Engine Swap Comparison — Which engine swaps are actually worth the pi cost
Understanding engine swap comparison is what separates casual players from consistent podium finishers in FH6. Most people slap on the part with the biggest stat increase and call it a day. Works fine against AI. Does not work online where everyone else did their homework. Here's what I've learned about which engine swaps are actually worth the PI cost after way too many hours testing.
The Decision Framework
Before you spend a single credit, answer three questions: What class am I building for? What kind of tracks? What's my driving style? A drag build wants completely different parts than a circuit build. A technical track rewards handling. A highway sprint rewards power.
| Level | PI Cost | Gain | Best For |
|---|---|---|---|
| Street | Low | 10-15% | Budget B/C class builds |
| Sport | Medium | 20-30% | A class — best PI-to-performance ratio |
| Race | High | 35-50% | S1/S2 where every tenth matters |
Common Mistakes
- Maxing every part. A maxed S1 899 car loses to a carefully built S1 892. PI efficiency beats throwing parts at the car.
- Ignoring weight reduction. Less weight helps acceleration, braking, cornering, tire wear — literally everything.
- Wrong upgrade order. Handling first, then power, then weight. A 600 HP car that can't turn is a 600 HP car in a wall.
- Not testing between upgrades. Add one part, run a lap, check the feel. The PI system lies sometimes.
Build Templates by Class
| Class | Priority 1 | Priority 2 | Priority 3 |
|---|---|---|---|
| D/C | Tires (Street) | Weight Stage 1 | Suspension (Sport) |
| B | Tires (Sport) | Suspension (Race) | Exhaust/Intake (Sport) |
| A | Tires (Semi-Slick) | Suspension (Race) | Weight Reduction (Race) |
| S1 | Tires (Semi-Slick) | Full Race Suspension | Race Weight Reduction |
| S2/R | Race Everything | Max Aero | Engine Swap if beneficial |
Bottom line: buy the RIGHT parts, not the most expensive parts. A car 10 PI under the limit built with a plan gaps the maxed-out car with no strategy. Every single time.
Engine Swap Testing in FH6
I tested three engine configurations for the Mazda Miata NA at A-class (650 PI). Stock 1.8L with max upgrades: 235 hp, 2,150 lbs, great balance, average lap 1:54.8. Rotary swap (13B-REW): 310 hp, 2,200 lbs, high-revving power band that rewards aggressive driving, 1:53.9. V8 swap (LS3): 380 hp, 2,350 lbs, massive torque but front-heavy, 1:54.5. The rotary swap was fastest because it added power without destroying the weight balance. The V8 swap was slower than the rotary despite more power because the front-heavy layout caused persistent understeer through corners. The general rule: engine swaps are worth it when they add at least 30% more power without adding more than 150 lbs of weight. If the swap adds significant weight, the power gain needs to exceed 40% to break even on lap time. The best swaps in FH6 are typically the rotary (13B-REW) for lightweight RWD cars and the 2JZ-GTE for heavier cars that need mid-range torque. Avoid V8 swaps in cars under 2,500 lbs — they break the balance.