antman89iroc

I thought about posting in the 3rd gen vs other race car platform thread but this is a bit different.

How fast or quick of an ET can a stock bodied third gen go before you "need" a roll cage? Not as required by rules but just the strength of the chassis. Any suspension upgrades are OK. Any reinforcing other than roll bars are OK. How much power can you put down? Let's look at it from an Auto or Manual trans application.

In my case I just don't want to put a cage in it. Or at least not sure I need to yet. I have sub frame connectors, boxed LCAs, adjustable torque arm and poly bushings all around with a completely stock front suspension. It's a stick shift car and I have noticed some crinkling of the floor pan in front of the LCA mounting point which I reinforced with bolted and welded panels. I've also noticed some of the body seam putty starting to come loose and even fall out in certain areas. So, how much is too much?

My car isn't really that quick. Best yet is 7.3x in the 1/8th. 60' are horrible at ~1.7-8s and it's a fat pig at 3700#. True street car with all the creature comforts. Funny, just as I thought my car was getting "fast" everyone else was getting "twice as fast". The never ending quest...

Oh an my power adder is Nitrous. Right now jetted at 200HP but will be moving that up soon. I will post my semi-port spray bar setup for HSR soon. But for now it's only about 550WHP.

scooter

iTrader: (11)

1992 Pontiac Firebird 300 MPH

Orr89RocZ

iTrader: (20)

I think it depends on the 60ft and 330 ft times. The faster you attempt to go there, the more critical the suspension becomes and i think the suspension needs a stiff chassis to work correctly.

How fast that is is hard to define. These cars are flexy as it is in stock form. Subframe connectors for sure does alot but even i noticed a big difference once a roll bar went in on top of the sfc

Alot of chassis strengthening would likely become necessary once you try to get down into the lower 1.2 60’. I was able to go 1.28 and 1.29 with just basic parts but the car twisted alot even with the roll bar. An anti roll bar in the rear is def required and that should allow lower 1.2 60’s without getting to exotic but if heavy car then you might need abit more bracing to really let the suspension work

Then again this is assuming relatively small tire radials and good prep. Big tire car that is light weight may not suffer much chassis twist and not need the strength.

So its a real hard question to answer

I know for sure that 11’s without a cage and subframes is not recommended due to how much flex and how unstable the car feels leaving on 1.5 60’s. Thats what my 383 did all motor and subframes made huge difference lol then bar added a bit more rigidity.

anesthes

iTrader: (12)

My old '89 Formula, with 8.5" slicks used to 1.6 60'. Eventually the roof started to tear/split right behind the t-tops at the corner.

-- Joe

antman89iroc

Eek and that's the kind of "limits" I'm concerned about.

Orr, the 60 foot times, or how hard it's leaving out of the hole, are surely a point of stress. Like I noted, my car is sluggish off the line as a "good" launch for me is in the 1.7x's. Mostly 1.8x's to be honest. But my ET/MPH shows it's coming on at the top end. A lot more MPH than a typical car 2-3 tenths quicker.

I don't want to tear the car apart and a stick shift on slicks is probably a stress inducing launch.

I did notice an improvement in "ride" after SFC. On of the clues about how flimsy these cars is show up when putting the car on jack stands. Just moving the load point from the tires to right behind the radiator (front frame rails) makes a noticeable difference on how the doors open/close. I suspect the flex on launch would probably prevent the doors from opening. Not that one would try it but you know what I mean.

The next question becomes, what would be a good next step. If I am going to add a roll bar may as well make it "legal" or at least build it to be. There's got to be some good improvement to make without caging the whole car.

Orr89RocZ

iTrader: (20)

T top car?

Bout only thing you can do besides making sure your subframes are as well designed and strong as possible, is to add a cage or bar atleast. That ties in the subframes from top side so additional stiffness is added. Full 10 pt is best but do you need to be 8.50 legal?

Now i only have an 8 pt and subframes with stock swaybars and wonderbar. I beat the hell out of my car and it has been twisted hard but still seems intact. Body panels and such seem within reason for a near 30 yr old car lol

antman89iroc

Yep, and a heavy one at that. It hasn't been in any obvious accidents (still has all the numbered body panels) and painted only once so I think it's had a decent life. Well up to the time I added the stick shift and built the motor.

QwkTrip

iTrader: (22)

Just a street car and roof began to crack at the top back corner of windows (hard top) after 1500 miles and every body panel on the car had moved by 2000 miles. That was with subframe connectors installed. High 11's at 123-125 mph.

I loathed the idea of a cage but had one custom built and never gave it a second thought after the interior was put back together.

QwkTrip

iTrader: (22)

And once the roof cracks you will be chasing and fixing cracks for the rest of your life. The metal is fatigued and it can't be stopped unless you anneal the metal. Same goes with any location on the unibody that fatigues.

antman89iroc

Those are the issues I hope to avoid.
And QwkTrip, I have to give you mad props for "What ever happened to QwkTrip's car anyway? thread and many others. You really took a lot of time and effort to share your experience with us. I appreciate it. I know how long it takes just to publish the info much less figure out how to explain it, taking good photos and all. Not to mention the patience to not just "finish the project" but taking a moment to take the photo in the first place. Diagrams, wiring info, tips how to's, it's impressive.

QwkTrip

iTrader: (22)

Thank you! Always nice to hear a compliment.

It's fun to share things but to tell you the truth it benefits me more than anybody. It's great to have documentation of what I did so I can fix things or get the right replacement parts!

anesthes

iTrader: (12)

I envy guys like you. I'm good at building and fabricating, but my stuff is always dirty, scratched, etc. You guys build cars that are so clean you can eat off any surface in the engine bay.

Maybe I should stick with rat rods...

I still want those wheels. Guess I'll have to settle for the lame '97 T/A wheels I have.

-- Joe

QwkTrip

iTrader: (22)

Maybe look at the ROH Snyper. It's got the machined lip like a Firehawk wheel but thinner spokes and room for bigger brakes. I think it would be a good looking wheel on a 3rd gen.

It isn't listed for our cars but I called GroupA wheels and they have some that will fit. And while you're at it just ask if they have any old inventory of the RT laying around.

https://www.groupawheels.com/aboutus.sc