Shark Werks3.9 Liter Engine Upgrade for 996 / 997 GT3 / RS

Product type: Engine
  • 911 GT3 RS - 997
  • 911 GT3 - 997
  • 911 GT3 - 996

Product Description

As of 2020 (and 25+ builds) we concluded the 3.9 program and no longer perform this upgrade and instead moved focus to the 4.1 program.. As 2017 we began performing our SharkWerks 4.1L engine conversion for the 997.1 generation of GT3s. You can visit the project gallery for some examples.

Horsepower: 502 HP (+21% over stock)
Torque: 355 ft/lb (+18% over stock)
Redline: 8800 RPM (+400 over stock)

SharkWerks full 3.9L engine conversion for the venerable Porsche 997 GT3 motor has been tried and tested since 2009 on cars all over the planet. Tuned in the extreme heat of Arizona on EVOMS' Mustang Dyno the 3.9L engine conversion brings up the horsepower from a factory 3.6's 385rwhp (415hp) to 458rwhp (502hp) and from 274rwtq (300tq) to 326rwtq (355tq). The EVOMSit software (featuring IST and SP) is calibrated for either 91 or 93 octane levels. With more than fifty foot pounds of torque made available in the lower rpm range as well as an additional 70plus HP in the higher RPMS the character of the motor is amplified and even extended by an additional 400rpms. Utilizing our light-weight Piston kit we are also able to improve upon the already-quick throttle response and revs to an even more lively level.


  • SharkWerks/EVO Piston & Cylinder Kit - 3.9L
  • SharkWerks/EVO Head Stud Kit 
  • SharKWerks/EVO Spec Intake & Exhaust Camshafts
  • Tuning:
  • EVOMSit Engine Software for 91 Octane or 93 Octane
  • Exhaust: SharkWerks Center Exhaust Kit (SharkWerks/EVO Light-Weight Cup-Style System also available at extra cost)

Top End Build Kit:

  • Cylinder Base Gaskets
  • Head Gaskets
  • Cam Tower Gaskets

Billet Lightweight Crankshaft Pulley
Lightweight RS Flywheel Conversion (not required for RS model cars)

Option 2 (for higher mileage cars we also provide a bottom end build at additional cost)

Balance Rotating Assembly:

  • Crankshaft
  • Flywheel 
  • Rods
  • Pulley

Bottom End Rebuild Kit:

  • Main Bearings
  • #8 Nose Bearing
  • Rear Main Seal


Frequently Asked Questions:
Q) What vehicles is the 3.9L upgrade available for?
A) The upgrade is available for 2004-2005 996 GT3 models, and 2006-2008 997 GT3 or GT3RS models only. It is not available for Porsche Cup Cars, standard Carrera, Carrera S, 4S and GTS or Turbo and GT2 models.

Q) Do you offer the 3.9L for sale as a kit so I can install myself / have my mechanic install?
A) Sorry, we do not offer the 3.9L as a kit. Due to special in-house tools required for the engine build and to ensure quality control, the engine or car must be sent to our facility in northern California, or our authorized partner in Arizona.

Q) What is the time required to complete the upgrade?
A) Typically the upgrade requires 5 weeks to complete. If the bottom-end or heads require additional service, it may be slightly longer.

Q) What is the cost to complete the upgrade?
A) The price depends on the vehicle, mileage, and options. This can vary based on the US-Euro exchange rate. Please call or email for a detailed estimate.

Dyno Chart with baseline stock 997 GT3:

Drag Race: Stock 3.6L GT3RS vs Shark Werks 3.9L GT3RS:

See the feature in Excellence Magazine, and on World Car Fans.


Press Coverage

"This 3.9 vanquishes every GT3 flat six I’ve tried. ... Put simply, it’s the best normally-aspirated flat six I’ve tried."

-Excellence Magazine, April 2010

"The 3.9-liter engine has power and torque coming out of its ears"
"It is the same kind of feeling I had with the RS 4.0"

-Total 911 Magazine, Issue #84

"...the 3.9-liter conversion is a sensational improvement that actually jumps over both the second-generation 3.8 and the RS 3.8..."

-European Car, May 2012

"The acceleration is awesome. It's going to kick some Ferrari ass"
"Feels very close to a race car"

-Tanner Foust, Battle of the Supercars Episode 1, Season 1


Trying to decide between a 3.9 or 4.1?