What do you do if you have just built a Supercar prototype thats been held back by 1980s Diesel tech? And what if you just so happen to have a few custom built prototype V12 engines left over from a recent Collaboration with Kraft Haus Technik?
Why not combine the two?
Enter the 1991 IMR RC-039 G-Sport.
As you can see it is almost identical to the 1990 D-Sport, except for a few wings to add downforce at high speeds and some wider wheels. The main difference obviously comes down to the powertrain. In fact it uses the same IMP J33 based V12 engine as the KHT Atlantic and Atlantic GT, it even has twin turbos just like the KHT. However whereas the Atlantic uses a custom KHT Turbo setup, the G-Sport engine benefitted from IMPs comparatively much more vast resources. The engine features hollow prototype camshafts with increased lift and duration compared to standard IMP J-Type cams. The cylinders have been overbored from 88mm to 92mm while keeping the default 90mm stroke, netting a displacement increase of 0.6L for a total displacement of 7179cc. Since the thinner cylinder walls weaken the aluminium engine block, internal bracings have been added to compensate for this. The engine uses 8,2:1 compression forged steel pistons and two IHI turbochargers with a 60,5mm Turbine and 60,5mm Compressor. Using a relatively low boost threshhold of just 0,6bar the engine produces maximum boost at 2800rpm. Fuel mixture is comparatively lean coupled with advanced ignition timing for reasonable volumetric efficiency. Despite this it is capable of producing 720hp and 890Nm on 95 octane premium fuel.
Apart from a stronger transaxle and retuned suspension the RC-039 itself hasn’t been altered. It retains the comfort oriented interior designed primarily for high-speed long distance traveling. It now accelerates from 0-62mph in 3.3 seconds and will reach a top speed of 362,7kph. If it wasn’t just a prototype it’d be king of the Autobahn, which is why it’s been nicknamed “Autobahn” by a number of people in honour of a lost prototype built by IMP in the late 1930s.
1991 IMR RC-039 G-Sport “Autobahn” Concept:
IMP GJ72T Custom Twin Turbo V12, 92x90mm, 7179cc, DOHC 48V, 718hp @ 6800rpm, 893Nm @ 4500rpm, 348kg (wet)
5-Speed manual transmission, MR Layout
1585kg curb weight
0-100kph: 3.3s
Top Speed: 362,7kph (226,7mph)
Fuel consumption: 15,6L/100km
Projected price: 340.000DM