Fiero engine swaps and Fuel
Economy vs. Performance
With so many engine swaps available for the Pontiac
Fiero, the question inevitably boils down to two main concerns for most people:
performance and fuel economy. In this modern era, you can have both.
Below is a list of some engine swaps we have done in the past and what the
results were concerning performance and fuel economy.
Stock 5.7 iron-head LT1 paired with a
4T60-E auto trans that had 3.06 gearing:
- Best 1/4 mile performance: 13.2 sec @ 100mph
- Avg hwy fuel economy: 24 mpg (unknown speed)
- Fuel octane required: 89 minimum
5.3 LS4 Displacement On Demand (w/
mildly ported heads) paired with a 4T65-E HD auto trans that had 2.93 gearing:
- Best (to date) 1/4 mile performance: 12.9
sec @ 105mph
- Avg hwy fuel economy: 28 mpg @ an avg speed
of 65mph (according to trip computer, DoD functioning)
- Avg hwy fuel economy: 23 mpg @ an avg speed
of 65mph (according to trip computer, DoD NOT functioning)
- Best fuel economy: 34 mpg @ an avg speed of
50mph (according to trip computer)
- Fuel octane required: 91 minimum
3800 Series 2 Turbocharged (w/ ported
heads) paired with a 4T60-E auto trans that had 3.33 gearing:
- Best (to date) 1/4 mile performance: 12.2
sec @ 113mph (using a TB0348 turbo and 15psi boost)
- Avg hwy fuel economy: 29 mpg @ an avg speed
of 65mph
- Fuel octane required: 93 minimum, 110 octane
for max performance
3800 Series 2 Supercharged (w/ smaller
SC pulley and 1.8 rockers) paired with a 4T65-E HD auto trans that had 2.93
gearing:
- Best 1/4 mile performance: 13.0 sec @ 100mph
- Avg hwy fuel economy: 30 mpg @ an avg speed
of 65mph
- Fuel octane required: 91 minimum, 94 octane
for max performance
Stock 3800 Series 2 N/A paired with a
4T60-E auto trans that had 3.06 gearing:
- Best 1/4 mile performance: 14.5 sec @ 92mph
- Best hwy fuel economy: 37 mpg @ an avg speed
of 65mph
- Fuel octane required: 87
Stock 3.4 DOHC V6 paired with a 5-speed
Fiero Getrag 282 manual trans that had 3.61 gearing:
- Best 1/4 mile performance: 14.1 sec @ 98mph
- Avg hwy fuel economy: 28 mpg @ an avg speed
of 65mph
- Fuel octane required: 87
Stock Fiero 2.8 V6 paired with a 440-T4
auto trans that had 2.84 gearing:
- Best 1/4 mile performance: (not tested)
- Best hwy fuel economy: 40 mpg @ unknown
speed (customer reported)
- Fuel octane required: 87
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