0 - 100 km/hr for a standard 500 SLC is 7.8 sec. with 4 speed autobox. The standard 500 SLC tips the scales at 1515 kg.
0 - 100 km/hr for a standard 6.9 is 7.4 sec. A standard 6.9 tips the scales at 1935 kg.
If this car has alloy panels and a 4 speed autobox and without hydraulic suspension, it should weigh around 1650 kg.
My guess for 0 -100 km/hr would be around 7.0 sec. I notice that the air intake is not so restrictive as in a standard 6.9. and I would really like to know what other engine mods. have been made.
I can't calculate it exactly, because I don't know what the proportional constant would be; I have only guesstimated here. That comes from testing.
For the same vehicle weight, if you wish to cut the acceleration time in half, you have to proportionally cube the horsepower.
T/2 prop. to hp cubed.
Applies to all sorts of engineering applications. (aircraft, marine, automotive, etc.).