AccuFab install with a twist

[Shadowman]

I have just installed the AccuFab exhaust however I chatted with John in advance and FYI he was initially reluctant had him ship me one that was not polished because my intention was to wrap the tubes as I have on numerous gals over the years with great success. John is a great person to work with and during the process he shared that he was building a new set of jigs aka welding fixtures to make the resulting product even better. Well I never saw any of the original pieces however this one is “spot on”. The fit of the tubes and the subsequent Tig welding completed is eye candy to me being a racer at heart and would never grind and polish them away.

Now I know that this process will not be for everyone because many enjoy and appreciate the highly polished look and this I truly understand and respect. However for myself I wanted an exhaust that was mechanically sound, pleasing to look at, and not a source of special attention. This is why I elected to have even the tips appear as OEM.

My goal was to further reduce the heat with the engine bay particularly the heat that seems to have caused issues with more than one set of vents in the clamshell.

Takes care

Shadowman

 

[Spirit]

Shadowman,
Looks Good.
I LIKE IT !!

 

[Fubar]

That is hotness. I'm surprised you didn't have them ceramic coated. I've been told that it creates better heat reduction (although I have never measured it). The ceramic wouldn't look as cool tho.

 

[eshrink]

I would need some coating on the exhaust not only for heat dissipation but for appearance. As Chip Foose says about his cars, the engine is the jewel inside the box. The GT's engine compartment is a showcase of technology.

The problem I have, and I fully intended to buy an aftermarket exhaust, is that even baffled, all of these systems (to my ears) are a harsh raspy sound. They do not have that deep, rumbling, tonal sound of the muscle cars of yore. I have wondered, and stated, why someone could not make a system using a small aftermarket (not unlike Tubi) muffler but something along the lines of a Magnaflow, etc that reduces temperature while also providing a muscle car sound.

Then again, I never liked straight pipes on my Harleys. Over the years, I always used exhausts that incorported a muffler in some form. I do not care for the deceleration backfires which has a ricer quality to me.

I imagine with so few cars as a potential market, there is not much incentive to create such a system.

- doc

 

[Fubar]

Borla has always produced my favorite sound on American cars. I think the GT's "rasp" may be based on the short travel of the Mid-Engine exhaust. Most American Muscle cars have a long exhaust system and I'm sure that allows for a "rounded" sound.

 

[eshrink]

Fubar:

Exactly. Few realize this. It is what killed the Corvette sound as of 1963. Long exhaust pipe and short tail pipe.

The early muscle cars had the muffler just rear of the front seats with tailpipes extended, unimpeded to the rear of the car.

It had time for the pulse to create a reverberation. Indeed, as of 1966, they began putting resonators at the end of the tailpipe to lower the noise level. Fortunately, they were easily removed.

It was a great sound, and you can hear it on any Mopar, FoMoCo, or GM product of "the day."

Glasspak mufflers readily replaced the stock ham cans and created character to the sound.

I do not, and never will, like the rough, raspy, atonal sound of straight pipes. Indeed, it is difficult to tell the different between a car with muffler-less exhausts and a passing 80s delivery van with mufflers rusted out.

Apparently, Magnaflow and others attempt to deal with this, but let's face it, the new Mustangs suffer from the same problem...but not as badly as do our GTs.

- doc

 

[SLF360]

interesting sounddiscussion

Very intersting posts, eshrink and fubar !
I have since two weeks the catless pipes, into the borla in. - I must say, I love that sound ! When you start out nice and quiet, but when you hit it its a rocketship at launch... Anyone else have that combo !? What you guys think of it? Pity I didn't make it to the rally and be able to judge the various systems. Love the accufab look to it. Wow !

Stefan

 

[eshrink]

Stefan:

Exhaust note are predominately middle and high frequencies.

At a simple level, play a loud speaker out-of-doors vs. playing one in a small room. Same "note" but two different aural impacts based upon impact of the room on the character of the sound. A speaker in an anechoic chamber sounds quite different from one played in your family room.

Having the sound unfiltered emerging from a short steel pipe will sound different than having one slightly "muffled" and resonating down a long pipe. Small pipes will sound different from those with larger inside diameter.

You can demonstrate this to yourself in any number of ways including whistling out loud and then through a tube.

(Please note that if you whistle through a tube you might wish to avoid doing this in front of the family or in certain areas of town).

- doc

 

[Shadowman]

All good comments; and once again the topic remains strong.

I opened this thread by stating this will not be for all because some will want the polished “bling” exhaust to be seen, talked about.

I agree that the motor is one of the jewels as such I have the hoods and bonnets open on all of them all the time; my eye candy. However the portion of the exhaust that resides behind and under the air box (at least for me) is not the focal point it fact I do not want it to be. Furthermore; as stated my quest remained as it has for years; to reduce whenever possible secondary damage caused by heat.

