"Uncle Sam!" Cried everyone in surprise. "How did you do it so quickly! You can't go too fast here!" Asked Ranran, taking a breath. William saw her red lips tremble.

"That's all right. It's no easier to get Sam into a car accident than it is for space travels. Actually, I took a shortcut to get here." He said, opening a secret door. A long straight was behind. No wonder he got here in such a short time.

"I heard you were refitting the engine. Is this the one?" Said William, pointing to an engine with a red cylinder head.

"Yes, that's it. The six-cylinder engine now has a 3.0-liter displacement. With a high pressure common-rail fuel injection system and turbocharger, it can deliver 270 metric horsepower and 500 Nm. I wonder if I can revamp it up a bit to squeeze a little more power. Of course, this is not necessary, because it is obviously not enough to merely strive for extreme power. As a qualified automobile engineer, you also need to consider other factors, such as fuel consumption, longevity, parts versatility and so on."

"Then now I have two things to ask you, which I do not know whether to say."

"Whether you should say doesn't matter because you've done such a great favor to my daughter." Sam replied without hesitation.

"First, I would like to ask you to help me verify that the powertrain performance of my plane and my racing car is good enough. If you think it is necessary to replace, please make a drastic modification. Second, for the note that gives the clue, I want the right and complete clue to synthesize a potent catalase inhibitor."

Sam nodded and removed the hoods of Photon and Natalie. First he went to the plane and said, "Please introduce me to the parameters of this engine, such as maximum power, peak torque, range, thermal efficiency and so on."

"OK, but I don't know if you're confident enough to refit an airplane engine well."

"Don't worry, in Uncle Sam's garage, there will never be machines-related questions that I cannot solve!" All the party could see was him patting his chest and smiling confidently.

"This is a 32-liter H-type 16-cylinder six-turbocharged ceramic diesel engine running on blue-green algae diesel. It produces 2,560 braking horsepower at 3,600 RPM. In order to achieve good performance, I used 75% silicon nitride ceramics, 15% graphene and 10% cast iron. This ensures high enough output power and long enough life at the same time. I also found a six-blade co-axial counter rotating propeller, which makes better use of the engine's power while offsetting the reverse torque. As a result, the airplane can fly at a maximum cruising speed of 750 km/h and a maximum speed of 850 km/h. There are several large fuel tanks in the wings with a total capacity of 1,000 liters, which gives it an amazing range of 2,300 kilometers." William rattled off the long list of information.

Uncle Sam exclaimed, "32 liters, six turbines! No wonder it has 2,560 horsepower and 850 km/h. But the average fuel consumption is only 2.3 kilometers per liter, which is a little small for a plane. By rights, silicon nitride ceramics aren't bad -- hey, boy, did you get that range at top speed?" He asked William.

"I think so... Anyway, I remember all the turbines coming in all the time."

"Oh, that's the high load condition. But I think you've got six turbines a bit too many..."

"I think so too." Said Photon, "Despite all these turbines, my ceiling is only 12,000 meters."

"It seems that only the turbines is difficult at high altitude." Uncle Sam said carefully, "Look, boy, I will take this engine down for you and build you an optimized version according to it. To my credit, this engine of yours is a real rarity. Though those turbines are a lot, yet they as well as the insulation of silicon nitride ceramics managed to give you both high power and high thermal efficiency, which was almost impossible to achieve with a metal engine in the past. And another highlight is your propeller. This arrangement effectively avoids the torque effect of take-off and slightly increases the efficiency of the engine's power output. In terms of the disadvantages, I think there are only two. The first, and the big one, is that you have too many turbines, which will affect the performance at high altitude and may add extra weight to the airplane, resulting in a loss of range. Second, this one is not very important, but I think it's worth considering: you just mentioned that cast iron is only 10%, and I think too little cast iron can be a potential source of engine understrength when increasing the pressure in the cylinder by increasing the compression ratio or other means. While I have to compliment you on the fact that you've refitted the engine perfectly, I suggest you switch to a turboprop engine as you want to get enough power without losing efficiency. Because it can be simple enough and powerful enough to save you more fuel, it may help you increase your range. In addition, I like your 40mm plasma cannon in propeller shaft, but I think it would be better to replace it with a three-barrel 30mm plasma cannon. This allows it to be placed directly at the propeller hub without passing through the engine. Anyway, I'll try my best to adjust the new engine for you. If I started tomorrow, I would need two or three days."

"Thank you for your professional evaluation!" William bowed, "I'm sure I'll appreciate your optimized engine."

"And this racing car, right?" Sam pulled Natalie's heart out.

"That's right."

"I think I'd better change the powertrain at the same time, and what do you think?"

"Good idea!" Natalie clapped her hands.

So Sam removed the gearbox, carbon fiber drive shaft and rear axle, as well as the front axle and steering wheel.

"I'm looking forward to it, Uncle Sam. It's getting late. We'd better go to bed early so that we won't delay your work." William was so preoccupied with the transplantation that he didn't notice that the mother star was about to set again. Darkness fell as it gathered its bright blue glow. Like a blanket studded with thousands of diamonds, the starry sky enveloped the earth. The people in the streets began to dwindle and the lights came on one after another. And the lamp in the room was sensitive to feel the change of light, quickly lighting up. The white light was shining on an engine, and its gilds were glittering.

Soon they were asleep. But Uncle Sam didn't, because he changed his mind.

"I intend it to be a sleepless night." He muttered, when he heard the sweet snores of the others as they slept, "I told them I should need about two or three days. In fact, if I stay up tonight, I will be able to give William the new engines tomorrow morning. And I will give him two! They have helped my daughter so much that I should give him as soon as possible! And I have to look up information about codon, which I think I wrote down on a special book. It's in a locker somewhere. I can't remember right now, and I need to look for it. Forget it! Upgrading the engines matters, so I'd better get started quickly!"

