Why a 4th gen chassis? I agree with Costas: 3rd gens are lighter to start with, so why bother dealing with a 4th gen? 3rd gens are cheaper to start with too!

I don't now 3rd gen's.
Is there is significan improvement in suspension design in a 4th gen vs a 3rd gen?
Are they pretty much the same car, different body?

Yea, you can actually work on a third gen (I've owned both, even built a race car out of a third gen once). The front suspension is a strut setup instead of the upper and lower a arms, but the cars handle well and it works. I'd start with a third gen and make it a Firebird body for better aero. We're down on HP (with a 6 cyl) and need all the help we can get.

i will not debate the advantage/disadvantage of 3rd gen/4th gen. i do like the 4th gen font suspension better.
as for weight. we have 3rd gens here that are bairly @ the minimum for CMC (3150) and i have built 2 4th gens now that have matched that weight, and need balast to get to thiers (3200) - w/ driver for both.

what i would like to see here is talk of thing to get a V-6 car down in weight w/in AI rules. things like VFN hood and hatch, lexan glass, carbon doors, K-member, and the cutting of any structure allowed that things like a cage (minimal to keep weight down) and subframe connectors would provide addequate stiffness for the chassis. the brakes could be left to 98 and up stock parts as the car would be light, no need for 4 pot fronts. i would cut out all the roof structure too and just keep the fiberglass skin in place.
i havent read the AI rules more than once and it was some time ago. i also realize what some have said about the cost of such a car like this. w/ a normal V-8 car, the HP would have to be matched w/ the weight, but not so w/ a V-6 car.
good debate, lets keep it going. V-6 cars can be had in good running shape here for under $3K.

I poked around to try to find out what an Lt1 and a v6 (whatever the engine designation is) from a 4th gen f-body weigh, but couldn't find anygood data. Anyone know?

Jason

Hood & hatch: legal
Lexan: legal
carbon doors: illegal
K-member: legal, if you can find one strong enough to trust

As far as cutting on the tub:

