CONTEST GLOWPLUGS

1.2 volt - 2.0 volt

CHR = COMPARATIVE HEAT RATING - This denotes how `hot the plug is within 'the Fire Power range but it does not directly relate to any other range.

SHR = STANDARD HEAT RATING - This denotes how hot the plug is on the `Standard Heat Rating scale. Any plug can be rated on this scale and it allows plugs to be compared from different ranges. The scale runs from 0 to 100 :-

0 = Excessively Cold 100 = Excessively Hot

DEFINITION OF HOT AND COLD - If an engine is adjusted to run well on plug A: And when plug B is substituted it is noted the needle valve must be leaned to get equally good running: Then plug A is said to be `hotter than plug B. Plug B is `colder' because the element needs the extra heat, generated by the leaner mixture, to reach the optimum operating temperature in the required time.

CORRECT SELECTION OF HEAT RATING can give up to 2000 rpm power increase and improved throttling. Too cold a plug will cause loss of power and or poor throttling. TOO HOT A PLUG will also cause loss of power and or poor throttling but, additionally, it can cause pre-ignition, overheating and detonation leading to FAILURE OF THE PLUG and DAMAGE TO THE ENGINE. When a needle valve is leaned, the leaner mixture heats the plug element faster and advances the ignition. Maximum power is achieved when the ignition timing is optimised. If the plug is too hot, then, although the timing can be optimised the mixture is still too rich for absolute maximum power. But, if the needle is further leaned, then the ignition becomes too advanced and again loses power. With the FIREPOWER RANGE it is possible to fit a colder plug so that when the needle is leaned to give optimum timing, it also gives optimum mixture AT THE SAME TIME and thereby gives ABSOLUTE MAXIMUM POWER with extremely good throttling.

SELECTION OF THE CORRECT PLUG can only be made by testing and in most cases the plug that produces the highest rpm is the best choice. Other parameters to look for are:- lowest reliable idle speed; cleanest pick-up from idle having allowed time for the engine to cool; strongest mid-range pick-up and an uncritical main needle setting. HIGHLY TUNED RACING ENGINES will probably require an F2, F3 or F4. HIGH PERFORMANCE CONTEST ENGINES F3, F4 or F5. HIGH POWER SPORTS ENGINES F4, F5 or F6 and REGULAR SPORTS ENGINES F5, F6 or F7. But there are many exceptions to these suggestions, so don't be afraid to experiment - though be careful to avoid detonation when trying hotter plugs by setting the needle a little on the rich side. Two important factors that influence the choice of plug: If the NITROMETHANE content is increased significantly a colder plug will be needed if the COMPRESSION RATIO is reduced a substantially a hotter plug will be needed.

THE FlREPOWER RANGE of plugs, in effect, gives the user the means to FINE TUNE THE MIXTURE at maximum power. This not only increases the power further and improves the throttling but it can also increase the MILES PER GALLON BY UP TO 40%! The FUEL savings on the first few outings could well pay for the plugs ! AT MODEL TECHNICS we have been running engines to test FUELs, additives and oils for over 20 years. In that time we have logged around 18,000 hours of running using 300 different test engines and BLOWN 7,000 GLOWPLUGS. We must have tried just about every plug that was ever made but we never found a plug, or range of plugs, that gave us all the parameters that we required. We have long been struck by the fact that engine design has taken many giant leaps forward while GLOWPLUGS WERE ALWAYS VERY MUCH YESTERYEARS TECHNOLOGY. Until now, for us to do a comprehensive test, we had to select plugs from many different manufacturers' ranges and each with widely differing characteristics, e.g. XXX No.1 a nice hot plug but burns out quickly, YYY No.2 a warm all round plug but poor top-end performance, ZZZ No.3 a cool plug but seldom lasts to the end of the test, AAA No.4 a good cold racing plug but with poor throttling and pick-up. Glowplugs were an area that seemed to need a lot of research and development. But this R & D could only be afforded by a company who could fund it by manufacturing and selling a product So, Model Technics decided to make glowplugs.

