Trooper modification

[Fred W]

If someone can post some closeup pictures of the cuts in the end of the pipe, maybe there is a way to eliminate the fluttering without the tail cones.

Mark,

I would not expect there to be any measurable change in MPGs. Most of the exhaust pipe's restriction is still there (think cats).

 

[Bustanut joker]

I'm in the same weather pattern as you Mark,winter storm warning for Ice and snow tonight. :cold:

Might be several weeks before I can get any numbers

 

[wheatonFJR]

...I would not expect there to be any measurable change in MPGs. Most of the exhaust pipe's restriction is still there (think cats).

Thanks Fred for addressing that...

but I don't know any better...is airflow restriction the only contribution by the exhaust system (not considering the O2 sensor) to variance in the fuel mileage equation?

 

[rogdeb]

, Also need to pull the filings out between the end and the facial piece.

Or stick a vacuum hose in there ??

Good mod though

Do I get the rights to the vacuum part of this mod? :lol:

I'm doing the mod this week Thanks Trooper ... and c'mon Garauld !

 

[Fred W]

...I would not expect there to be any measurable change in MPGs. Most of the exhaust pipe's restriction is still there (think cats).

Thanks Fred for addressing that...

but I don't know any better...is airflow restriction the only contribution by the exhaust system (not considering the O2 sensor) to variance in the fuel mileage equation?

Yeah, pretty much.

But the restriction, or resistance to flow, is not just a static or linear thing. In other words, just opening up the end of the pipe doesn't always produce the intuitive results. This is because the exhaust is not a laminar flow, but rather occurs in high pressure pulses with each exhaust stroke flowing in waves out the pipe, followed by a lower pressure behind those waves. Exhaust system designers attempt to tune the system such that an exiting high pressure wave will draw the exhaust from the next opening cylinder to some extent. So when we mess around with restrictions at the end of the pipe is can actually mess up that effect at the head end (at certain rpm ranges), even though it has reduced the overall restriction of the system.

Same sort of thing can happen at the intake end when you chop open the air boxes. It's pretty complicated fluid dynamics stuff. Certainly beyond my capabilities. But I guess the good part is that we aren't really affecting it all that much.

 

[wheatonFJR]

Thanks Fred.

So yer saying that even though the aft end of the muffler is downstream of the cat...it still might have some small effect on the flow.

...In your opinion, neglegible.

 

[Fred W]

Perzacly. Might be positive, might be negative, probably negligible.

Wanna know the weather tomorrow?

I may give it a go myself. From the clips it sounds like it can be negated somewhat by using the spiffinacious Garauld cones, or some other dB modifier contraption, if I later decide I don't like it.

 

[HotRodZilla]

I like it with the tailcones. I didn't know they made any difference in sound, but I also hear the "flutter" with my pipes. I think it's just the extra air being pushed. I may have to call Gary.

 

[wheatonFJR]

Well, since Fred has stated that I will gain 5mpg* by performing this mod...I'm on board with this mod...as soon as I get my other mechanical work (calipers/middle gear assembly seals)on my bike taken care of.

* (not exactly)

 

[Trooper]

For those of you that have done it, I hope you like it. I think it just pushes the exhaust note right where it needs to be. Thanks bogus for the comparison. I think I might need to get a set of the tailcones. I hope they will be made again. I'm glad you guys like it. Hope all do but I know that is unrealistic. Still love the sound and love the price. Take it easy -Trooper.

 

[wheatonFJR]

https://www.youtube.com/watch?v=-i9UC35MV_0

Thanks for posting up this audio/video comparison!!! :clapping: :clapping:

 

[rogdeb]

https://www.youtube.com/watch?v=-i9UC35MV_0

Thanks for posting up this audio/video comparison!!! :clapping: :clapping:

Agree :clapping: :clapping: -- made my decision for me.

 

[bigtallguy]

I'm about 3/4 way through this and it has been quite the pain in the ass.

I'm finding that the welds on the inner pipe need to be sawed through also, and I burned up one hole saw and am in the process of destroying the second.

Got the left side done but had to make a trip to the hardware store to get another hole saw for the right side. When the second saw started failing, I went ahead and cut the pipe at the weld, trimmed the weld down, and am now working with the hole saw again. Then everything was red hot and my drill was smoking a little so I'm waiting for it to cool down before I start again. I didn't buy cheap tools so I'm suprised.

Did anyone else find it this hard or is it just me?

 

[Bogus]

By "not cheap tools", did you mean your drill, or the hole saw? A K-Mart hole saw would probably fail like that. Also, are you sure that the hole saw was meant for cutting metal, and not just wood? I got a bi metal hole saw from Ace that already had an arbor attatched. As I stated in my previous post, after I got through the first baffle, I kind of wiggled the drill around a little to make sure I was through. Apparently, that took about half the teeth off the hole saw, but it still ripped through the second muffler in short order. It took about 2 1/2 dremel cutting wheels per muffler, but wasn't much trouble. Even taking the mufflers off after the pipectomy to shake out the shavings, I don't think I spent more than an hour on the whole deal.

 

[bigtallguy]

The hole saw's were the bi metal type, one from Ace and one from Lowe's. It seemed like they were getting hung up on the welds and just spinning instead of cutting. I could see the inside of the teeth were wearing down first and then they started bowing out. Removing the weld with the dremel prior to sawing again worked pretty good.

Anyway, it's done now and I like the sound

 

[Bustanut joker]

I used one of the multitude of Milwaukee hole saws I have.. The bi metal these guys produce is about bullet proof.

 

[Bogus]

Glad ya got it done :yahoo: Bet it was still worth it though!

 

[bigtallguy]

It was worth it, the sound is much more throaty and just loud enough. The only thing I don't like is that I can hear air rushing out while coming off idle. Would cutting the inner pipe a little shorter help that?

 

[wheatonFJR]

The only thing I don't like is that I can hear air rushing out while coming off idle.

WTF??

Yikes...

 

[bigtallguy]

The only thing I don't like is that I can hear air rushing out while coming off idle.

WTF??

Yikes...

Not as bad as it sounds, more like turbulence caused by the new hole. I'm just wondering if cutting the inner pipe a bit more would give the exhaust enough uninterupted flow to reduce, or eliminate, what I'm hearing.