260z Frame & rollbar support (Blower application)

[Dans toy]

Lots of interesting cars on Hybrid Z. I've used several good Ideas in building my own project. I have a question reguarding reinforcement in the door area, particularly from Z owners who are using forced induction in combination with higher traction tires for 1/4 mile use. I have a full frame under my 74 260Z with a 4 point rollbar but reluctant to weld in angular support through the door area. Curious what you guys with torque monsters are getting away with. My project uses a 6.0L with a Magnuson112 supercharger, 2000 stall torque converter & 255 drag radials. Appreciate any opinions offered. Dan

[Cable]

I guess it might depend if you have an early or later 260z.

 

My last 280z had a Big Block Chevy 454 swap and it made a boat load of low end torque. I never felt the need to install a roll bar or cage due to structural concerns even when racing with drag radials.

 

Although some might disagree, I don't believe adding door bars would add much in terms of structural support. You need to step up to a full cage w/halo in order to gain a decent amount of structural strength increase.

Edited September 14, 2010 by Cable

[Dans toy]

I guess it might depend if you have an early or later 260z.

 

My last 280z had a Big Block Chevy 454 swap and it made a boat load of low end torque. I never felt the need to install a roll bar or cage due to structural concerns even when racing with drag radials.

 

Although some might disagree, I don't believe adding door bars would add much in terms of structural support. You need to step up to a full cage w/halo in order to gain a decent amount of structural strength increase.

Cable

Thanks for your input Dan

[Dans toy]

Cable,

curious if you had a frame under your big block car. Dan

[Cable]

Cable,

curious if you had a frame under your big block car. Dan

 

Just as it came from the factory.

[Dans toy]

Just as it came from the factory.

Cable, thanks for your input. My 260 is likely an early model. The frame support under the car is small and the same on both sides. I've heard thats one of the changes. Also read comments about the unibody thickness being upgraded to a heavier gauge. Does that sound right to you? I'm on the fence with this door support idea. If I go forward with it the tubing (door way stiffner) welds to the rollbar at rib height , passes by the thy area where weld-in support extends up from 2x3 boxed steel that crosses under the seat, grabs the main frame rail then extending to the tunnel where the trans support carries through. The door stiffner would continue down, welding to a reinforced area by the feet then pass through the floor angling into the frame within the wheelwell. I'm confident that this would help with my concerns but its a lot

of extra work that may not be necessary and I don't like the idea of opening the car door to a hunk of steel between me and the seat.

Good fortune to all, Dan

[Dan Juday]

...My 260 is likely an early model. The frame support under the car is small and the same on both sides. I've heard thats one of the changes. Also read comments about the unibody thickness being upgraded to a heavier gauge. Does that sound right to you?...

 

From personal experiance I can tell you that Nissan definately used heavier gauge steel in the later 280's than in the 240's. However, it's clear there were changes every year (and multiple changes in '74) to the S30 unibody, and that's just the USDM versions.

 

Bottom line: If you're doing some serious drag racing (sounds like you are) you need to be concerned about safety and rollover protection. Build the car to protect yourself first. That alone may be all you need to reinforce the body.

[Dans toy]

Point take-in . Thanks

There are also track requirements based on 1/4 mi. times. May not have any choice . Dan