I have some new LAF exhaust and torque cones for my chopper, Been reading that they can burn up valves. Is the tuning of these pipes that difficult ? or should I try to sale them and keep V&H Big radius. Bought the pipes at a shop going out of business for cheap. plus heard that these are the loudest pipes out there. Is this true? Any help from those who have tinkered with these will help

 

I would stick with the big radius. Had a friend that had those. Put them on without torque cones and lost alot of low end. Put cones in and felt like he may have gotten a little low end back, but it sounded kinda like the old VW air cooled engines did. He got rid of them and got the big radius and likes them much better. I don't think they were any louder than the big radius anyway and the br's have a much deeper tone.

 

DO TORQUE/REVERSION CONES REALLY WORK?
To put it simply, yes it can and it can’t. So what brought this about was reading a thread on another site which had some misconceptions woven into it. This will be simplistic in form and I encourage others to chime in. Like they say, knowledge is power, so power to the people.
The theory is that these devises will restore power lost when a non efficient exhaust system is used, aka drag pipes.
I must devolve into the automotive world of headers. How many times I have heard of someone putting on a set of headers and saying he has a tuned exhaust – wrong! It says so on the box they claim – wrong again!! Actually I have seen cast iron buck horn manifolds (especially those that were flow cut) with appropriate tubing with balance tubes turn in numbers that rival headers.
Headers are tuned out of the box in that the primary tubes are of equal size and length (there are deviations in the market). All other things being equal, each cylinder can have equal flow rates (not going into math here). The primary pipe sets the initial rpm point where boost is created. This boost can be altered by primary tube size, shape, length and importantly the induction system. All things being equal, short primaries transfer torque from below to above peak without significantly shifting rpm, the opposite holds true also.
Here is where true tuning of headers takes place. A spool piece is supplied with the headers called a collector. A drag engine operated above peak will see no benefit from a collector but a street engine will. Engines operated below peak will produce more torque and the further below peak the engine runs, the more improvement a collector will provide. The use of balance tubes in the right locations will improve low end torque even more. Without going into math, the collectors are installed into a system and dyno runs are made, small sections are removed and more runs are made until torque numbers rise and then drop. This will be the collector volume needed to tune the headers, simplistic explanation but enough to make a point.
Bernoulli’s theorem P/P + v2/2+GZ= constant, where fluid pressure divided by mass density of fluid plus gravity acceleration times vertical height plus fluid velocity divided by two equals a constant flow. While this theorem primarily applies to a non-compressible fluid, it can be applied to a steady compressible flow like gas (which is a fluid). Forget the math, just remember sum of all energies remain constant provided no work is done by the gas flow or upon it, meaning, where there is a velocity increase in a fluid flow there must be a corresponding pressure drop.
I brought out this theorem to make a second point. I am going to make a slight divergence to a two cycle expansion chamber. I am not getting into the science but will make a few observations. The header pipe, divergence cone and convergence cone act together to control pressure (sound wave) waves to reduce positive waves and reflect back negative waves (returning or reversion) to coincide with the exhaust port opening to better empty and refill the cylinder. There is one very important part that I will emphasize and that is the stinger and so Bernoulli’s theorem.
The stinger acts as a pressure bleed and controls backpressure in the system. The size and length is critical as it controls wave action and can increase engine performance. Now to the torque cone, consider the smaller section of the cone as the primary tube in a header and the stinger on the expansion chamber. Likewise, the drag pipe can be considered the collector of a header and the chamber on a two stroke system.
We will now call the small opening in the cone an orifice or venturi. This opening needs to be placed strategically to have the greatest pulsation reduction with the lowest pressure drop – aka- point with maximum velocity in the standing wave field of resonance; this means the reduction in amplitude of the acoustic wave form. This is accomplished by controlling flow and backpressure like the stinger on an expansion chamber. As the gas goes through the opening, according to Bernoulli’s theorem, velocity increases and pressure drops. Now as the expanding gas moves further away from the opening, the acoustic wave drops further in amplitude, the larger drag pipe tubing acting as a collector.
When the positive wave stops with valve closure, a reflected wave or reversion occurs. Two things happen one being that the orifice restricts the negative wave from reaching the exhaust port and second, the wave forms that are 180 degrees out of phase cancel each other out further reducing pressure. This allows for better exhaust flow. This is a simplistic example and does not account for temperature, induction, displacement and rpm. Now the size, length and orifice size in conjunction with the rest above sets the rpm range where this will occur. So there is only a sweet spot where improvement will be greatest and falling off on either side. Harley was not stupid when they used balance tubes in their exhausts. There was a lot of engineering that went into their systems and they perform quit well. The use of balance tubes on drags can have benefits also but they must be placed in the system strategically also.
So a torque cone can work if the engine as a system is configured right for the desired range of improvement. But if something is amiss, they are not of much help.
An orifice baffle works similarly with the addition of louvered or perforated tubing which will mellow out the tone by allowing the wave to enter the chamber and reflect off the drag pipe wall back into the flow in a non-directional flow cancelling out any wave that is 180 degrees out of phase. Because the orifice is further from the maximum flow area, the performance will not be as great. The lollipop washer in my opinion is counter- productive. They will help out an engine whose induction is not up to par for optimum flow and mixture in that range but it is a hit and miss. They are good to reduce sound. It has been said that Honda used or invented this technology and they point to the 305 scrambler. I owned one and this is not true. The snuff-r-not was invented by Allen Lader (good ole American boy) and it was a popular conversion not for power but for sound. The scrambler was a dual purpose machine and the pipes were small in size and of equal length and ended in a two to one muffler. I removed the muffler and installed chrome diffusers instead of the washer. If the 305 needs to be remembered, it was the built in oil centrifuge that strikes my mind, way better than paper filters today. This was a formidable machine with a stock 9k redline. I over built mine and it would shatter the piston rings about every third run, so much so, I invented a way to pull the uppers without de-framing the engine, thanks to Honda providing a master-link timing chain removable from the bottom.
Personally I do not use them, like in karate; it takes more energy to stop a blow than to redirect it. I do not have any science for it but I get fairly good results from home-made church key baffle. I key the tabs to cause a swirling motion of the gases. I can add or subtract cuts and change angles to suit. This resists reversion as the cuts act like blocks plus the angles reflect back the wave in different directions changing amplitude and frequency thereby cancelling out more 180 degree out of phase waves like the perfs in tubular baffle. The whole idea behind exhaust flow is to control the flow so that it is laminar and not turbulent by cancelling out pressure waves and its harmonics as much as possible.
Like the everlasting oil issue, so be it with exhausts, so what say you in the exhaust world, what are your opinions?

