Talking About Horsepower Without Considering Gearbox and Weight Is Nonsense

Talking About Horsepower Without Considering Gearbox and Weight Is Nonsense
Original Author: Fisher Discount
Updated: November 21, 2024


🚗 Horsepower vs. Reality: How to Judge Performance 🚗

Don’t just rely on horsepower to compare vehicles! ⚖️ Factors like weight and gear ratios are equally critical. Let’s explore:


🛠️ Key Metrics for Comparison:
✅ Power-to-Weight Ratio
✅ Virtual Torque-to-Weight Ratio
✅ Gearbox and Suspension Design

💡 Fun Fact: A Civic outperforms a Jetta despite similar specs due to better torque utilization!



Before diving into the topic, let’s look at some comparative numbers:

1983 Honda City Turbo II (FA): ER-T engine, max power: 110 hp @ 5000 rpm, max torque: 16.3 kg·m @ 3000 rpm, 5MT, 4.066 final drive, weight: 735 kg, power-to-weight ratio: 149.6 hp/ton.
Civic EF9 with DOHC VTEC (First Model): B16A engine, max power: 160 hp @ 7600 rpm, max torque: 15.5 kg·m @ 7000 rpm, 5MT, 4.266 final drive, weight: 1050 kg, power-to-weight ratio: 152.38 hp/ton.
1993 Honda Accord SiR (CD7): H22A engine, max power: 190 hp @ 6800 rpm, max torque: 21 kg·m @ 5500 rpm, 5MT, 4.266 final drive, weight: 1330 kg, power-to-weight ratio: 142.8 hp/ton.
2006 JDM Civic 2.0L (FD2): K20A engine, max power: 155 hp @ 6000 rpm, max torque: 19.2 kg·m @ 4500 rpm, 5MT, 4.562 final drive, weight: 1300 kg, power-to-weight ratio: 119.2 hp/ton.
2013 Honda Odyssey 2.4 (RC1): K24W engine, max power: 175 hp @ 6200 rpm, max torque: 23 kg·m @ 4000 rpm, CVT, 5.047 final drive, weight: 1780 kg, power-to-weight ratio: 98.3 hp/ton (Absolute versions may offer slightly higher power).

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The Real Deal About Horsepower Comparisons
Today, automotive media—especially self-proclaimed online "experts"—often compare engines from different manufacturers: "Brand A’s 2.0T has 200 hp, while Brand B’s 2.0T has 250 hp, so B must be better." Such shallow comparisons often overlook critical factors like the vehicle’s weight and gearbox, leading to misguided conclusions.

For a more meaningful comparison, factors like power-to-weight ratio are essential. These numbers, which used to be included in promotional materials, give consumers a clearer picture of performance rather than relying solely on advertised horsepower.

Case Study: Comparing Two Honda Models
A: 10th-Gen Civic (FC1): L15B8 turbo engine, max power: 177 hp @ 5500 rpm, max torque: 22.4 kg·m @ 1700–5500 rpm, weight: 1302 kg, power-to-weight ratio: 136 hp/ton.
B: Honda CR-V (RW1): L15BL turbo engine, max power: 193 hp @ 5600 rpm, max torque: 24.8 kg·m @ 2000–5000 rpm, weight: 1519 kg, power-to-weight ratio: 127 hp/ton.

At first glance, the Civic’s power-to-weight ratio suggests it should outperform the CR-V. However, in real-world driving, the CR-V doesn’t lag behind, especially in overtaking scenarios. The reason lies not just in raw horsepower but in factors like torque amplification through the final drive ratio.

Introducing "Virtual Torque-to-Weight Ratio"
While unofficial, this metric can provide insights when choosing between closely matched vehicles, particularly automatics and CVTs. The formula is:

Max Torque (kg
\cdotp
m) × Final Drive Ratio ÷ Vehicle Weight (tons)
=
Virtual Torque-to-Weight Ratio
Max Torque (kg\cdotpm) × Final Drive Ratio ÷ Vehicle Weight (tons)=Virtual Torque-to-Weight Ratio
FC1: 22.4 × 4.81 ÷ 1.302 = 82.75 kg·m/ton
RW1: 24.8 × 5.64 ÷ 1.519 = 92.08 kg·m/ton
FK8 Type R: 40.8 × 4.11 ÷ 1.38 = 121.5 kg·m/ton
The CR-V’s higher torque and final drive ratio give it an edge in low-to-mid-speed acceleration, despite a lower power-to-weight ratio.

Comparison with the Competition
Let’s compare two C-segment vehicles: the 2019 VW Jetta 1.4T (A7) and the 2018 Honda Civic 1.5T (FC1):

Power-to-Weight Ratio:
Jetta: 148 hp, 1365 kg → 108.4 hp/ton
Civic: 179 hp, 1309 kg → 136.7 hp/ton
Virtual Torque-to-Weight Ratio:
Jetta: 25.5 × 3.23 ÷ 1.365 = 57.1 kg·m/ton
Civic: 24.5 × 4.81 ÷ 1.309 = 90 kg·m/ton
The Civic consistently outperforms the Jetta in both metrics, which, combined with its superior suspension and design, explains its global popularity.