Technology for fire sport attack is constantly moving forward, but individual modifications must be designed so that the aggregates comply with the rules of fire sport competitions. A very popular modification of PS12 aggregates has become the installation of tuned exhaust headers, which replaced the stock cast iron manifolds and the stock muffler.

Ing. Tomáš Mück has been dealing with the development of tuned exhaust headers for TAZ engines under the TOMMÜ brand since the 1990s. His headers became a popular product not only for their main benefit – an increase in performance parameters (repeatedly tested on an engine dynamometer) but also for their specific sound. Initially, exhaust headers tuned for TAZ engines with displacements of 1.8-1.9 l were on offer. After the expansion of crankshaft modifications for higher strokes, exhaust headers tuned for TAZ engines with a displacement of 2.0-2.1 l were added to the offer.

In the past, fire attack rules did not allow the use of tuned headers in competitions with TAZ engines in the original displacement (visible structural modifications were not permitted). Ing. Tomáš Mück designed a tuned resonance muffler, which is mounted on the stock cast iron exhaust manifold. Similar to the design of exhaust headers, the properties of unsteady flow were used in the muffler design. This modification also brought a noticeable increase in performance parameters compared to the stock muffler, accompanied by a dynamic sound effect.

Many firefighters showed interest in exhaust headers also for their aggregate with a TAZ 1.43 engine. Although previously available headers were tuned for engines of larger displacements, they also have a positive effect on performance parameters for TAZ 1.43 engines. Some teams thus use two variants of exhaust piping – with a modified resonance muffler or with tuned headers (depending on whether they participated in league or non-league competitions with looser rules). However, it is obvious that headers designed for engines of higher displacements cannot ensure optimal parameters simultaneously for an engine with a stock displacement.

In 2021, customers motivated us with their requirements to conduct market research, which confirmed that many fire brigades have the opportunity and interest to use tuned headers also on aggregates with TAZ 1.43 engines at selected competitions. Such an impulse cannot remain unanswered by an avid engine engineer – and so we started development.

When designing the new headers, we assumed they would be mounted on TAZ 1.43 engines in sports modification (including a modified camshaft, increased compression ratio). These parameters were taken into account in the calculations.

At the end of 2021, based on theoretical calculations, we manufactured the first prototype of the new tuned headers. After that, we just waited for suitable weather conditions to test the headers directly on the competition track.

We performed measurement of the water delivery of a firefighting aggregate with a TAZ 1.43 engine modified in October 2019 at TOMMÜ Studénka. The engine achieves a max. torque of 131Nm at 3250 rpm and a power of 56 kW at 4250 rpm and is optimized on an engine dyno with cast iron manifolds and a TOMMÜ resonance muffler. Water delivery was measured on hoses 2x B65, 4x C42. Several repeated measurements took place, both with cast iron manifolds and the TOMMÜ resonance muffler, and with the new tuned headers designed in our company. During the measurement, the engine speed course was recorded.

In Figure 1, individual phases of the fire attack can be traced from the speed course versus time: From idle speed, the operator slightly "added throttle" to prepare the engine for load. Subsequently, a drop in speed can be observed, i.e., the time when the pump is filling with water. After filling the pump, the operator closed the valve on the distributor and fully loaded the engine. The speed starts to rise and the hoses fill with water. Upon water discharge from the nozzles, the engine speed starts to rise more steeply again.

Thanks to precise speed measurement, we are able to measure the discharge time and compare the engine with the resonance muffler and the engine with tuned headers against each other. This comparison is marked in Figure 2 (the blue curve represents the engine speed course with cast iron manifolds and the TOMMÜ resonator, the other curves represent several repeated measurements with the new tuned exhaust headers). From the speed course, it is evident that the water delivery time is also influenced by how high the engine revs in the "preparation" phase (we intentionally also recorded the delivery course from lower initial speeds, see the yellow curve). Regardless of these initial speeds, in all measurements with exhaust headers, we observed a noticeably shorter delivery time compared to cast iron with the TOMMÜ resonator. The average improvement in delivery was approx. 0.4 s. In measurements with headers, a steeper increase in speed is noticeable at the beginning of delivery and immediately after water discharge from the nozzles (the engine has more power, revs up faster). After optimizing carburetion and ignition advance, we expect further shortening of the delivery phase.

