HEMI, i.e. hemispherical motors from the USA - is it worth checking?
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Powerful American HEMI engine - what is worth knowing about it?
Powerful Muscle Cars could not be powered by small units to count in track racing. Therefore, under the hood of this American (today's) classic, it was always necessary to mount large engines. Power per liter was a bit harder to come by in those years than it is now, but that wasn't a problem due to the lack of limits on emissions standards and fuel consumption. Even before the First World War, it was not easy to get several horsepower out of an engine, so solutions were found to fix it. Therefore, engines with hemispherical combustion chambers were developed. Do you see the light at the end of the tunnel now? The HEMI engine appears on the horizon.
HEMI engine - combustion unit design
The creation of round combustion chambers contributed to a sharp increase in the efficiency of internal combustion units to such an extent that many global manufacturers began to use such solutions in their cars. The V8 HEMI wasn't always Chrysler's flagship, but there was more to these designs than power. What was the effect of building the combustion chamber in this way?
HEMI engine - principle of operation
Reducing the shape of the cylinder (round) led to a better spread of the flame when igniting the air-fuel mixture. Thanks to this, efficiency was increased, since the energy generated during ignition did not spread to the sides of the cylinder, as in the designs used earlier. The HEMI V8 also had larger intake and exhaust valves to improve gas flow. Although in this regard, not everything worked as it should, due to the moment of not closing and the simultaneous opening of the second valve, which is technically called valve overlap. This was due to the unit's higher demand for fuel and not the best level of ecology.
HEMI - a multi-faceted engine
Many years have passed since the design of HEMI units in the 60s and 70s won the hearts of fans of powerful units. Now, in principle, these designs are completely different, although the name "HEMI" is reserved for Chrysler. The combustion chamber no longer resembles a hemispherical one, as in the original designs, but the power and capacity remain.
How did the HEMI engine develop?
In 2003 (after the resumption of construction) how did you manage to meet the current emission standards? First of all, the shape of the combustion chamber was changed to a slightly rounded one, which greatly affected the angle between the valves, two spark plugs per cylinder were included (better energy distribution properties after ignition of the mixture), but also the HEMI MDS system was introduced. It's all about variable displacement, or rather, turning off half of the cylinders when the engine is not running at low loads.
HEMI engine - opinions and fuel consumption
It is difficult to expect that the HEMI engine, which in the smallest version has 5700 cm3 and 345 hp, will be economical. 5.7 HEMI engine in the 345 hp version. consumes an average of 19 liters of gasoline or 22 liters of gas, but this is not the only version of the V8 unit. The one with a volume of 6100 cm3, according to the manufacturer, should consume an average of just over 18 liters per 100 km. However, in reality, these values exceed 22 liters.
What kind of combustion do the different HEMI options have?
Hellcat's 6.2 V8 is also great at burning fuel out of the tank. The manufacturer claims about 11 liters per 100 km on the road, and you can imagine that a beast with more than 700 km should burn its fuel when driving faster (more than 20 liters in practice). Then there's the HEMI 6.4 V8 engine, which needs an average of 18 l/100 km (with reasonable driving, of course), and gas consumption is about 22 l/100 km. It is obvious that with a powerful V8 it is impossible to achieve combustion, as in a city 1.2 turbo.
5.7 HEMI engine - defects and malfunctions
Of course, this design is not perfect and has its drawbacks. Given the technical problems, copies produced before 2006 had a faulty timing chain. Its rupture could lead to a collision of pistons with valves, which caused great damage to the engine. What are the disadvantages of this engine? Primarily:
- nagarobrazovanie;
- expensive details;
- high cost of oil.
The manufacturer also recommends not exceeding the oil change interval per 10 kilometers. Cause? Settlement scale. In addition, the parts themselves are not always the cheapest if you buy them in our country. Of course, they can be imported from the US, but it takes some time.
What is worth knowing about HEMI oils?
Another problem is the SAE 5W20 engine oil designed for these units. Especially recommended for those models that have a 4-cylinder deactivation system. Of course, you have to pay for such a product. The capacity of the lubrication system is more than 6,5 liters, so it is recommended to buy an oil tank of at least 7 liters. The cost of such oil with a filter is about 30 euros.
Should I buy a car with a HEMI V8 engine? If you don't care about fuel consumption and you love American cars, then don't even think about it.
