1989 930 Turbo G50 Promodet Backdate

“Wangan & Shuto Expressway or fun circuit spec”

The words from the owner. Whether or not you are a fan of Japanese tuning, these words have deep meaning especially when coming from an OG in the air-cooled 911 world of Japan. Fully built by Komine at Promodet. Same owner for 20 years and best friends with Komine owning a shop called K Factory “powered by Komine” together.

It is to no surprise that Japan has been making headlines in all areas of life lately as their 20-40 years of knowledge and precision in all fields is finally making its rounds through many media outlets for essentially having the best of everything. The car scene and tuning no less, with any culture there is the good and the bad. We at RMC have made it our mission to find the “Special Cars” and have tapped into outlets that are not available to most who are even deeply rooted in the scene. This 930 has history, tells a story and has an aura that is clear as day. 

This is one of the baddest Backdates stateside, with a foundation of a factory 911 Turbo, and being a one year only g50 making it the ultimate chassis for G bodies. If all around purpose were a car it would be this one. Wether it’s low speed around town, 200mph, or HPDE, it was built to do it all. One of the fastest backdated cars to come out of Japan thanks to the huge diet, Promodet drivetrain combo, functional aero and suspension + brake combo. This is not a fresh built to sell backdate, more so a honed and dialed machine. 

A reliable 550hp heart delivers surprisingly linear power thanks to Komines One-off Turbonetics turbo, flame bent equal length header, and tuning that has made this an easier to control machine than most cars built to this level. Noises are emitted of which you would never not have smile on your face, not even after 5 years of ownership. The plan with this engine was a simple one, very easy to maintain, easy to find parts, and built for strength. Cooling comes from a Promodet one-off 3 layer intercooler and huge 935 style front mounted oil cooler. 

2360 lbs is a hard to achieve weight being a turbo base, 600lbs less then factory. Starting by deleting the sunroof, then to a full frp rsr backdate, frp hood, and doors. The chassis has undergone various reinforcements by Promodet including the stitch welded front end and reinforced shock towers for the RSR coil-over conversion. A full 6 point cage helps to add safety, and stiffness. Being a bolted in cage allows for the removal of the front bars if needed. The body is in great shape, with beautiful lines and at no point does it cosmetically show like a frp kit. Very few rock chips can be seen on the exterior. The interior is nice, with a very CS style dash and general interior finish. Some areas could use a repaint but we like the raw look. Contrary to popular belief a gutted 911 does not sound as loud as you think it would in the cabin. 

We are very excited to find a special home for this car, this car will only be sold to someone with prior experience in vintage sports cars. The previous owner although in Japan would like to also keep in touch with the new owner as he is active on social media and has documented his own process through a blog that will be shared once deal is completed. 

Spec sheet:

550hp | 2360 lbs

57k km

73 RSR backdated 

5 year build completed in 17’ 

Engine refreshed 6k km ago. 

Recent work – valves were adjusted, all fluids changed, compression tested, new Michelin pilot sports

Test done cold

1: 122

2: 120

3: 122

4: 123

5: 122 

6: 121

• Split case 
• Full balance and blueprinted rotating assembly
• Crankcase’s have been dowel pinned (935 style)
• Polished crank 
• Custom grind SC came by Promodet 
• Reinforced valve springs 
• Copper fire ringed heads
• ARP headstuds 
• Reinforced piston bolts
• Upgraded rods
• Treated stock pistons 
• “Big Port” ported heads Komine SPL
• Full balance and blue printed rotating assembly 
• One-Off Turbonetics turbo 
• One-Off muffler
• HKS Wastegate 
• Handmade flame bent headers / Screamer pipe
• One off 3 layer I/c
• NAPREC 80mm TB
• Works Oil cooler + 964 Oil cooler with fan 

• G50/50
• Promodet trick factory LSD
• 996 turbo clutch
• Light weight flywheel 
• Wevo short shifter

• MoTeC M4
• MSD 6A
• New bolt ignition tuning
• HKS EVCII + Scramble boost 

• 928S4 front –  Endless 355mm rotor
• 930 rear brakes
• 964 custom hub fr
• Coilover conversion with Bilstien rsr kit 
• Spot weld treatment
• M Machines strut bar