How rigid is this chassis?
 

Got to thinking about that tonight. I’ve been drilling holes and moving metal to fit all this power and hardware into this car. I’m noticing that everything bends, drills, stretches and tears pretty easily...started wondering at what point do you need to add a cage to strengthen the chassis?

When you are required by a race track.
Or when you have 5 point harness and need a roll bar as per scca rules. Or at least that was the new rule with having 5 point harness.

Thanks but I’m not talking about race track rules...I’m talking about stresses on the unibody and chassis flex. The seems on this car are spot welded and glued together, they come apart pretty easily. It was designed for 200hp right? Doing an engine swap, we are throwing double or triple or more hp at it. Even the subframes are not super beefy...the sheet metal in between the subframes is pretty weak.

Some others that have done swaps may be able to answer, how well does the car seem to handle the extra power and torque?

Not very. It twists like a wet noodle.

The car is designed to crumple on impact and absorb the forces instead of the driver. If you "beef" it up too much you negate all of that engineering and risk being pulped in a crash.
Conversely if you start drilling holes, tearing and stretching things then it may crumple more than it should and crush you.
When you swap engines you pretty much change the whole engineered safety aspects of the car and there is not much you can do about it. It is the compromise and risk that you have to accept.

Starting to think a cage of some sort is probably a good idea.

With the HP you're going to install,,, it certainly couldn't hurt. What do you think one would run,,,, $3k or so??

Is this going to be a street car? Cages are designed to be used with a helmet and can be very hazardous when used on the street without one.

ITT: a bunch of people who haven't played with actually floppy chassis from early 90s japanese cars.

Definitely a smart thing to think about...and I hadn’t thought about that. It’s a street/track toy.

I really don’t want a cage in it but I think this thing is going to need some rigidity added to it.

I’m thinking something along the lines of this...

http://cdn.speednik.com/wp-content/b...e-complete.jpg

Are there any sort of sub frame connectors available for these cars?

They are all over the place...few hundred to a few thousand.

For safety, you typically need a fixed back seat and helmet once you get a roll bar in. And a helmet on the street is usually not legal.

The chassis is reasonably stiff for what it is, but that's because of how it's engineered. It doesn't have to be thick materials or insanely strong glues, etc; it's all in using the materials so they're strong in the direction they will be stressed.

Hmm, it did feel pretty tight the few times I drove it before I started the swap.

Maybe it is strong enough when stressed as intended...but yeah it definitely seems pretty flimsy when I’m banging on it with a hammer lol :bonk:

I think having a sheet of aluminum bead rolled for strength behind the rear seat isn't a bad idea, or a copy of Spencer Fabrication brace