TWO YEARS LATER and £60,000 poorer we are pleased to report our progress. Our first decision was to produce a range of plugs where all the plugs had excellent characteristics and similar characteristics but DIFFERENT HEAT RATINGS. We long ago realised the absolute necessity of matching the heat rating of the plug to the engine ! compression ratio / silencer system l FUEL / rpm range to obtain maximum available power with first rate throttling and pick-up. After exhaustive testing we concluded that this could be achieved but that we needed exacting control of the catalytic action of the platinum alloy element. More than that, it meant a special alloy for each different heat rating. We believe we are the only model company with the expertise and technology to develop such elements. Further testing showed that we needed a MINIMUM OF 6 PLUGS with 6 different heat ratings to cover the wide variety of engines available today under all the differing circumstances of their use. All this had to be accomplished with elements that would be very long lasting and withstand the overlean run that all modellers are guilty of occasionally. Additionally, for everybody’s convenience, we wanted our plugs to be able to be used with any source from 1.2 volt to 2.0 volt. All these things have been achieved with the FirePower range.

ANOTHER MAJOR PROBLEM with present-day plugs is a proneness to LEAKAGE THROUGH THE SEAL between the centre electrode and the body. By careful design, taking into account the expansion rates of the various materials used and putting COOLING FINS ON THE CENTRE ELECTRODE to avoid extreme temperature differences, we have achieved a seal with the FirePower plugs which we have yet to blow on test. Since, under racing conditions, the seal is as likely to blow as the element with other plugs, the FIREPOWER SEAL is itself a giant step forward in plug design.

S0, WITHIN THE FIREPOWER RANGE is a plug .to ideally suit every engine under all circumstances. It will give the maximum available power, it will take lots of abuse and it will last and last and last. And, due to each plug body and its element being a TOTALLY MATCHED SYSTEM, it will achieve all the above with lively starting, reliable idle and extremely powerful pick-up throughout the rpm range.

OUR INITIAL DESIGN CONCEPT was to produce an out-and-out contest range of plugs - and this we have done. But, we have always worked on the assumption that they would also make SUPERB SPORTS PLUGS - and the FirePowers have certainly shown this to be true. We have tested around 80 engines with a large selection of plugs and in every case one of the FirePower plugs proved to be superior to all the other manufacturers' plugs. Of these 80 engines, 60 were sports engines and most of them showed DRAMATIC IMPROVEMENTS IN PERFORMANCE on FirePower plugs. So, whether it is to win championships or for Sunday afternoon recreation, take the agro out of the engine and fit a FirePower. But we can't promise anyone they will win contests by using a FirePower, because we expect the other contestants will be using them anyway!

OVERLEAF we are showing 24 ENGINE TESTS and although there is a lot to be learnt from studying them it must be borne in mind that the tests were conducted over a 6 MONTH PERIOD and factors such as outside temperature, humidity and wind speed varied greatly and would have influenced the results to a significant degree. Most of the engines shown are sports engines since the majority of competition modellers are already aware of the need to match the heat rating of the plug to their engine l set-up. The tests were conducted with all six FirePower plugs, and as a control, a highly rated plug we have called the PCP93. The PCP93 was selected because it was universally considered to be the world's most Popular Contest Plug in 1993 and a plug we knew well since we have used it as a standard for many years.

