WHY IS CHROMOLY LIGHTER THAN MILD STEEL?
The weight loss is directly related to the tubing wall thickness. Chromoly due to it’s metallurgical makeup is a stronger material, so NHRA allows for a smaller wall thickness with no loss in strength when compared to mild steel.
WHAT IS THE WEIGHT DIFFERENCE BETWEEN MILD STEEL AND CHROMOLY?
For 1 5/8″ tubing, mild steel (ERW seam tube) has a typical wall thickness of .134″ and weighs 2.134 lbs per foot. 1 5/8″ 4130 chromoly tube has a wall thickness of .083″ and weighs 1.367 lbs per foot. Doing the math that shows a weight difference of 36%. Your average 10 point cage has approximately 65′ of tubing. Built from mild steel the cage would weigh 140 lbs. The same cage built from chromoly tubing would weigh 89 lbs.
WHAT ARE SOME OF THE DOOR CAR SFI SPECS?
- 25.5 – Full Bodied Car Stock or Modified/OEM Floorpan and Firewall with OEM Frame or Uni-Body Construction – 7.50 to 8.49 Seconds; 3,600 lbs. Maximum. May be Mig or Tig welded mild steel or Tig welded chromoly.
- 25.4 – Full Bodied Car Tube Chassis – 7.50 to 8.49 Seconds; 3,600 lbs. Maximum. May be Mig or Tig welded mild steel or Tig welded chromoly.
- 25.3 – Full Bodied Car with Aftermarket Body Shell and Tube Frame, OEM Body Shell and OEM Frame with OEM or Modified Floorpan and Firewall, or Uni-Body with OEM or Modified Floorpan and Firewall Roll Cage – 6.50 to 7.49 Seconds ET; 3,600 Lbs. Maximum. Must be 100% Tig welded chromoly.
- 25.2 – Full Bodied Car Tube Chassis – 7.49 Seconds & Quicker; 3,200 lbs. Maximum. Must be 100% Tig welded chromoly.
- 25.1E – Full Bodied Car Tube Chassis – 7.49 Seconds & Quicker; 2,800 lbs. Maximum. Must be 100% Tig welded chromoly.