Now the backfiring you mention on deceleration; I looked into this and ask several about it and even listened to the various clips. All are similar in this regard. I do not feel that baffles will stop this because I think that it has more to do with the unburned fuel rather than anything thing else. I share this because all systems that I heard had a more pronounced case of it when cold while in OBDII open loop mode when compared to once they are fully warmed and go into closed loop.

Lastly the comparing a Harley with drag pipes and the AccuFab, IDA, Kenetic's exhaust section are not apples and apples because the GT (on most gals) maintain the cats which offer significant muffling. As for creating a sound like Tubi or ??? there is no doubt that this can be done however any muffler can will be a heat sink therefore me of no interest furthermore most seem to looking for the sound reminiscent of the GT’s of days gone past as such a strong presence with a little burble is not only acceptable but also desired.

Thank you all again for the comments

Shadowman

 

[eshrink]

Shadowman:

If I recall my few mechanical engineering courses, the popping on deceleration is caused by leaning of the fuel mixture as back pressure changes. Did I recall that incorrectly? Could be. I do recall that muscle cars suffered a degree of valve scoring due to the backfiring; perhaps the computer obviates that.

The sound of Harley straight pipes may be apples and apples, after all, since both are ungoverned (by muffler) sounds. In either case, the illustration was that a Harley with a suitable muffler adds nothing to back pressure but adds tone by impacting the exhaust pulse.

I think that good looking headers and exhaust can do much for the appearance of a car. That is just me, but just after looking at the intake and valve covers, my eyes drop to the exhaust system. I guess it is much like noticing hair vs. eyes on a portrait.

I remember reading that a small muffler can dissipate heat, but I never knew if that was empirical or speculation. In either case, at present a muffler based throaty exhaust has not been announced although one GT owner had talked about developing one this winter.

- doc

 

[Shadowman]

Great comments

The burbling with the tail section on the GT has no cause and affect on the motor; too far removed and after the cats. Furthermore it takes something to create the burbling aka fuel and then on deceleration the engine goes to a extreme lean situation the combination of extreme lean and unburned fuel causes the burble; so you are correct but one needs to add fuel to it as well.

I was indicating that the open pipes on the Harley are just that; an open pipe however most of the GT's retain cats as such have a muffling device in place.

As for looks; this issue will forever remain subjective. I like this fact because for me it would be an ugly place if we all lined up with exactly the same clothes and personal props.

Yes; I like the looks of a highly polish system on a static display, I like the looks of coated exhaust such as applied by HPC where it is a natural looking finish, I also like the looks of a straight out of the box Tig welded Inconel or Stainless Steel exhaust however I also like the look of a well wrapped exhaust particularly when form follows function.

In my case the goal was likely different than yours which is perfect; neither better only different.

By wrapping the exhaust the air box and the vents will likely survive with no issues, I will likely maintain a more consistent engine bay temperature as such there should be less behind the scenes PCM adjusting taking place made as the result of the fluctuating IAT readings, I will never scorch my arm on the exposed stainless steel pipe, and lastly my exhaust remains a cool (a play on the use of the word) component of the engine bay and not the focal point.

A point that has not been shared is the fact that the OEM muffler is a dual wall canister which albeit not as extreme as the wrapping measures I undertook offer similar benefits.

In my opinion the ideal situation would be a rear section mandrel/water bent using dual wall tubing; now this would be the ticket.

The numerous systems being offers all have many common factors; lighter, less captured heat within the engine bay, more aggressive sound, and the claims of more HP. On this issue I think that IDA presented the best documentation, lower engine bay temperatures = more consistent HP because as the heat rises the IAT tells the PCU to pull timing and likely add fuel.

Thanks for the friendly bantering

Regards

Shadowman

 

[Shadowman]

Wow numerous comments about the method used for this particular install

I thought that I would share what it looks like all tucked in. It blends with the engine bay nicely

Shadowman

 

[nota4re]

strong presence with a little burble is not only acceptable but also desired.

The Ford Rear Exit Header Exhaust has the burble-ing in spades. On any deceleration the burbling is very pronounced. Once rpms drop below 2500 it will burble and lightly pop. It sounds very angry to be slowing down. I too think this sound/behavor is desireable and I love this trait of Ford's exhaust.

 

[B O N Y]

This Stillen GT sure sounds good! (video)

http://www.fast-autos.net/featureCars/12/

yeah it does, great post...

 

[SLF360]

This Stillen GT sure sounds good! (video)

http://www.fast-autos.net/featureCars/12/

Mine sounds even better.. FRPP catless headers & Borla.

How do I post a soundfile ?