SFI Clarification and details please

Shocks, Springs, Brakes, Frame, Body Work, etc

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SFI Clarification and details please

Post by Bearwen.us »

Before I contact SFI and ask I thought I would post it up here.
I am going to buy the spec / build sheet from SFI but not sure which set to buy.

here are the ones I am looking at straight from the SFI website.

SFI Spec 25.3D 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
Effective Date: July 2, 2021

SFI Spec 25.4D Full Bodied Car Tube Chassis – 7.50 to 8.49 Seconds; 3,600 lbs. Maximum
Effective Date: July 2, 2021

Ok for the Spec 25.3D what is an aftermarket body shell considered is it a full carbon / fiberglass one piece body is it multiple panels can it be the original outer skins welded together or separate pieces or can it be handmade aluminum panels or one-piece body?????

Also Spec 25.3D If the original vehicle is a unibody car what is a modified floor pan and what is a firewall roll cage??? I am wanting to have a fully back halved rearend and a full tube front suspension as well

Spec25.4D says full bodied car tube chassis so if my car is a unibody I can cut the floor out and the firewall and just set the body down onto the tube chassis? Can I just have the outer skins of the car and no inner fender structural OEM support?

Also I would prefer to build the chassis from mild steel DOM as I want this to be a streetable car for drag and drives. I can and do have a tig welder but would prefer to mig weld it. This vehicle is for fun maybe outlaw no prep racing (on track no street racing ). Weight isn't a big issue to me and I'm pretty sure 6.50 to 7.5 is plenty fast for me and my son (we enjoy the build as much or more than the racing )

Thanks for any clarifications you guys can give me.
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Re: SFI Clarification and details please

Post by BillK »

I would probably look in the NHRA rulebook first. All of the information might be there without having to buy it from SFI.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

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