With the above measurement, we ended the testing phase of the new product and are officially launching it for sale. In case of interest, we accept orders for exhaust headers by email. Delivery time on request, depending on current workload.

Introductory price: 5,800 CZK

Testing of the new exhaust headers was carried out in cooperation with PS12 Group s.r.o. Žilina, Slovakia (www.svethasicov.sk), which also accepts orders for our new tuned headers TAZ 1.43. Special thanks go to the company owner and volunteer firefighter Ing. Pavel Tvarovský for preparing and conducting the testing.

To understand the problems associated with installing lightened connecting rods and pistons, we will first state several basic theoretical facts. The effective power of a four-stroke internal combustion engine can be expressed by the relationship:

It is therefore clear that we can achieve an increase in the power of a combustion engine in several ways:

• increasing displacement (larger bore, stroke, or more cylinders),
• increasing engine speed,
• increasing mean indicated pressure,
• increasing mechanical efficiency.

Let's look closer at the question of mechanical efficiency. Mechanical efficiency characterizes mechanical losses in the engine, both losses independent of engine load (driving aggregates and valve gear) and losses dependent on engine load (friction losses dependent on pressure in the combustion chamber), and also losses during cylinder charge exchange (emptying the cylinder of exhaust gases and filling it with fresh mixture).

The figure below shows the losses of individual engine parts. As can be seen, friction losses increase with engine speed. The most significant component of friction losses is represented by the movement of pistons, connecting rods, and the crankshaft. Friction in crankshaft bearings represents 10 – 15% of power loss, for connecting rod bearings it is about 5 – 10%. Reduction of mechanical losses can be achieved in several ways, involving design and surface modifications. Another very important parameter is the choice of component material and the choice of lubricating oil used.

Individual parts of the crank mechanism are dynamically stressed by:

• inertial forces of reciprocating masses,
• inertial forces of rotating masses.

Inertial forces of reciprocating masses act in the same direction as forces from gas pressure and are given by the product of the mass of all reciprocating masses and their acceleration:

Inertial forces of rotating masses are given by the mass of all rotating masses, their angular acceleration, and the radius of rotation (in our case, the crankshaft arm, which is equal to half the stroke):

From the above, it is clear that by reducing the weight of individual parts of the crank mechanism, we can reduce inertial forces, and thus reduce friction losses. In reality, however, the situation is more complex.

It is true that if we install lightened pistons and (or) connecting rods in the engine, we reduce friction losses. But at the same time, we affect the entire dynamics of the engine and unbalance the entire system. The original crankshaft counterweights are unnecessarily large in this case and cause additional stress on the main bearings. This leads to excessive wear of the main bearings and crankshaft journals. The counterweights therefore do not balance, but "overbalance".

If, therefore, there is a reduction in masses in a previously balanced engine, adjustment of the crankshaft counterweights is also necessary. Balancing the crankshaft is a chapter in itself. Balancing the crankshaft is a necessity when building an engine, but first of all, it is necessary to modify the crankshaft (machine the counterweights so that they balance the actual effect of the inertial masses of the connecting rods and pistons).

Among motorsport fans, the term "tuned engine" is often bandied about. Have you ever asked yourself what it means when an engine is "tuned"? Engine tuning is a very interesting field of science, and people come to it via various paths. In today's post, a representative of our company, Tomáš Mück, will describe his story.

We return to the beginning of the 70s; in the then Czechoslovakia, four racing circuits were popular in our locality – Štramberk, Ostrava, Těrlicko, and Havířov Šenov. At that time, in classes 1000 cm3 to 1300 cm3, practically only Škoda and Zhiguli cars raced. According to the technical regulations of that time, no noise mufflers were mandatory.

