Engine conversions
If your M96 or M97 engine needs a rebuild, or you want to avoid future damage, or you simply want more performance, an oversized rebuild from Hartech is the perfect choice. More torque, power and drivability throughout the rev range, built on the same Nikasil cylinders as our repairs.
Why capacity beats tuning
Unlike most tuning, which usually gives a relatively small benefit in a narrow part of the power band, an oversized rebuild provides more torque, power and drivability throughout the whole rev range, without needing to rev the engine to maximum all the time.
Tuning aids for a standard-capacity engine usually rely on shifting the power band upwards and losing mid-range torque, often making a car look faster on paper while it is slower through the gears, because, contrary to popular opinion, acceleration is proportional to rear-wheel torque, not BHP. When we dyno-test customers’ cars with different inlet or exhaust systems they are often less powerful than standard: Porsche knew what they were doing.
Building an oversized engine achieves both an increase in mid-range torque and BHP, better throttle response and acceleration anywhere in the rev range, and a much easier car to drive fast without revving it out, which also reduces stress on mechanical parts. Top-end BHP rises roughly in proportion to the increase in capacity, while mid-range torque usually increases even more.
- Mid-range torque and BHP
- around 15 to 17% more
- Top end
- around 6 to 10% more
- Cylinders
- Nikasil-coated aerospace-alloy wet liners, fully closed deck, with additional ribbing for heat transfer
- Pistons
- Developed and manufactured with a leading F1 supplier after extensive trials
- Intermediate shaft
- Larger bearings available for all models
- Machining, assembly, testing
- All in-house; remaps by our specialist
Conversions available
Each conversion is a full rebuild with oversized cylinders and pistons, so it addresses the known weak points of the engine at the same time.
| Engine | Converted to | Notes |
|---|---|---|
| 996 3.4 | 3.7 | Independent video review of a 3.7 below |
| 996 / 997 3.6 | 3.9 or 4.1 | Gen 1 3.6; conversions up to 4.1 litres now offered |
| Cayman S 3.4 | 3.9 | 987 and 981 |
| 997 3.8 | 4.1 | |
| Boxster S 3.2 | 3.7 | |
| 997 Gen 2 | in development | Ask for the current position |
Prices follow the same approach as our rebuilds: the engine is assessed and stripped first. Rebuild starting prices give the base; ring 01204 302 809, option 1, for a figure for your car.
Measured results
We are reluctant to quote exact figures, for practical reasons: different cars of the same model start from different outputs, different dyno providers give different results for the same car, there are several kinds of dyno, and several methods of testing. We are happy to show before-and-after results from our own cars.
Gen 1 3.6 converted to 3.9, against a standard Gen 1 3.8
Cayman S 3.4 converted to 3.9, against a standard 3.4
Adjusted to compare with the owner’s manual figures.
A full technical report covering tuning, torque, BHP, gear ratios, design and performance is available by email to interested parties: ask when you get in touch.
Proven in racing
The conversions grew out of racing. Hartech-built engines, using the same basic technology while fully complying with the regulations, won the BRSCC Boxster Championship, and classes 1 and 2 and the overall championship of the Porsche Club Championship in 2017 and 2018, taking the first three places in class 1 in 2018, all completing a full season at the front with complete reliability. Hartech-engined cars took the top three places at Oulton Park in the 2020 PCGB Motorsport Championship and were on the podium at Donington Park in April 2024.
Different examples of the oversized engines have been independently tested, with positive feedback, by 911 & Porsche World (November 2018) and by private owners.
Drive one before you decide
We have examples available for road test, by appointment, for interested owners who already have a suitable donor car. For public safety and to comply with our insurance, tests are accompanied, conducted locally within speed limits, and intended to demonstrate the improved drivability, flexibility and potential performance under the instruction of our staff.
Conversions on film
Talk to us about a conversion
Tell us the car, the engine and what you want from it. If the engine needs a rebuild anyway, this is the point to decide.
01204 302 809
Option 1 for engines, option 2 for servicing and the workshop
- Open
- Mon–Thu 07:15–17:45
- Closed
- Fri, Sat, Sun, bank holidays
- Drop-off
- Before 17:00; locking up starts 16:45
- Address
- Firwood Industrial Estate, Off Thicketford Road, Bolton BL2 3TR