-Dean

JAM1775 · #13 (**permalink**) 02-21-2005, 02:42 PM

I am thinking of a $38 Dynomax muffler. They are in Jegs , item # 289-24219 Dynomax Bullet mufflers with 3" inner tube. The inlet is also 3" but I figure that could be cut at the weld and attached to my 3.5" pipe at the muffler's tapered inlet. The exhaust tip is also 3" but that is not problem as that it is only 2.5" , can be cut or slip right inside my existing baloney tip extension. I'd gain from 2.25 to 3" inner tubes. Do you think the Dynomax mufflers will do the trick ?

bmcmillan · #14 (**permalink**) 03-15-2005, 08:43 AM

JAM,

Did you ever get the Dynomax's? Do you know if they are perforated or louvered?

Exhaust is a complicated subject and most of the posts are musings on only one aspect at a time - scavenging, gases heating, cooling, pulsing, spiraling, backpressure, etc. The cam, timing, CID, aspiration, etc. all affect the exhaust - no two cars are alike.

Other factors also come in to play as well - ambient muffler heat, header/collector heat, styling, cost.

Tough subject. Maybe the only way to make the decision is to make a flange so that different pipes can be installed easily for different moods.

I am no closer to a decision now than when I started on this topic.

Brian

JAM1775 · #15 (**permalink**) 03-15-2005, 10:33 AM

I did get the Dynomax 3" ID/OD Race Bullet mufflers Part #24219.
The mufflers are perforated 3"in/out, 23.5" long,18"L/ 4"W casing.
Mods in process now at the welder's also included new merge collectors which I was conivinced would provide 15HP gain due to the smooth shaping of the air induction from 4 pipes to the straight 3" pipe. There is also a spike inside the merge collector to smoothen out the transition and put a slight spin on the exhaust. Similar merge collectors can also be purchased by Hooker or Dynotech in JEGS. I went for the MC's because of the 15HP brag but also for uniformity. They are installed by cutting the four pipes after they turn down the side. The MC will lead to butt welded 8-9" tube staying at 3" ID, flowing directly thru the 3"ID Dynomax and out at 3". On the exit we will slip the 3.5" exhaust cut out over the outlet and weld that to the muffler casing. The Dynomax mufflers are very well constructed using a fiberglass mat, wrapped in SS wire , gauranteed not to blow out.
Hmmm...we'll see ! I do think Red's SSS mufflers are better quality however. I'll send you photos as I'm not too good at posting them.

RedBarchetta · #16 (**permalink**) 03-18-2005, 11:58 AM

* * * U P D A T E * * *

Last night I pulled the pipes. Dang, these things came out waaaay too easy! Anyway, I just dropped them off at American Roadster in Placentia. Alex is going to tack weld them up possibly TODAY. If all goes well with that, then I'll drag them home over the rainy (!!!) weekend and make sure the fit is correct (the side bracket fitment is especially critical and has to be exact). Assuming everything lines up nicely, I will drag them back to Alex for final tig/finish welding. Then it's off to have them re-Jet Hot coated.

Curious, has anyone come up with a better fastener system for the collector gaskets? The 8 bolts and nuts only have a lock washer to keep them secure. I'd like to explore other ideas so that there are 16 fewer bolts to keep checking for tightness. Thanks for the inputs!

-Dean

Dave Bermani · #17 (**permalink**) 03-18-2005, 12:17 PM

Deano,

My sidepipes have a slip fitting so I can't help you there. But I do want to see what you've got...and hear it...once it's done. Now that I'm up and running I'll be visiting Alex too.

Dave

MidOHasp · #18 (**permalink**) 03-18-2005, 02:49 PM

Dean,

Copius updates with photographs appreciated.

Would love to see how this turns out for you - on all fronts. Visual, audible, performance!!

Amen on wanting a better way to attach the collectors to the headers. Wow...what a PITA!

My pipes need to come off (piss poor jet hot coating the first time, already developed cancer), and I kind of want to do something different. If not "one-off" then maybe "ten-off" you know?

JAM1775 · #19 (**permalink**) 03-18-2005, 05:09 PM

Good Luck Red ! Mine are due back from the welder early next week. I'll paint them flat black as soon as possible. Then they get mounted back on the car. I am extremely curious and somewhat apprehensive. Is a 3" tube too loud ? Oh well...too late now....in any event thanks again to you Red for the e-mail advice and inspiration !

dlampe · #20 (**permalink**) 03-18-2005, 05:42 PM

Hey Red, I just sent my pipes (copies of yours) to Swain Technologies for white coating. Thanks for the idea! I think this is going to be a huge improvement.