Back then, as a teenage boy, I couldn't miss any touring car race. And it was while watching one of them that the following story happened, which triggered everything. While passing through a turn around the racing car paddock at the Havířov circuit, it happened that one of the passing drivers had his tailpipe fall off. The commentator merely stated that the driver in question would now slow down because a piece of his exhaust had fallen off and he had lost part of his power. Given the level of knowledge at that time (a student of the secondary industrial school in Kopřivnice specializing in automobiles), one thing was not clear to me. After all: when someone loses 1 meter of exhaust, the length losses in the exhaust tract actually decrease, which should make the cylinder scavenge better and power should rise (?) This idea, however, completely contradicted what the commentator stated. Considering that I knew only three engine experts in my area (two of them were very skilled mechanics), I couldn't let it go and asked the experts in question at the first opportunity: How is it possible that engine power decreases after shortening the exhaust tailpipe?

I didn't get the right answer; I completely stumped the questioned experts with my question. This theoretical problem burrowed into my head so much that it decided my lifelong professional orientation. It was one of the reasons why I decided to go study combustion engines at university (and I didn't want to go to the army either).

In the then ČSSR, three departments at engineering faculties of universities oriented towards combustion engines came into consideration for me: Prague, Brno, Bratislava. Since the Bratislava department was unequivocally focused on the study of gasoline engines (among others, prof. Ing. Jaroslav Urban, CSc., the most recognized expert on carburetors in his time, lectured there). And mainly!!! the department was dedicated to the relatively new scientific field of "Unsteady Flow".

Today I laugh at the whole story because I already understand why no one could answer my question about the fallen exhaust back then. For the next 40 years, I studied the problems of flow in the piping systems of a four-stroke combustion engine to find the answer (not only) to the question of the fallen exhaust. And precisely thanks to this knowledge, today we can offer our customers, among other things, a proposal for an optimal intake and exhaust tract, a camshaft with suitable parameters, and a lot of other important data for their engine.

Steady flow is flow where pressure and flow velocity do not change with time at a given point in the pipe. An example of steady flow is, for instance, a vacuum cleaner. The movement of air (mixture) in the piping system of a combustion engine is controlled by pressure waves – we call such flow unsteady, meaning pressure and flow velocity change with time at one point in the pipe. Pressure waves of various amplitudes and wavelengths are constantly propagating here. Precisely thanks to unsteady flow, we can tune engines – we can design the optimal length and diameter of individual pipe branches (for the aforementioned vacuum cleaner, from the perspective of airflow, the length of the suction tube really cannot be tuned). And precisely the parameters of intake and exhaust piping systems have a huge influence on the engine's speed characteristic.

As we mentioned in the previous blog post, engine tuning is a relatively young scientific discipline. The goal of engine tuners is to deliver as much fresh air (or fuel-air mixture) as possible into the working cylinder. The basic principle of engine tuning is that the engine has as much power as the air it can process. And precisely by using pressure waves of unsteady flow, we can ensure quality scavenging of exhaust gases from the cylinder (open exhaust valve at the moment of arrival of a vacuum wave in the exhaust pipe) and subsequently deliver more fresh air into the cylinder (open intake valve at the moment of arrival of a pressure wave in the intake pipe).

Previously, mainly strength and durability tests of individual engine parts (crankshaft, connecting rods, pistons, ...) were done on engine dynos, optimal shapes of combustion chambers were researched, valve trains (camshafts) were optimized. From the point of view of engine performance, designers on engine dynos concentrated on tuning ignition timing and mixture composition (lambda mixing ratio). Classic tuning, i.e., the design of intake and exhaust piping systems, was taboo for engine designers in the past.

For an engine without a tuned piping system, significant performance parameters are achieved only by chance. Some might argue that for today's turbocharged engines, the turbocharger (supercharger) makes up for this handicap by pushing the missing air into the engine with overpressure. This is true on the one hand, but even in the case of a turbocharged engine, it is very appropriate to use well-tuned piping. When optimizing the intake manifold, we can achieve the required performance parameters with lower boost pressure. Every engine engineer knows what reducing boost pressure by e.g. 0.2 bar (20 kPa) means in terms of engine life and demands on cooling the charge air. Filling less compressed (less heated) charge air is a huge benefit for the thermal load of the engine; the pressure wave of a well-tuned pipe takes care of the rest. However, one must constantly keep in mind that a large volume of the intake piping system can lead to small delays in engine response to gas pedal movement.

