Characteristics of the N45B20S engine
The N45B20S engine from BMW, produced at the Hams Hall plant between 2006 and 2007, is a highly advanced and powerful powertrain. This engine was designed to be fitted to the BMW 320si E90 sports model, emphasizing its focus on high performance and reliability.
Design and Materials
The N45B20S engine has an aluminum cylinder block, which contributes to weight reduction and improved thermal performance. The engine’s power supply system is injection, which provides precise fuel metering and improved performance. The inline engine has four cylinders, each with four valves. The piston stroke is 88 mm and the cylinder diameter is 85 mm. These parameters, together with a compression ratio of 11, provide a displacement of 1997 cubic centimeters.
Performance and Environmental Standards
The N45B20S engine delivers 177 horsepower at 7,000 rpm and 210 Nm of torque at 4,250 rpm. These characteristics allow the vehicle to demonstrate excellent dynamics and acceleration abilities. The engine meets Euro 4-5 environmental standards, making it more eco-friendly than previous models.
Fuel Economy
For maximum performance, it is recommended to use fuel with an octane rating of 95. Fuel consumption for the BMW 320si E90 is 12.8 liters per 100 kilometers in the city cycle, 6.6 liters on the highway and 8.9 liters in mixed mode. Oil consumption reaches up to 700 grams per 1000 km, which is standard for engines of this class.
Maintenance and Service Life
For the N45B20S engine it is recommended to use oils with viscosity 5W-30 or 5W-40. The engine oil capacity is 4.5 liters and oil changes are performed every 10,000 km to maintain optimum engine performance. Despite the lack of accurate data on operating temperature, the engine demonstrates a high service life, exceeding 250,000 kilometers in practice.
Tuning and Potential
The N45B20S engine has tuning potential, allowing you to increase power to 200 or more horsepower without a significant loss of life. This makes it an attractive choice for motorists looking to improve their vehicle’s performance.
Reliability, problems and repair of the BMW N45B20S engine
The successor to the N42B20, which appeared in a limited edition in 2006 specifically for the BMW 320si E90. To some extent, the N45B20S engine is the successor of the old M44, also used on si models.
Compared to the simple N42, the new engine has a different crankshaft with a 2mm reduction in piston stroke (was 90mm), along with an increase in cylinder bore to 85mm (was 84mm). Cast iron liners were replaced with aluminum alloy liners, connecting rods were replaced with reinforced ones, compression ratio was increased to 11.
A new cylinder head with enlarged valves, with other camshafts and without the use of the Valvetronic valve lift system was used. A striking difference from all other four-cylinder N-engines is the carbon fiber cylinder head cover.
In addition to the 2-liter engine, the N45 series included a smaller displacement powerplant N45B16. Along with the N45 were produced other four-cylinder followers of the N42 – N43B20 and N46B20.
The replacement for the engine came out in 2011 in the form of a turbocharged four N13B16, with a working volume of 1.6 liters.
Problems and disadvantages of BMW engines N45B20
- Knocking inside the motor. The main cause of this, as a rule, is a damaged timing chain tensioner. And the latter are often quickly relaxed and become unusable after 100 thousand kilometers of mileage.
- Vibrates at idle speed. In this case, the most common cause is the Vanos system. It is cleaned as a repair measure.
Units of the N45 series have another obvious disadvantage – detonation of the fuel mixture. The problem occurs due to low-quality fuel or oil. The manufacturer of BMW categorically does not recommend using any alternative engine oil, as the consequences can be very serious – it may require a major overhaul to restore it.
Tuning the BMW N45B20 320si engine
Chip tuning
The N45B20S motor is not badly tuned, although it is quite expensive. There are tuning camshafts for N45B20 on sale, we take Schrick 268/260 (or others), put a cold intake, sport exhaust, flashing and get more or less urban ~200 hp for a fairly decent amount of money. For more output, you need to take even more evil shafts, port the cylinder head, change valves, in the end, the cost of tuning will be more expensive than 335i with N54/N55.
It’s rational to either do the minimum or leave it as is, because the standard N45 isn’t that bad either.
ENGINE RATING: 4+