* Discontinued, no longer available *

General FEATURES

The Bolly Carbon Fibre pipes / mufflers are the result of many years of development, featuring ;

Note: Some of the larger pipes now feature a Carbon / Aramid (Kevlar) composite weave material.

A) Low weight - between 20 and 60% lighter than metal.

B) Exceptional strength for weight. Stronger than alloy.

C) Dent resistant, and less prone to fatigue.

D) Generally quieter, by design and the materials. Carbon pipes have a better sound to the ear.

E) Better performance - using the latest designs, plus the production process allows the optimum shape to be produced. (Alloy pipes are often compromised to production methods).

F) Built in temperature gauge, via the colour change of the pipe.

G) Cooler running - leads to greater potential power. Our c/f pipe cools very quickly.

SPECIAL FEATURES

Due to the different materials used in Bolly pipes, several unusual features need to be noted.

A) The unique resin used to manufacture Bolly Pipes has a ‘built in’ temperature gauge. The colour will change with the operating temperature. As the pipe temperature rises, the resins colour will first change from a yellowish colour to orange, then reddish/brown and finally to black. The optimum operating temperature of the pipe is an ‘orange’ colour.

B) The pipes may make some 'crackle and pop' noises during the first few runs.

C) The pipes have an unusual smell which will soon dissipate with use.

D) The Resin and Carbon Fibre will withstand all exhaust temperatures...PROVIDING the pipe is cooled. DO NOT insulate the pipe

E) In some circumstances, the pipe may 'weep' exhaust gases. This is caused by the boiling out of any moisture present in the laminate, or from the expansion of the weave when hot. There is no detectable power loss from the weeping. Weeping is more likely to occur if the pipe has been 'run hot' at some stage, especially in it's first few flights.

USING BOLLY PIPES, General

The pipes are given a basic cleaning before packing. Before use; wash out with thinners or methanol.

Make sure the silicon joiner, is a good fit and in good condition. Use nylon cable ties for attachment.

Header springs are available from Bolly if required. Unfortunately it isn’t possible to mould in a header spring attachment plate as is common with some alloy pipes. A suitable arrangement can be made by twisting together a wire fitting.

If you wish to use a pressure fuel system.....

It is best to use a MACS brand thin wall 90 degree pressure fitting.

The Bolly pipe may be drilled and tapped to take a normal pressure nipple. Use a large bore nipple. Note that some pipes are fitted with a reinforced section (round) for this purpose. Care must be taken to provide a square seat for the nipple (use some cyno and filler, epoxy or silicon). Where possible use a pump system to supply fuel to the motor. On EQ pipes it is best to place the pressure fitting in the alloy header (but not on a bend). This is equally effective and more convenient that positioning it on the pipe.

For the ducted fan QP / DF pipes the Pitot style of fuel pressure fitting can also be used.

For racing engines, pipe pressure is the suggested fuel system. The 90 degree fitting is best placed at the front of the maximum diameter section (not critical). Crankcase pressure can be used (in conjunction with a .012 to .018" restrictor) for engines with less than 175 degrees exhaust timing.

The first ground run and test flight should be done with any pipe cowling removed for extra cooling.

When cowled, cooling air Must be provided, especially for the first third of the pipe length (hottest area) ... for cowled racing models, it is essential that cooling air be forced directly into this area. Don't forget the exit to any cowl needs to be much larger than the inlet.

At the completion of flying the pipe should be removed from the model and be allowed to drain ... front end down. If the pipe is to be unused for any time, wash out with lacquer thinners or methanol. Periodic cleaning will help maintain the good heat conducting properties.

Pipes that we have deliberately 'cooked' during testing have continued to work fine..... but it is not recommended, we will not offer any warranty on an over heated pipe. A well cooled pipe results in greater power and reliability. This applies to alloy or C/F pipes.

Most ‘P’ pipes are provided with the silicon attachment tube. It may be necessary to shave this to improve fit. The use of a petroleum jelly will ease fitting a tight assembly. Some ‘P’ pipes attach direct to the engines exhaust stack.

Alloy headers ... sharp bends and flow restrictions should be avoided. Most commercial headers need some finishing (filing or grinding).

The ‘P’ pipes should be anchored at the stinger and the ‘EQ’ types at the stinger or near the first baffle position. Where possible use some silicon or rubber between the mounting points and the pipe. On pattern ships, 'soft mounting' is highly recommended, especially if the engine is ‘soft’ mounted. Soft mounting pipes helps prevent any fatigue problems, especially for metal pipes which are fatigue prone.

The Bolly C/F pipes are less prone to damage than alloy, but if you are unlucky enough to puncture one, it can usually be repaired. Please arrange by mail or phone call before returning pipe.

Carbon pipes can be made to the customers' own design, at similar cost, if the mandrel is provided. Inquiries by mail or phone call welcome.

USING BOLLY PIPES, eq pipe lengths

As outlined previously, and later in this section, the operational length of the EQ style pipes is not directly related to the pipe length chart of several pages prior to this.

The general rules of thumb apply, for example, ....

Lower exhaust timings = shorter pipe, and lower rpm = longer pipe and visa versa.

The ideal set-up for the EQ style pipe is to set the operational length much longer (by 300 - 500 rpm) than where peak power is produced. The effect of this is that when in a vertical climb situation, as the increased load reduces rpm, the pipe is working at it’s best, and when the model is in a vertical dive situation, and rpm increase, the pipe goes further off tune (‘over the top’), which reduces power and ‘holds back’ the engine.

The graph is an approximation of the power and torque curve differences between open exhaust and an EQ pipe. The engine should be ‘propped & piped’ on the down side of the power curve.