The fact that unsteady flow is a relatively young scientific discipline can be traced in photographs of historic cars. In the interwar period, it was not yet known to designers what influence the parameters of the intake and exhaust tract have on engine characteristics. Exhaust piping was usually led by the shortest route into one common pipe and led to the rear of the car. Roughly from the mid-50s, we can already observe quite clearly the shapes of tuned exhaust piping in photographs of Grand Prix cars. It would be interesting to find out to what extent scientific calculations were behind the design of tuned piping in the 50s, or "mere" practical experience from dyno measurements. Given that the first technical calculations of unsteady flow appeared in literature only in the 60s, we infer that it is rather the second case (randomly measured results on an engine dyno).

I am convinced that in the 50s, designers knew based on dyno measurements that long (longer) exhaust piping works better. But they didn't know why. Previously, better results were often reached by chance; developers tested various pipe lengths on engine dynos (perhaps just because they needed to vent exhaust gases from the exhaust brake area). It must be added that this is also a way to improve the performance of a given engine, only it is very laborious and lengthy.

An example of the claim that higher performance parameters were previously achieved during engine development even by chance can be a story from the 50s. In England, which is the cradle of motorsport, single-cylinder Triumph racing engines were being developed in a small tuning company. From the basic version of the 250 cm3 engine, designers developed a more powerful engine with an increased displacement of 350 cm3 by maintaining the bore and achieving larger displacement by increasing the piston stroke. Classic engine development was underway (testing different cams, valve sizes, lengths and cross-sections of piping systems). One day it happened that for the 350 cm3 engine, the max. torque and power values jumped up. This, of course, always pleases developers, but on the other hand, they needed to find out why such an increase occurred. The finding was very curious: the mechanic who assembled the engine mistakenly reached into the neighboring shelf and fitted the 350 cm3 engine with a cylinder head from the 250 cm3 engine with smaller ports.

We can learn from this story, and we can unequivocally state that "the bigger the port, the better the engine" does not apply. Ports and valves therefore must be neither too large nor too small; there is only one correct size of ports and valves. The same applies to the parameters of intake and exhaust piping (a larger diameter of exhaust piping is worse than the optimal diameter of exhaust piping). In the next chapter, we will explain why this is so.

From the above example, it is clear that satisfactory engine parameters can be achieved by intuitive engine development using the trial-and-error method. This method is usually demanding not only in terms of time but also financially.

A typical Czech example of inappropriately chosen port size is the cast iron head of the Škoda 130 RS racing engine, which dominated at the turn of the 70s and 80s of the 20th century. This racing engine was developed at a time when excessively large intake ports were in fashion, which negatively affected the torque curve of the engine in lower and medium speeds. At that time, I already knew that to achieve optimal performance parameters, it would be necessary to reduce the intake port. According to the regulations of the then-valid Annex J of the FIA technical regulations, it was not permitted to add material to the given homologated part in any way (e.g., welding, gluing). At that time, I took advantage of the fact that the intake and exhaust piping was free, so I used the following solution, thanks to which we managed to reduce the inappropriately large intake ports. We extended the original large rectangular ports (36 x 32 mm) to a depth of approx. 60 mm with a 35mm drill bit, and the intake piping did not end at the cylinder head flange but continued for the mentioned 60 mm with a round tube of 35 x 1.5 mm diameter. By inserting such an intake tube into the intake port, we achieved a reduction in its cross-section, which positively manifested itself in the course of the torque curve.

