Driving guide

Reserve and engine

Now that you mastered the basics, we can move on to the core mechanic of this game: the reserve system. If you want to win (especially against the infamous CPU of this game), it’s important to maintain and gain more speed throughout the race. The reserve system is a mechanic that rewards players with more speed. In this guide, we will explain how the reserve system works, how it affects your speed, and how to use it to win the race!

What is reserve and engine power?

Reserve is a hidden value that represents how much extra speed you can maintain in the race. It is not directly visible to the players, but it is closely related to the engine power percentage that is shown on the HUD. The engine power percentage indicates how much faster you are going than your base speed, which is the normal speed of your vehicle without any items or boosters. For example, if you have 100% engine power, you are going at your base speed. If you have 150% engine power, you are going 50% faster than your base speed.

The reserve system in The Karters 2 is similar to the one found in Crash Team Racing, but with some key differences that make it stand out. One of the biggest differences is that the reserve value is converted to engine power percentage and directly affects your maximum speed. The higher your reserve value, the higher your engine power percentage, and the faster you can go! Another difference is that you can gain more reserve by doing tricks in midair after jumping off ramps or ledges or chaining full mini-turbos. This result in having a reserve system more dynamic and responsive to your actions as speed is changing all the time! In Crash Team Racing, reserve will be correlated to speed upgrades and there is a limit to the kart max speed as they are tied to turbo pads.

How to get reserve?

To gain reserve and increase your engine power percentage, there are few ways in The Karters 2:

  • Mini turbos (MT): This marginally gives you reserve and increases the engine % shown. For example, chaining 3 MT can increase your engine % from 100% to 115%. The more MT you chain together, the more reserve you accumulate.

  • Trick Jumps: This will give you a lot of reserve and a burst of speed. The amount of reserve will depend on the jump height as you will receive almost 10%+ instantly from landing after a trick from a long jump.

  • Items: Some items, such as Teleport Dash and Tank, can give you a significant amount of reserve. There is also the boost item which can give you a fixed amount of reserve for some duration.

How does the engine power percentage affect your speed?

The engine power percentage shows how much faster you can go than your base speed. In simple terms, let's consider the following example. Imagine your base speed is 100 (unitless and for the sake of comparing it to % better) and the engine % at is set at 100%. If your new engine power is 145%, then your new speed will be:

\text{new_speed} = \text{base_speed} \times (1 + 0.45) = 100 \times 1.45 = 145

This shows that the new speed will be 45% more that the base speed.

The relationship between reserve and engine power percentage is not linear, but rather exponential. This means that as your reserve increases, your engine power percentage increases at a faster rate. However, this also means that you lose reserve at a faster rate when you have a higher engine power percentage.

The exponential relationship between reserve and engine power percentage can be approximated by using two functions: one for increasing reserve and one for decreasing reserve. A possible formula for calculating your engine power percentage based on your reserve value is:

\text{engine_power_percentage} = f(\text{reserve_value})

where

  • f(\text{reserve_value}) = g(\text{reserve_value}) - k \times (t - t_0)

  • g(\text{reserve_value}) = 100 + 8 \times \log_{10}(\text{reserve_value})

  • k is a constant that depends on your current engine power percentage

  • t is the current time

  • t_0 is the time when you started increasing or decreasing your reserve

These functions show that as your reserve value increases, your engine power percentage increases at a diminishing rate by adding 8 times the logarithm of your reserve value to 100%. However, you also lose reserve at a linear rate by subtracting k times the elapsed time since you started increasing or decreasing your reserve from the previous function.

However, the value of k is not constant throughout all engine power percentage levels, as it is slower at around 135% for example where both engine power percentage gain and loss are lower. Therefore, we need to adjust the value of k according to the following table:

Engine power percentage range and k value
Engine power percentage range k value
100% - 120% 1
120% - 140% 0.8
140% - 160% 0.6
160% - 180% 0.4
180% - 200% 0.2
Above 200% 0.1

Additionally, the value of k is not constant within each range, as it varies depending on how many mini turbos you chain and how long you maintain them. Therefore, we need to modify the value of k by multiplying it with a factor that depends on these variables. A possible formula for calculating this factor is:

factor = m \times n

where

  • m is the number of mini turbos you chain

  • n is a constant that depends on the quality of your mini turbos (full or partial)

For example, if you chain three full mini turbos, then m = 3 , n = 1.5 , you will get a factor of 4.5.

For example, if your reserve value is 10 (which means you have no extra speed), then your engine power percentage will be:

\text{engine_power_percentage} = f(10) = g(10) - k \times (t - t_0)
g(10) = 100 + 8 \times \log_{10}(10) = 108%

This means that you are going 8% faster than your base speed. However, if you stop increasing your reserve at this point, and your current engine power percentage is 108%, then your engine power percentage will start decreasing by (1 \times {factor}) per second (since it falls in the range of 100% - 120%). Therefore, after one second, your engine power percentage will be:

\text{engine_power_percentage} = f(10) = h(10) - k \times (t - t_0)
g(10) = 108%, k = 1%/s, factor = 4.5, t_0 = 0s, t = 1s
f(10) = 108 - (1 \times factor) \times (1 - 0) = 103.5%

This means your reserve will drop to 103.5% after 1s.

How to maintain your reserve?

To maintain your reserve and speed, you need to avoid losing reserve by doing the following:

  • Avoid crashing into walls or obstacles

  • Avoid braking: This will also cause you to lose all reserve instantly if you are driving on the ground (160% can become 100% instantly and cause emotional damage). You can use break while jumping in the air to take sharper turns with the expense of losing some reserve. When you are in midair, you won't lose all reserve instantly but rather incrementally based on the duration of press (the exact rate is unknown).

  • Keep chaining mini turbos and jump tricks: This is the best way to maintain your reserve and speed, as it will constantly replenish your reserve and increase your engine power percentage. Try to do mini turbo as much as possible and use every opportunity to jump and do trick.

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