 

Man... my head is pounding...lol... I was wanting the loudest and coolest pipes I could get without damaging my engine. Plus wanted my buddies to ride away from me...hehehe

 

Funny, i just tuned my 99 softail with laf's today. I used the custom chrome jet kit. Needle adjusted 3 down from the top, 170 main jet, screw adjusted out 3 turns and seems to run great. I have the 1 3/4" laf's with a forcewinder intake. I also drilled the vacumn port with the supplied 3/16 drill bit. Had a 175 main in it at first, would hiccup at low rpm and back fire a little. The leaner 170 jet cured this. You will lose low end with these pipes no getting around it. I had to use a die grinder to open up the exhaust as the torque cones wouldnt fit flush for some reason.

 

Aside from the above mentioned mods my engine is bone stock. Doesnt sound anything like a vw, turns heads every where weather running or parked. The pipes look/sound awesome. I wrapped mine as i dont think they make heat shields for them. I had regular drags on it and didnt notice much change when i switched to the laf's performance wise. The laf's are louder. Im a firm believer that loud pipes save lives plus i love disturbing the peace

 

Thanks for the advice, do you have alot of decel pop? I'm like you, I like loud pipes... want to scare toddlers in their moms soccer SUV

 

It does have a fair amount of decel pop. It was worse before the torque cones though. If you go with them i would strongly suggest wrap or something to substitute for heat sheilds

 

I noticed this thread was started a while ago... and i hope you guys still remember more about it...I just put LAF pipes on my sporty 883.. Seems to fun fine, little loss in horsepower but i have my torque cones on the way, heres the problem, i have plenty of pop on the decel (without cones) I think the bike runs fine, but everyone where i work is telling me im not getting ANY back pressure, and my valves are going to be toast in no time, I probably have over 100 miles on the pipes, but these guys are starting to get me worried.... should i jet? HELP?!?

 

Same here