Another example from the domestic environment could be cited from Tatra Kopřivnice. Immediately after military service, I joined the engine development department at Tatra. At the beginning of the 80s, I already had my theory of unsteady flow "up and running" and began creating the first designs for sports engines. During this period, I was a member of the development team building the T613 engine for autocross. Thanks to the capabilities of the production plant, I had the opportunity to specify concrete parameters during the production of the cylinder head. During the production of cylinder heads, I modified the cores of intake and exhaust ports directly in the aluminum foundry so that the resulting castings had not even half the cross-sections of the ports. With a head cast in this way, I could work not only cross-sectionally but also significantly shape-wise on the parameters of both ports, and thus also change the port-valve angle parameter. It wasn't the only modification to the engine, but the result was very encouraging. After optimizing the mixing ratio and ignition advance on the engine dyno, on the third curve we reached approx. 65 HP higher power and approx. 70 Nm higher torque. When we handed over the sports engine developed in this way to Lojza Havel for installation in his buggy, we told him with a smile on our faces that he would have one extra Zhiguli in the buggy. Such a significant increase in engine parameters was achieved, among other things, by reducing the intake port from the stock value of 37 mm to 33 mm!!! Lojza Havel won the title of double vice-champion of Europe with this engine. Throughout my era at Tatra Kopřivnice, I continued to devote myself to the development of gasoline engines and left the company in 1991 from the position of head of the gasoline engine testing laboratory.

I personally have always preferred connecting theory with practice, and I verified all my theoretical calculation models on a real engine on an engine dyno. I consider the ideal procedure to be a precise theoretical design of the engine (engine tuning) in the first step and the production of individual engine parts with final parameters (cam, valves, ports, throttle body, intake and exhaust piping) in the second step. And precisely the first mentioned step, i.e., theoretical calculation of any four-stroke combustion engine, is what our company offers. Whether it is a single-cylinder or 12-cylinder, an engine with a volume of one cylinder of 50 cm3 or 600 cm3, a naturally aspirated or turbocharged engine, a carbureted or injection engine. For all these engines, unsteady flow works in principle the same.

Ferrari is a globally known manufacturer of super sports cars. But if you follow in the footsteps of Enzo Ferrari to the northern Italian region of Emilia-Romagna, you will come across dozens of other motoring museums and collections. The region is home to six automotive manufacturers (Ferrari, Maserati, Pagani, Lamborghini, Dallara, Ducati, Energica) and we can also find four international racing circuits here (Imola, Misano, Modena, Varano). On the roads here, you will meet mostly small Fiats (just like everywhere else in Italy), nor does the quality of the road surface suggest in any way that new supercars are born a few kilometers away. For how temperamental Italians are, here they mask their wealth behind traditional inconspicuous country houses surrounded by fields and vineyards.

This year I decided to plan such an unusual motoring weekend in Italy for my dad's birthday. Of course, I started by researching the Ferrari museum offer first. The museum dedicated to founder Enzo Ferrari is located in Modena – in the Czech Republic, the museum building is quite well known; the author of the futuristic design, which resembles the hood of a Ferrari car from a bird's eye view, is architect Jan Kaplický. The building is built right next to Enzo's birth house. The second museum, presenting the history of the Ferrari brand and the successes of the Scuderia racing team, stands just a few meters from the factory in Maranello.

But as I outlined in the introduction, filling the weekend itinerary was not easy at all, because I needed to select the best from a very wide range of other museums for a limited time space.

First, we included a visit to the Museo Horacio Pagani in the Saturday program. An experience beyond expectations! The museum is not very large in area, but shares a lot of interesting information with visitors – both from the life of master Pagani (an expert on carbon fiber) and technical facts. An unmistakable sign of these supercars is the four-pipe exhaust tip, which is also depicted in the carmaker's logo. One of the models exhibited in the museum is the Zonda "La Nonna" (translated as grandmother) from 1998 – the car earned this nickname after driving 1 million kilometers (the car served exclusively for testing and developing new components). Also on display is the Cinque model, of which only 5 coupes and 5 roadsters were produced (the fifth roadster is exhibited in the museum). Such small series places carbon supercars among the most expensive cars in the world (prices are quoted in millions of euros). On working days, it is also possible to book a tour of the factory, which is located right next to the museum building. I will have to come back here.

Another stop on our trip was the Collezione Umberto Panini in Modena. A renovated farm building in the middle of a farm offers a view of an unusual collection. We can find here primarily several significant historical pieces from Maserati. The two-story building is, however, filled with other historical vehicles, motorcycles, and separate engines. The collection is open to the public every day except Sunday and admission is voluntary.

