Model Engine Company of America
4-16-2025

Black HP Tuned Pipes and Headers

HP tuned pipe systems are high quality construction and are finished with a great looking and heat dissipating black finish. All headers are strap on type so they will fit a variety of engines.

SPECIAL PRICES

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Tuned expansion chambers are muffled so you won't have any noise problems. In fact HP tuned pipe systems are quieter than most standard engine mufflers and provide you a bunch more power.

Weight of the .40 pipe is 3.7oz and the .61 pipe is 5.5 oz.


Tuned pipe chamber for .40-.46 size part number HP TP40

Tuned pipe chamber .61 size part number HP TP61

Header Price includes header, straps. Silicone joint tube extra cost.
Click for the whole list of HP headers and Pipes

STYLE New P/N FITS OLD P/N A B C D Material
Tight HPHD-614 HP 20, 40, ETC 66111084 4.25 1.625* 1.25 16MM Steel
Tight HPHD-613 HP 20, 40, ETC 66111083 4.0 1.75* 1.375 16MM Aluminum
Tight HPHD-612 HP 20, 40, ETC 66111082 4.125 1.0 0.7* 16MM Aluminum
Normal HPHD-622 HP 20, 40, ETC 66211082 4.5 2.625* 2.25 16MM Aluminum
Normal HPHD-624 HP 20, 40, ETC 66211084 4.25 2.625* 2.25 16MM Steel
Extended HPHD-625 HP 20, 40, ETC 66211085 4.5 3.5 3.25* 16MM Steel
Extended HPHD-623 HP 20, 40, ETC 66211083 4.25 4.25 4.00 16MM Aluminum
                 
Normal HPHD-822 HP 20, 40, ETC 86211082 4.25 2.75 2.5* 18MM Aluminum
Normal HPHD-815 HP 20, 40, ETC 86111085 4.25 2.75 2.5 18MM Steel
Extended HPHD-818 HP 20, 40, ETC 86111088 4.25 3.5 3.125* 18MM Steel
Extended HPHD-823 HP 20, 40, ETC 86211083 4.5 3.5 3.125* 18MM Aluminum
Extended HPHD-825 HP 20, 40, ETC 86211085 4.25 3.525 3.275 18MM Steel
                 
Tuck in HPHD-686 HP 61, HB 61, OS FSR 61, ETC 66311086 4.75 -1.00   19MM Aluminum
Normal HPHD-834 HP 61, HB 61, OS FSR 61, ETC 86311084 4.25 2.625 2.2 20MM Aluminum
Extended HPHD-935 HP 61, HB 61, OS FSR 61, ETC 96311085 4.25 3.375* 3.00 20MM Steel
All measurements are approximate.

 

Instructions on
HOW TO TUNE A TUNED PIPE
 
The HP TUNED PIPE SILENCER offers good exhaust muffling combined with considerable power increase to satisfy both environment protection considerations and the modelers demand for more power. In the 12.000-16.000 R.P.M. range, the HP TUNED PIPE SILENCER gains up to 1700 R.P.M. for your HP engine when compared to the standard silencer and up to 1000 R.P.M. when compared to the engine without silencer. The power increase is achieved by making better use of the combustible mixture.

Working principle of the tuned pipe... When the engine is operated with a standard silencer or without silencer, losses of unburnt mixture during the exhaust stroke occur. Therefore, the ensuing working stroke can use only the remaining part of the mixture to produce power. In the tuned pipe, cyclic pressure waves develop due to reflection of the exhaust gases by a baffle. During this "supercharging" process, unburnt mixture normally lost through the exhaust is returned into the combustion chamber thus improving the volumetric efficiency of the engine. The HP TUNED PIPE SILENCER yields this effect even without being matched to the operating conditions. For obtaining the full potential power gain, however, it is necessary to tune the ENGINE-TUNED PIPE SILENCER system precisely to existing operating conditions This is easily achieved by adjusting the manifold length. The HP manifolds are delivered with excessive length, and have to be shortened to suit the operating conditions.

 
TUNING THE HP TUNED PIPE SILENCER
  For tuning, a precision tachometer and two props of the same type with identical diameter, but with pitch differing by about one inch, are needed, for example.

For .61 engines --- 11x6 and 11x7 or 11x7 and 11x7.75
For .40 engines --- 10x5 and 10x6

In flight, the engine's speed is higher by about 1000 R.P.M. (depending on the model's velocity) when compared to a static R.P.M. with identical prop. For exact tuning on the bench, a prop should be used which has static R.P.M. coinciding with flight R.P.M. of the prop to be used on the model (for example, if 11 x 7 is the flight prop, use an 11 x 6 for tuning). When cutting down the manifold outlet (in 1/4" steps), R.P.M. will go up gradually. When no additional R.P.M. increase occurs, the length of the system is correct. Any further shortening of the manifold will decrease R.P.M.

Small deviations from the correct length can be compensated by adjusting the silicone tube, which also depends on the type and brand of propeller. The graph shows the principal form of the power curve.