THE CLICKS LEANER column refers to the main needle valve setting. In the . tests we did not use the needle valve of the test engine but one of our own remote needle valves which we have specially set-up for accuracy. Several different remote needle valves were used throughout the tests so care must be taken when making comparisons. The starting point for the number of clicks was always set at "0", for the F7 plug since this would invariably be the richest setting. The HEAD TEMPERATURE was measured by a probe in the cylinder head of the engine and the hole for the probe was drilled to within 0.020" of the combustion chamber. The MAXIMUM RPM was measured after 15 minutes of running to ensure complete warm through and was the highest rpm that could be attained with a stable head temperature. In a number of the tests a higher rpm could have been found but ~ only with an escalating head temperature which would have ended in severe overheating and all its problems. Care must also be taken in comparing our test engine results with SIMILAR ENGINES because our test engines are often a mixture of parts from more than one mark plus we test-run with a sophisticated silencer system that is 20 feet high! We have shown our FAVOURED CHOICE OF PLUG with an * and it is usually the one giving the top rpm because it also coincides with excellent throttling. But occasionally, when throttling is more important than out-and-out speed, a plug that is slightly lower on rpm, but with superior throttling, could be the best choice for the job.

THE ENGINE TESTS overleaf certainly prove that there are. positive advantages to using FirePower plugs, particularly if you test and use the best FirePower for the installation. But also as fascinating are some of the other features illustrated in the results. MORE NITROMETHANE usually produces more power, but you may have to change the plug to get it. HIGHER COMPRESSION can produce more power but you would have to choose the plug and FUEL to match. With careful study of the tests many trends can be seen, but with every trend there seems to be exceptions. This is because the full theory behind glowplug ignition is extremely complex and must take account of the interplay between compression ratio, `hotness' of plug, variable lower explosive limits, variable upper explosive limits, temperature at various points/ times, gas flow, flame propagation and many other factors. But, at the end-of-the-day, thank goodness there is a practical answer. Just TRY THE FIREPOWER RANGE, or the likely part of the range, and simply CHOOSE THE PLUG THAT GIVES MAXIMUM RPM with super throttling.

 TEST

 S/TIGER 25 - Comp Ratio Standard - Prop 8x4 - Fuel Duraglo Str

S/TIGER 25 - Comp Ratio Standard - Prop 8x4 - Fuel Duraglo 16

 HB61 - Comp Ratio Standard - Prop 11x5 - FUEL Dynaglo Str

  HB61 - Comp Ratio Standard - Prop 11x5 - FUEL Dynaglo 10

 FOX 25 BB - Comp Ratio Standard - Prop 8x4½ - FUEL DuragIo Str

  FOX 25 BB - Comp Ratio Standard - Prop 8x4½ - FUEL DuragIo 16

 FOX 25 BB - Comp Ratio Lowered - Prop 8x4½ - FUEL DuragIo Str

FOX 25 BB - Comp Ratio Lowered - Prop 8x4½ - FUEL DuragIo 16

T/TIGER15 - Comp Ratio Standard - Prop 8x4 - FUEL GX-5

T/TIGER15 - Comp Ratio Lowered - Prop 8x4 - FUEL GX-5

OS21 - Comp Ratio Standard - Prop 7x4 - FUEL Dynaglo 16

WEBRA CHAMP - Comp Ratio Standard - Prop 10x6 -FUEL Duraglo Str

WEBRA CHAMP - Comp Ratio Standard - Prop 10x6 -FUEL Duraglo 10

ENYA 46 4 Stroke - Comp Ratio Standard - Prop 11x6 - FUEL DynagIo Str

ENYA 46 4 Stroke - Comp Ratio Standard - Prop 11x6 - FUEL DynagIo 10 

S/TIGRE G-34 - Comp Ratio Standard - Prop 10x4 - FUEL Duraglo Str

S/TIGRE G-34 - Comp Ratio Standard - Prop 10x4 - FUEL Duraglo 10

ENYA 60 - Comp Ratio Standard - Prop 10x6 - FUEL GX-5

ENYA 60 - Comp Ratio Standard - Prop 10X6 - FUEL GN-10

OS21 Buggy - Comp Ratio Standard - Prop 7x4 - FUEL Dynaglo Str

OS21 Buggy - Comp Ratio Standard - Prop 7x4 - FUEL Dynaglo 16

HP40 - Comp Ratio Standard -Prop·9X6·- FUEL SupagIo STR

HP40 - Comp Ratio Standard -Prop·9X6·- FUEL SupagIo 16