VTI Bottom-End Kit – Alfa Romeo 1750 Nord

Description

Developed in collaboration with VTI Engineering and top Italian manufacturers

This high-performance bottom-end kit has been engineered to maximize the durability and performance potential of the Alfa Romeo 1750 engine. With forged pistons, precision-engineered liners, high-quality bearings, chains, and gaskets, it provides the structural strength required for both fast-road and competition builds.

Engineering Basis

• Engine base: Alfa Romeo 1750 (original bore × stroke 80 × 88.5 mm, displacement 1,779 cc).
• Bore options:
  • 80 mm (standard) → 1,779 cc
  • 81 mm → 1,823 cc
  • 81.5 mm → 1,845 cc
• Compression ratio options:
  • 10.5:1 – compatible with 91–93 octane fuel
  • 11.0:1 – optimized for performance with premium fuels
  • 11.5:1 – maximum performance potential with high-octane fuel
• Geometry considerations:
  • Standard 1750 is undersquare (stroke > bore).
  • Increasing the bore to 81 mm or 81.5 mm moves the design closer to a square engine, improving combustion chamber efficiency and allowing higher RPM operation.

Piston and Liner Engineering

• 20% narrower intake skirt reduces friction and sharpens throttle response.
• Controlled compression decay after TDC improves gas flow and combustion efficiency.
• 40% reduction in exhaust skirt load enhances long-term durability.

Kit Contents

• Forged pistons with conventional rings, standard pins, and wire locks.
• Precision-engineered High-Performance liners in 80, 81, and 81.5 mm diameters. Ductile Iron.
• Reinz head gasket and full engine gasket set.
• Standard rod and main bearings (oversize options available).
• IWIS race/road timing chains (top and bottom).
• Thrust washers, lock tabs, and full hardware kit.

Performance Potential

Stock Baseline (80 mm bore, 9.0:1 CR, twin carbs)

• ~130 hp @ ~6,000 rpm
• Usable rpm range: up to ~6,700 rpm

With Kit – 80 mm bore (1,779 cc), 10.5–11.5:1 CR

• Fast-road build: 140–150 hp @ ~6,800 rpm
• Race build: 160–170 hp @ ~7,200 rpm
• RPM increase: +700 rpm safe operating ceiling compared to stock

With Kit – 81 mm bore (1,823 cc), 10.5–11.5:1 CR

• Fast-road build: 145–152 hp
• Race build: 165–172 hp
• RPM ceiling: ~7,700 rpm
• Advantage: displacement gain and improved bore/stroke ratio (closer to square), improving breathing and combustion stability

With Kit – 81.5 mm bore (1,845 cc), 10.5–11.5:1 CR

• Fast-road build: 148–155 hp
• Race build: 168–175 hp
• RPM ceiling: ~7,500–7,600 rpm
• Advantage: near-square geometry delivers stronger high-rpm power, smoother operation at speed, and greater torque across the band

Figures assume sport/race camshafts, 45–48 DCOE carburetors, ported head, and stainless-steel 4-2-1 exhaust. Headers typically add +10 hp through improved scavenging.

Please contact us if you need an accurate head job.

Advantages of Approaching Square Geometry

• Higher rpm capability: shorter effective stroke-to-bore ratio reduces mean piston speed, allowing safe increases in rev ceiling.
• Improved breathing: larger bore accommodates greater valve area and improves airflow into the combustion chamber.
• Better balance of torque and power: undersquare engines excel in low-end torque but run into rpm limits; approaching square retains torque while extending usable power at the top end.
• Enhanced efficiency: more favorable chamber shape improves combustion stability and reduces pumping losses at high speed.

Summary

This bottom-end kit provides a complete performance foundation for the Alfa Romeo 1750. By offering bore sizes up to 81.5 mm and compression ratios up to 11.5:1, it transforms the engine from its stock ~130 hp into a 150 hp fast-road specification or a 170+ hp competition specification.

Approaching a square engine geometry allows higher rpm operation, stronger breathing, and a more responsive character, while forged pistons, precision liners, IWIS chains, and high-quality bearings ensure durability. This is the definitive bottom-end solution for extracting both reliability and maximum performance from the Alfa Romeo 1750 platform.