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HybridZ

240Z Structural Reinforcing for the Power of an LS1


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I would suggest you start reading them all. THere are a lot of different schools of though, so depending on what you plan to do with your car some thought might work better for you than others. I personally have built 2"x3" subframe connectors, have a SCCA rollbar and will tie that into my strut towers.

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I agree with BillZ260, read through the posts and based on what you plan for your car decide what you want to do. There is no one answer for all circumstances.

 

I'm installing an LT1 and have the material to extend the frame rails. I'm going to tie them to the rear sub-frame, install a rollbar and put strut tower braces on the front and rear.

 

It's probably overkill because my car will primarily be a daily driver but I want to be able to AutoX and road race so I'm doing the extra.

 

I know I need to comply with the rules for the various racing classes but the engine swap puts me in the "real" racecar classes anyway and who knows I might change my mind about the amount of reinforcing I do. At a minimum I'm going to extend the frame rails and tie them to the sub-frame and install a rollbar.

 

Wheelman

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just curious guys..........has someone installed a sbc without modifying the subframes?

 

Sure, just depends on how long you want the shell to live. I'd say you can get away with it in a 280Z with just things like strut bars. The 240Z is lighter and a "flexy flyer" and should get some other upgrades. My buddy has run his 400 SBC in a 240Z for over a decade with 225HP/400 ft lbs at the rear wheels. Of course, he's gone through 4 different shells, a couple due to wrecks and the others due to the stress cracks (actually rips) in the C pillars. Of course, it's also a street/autocross/track car that is driven to it's limits, but you get the idea.

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I think the subframe connectors are a good starting point. They provide a lot of reistance to lengthwise compression and expansion along the chassis. They still allow a lot of stress to be carried by the roof area of the car though, which tends to come apart at the upper portion of the rear hatch where the pillars are welded together (right above the rear quarter windows). If you could connect the front and rear wheel wells together with a long bar, it would help quite a bit. Access in and out of the car would be ala Dukes of Hazzard, so you'd have to compromise and run a bar from each wheel well to a point on the floor near the side of the seat. Braces from the front strut towers to the firewall would help a lot too. Of course there is always the option of going with a full cage as well. All depends on how much $$$$$ you want to throw at it.

 

 

 

Mike

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Of course, it's also a street/autocross/track car that is driven to it's limits, but you get the idea.

 

I think autocross and track put considerably more loads into the chassis then "V8 torque." I know lots and lots of track Zs that make no more then 200hp have similar chassis degredation problems.

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You know, after I posted that message, I was thinking about adding something to that affect. I'd say that when you setup the car for extreme handling for auto-x or track use, there is no doubt that it will stress the chassis much more than what the average V8 Z that's run on the strip on occasion will ever see. I keep forgetting that the "auto-x & track" hybridz group is a bit smaller than the driver/straight-liner group. :wink:

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i have a 76 280z......i'm not planning to build and extreme hp v8, just wanna have a v8 in it. also, this is not a daily driver car, it's more like a toy car, for looks but ofcourse will have atleast 225-250 hp. is it necessary to upgrade the subframes? appreciate any input......

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My LS1 powered '77 280Z has front and rear strut tower braces and a 4-point roll bar. I've been driving it for a year now (7,000 miles) - including two trips to the dragstrip and one track day at Texas Motor Speedway. It seems to be holding together OK.

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i have a 76 280z......i'm not planning to build and extreme hp v8, just wanna have a v8 in it. also, this is not a daily driver car, it's more like a toy car, for looks but ofcourse will have atleast 225-250 hp. is it necessary to upgrade the subframes? appreciate any input......

 

With a couple hundred pounds of additional metal in a 280Z, I don't think you need to worry about it unless you turn it into more of a race car. For what you are looking at doing, you should be fine. Strut bars are always a good idea, anyway.

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