Uncle Sam got up, took a water glass from a table beside, opened a drawer, and found a bag of coffee. He boiled the water from the kettle, poured it into a cup, poured the coffee, and stirred it a few times with a small iron spoon. A strong aroma of cocoa beans immediately hit the face. "Hmm!" He drank half the glass and immediately felt as light as a swallow. His muscles gained strength again. Then he bent his arms, and saw that the bulge of the biceps on his upper arm was about a few centimeters thick. "Start!" He shouted excitedly. The lights in the room were rickety.

Sam thought for a moment and decided to go to another room. Opening the door, he found a tall 3D printer. "It's quick and nice to use this." He muttered as he turned on the printer. He walked quickly to a tall green cabinet, opened the door, took out large packages of silicon nitride ceramics, graphene, as well as cast iron, weighed them and loaded them into another large machine. "65% silicon nitride ceramics, 10% graphene and 25% cast iron is good." He said, turning on the power to the machine and waiting for it to synthesize the composite. It took two hours, during which time he also used a computer program to disassemble the engine into 800 parts that the printer could print, and carried out a simulation run to finally determine a series of key machining parameters.

"I have to build more turbines. This will ensure that the engine will still produce high power at an altitude of around 15,000 meters. Because it is a gas turbine, it is compatible with a variety of fuels and produces more power in a smaller volume. Also, I like the propeller hub cannon he used before, and I have to get him a better one. Well, that's it. Just a minute. When the material is synthesized, I will print the accessories and assemble the engine."

The clock struck eleven o'clock and the machine successfully produced the composite material. So Sam went back to the printer and pressed "Open". Two doors opened slowly. He poured in the composite material, pressed a few more keys, and loaded the setup into the printer.

"Exciting times are coming!" He pressed the "Start" button. The printer worked smoothly, and in about an hour, all 800 parts were printed.

"Good! This is the final stage!" He methodically removed the parts and placed them on the wide workbench behind him. He drew up an armchair, seated himself in it, put on his spectacles, turned on the little light in front of him, and, with the tools in his pocket, carefully organized the parts gradually into a great whole. The smile on his face widened as the shape of the engine was revealed. When he effortlessly fitted the last piece into place, he examined the heart he had created in front of him, caressing it with his white gloves as if he were caring for a priceless work of art in perfect condition.

"Come on, test!" He pulled the engine into the testing room and plugged in the battery.

"Da -- Vroom! Vroom......" The parts were operating normally and orderly without any indication of malfunction. Sam put a coin and it didn't tip over after five minutes.

"It's a big deal," He said, pushing the gas until the engine was running at full capacity. He recorded the following data,

Model: CT73

Fuel Type: Any material that can be used as a fuel (CH4 -- C16H34 or blended fuel is recommended)

Number of compressors: 7

Number of turbines: 3

Gearbox gear ratio: 10

Rated power/Revolving speed: 3,300Ps/20,000 RPM

"Excellent set-up. I'm sure he won't fail to appreciate the turboprop engine." Sam smiled confidently. He then spent another hour creating Natalie's new heart.

"I think a change of thinking is necessary." He said to himself, "William used the method of big displacement and high power, but I think we should focus on the lightweight problem. As the saying goes, 'It's better to lose ten horsepower than gain one kilo'. Lightweight is very helpful in improving the top speed of a car. So it is not a bad idea to use a small engine with high pressure. Gee, I know diesel rotary engines. I haven't used it on many sports cars, but those cars are still perfect. The silicon nitride ceramics I have here are strong enough to withstand that kind of pressure, not to mention other reinforcement materials. There, that's it!"

The results were as follows,

Model: 2.0T 4 rotors

Total displacement: 1995 cc

Rated power/Revolving speed: 500Ps/9,000 RPM

Peak torque/Revolving speed: 400Nm/1,000~8,000 RPM

"This is great! But the rear drive layout is prone to starting skid and oversteer. I will add two electric motors as well as an air conditioning system, and improve leather seats. You know how exhausting it is to drive a racing car drenched in sweat for a long time! Therefore, it is also important to ensure the driver's comfort. As far as the extra weight is concerned, it's not that much, and I think a lot of torque can overcome. I used an assist clutch, so William's left foot won't ache, although he won't need to press the clutch pedal most of the time. The use of the kinetic energy recycling electromagnetic braking system means I don't need to install a mechanical braking system, and William is able to reap more acceleration when leaving the bend. After the transplantation, Natalie is expected to reach a top speed of 380 km/h with a combined power of 1,000 horsepower. The gearbox, drive shaft and other parts are all good, so I just need to put them back. My work is done!"

The clock pointed to twelve thirty. He kept the two works of art carefully lest they should knock against each other. He looked out of the window. The night was still closing in. Outside the window again floated the snowflakes in succession, and soon the ground was thick with snow.

The effect of the coffee wore off and drowsiness came over him. He took a blue pillow, walked over to the wall, and carried the folded quilt and pillow from the tall chair onto the green sofa opposite. He raised his hand to turn off the light, and his eyes were only looking out the window at the snow.

"Oh, that cat's been trapped for another day." He shook his head helplessly, "William and his fellows must get him out as soon as possible!"

His eyelids hung like a hammer weighing several tons, and he could not open them. He took off his overalls and leather shoes and put on the slippers beside the sofa, revealing the T-shirt underneath. He pulled back the quilt and lay down on the sofa. Soon a sweet snore came from his nostrils.