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Discussion Starter #1
I'm intent on installing an LS1 into my recently aquired '73 GT and so have searched for detailed descriptions of another's successful frame modifications to withstand 350-600lb.ft. of torque in an Opel GT. I've found mentions of V8 conversions on the Net and in "The Blitz," but no specific info on frame strengthening; and I'm sure much more work will be required on the frame than engine/transmission mounting.
I'm not interested in drag racing; I'm aiming for a 0-60 time of around 3.5sec. for a car capable of competition, but used mostly for every-day, high-traction fun. And so, aside from suspension modification, I must determin the correct placement, thickness, and shape of sub-frames to minimize weight gain and provide necesarry strength.
I have no experience with frame work (though for automotive in general, I have restored -body-off- the Datsun 240Z I drive regularly), so I've bought these books: Chassis Engineering, Metal Working Handbook, and Race and Rally Car Sourcebook. I invite any informative comments you may like to make. I've got plenty of time till I'll have the time to begin cutting and welding, and won't do anything till I determine what should be done.

- Sean
 

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This is a modification that hasn't been taken too kindly by the Opel community in the past. I think it all comes down to the number of GTs that have been hacked up with the intent to install a V8 but are never finished. People either give up after realizing the size of the task they have just undertaken or once they realize it just isn't going to be safe to drive.

You've already come to realize that the body and suspension are going to need some serious work both to handle the power and the weight on the front end. This puts you a step ahead of most of the rest! Please keep us informed on your progress in both the design and the implementation, and I wish you luck in you venture!

-Travis
 

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You might want to take a look at the book "Engineer to Win" by Carroll Smith. While the book is primarily about fabrication of a race car from the ground up, I believe that it may be helpful in helping you learn to fabricate the frame members you are looking into putting into your GT. The chassis Engineering book you have is also pretty good, but I think this one may be more helpful. The book is full of info on material selection, strength, and design. They have it on amazon.com. I am a student at the University of Oklahoma in Mechanical Engineering, and a member of the Formula Society Engineers team. We build a mini Formula 1 Car each year, and this book has been extremely useful to us. Good Luck in your project... Let me know if you have any other questions about fabrication, I am in charge of the Frame/Chassis for next years car... and I am working in a machine shop this summer so I may be able to help you out. If you find any info out there on this conversion please post it... I seem to remember seeing a 302 Ford Opel GT project somewhere on the net... and if, in your searching, you find any info on the C20LET swap please post it... That is what I plan on putting into my GT... Adam Marshall
 

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Discussion Starter #5
I've found that S&W racing produces a 8-poin roll-bar and a 10-point roll-cage. Does anyone know of a GT with one? S&W is also in the process of making a full tube-frame for the GT, but this may be overkill for less than 600HP.

Also, at www.trappeauto.com there is a GT with a narrowed rear live-axle and a roll bar. I'm curious about the long-term results of such projects - to know what has worked well with high HP engines.

- Sean
 

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A V8 inna GT?

While it's possible - I wouldn't do it.

GT's are famous for rusting and rotting. The only way I'd consider a partial (where you fab up subframes and tie the whole mess together is if I started with a pristine GT. If you post that you're about to cut up a pristine piece - a lot of folks here will get upset.

The prob with a rusty one is EVERYTHING, including frame box sections is susceptible to rust. A rusty stocker can get 'loose' - jack up the corner of your car and see if the doors still close! Mix in some HP, and you're sure to twist the crap outta the body.

About the only way I'd even consider doing a V8 GT swappie is to fab up a complete rolling chassis with the requisite stiffness, cut away the substructure of the GT, and drop it on.

To be honest with you, it's probably easier to build a car from scratch Keep in mind these two things:

a) When the car was originally built, it was designed for 60 HP. Us 'Mericans got the big motor at nearly 90 HP. When you solve for power/weight, a GT flat flies with 240 HP. You can get this HP with a MUUCH smaller motor these days.

b) The front-mid config of a GT means the soles of your feet are even with the 2/3 cylinder wall. A V8 takes up a LOT more width in this area - MAJOR surgery is required to make it 'fit'.

Do take care. I did similar swappies as a kid with Pintos, Vegas and Monzas. If it's not set up right, it's a mess. A better choice would be to start with a Manta or Ascona and gain some experience with the swap before attempting the mother of all swappies.
 
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