3.2.1. The Effect of WPO Blends on Brake Power

The engine powers produced using pure gasoline and WPO–gasoline blends are shown in Figure 5. The pure gasoline produced the highest engine power of 1.339 HP. In comparison, the WPO–gasoline blends produced 1.287 HP, 1.244 HP, and 1.229 HP for WPO-RON88-10, WPO-RON88-20, and WPO-RON88-30, respectively. With the increase in engine speed, the brake increased. At 1500 rpm, the pure gasoline fuel gives the highest engine power, which is 1.339 HP, while the WPO–gasoline blends produced 1.287 HP, 1.244 HP, and 1.229 HP for WPO-RON88-10, WPO-RON88-20, and WPO-RON88-30, respectively. At medium speeds of 2000 rpm and 2500 rpm, the engine powers obtained were 1.72 HP and 2.002 HP, respectively, using pure gasoline. On the other hand, when WPO-RON88-30 was used, the engine powers were reduced to 1.392 HP and 1.721 HP, respectively. The RON88 fuel produced the highest engine power of 2.219 HP at 3000 rpm engine speed, while the WPO–gasoline blends obtained 2.19 HP (WPO-RON88-10), 2.05 HP (WPO-RON88-20), and 1.99 HP (WPO-RON88-30). The WPO-RON88-30 blends gave the lowest engine power output. From the figure, it can be seen that the addition of 10% WPO with RON88 does not change the engine power output significantly compared to the pure RON88 result. This can be attributed to a small percentage of low RON and the low calorific value of the WPO in the blend. This is different from the results obtained by Ravinanath et al. [39], which showed an increased power output with increased ethanol content of the blend.

**Figure 5.** Effect of WPO-RON88 blends on engine power compared to RON88.

#### 3.2.2. The Effect of WPO Blends on SFC

The SFCs of WPO–gasoline blends and pure gasoline are shown in Figure 6. Based on Figure 6, the SFC of WPO-RON88-30 was the highest compared to WPO-10, WPO-20, and RON88. The SFC of WPO-RON88-30 at 1500 rpm was 0.351 kg/kWh compared to 0.3496 kg/kWh, 0.3295 kg/kWh, and 0.3254 kg/kWh for WPO-RON88-10, WPO-RON88-20, and RON88, respectively. Furthermore, the BSFC for WPO-RON88-10 showed identical results to that of RON88 at 1500 rpm and 2500 rpm, which was 0.3295 kg/kWh and 0.404 kg/kWh, respectively. In general, the values of SFC from gasoline–WPO blends were close to gasoline blends, and can be used as a reference fuel for further development with other variations in future research. With the increase in engine speed, the SFC is in line with the existing literature [40]. In addition, with the increase in concentration (%) of WPO in

the mixture of RON88-WPO, SFC is increased. This could be due to the lower calorific value of WPO compared to RON88. Cleetus et al. [22] obtained similar results from gasoline–WPO blend when tested in a SI engine.

**Figure 6.** Effect of WPO-RON88 blend on SFC compared to RON88.
