The Stovebolt Site Forums The Shop Area The HiPo Shop V8 swap, what can the stock frame handle ?

Im doing a v8 swap and mustang ii front hub to hub kit from hiedts. I havnt built the small block yet, but have several options laying around. My dilemma is.....how muck hp and torque can a 51 chevy 3100 frame take, or what could i do to make it handle 4 to 5 hundred horse? I do not want to transplanta different frame. Can anyone help. Id be so greatfull!

box the frame back to the transmission crossmember. Try to stay around 400 horsepower.You won't be disappointed

Nice, i was worried it might not take it. If i do want to go bigger, would crossbracing do the trick? Thanx for the help

Have another frame ready once you box it. It's not a matter of "if", just "when" it will develop a bunch of severe cracks. Making a frame too rigid is a huge mistake. I ran boxed frames on the dirt tracks, plus roll cages that looked like a bridge builder's nightmare. Our frames cracked, early and often. Letting the frame flex somewhat is a lot smarter, but it can't be done with a round track car because the spring rate transfer requires a rigid frame. On the street, you need to keep the boxing to an absolute minimum. Building 100+ frames from the floor up taught me a thing or three about stresses, vectors, and just how foolish some ideas about frame design can be.
Jerry

Thanx jerry, the names ben. What do you think of the cross bracing. Chasis engineering sells such a bolt on thing, would that do the trick in your experience?

Gobs HP and torque won't hurt anything if your wheels are just spinning! I am assuming though that with that much engine, you are helping out the rest of the drivetrain to get the power to the ground and not just spin tires, correct? I suppose it also depends on if you are launching it a bunch or how exactly you are planning on driving it! I had a 350 in my 59 Suburban and never had any issues, but the 302 in my Willys wagon cracked the front frame a bit... partially because of how I welded in the front engine mounts and partially because of 4.10 gears, 2:1 transfer, and 33" swampers on it! not near as much HP and torque out of the engine as you are talking about but, lots of stress on the frame.

A little more information about your intentions with the vehicle would help. Are you planning to use all that HP regularly, or is the HP number just a "general information" question? The small blocks we ran on the round track were in the 600+ HP range, and we used all of it often, like 3-4 times a lap on a 1/4 mile oval track. It was not uncommon to lift the left front wheel several inches off the track while coming off a turn, even with a very rigid roll cage and frame. Very few street machines ever see that kind of stress, even with some energetic stoplight launches.

If you're going to be drag racing on a routine basis, build the chassis with that in mind, maybe with the cross brace you mentioned. Otherwise, just be sure everything you add to the frame is square and straight, with a minimum of welding involved. Good luck!
Jerry

Thanks for the help. To answer your question......its gonna be a street truck for dailey driving, but not comuting. Also, we want to do some grudge racing at the drag strip mabe three times a month. So, hatd launches are a must. I will be doing a four link in the rear, and it will hook up eventualy. At least that our dream! Thanks again

C channel frames are pretty much the same between brands and with that in mind the frame that gave the least trouble when we were pulling was was an unboxed Ford pickup frame with a 1500hp Arias engine. The next least troublesome was a round tubing frame on a 4 (or 5) engine pull tractor with a twist factor designed into the frame. By far the most cracking occurred on the short, rigid, triangulated and cross braced everywhere sprint car and super modified all round tubing frames. If you do box a section of a frame leave a 60 degree taper at both ends or even better a parabola shaped cut out on the ends of the boxing plates. This lets twist transition from flexible to rigid over a spread out distance rather than concentrated at one point which is a crack waiting to happen.

The old frames were designed to twist. We all see those guys on TV boxing their frames. Usually it's a hot rod, purpose built frame. This should not be done on our AD or TF's as Jerry said. These trucks had big old heavy motors. Most of the time heavier than the V8's you put in them later. So the frame can take it. They also had a 4X4 kit added to them sometimes. Those guys on TV go nuts with that boxing crap....and you can do harm to the metallurgy and the original design intent by welding and not knowing what you are doing. If you are going to build dragster HP, get an aftermarket frame. If you go beyond 70MPH you will need brake, steering, suspension upgrades up the yin yang. (I really think 60MPH but everybody here would balk at that)

Thanks guys, ive talked to others
Who seem to agree with most of you. I do have to box a small section for the IFS kit im installing, but i will modify the box plates. Ive decided to leave the rest alone, and probably wont get over 400 hp out of the small block im building anyway. Im going to pull out the tri-five rear end and swap it with a ten bolt with disc, so steering and stoping will be covered. We just want a nasty little hot rod, not a dragster, so thanks again for the advice. Sooo glad i joined stovebolt!!