The highlight of our Saturday program was the already mentioned Enzo Ferrari Museum in Modena. The interior of the building is just as stylish as the bodywork of cars with the prancing horse logo on a yellow shield. Precision is felt from all sides, white walls and white floors emphasize the elegant features of the exhibited Ferrari models. After a few minutes of our visit, the lights slowly dim, more prominent music sounds, and one wall of the hall turns into a projection screen on which we watch a short film about Enzo's life. Another dimension is given to this experience by the silhouettes of individual cars that are spread around us. Ferrari cars are works of art and the interior of the museum with its presentation also acts as an artistic impression. However, the biggest smile on our faces was conjured by an inconspicuous side room in which separate engines are exhibited. Unlike Pagani, who designs his own bodies and uses Mercedes-AMG engines to power them, Ferrari mounts exclusively its own engines in its cars. So there was something to look at. Part of the museum is also Enzo Ferrari's birth house, in which selected significant cars are to be seen (the first model of the Ferrari carmaker 125 S, F40, Schumacher's F1 single-seater and others).

On Sunday morning, we continued in the same spirit – we moved to the second Ferrari Museum in Maranello. Although the museum worker told us to reserve about an hour for the tour (resp. 1.5 hours with sufficient reserve), we spent over 3 hours here (similar to the previous day in Modena). For many exhibited vehicles, their power units are also placed in a display case. Despite the austere information on the labels for individual exhibits, we can entertain ourselves for quite a long time with each of them. A motorist's paradise! Especially when we move to the room with F1 single-seaters, in the center of which we can view the engines themselves from close range.

We resisted the offer of a 10-minute ride in an F1 simulator, but we did not miss the opportunity to ride in a shuttle bus with a tour of the factory. The bus only drives into the alleys between individual factory buildings, but who can say they saw the Ferrari factory live? The only factory in the world that produces cars with the Ferrari logo, which manufactures almost all components itself, which sticks to manual work to the maximum extent, and which devotes individual care to every single customer. The tour of the factory was enlivened by a very interesting commentary by a guide (just like in the whole museum only in Italian and English). At the end of this small excursion, we also looked into the area of the Scuderia Ferrari racing team, which boasts its own test track Pista di Fiorano (the holder of the track record from 2004 on the 2.997 km long circuit is champion Michael Schumacher with a time of 0:55:999).

To end our weekend program truly in style, we moved to the city that hosted the San Marino Grand Prix for years. The Autodromo Enzo e Dino Ferrari racing circuit in Imola is a mandatory stop for every F1 fan. On selected days, free entry for pedestrians is reserved on the circuit. So we used the opportunity to walk a piece of the track, including the Tamburello curve, where Brazilian champion Ayrton Senna died in 1994.

From Imola, it is only less than an hour's drive by car to the airport in Bologna, from where direct flights fly to Prague and Vienna (excellent accessibility for Czech citizens). If you are a lover of super sports cars, then a visit to the Italian Motor Valley will be an unforgettable experience for you. A program for a whole week could be planned here without problems. Although the Covid pandemic slightly limited our options, even so, we had a very busy and inspiring program.

A few days ago, I got a tip for a documentary from the 10th year of the Rally Paris Dakar commented by my dad, Tomáš Mück. I didn't even know of its existence until now.

Thanks to this video, after more than 30 years, I watched filmed footage that I had only heard about from stories until now. I nostalgically reminisced about those winters when we waited at home by the landline for a call from a satellite phone from the Sahara (the crew could call home during the race and assure their loved ones that they were okay).

For the next 10 years, the end of January symbolized a reunion with my dad for me. Full of exhaustion, several kilograms lighter, with a big bag strangely smelling of exotic Africa, but always with a smile on his face and full of unusual experiences.

Let's remember one of the historical years when Dakar was still driven by compass (or by the sun). The year when a Czech crew occupied the gold spot at the finish of the Dakar rally for the first time (and of which my dad was also a member). And it is no coincidence that the car was powered by an engine that dad also designed in a small team of Tatra employees.