7.3 Frame
The entire tub, floorpan, firewall, and frame assemblies including the cowl and windshield frame must remain in the stock position and cannot be relocated. “Cowl” is defined as the metal structure installed by the factory between the firewall and base of the windshield. “Frame” and “framerail” are defined as the parallel boxed metal rails running the length of the car that form the basis of the unibody or frame. “Floorpan” is defined as the sheetmetal forming the floor and trunk floor of the car. Cars may not be “channeled” to raise the floor within the body or lower the body below the frame rails. The only modifications to these structures allowed will be in the following instances and no secondary purpose for a modification is allowed (i.e. electrical cable passage facilitating suspension clearance). If a modification is not listed below it is specifically not allowed.
a) To facilitate the addition of safety equipment such as subframe connectors and roll cage bracing (i.e. roll cage may extend through the firewall to strut towers);
(IMG:http://www.frrax.com/rrforum/style_emoticons/default/cool.gif) To facilitate plumbing or electrical access.
c) To facilitate transmission fitment or access.
d) For installation of a fuel cell or fuel tank access. S197 chassis Mustangs may relocate the fuel tank from the rear seat stock location to the trunk area behind the rear axle.
e) For exhaust clearance. This does not allow exhaust components to be run through the firewall, which is not allowed.
f) To facilitate installation of and access to ignition and induction components in 4th generation F-body GM vehicles. Allowed modification is restricted to removal or clearancing of the cowl/wiper bucket area. The cowl and firewall must remain otherwise intact.
g) The floorpan may be modified for the purpose of facilitating the installation of a three-link type suspension. Such modification is limited to a hole being cut in the floorpan to allow the “third link” to pass through the floorpan to the attachment point in the cockpit. All components that intrude into the cockpit must be covered.
h) Rear framerails may be “notched” for suspension clearance in AIX only.
7.3.1 Radiator core supports may be removed or modified but frame rails must remain intact.
7.3.2 All cars must have OEM front and rear shock towers in the same location as stock. AI cars must utilize the OEM rear shock towers for rear shock attachment. Attachment of camber or caster adjusting devices is unrestricted. AIX cars must have OEM shock towers in place and resemble the factory build, but attachment points are free. The shock towers may be modified to facilitate suspension component fitment (i.e. SLA, etc) but must retain the general shape, structure and location as stock.
7.4 Body/Interior
7.4.1 Cars must have neat and clean appearances. All panels must fit properly and be free of sharp edges. All panels must be painted. No vehicle will be able to compete in more than one event with obvious body damage or unpainted body panels.
7.4.2 American Iron Extreme cars are unrestricted in all body panel material and modification. AIX cars are allowed to remove rear inner fender metal structures to facilitate tire fitment (“mini-tub”), but an alternative structure must be put in place to cover the tire and seal the tub assembly.
7.4.3 Only OEM (or the equivalent replacement of same type and material) body panels may used in the American Iron Class except as noted in Sections 7.4.4 and 7.4.7.
7.4.4 Composite hoods, hatchbacks, trunk lids, front fenders, fender flares, and bumper covers (fiberglass/carbon fiber, etc.) are allowed within the power to weight ratio constraints of the American Iron Class.
7.4.5 Acid dipping or body panel lightening is not allowed in the American Iron Class.
7.4.6 AIX vehicles may modify fenders for any purpose, but when viewed from above the top half of the tire must not be visible. AIX vehicles may use composite or other materials for the entire fender or quarter panel.
7.4.7 AI vehicles may modify wheel openings for the purpose of tire clearance only but when viewed from above the top half of the tire must not be visible. Composite (fiberglass/carbon fiber, etc) front fenders and rear fender flares are allowed.
7.4.8 All interior modifications (including removal of the dashboard and wiring) are allowed provided that the modifications do not conflict with any other rules contained herein or the NASA CCR. Dashboards may only be removed if acceptable replacements are installed (i.e. fabricated aluminum panels).
7.4.9 Lexan or polycarbonate material may replace windshield (3/16” min thickness for windshield), rear glass and side windows provided it is installed in accordance with the NASA CCR. Center bracing must be installed in the inside to support the windshield if Lexan is installed.
7.4.10 Spoilers and airdams are unrestricted but must be fixed for competition. Rear wings or rear spoilers installed on AI cars must not extend more than 1.5 inches beyond the outline of the rear bumper and not more than .75 inches on either side of the body when viewed from above.
7.4.11 All holes in floors and firewalls must be sealed according to NASA CCR.
7.4.12 All vehicles must start a race with a minimum of two functioning brake lights.
7.4.13 Hood and rear deck pins are recommended to secure the hood, trunklid, or hatchback.

Here's the whole rulebook:http://www.nasaproracing.com/rules/American-Iron-Rules.pdf



I'm not sure what you're saying here, but you still have to make the 9.5lbs/hp and 9lbs/ft-lb rules. So, assuming a 2600lb car race ready you could make 273hp and 288ft-lb.

Since we're now on the subject, is there an aftermarket, lightweight 4th gen hatch that I'm not aware of. We've already got lexan in ours, but it still weighs a ton!

Jason

SVO Mustang was the first thing I thought of when I read that in the AI rules long ago.

VFN offers a hatch for the camaro, it's a pin on and supposedly weighs 8#. The description says for steel car, so I assume that means a stock body.
(IMG:http://www.vfnfiberglass.com/9302camhatch.jpg)
(IMG:http://www.vfnfiberglass.com/9302camhatch2.jpg)

I just found the page I wanted to reference earlier. Not sure how accurate these weights are as the page has been around for a long time and doesn't look like it's been updated recently.

http://www.bfranker.badz28.com/fbody/weights.htm

According to that page, the LS1 is only 30lbs heavier then the 3800II in standard trans form. The next part is purely speculation on my part, but my guess is that the LS1 is actually lighter (or at least break even) if you compared only engines, because the LS1 got the T56 and the 3800 got the T5.

While the 3800 would place the weight back further in the chassis, I'd guess a stock LS1 (294hp/311tq max) with a 2800lb race weight would be an interesting combo given the fat power band.

The fox chassis can be made very light, but the turbo 4 is not so much so. The Iron block SBC’s are a good 200# heavier then a plain old 5.0, those things are small and light, and the turbo four was a special version of the 2.3 cast in Lima that weighted within a few lbs of the 5.0.

I’ve seen V8 fox chassis in stripped down road race trim that were around 2650lbs with driver, so I wouldn’t be surprised to see a turbo 4 in the 2500-2600lb range.