Yes, it does sound nice indeed. Perhaps that's due to the double firing order swap we applied on this motor. If it doesn't make more power this way, it sounds great at least
The suspension is pretty much complete now, including the anti-roll bars:
To keep the period looks I combined the vent and springs elements of a modern radiator cap with the top of an old one:
The cooling system though needs further attention. I thought I'll be very clever and tried the waterless cooling system from
http://www.evanscooling.com. It's main advantage is (and that might be the only one), that it doesn't boil, it's boiling point is so high. But during the first engine runs I found out about the disadvantages: It's a slippery, very smelly substance, and - of course - does not evaporate. A spill stays there forever. Distributing this on a racetrack would probably not make friends. At this point I am thinking to switch to water...
Coming back to the suspension and springs, I warned you I'll narrate on the calculations I did. Some might skip this part I guess
Please let me know, if I made fundamental mistakes here - though I must say that the resultant spring rates worked perfectly and the car settled on the exact ride heights I had planned for.
So what I wanted to know were the spring rates and lengths. To calculate these I needed the following elements:
1. Motion ratio MR
2. Wheel to spring rates Wr and Sr
3. Sprung mass
4. Shock absorber lengths fully extended, at bump and ride height and resulting spring lengths
1. I measured the motion ratios which is how much the wheels move per movement of one unit at the springs. This came out at 1.6 to 1, both in the front and rear.
2. If movement and weight/force are combined, the square of the motion ratio applies. So, 1.6square = 2.56. This means that the spring rates are 2.56 times the wheel rates.
3. We measured sprung mass by putting the car on two scales, in the back and front, wheels and uprights resting on the ground. We measured 212 kg per side in the rear and 112 kg per side in the front.
4. Shock travel from fully extended to ride height was 4cm both rear and front. The resulting (relaxed) spring lenghts were 9in front and 10in rear.
Then I solved the formula "Sr/Wr = MRsquare/1" for Sr:
Sr = Wr x MRsquare x sin a
Whereas:
- Wr is 212 kg / (4cm x 1.6) = 33.13 kg/cm in the rear and
112 kg / (4cm x 1.6) = 17.5 kg/cm in the front.
- MRsquare is 1.6 x 1.6 = 2.56
- sin a corrects for the inclination of the shock absorbers. The rear shocks are inclined about 70°, so sin 70° = 0.94. The front shocks are vertical, so sin 90° = 1.
So, spring rate for the rears is: Sr = 33.13 kg/cm x 2.56 x 0.94 = 80 kg/cm, or 450 lbs/in
and spring rate for the fronts is: Sr = 17.5 kg/cm x 2.56 x 1 = 45 kg/cm, or 250 lbs/in
As mentioned before, these rates resulted in the exact ride heights I wanted - so something must have worked right
However, what really put me off was to find out - and this probably shows that I still don't really understand what's going on
- that I could get to the same results much more easily by calculating the weight the spring has to support at the respective ride heights and divide by shock travel from extended to ride height:
Rears: 224 kg x 1.6 = 340 kg
340 kg / 4cm = 85 kg/cm, corrected by sin a = 80 kg/cm
Fronts: 112 kg x 1.6 = 180 kg
180 kg / 4cm = 45 kg/cm
Good night