VTI Engine Package – Alfa Romeo 1750 Nord – Full 1850cc Conversion +45BHP

Description

Developed in collaboration with VTI Engineering and top Italian manufacturers

This high-performance bottom-end kit is engineered to strengthen and elevate the Alfa Romeo 1750 Nord engine for fast-road, track-day, and full competition use. It combines forged pistons, precision liners, high-grade bearings, IWIS timing chains, and Reinz gaskets to deliver durability, stable high-RPM operation, and a clear pathway to higher torque and horsepower.

Engineering Basis

• Engine base: 1750 Nord — 80 × 88.5 mm (bore × stroke), 1,779 cc.
• Bore options (with supplied liners & pistons):
  • 80.0 mm → 1,779 cc
  • 81.0 mm → 1,823 cc
  • 81.5 mm → 1,845 cc
• Compression ratio options: 10.5:1, 11.0:1, 11.5:1 (fuel quality to match).
• Geometry: Stock 1750 is undersquare; increasing bore moves the engine toward square, improving breathing and extending safe RPM capability.

Piston & Liner Engineering

• 20% narrower intake skirt for reduced friction and improved throttle response.
• Controlled compression decay after TDC to optimize gas flow and combustion efficiency.
• 40% reduction in exhaust skirt load to enhance durability under sustained high load.

Kit Contents

• Forged pistons with conventional rings, standard pins, and wire locks.
• Precision-engineered liners.
• 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 complete hardware kit.
• Camshafts
• Intake and Exhaust Valves
• Valves Guides
• Valves Springs
• Timing Pulley
• Full Gasket Kit
• Carburettors Mounting
• Sport Sparks
• Sport Flywheel
• Sport Horns
• Valves Seals

Performance Potential

Stock baseline (80 mm bore, ~9.0:1 CR, twin carbs): ~130 hp @ 6,000 rpm, usable to ~6,500 rpm.

With Kit – 80.0 mm (1,779 cc), 10.5–11.5:1 CR

• Fast-road: 140–150 hp @ ~6,800 rpm
• Race: 160–170 hp @ ~7,200 rpm
• RPM ceiling: ~7,000–7,200 rpm
• Gain over stock: +10–20 hp (fast-road), +30–40 hp (race), +500–700 rpm ceiling.

With Kit – 81.0 mm (1,823 cc), 10.5–11.5:1 CR

• Fast-road: 145–152 hp
• Race: 165–172 hp
• RPM ceiling: ~7,200–7,300 rpm
• Advantages: +44 cc displacement and a more favorable bore/stroke ratio → improved mid-range torque and airflow.

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

• Fast-road: 148–155 hp
• Race: 168–175 hp
• RPM ceiling: ~7,400–7,500 rpm
• Advantages: +66 cc displacement and near-square geometry → stronger top-end, better stability at high rpm, broader usable band.

Assumptions for the above figures: appropriate sport/race camshafts, 45–48 DCOE carburetors (or equivalent induction), ported cylinder head, and a tuned stainless-steel 4-2-1 exhaust. Properly designed headers typically add ~+10 hp via improved scavenging.

Why Moving Toward Square Helps

• Higher RPM capability: reduced mean piston speed at a given rpm improves reliability at the top end.
• Improved breathing: larger bore supports greater valve area and less shrouding, increasing volumetric efficiency.
• Balanced output: maintains the 1750’s strong mid-range torque while extending peak power and usable rev range.
• Combustion efficiency: geometry and chamber improvements support stable, efficient burn at elevated rpm.

Summary

The 1750 Nord bottom-end kit provides a robust, tunable foundation with proven components. With bore options up to 81.5 mm and compression ratios up to 11.5:1, builders can develop a stock ~130 hp engine into a 140–155 hp fast-road package or a ~170 hp race unit, with safe rpm capability in the 7,200–7,500 rpm range when paired with appropriate camshaft, induction, exhaust, and valvetrain upgrades. The engineered piston features and premium chains/bearings/gaskets ensure durability and consistent performance under demanding use.

Here’s the updated comparison chart with all four classic Alfa Romeo Twin Cam engines (1300, 1600, 1750 Nord, 2000 Nord) plus the 2000 Twin Spark, including bore options, displacement, compression ratio ranges, estimated horsepower, rpm ceilings, and geometry notes.