BEST SIZE ITB’s for K24 K20 engine

ITB (Individual Throttle Body) setups for Honda K24 and K20 engines provide a unique driving experience, blending the thrill of high-revving naturally aspirated power with the raw, mechanical symphony of individual throttles. While not as power-dense as turbocharging, ITBs offer distinct advantages in throttle response and sound, making them a sought-after modification for enthusiasts focused on driving enjoyment rather than sheer numbers.

Key Components and Build Details

Here’s a look at a well-rounded build for a K24/K20 hybrid engine, detailing the crucial parts involved:

• K24a3 Block and Crank
• Scat I-beam Rods with ARP2000 Bolts
• Nippon Racing 12.5 CR Pistons
• K20a (DC5R) Oil Pump and Oil Pan
• Skunk2 Tuner Stage 2 Cams
• Honda K20 – 50deg VTC Gear
• Supertech Forged Valve Locks and Keepers (7 degrees)
• Skunk2 Valve Train
• Honda Head Gasket, Chains, Guides, and Tensioner
• BMW E92 M3 Throttles
• Mitsubishi Evo 7 – 560cc Injectors (Running E50 Fuel)
• Haltech Elite 1000 ECU
• Tri-Y Header and 76mm Exhaust

When selecting ITBs for your K24/K20 setup, size is a critical factor affecting performance across the RPM range.

Here’s a detailed breakdown of different ITB sizes and their impact on performance:

1. 52mm ITBs:
   • Pros: Excellent mid-range power, ideal for street driving.
   • Cons: Falls slightly short at high RPMs (~8000 RPM).
2. 54mm ITBs:
   • Pros: Better top-end power while maintaining good mid-range performance.
   • Cons: Slightly less low-end torque compared to 52mm.
3. 56mm ITBs:
   • Pros: Improved high RPM power, suitable for track use.
   • Cons: Can sacrifice some mid-range torque and drivability.
4. 62mm+ ITBs:
   • Pros: Maximum high-end power, ideal for heavily modified engines.
   • Cons: Significant low to mid-range torque loss, less suitable for street driving.

A common setup, as discussed in various enthusiast forums and user experiences, shows that 52mm ITBs are a popular choice for a balanced performance. Users report strong mid-range performance, crucial for everyday driving scenarios where the car spends most of its time.

Practical Considerations

• Sound: ITBs are known for their distinctive intake noise. While some might find it too loud for daily use, many enthusiasts appreciate the mechanical symphony.
• Drivability: Larger ITBs might provide more top-end power but can make the car less enjoyable to drive on the street due to reduced mid-range torque.
• Engine Tuning: Proper ECU tuning is essential to maximize the benefits of any ITB setup, ensuring smooth power delivery and optimal performance.

The decision to install ITBs on a K24/K20 engine should consider both performance goals and the driving experience. While larger ITBs can offer peak power advantages, smaller sizes like 52mm or 54mm often provide a more enjoyable and practical power curve for most applications.

Ultimately, the choice comes down to personal preference and intended use. Whether you’re after the raw, engaging experience of ITBs or chasing peak dyno numbers, the journey is as rewarding as the destination.