The upper main spring has to be in compression to take the static weight of the car.
If the car weighs 800kg i.e about 1800lbs then assuming 50/50 weight distribution there is 900lbs at the front or 450lbs per corner.
If the spring rate was 150lbs/inch for example, that would need 3 inch compression to just take the weight of the car.
Maybe a bit more with your surge inducing "heavy" V8 lump.
