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Frame Reinforcement Upgrades?


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I'm gonna chance this thread on this forum and see what you guys think. I know it's more of a hybridZ question, but I wouldn't mind other perspective, too. :) I'm doing an LS1 conversion and want to reinforce the frame pretty darn well to handle the torque. I'm thinking of going with a supercharger or moderate NA build. Either way would like close to 400 to the rear wheels. Not hard to do with an LS1 engine.

What do you guys recommend for frame reinforcements? A quick search revealed the bad dog options, but I'm thinking of picking up the steel myself and custom welding it in. How does this effect eligibility for competition racing? Anyone have good links or ideas? Thanks!

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Assuming that the style of competition racing are you considering includes going around corners...

There are specific rules for each class regarding roll cage / body reinforcement. If the rules in your specific race class allow the cage to tie in both the front and rear strut towers then you can increase the chassis stiffness substantially. If you can't extend the cage past the firewall then generally the floppiness of the nose on these cars is your limiting factor. You need to reinforce the chassis so that forces can move efficiently corner to corner across the car as much as the rules allow while minimizing weight.

If you decide to go the frame rail route. Bad Dog frame rails are very well made and an excellent value. I have a set in my garage that are going on my track car next weekend.

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Hey Steve, thanks for the reply. I am pretty interested in auto cross, drifting, and circuit. I feel that I should build the car primarily for circuit or touring car racing.

I am not really completely against bad dog frame rail connectors or replacement rails, but I was actually thinking of welding in 1.5" x 3" tube with a wall thickness over .090. I would like to weld the roll cage in to the frame rails for extra strength. The main problem I am having here is what you mentioned, how to make it comply with multiple racing classes. I want the car to be fairly strong, so if I can extend it to the front, I definitely would.

Are strut tower braces generally accepted in mosacing classes?

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If you are going to do any racing beyond a hobby, meaning something with a rule book, then keep the book with you, read it, read it again, memorize it, sleep with it, and then build the car to those specs. Autocross, and touring car racing have extremely focused groups. Build the car to fit one of those classes and stick to it. If you want to dabble in both with the same car, then you need to do twice as much reading. Build a car that can adheres to the strictest requirements and then you may be okay with other forms of racing, but at times, tires, sway bar sizes, roll cages, all can bump you into an entirely different class. Autoracing is usually not a one car fits all type of thing. I would suggest you narrow your focus to what you REALLY will actually be doing and then build accordingly.

Right now It sounds like you are more of a hobbyist who wants to try a bit of everything for fun, which then build the safest car you can and have at it. But building a car without a clear focus on what it will be used for almost ensures you will build the wrong car and spend too much.

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I’m not sure which sanctioning bodies allow strut tower braces. I know that the NASA and SCCA rules are readily available on the web. I suggest that you make a list of who you specifically want to run with and google the rules.

Maybe someone with more experience than me will chime in but as I understand it, it's important to not just tie the strut towers together in the front but to triangulate them to the firewall and/or cage. The nose of these cars tend to bend at the firewall, especially if spring rates exceed 250 or so in the front. If you don't deal with the floppy nose the car itself becomes an undampened spring. Also, don't just throw steel at it. Figure out the week spots and reinforce as little as you need to. Weight is your enemy even if you have +400HP. The more it weighs the harder it is to stop, change direction and accelerate. You will also consume more tires, brake pads and fuel.

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