I got my 2007 NASA racing technical inspection on Sunday. Aside from a few minor infractions that need to be fixed, the #431 Crossfire will remain in TTD class for the season.

Official weight was done on a Longacre 4 point scale system with a full tank of gas, driver and safety gear.

Competition Weight: 2,791 lbs

Weight Balance
Left Front: 756 lbs
Right Front: 778 lbs
Left Rear: 637 lbs
Right Rear: 621 lbs

One very critical thing that the Technical Inspector noted, the gas tank is exposed directly behind the driver / crush barrier (OEM placement). He recommended that I install a racing fuel cell, or a plexiglass divider behind the driver. And at the very least a fire extinguisher system inside the cockpit.

The good news is I get to stay in TTD !!!

 

That's a pretty nice weight distribution - if you lose 20 lbs, the front will be balanced!!!?
Presumably the battery is in the rear?
Is there any/much more you can remove from the car? (i.e. compensate for the fire extinguisher.)
Smaller fuel cell will obviously save some lbs!

 

The battery is still in the OEM position... I'm going to bring it to the rear compartment, passenger side inside the divot where the jack was. Perfect little cubby hole for the battery... I'm sure the battery weighs 30+ lbs, so moving that back should help the balance a bit.

I ran the car for about 10 laps yesterday after my tech inspection... This was the first time I drove the car with the new (BUTT UGLY) aero wing. I must say that it feels very balanced now and the wing held the rear-end down enough to give me another 20 mph on the big sweeper turn at Willow Springs without the "FLOAT" that I have experienced in the past. I also maintained my normal speeds on the straightaway... So the downforce from the wing doesn't seem to be slowing me on the straights, just helping me on the faster turns... It's currently adjusted at -11 degrees.

I have to do some measurements, but I think an 8 gallon rectangular fuel cell will fit inside the roll cage in the rear compartment... 8 gallons will hold me for about 20 laps which will be fine for the normal 20 minute races. It's going to kill me when I do the 3 hour enduro races though !

I can also put the C02 / Halon tank in the rear (12 lbs) with a release cable in the cockpit and still make the tech inspectors happy...

There's really nothing I can do to lighten the car more, because if I go any lighter I will get bumped-up into a different class... All of these rules are based on various modifications and HP to Weight ratios... STUPID RULES.

I'm now looking forward to running the first points race at California Motor Speedway on March 17th & 18th... This wing should help me shave a good 5 seconds off my times from last year...

It's all a work in progress... Now if I can learn how to drive, I'll do some serious damage... LOL.

 

any chance you can lower the rear spring height to take some weight of the front end?

 

You mean shift the center of gravity ?

 

uh yeah, what else does moving the weight do? how many inches from the front bumper is your CG located vs. stock cg?

 

Have you considered a secondary removable fuel tank for when you do the enduro?

 

Well unfortunately I have never been able to find a stock CG and never had my car 4 point weighed before I started ripping it apart.

I'm no math whiz so all I can give you is the current four point weight so if you find the stock numbers, you can figure it out. This is with driver / safety gear / full tank.

LF 756
RF 778
LR 637
RR 621

Looks like the CG is falling about 53% forward... or about 53/47... But since I installed the new rear wing I've calculated appx. 185 additional lbs rear downforce at 135 mph. this would shift the CG back.