online170

This very point has been brought up before. Im learning this in class right now, so why dont we put this theory to test. Stresses induced occur in several different ways, the basic formula is STRESS = FORCE / AREA. The area varies depending on if its shear, or torsion, or whatnot.

Would somebody have cross sectional dimensions, and over all length for the two SFC? Lets keep it simple and only count the "relatively" straight members, no fancy angles or anything like that.

We dont know the forces induced, but we can assume a value and see which one is more "stressed".

You are right about the shape being stronger, but im skeptical because the square design uses more material. I wouldnt be surprised if they were both VERY VERY VERY close.

jayg

Alston and Global West SFC's.

https://www.thirdgen.org/forums/atta...s-dcp05021.jpg

UMI Performance

Hello,

Yes we currently ship all Canada orders USPS Priority mail or UPS, which ever the buyer choices. We do have a new system set-up with UPS called World Ease that allows us to collect the buyers brokerage fee's and taxes up front so there is no cost to you when it arrives at your door. Plus we get a discount with UPS to use this system so we can offer our savings to the buyer

Our SFC's are oversized per UPS and USPS, the US Postal Service will not ship them so they must ship UPS.. so unfortunately we can only quote you one price for that item.

If anyone has any additional questions regarding our SFC's please ask and I will be glad to help.

Thank you!
Ryan

Oscar

The square design probably has more metal to make up for the square design. Since theoretically the circular design is stronger, it wouldn't need as much mass. For all we know they may be equal in strength. I'm sure the forces that are needed for either design to fail are far beyond what the car could realistically ever generate under any condition. Other things on the car are most probably likely to break first.

krisb410

iTrader: (9)

I'd like to see some pics of SFCs on a car that has been wrecked. I wonder if they add any safety factor?

KYLE87

iTrader: (5)

Delete

CaysE

I'm really surprised to read the polls and all these posts. Back before I got out of thirdgens, Spohn was the hands-down choice.

KYLE87

iTrader: (5)

Delete

CaysE

I remember everyone getting into the same argument about boxed vs. tubular, it was eventually agreed that they're about the same strength but the Spohns are lighter. How can you go wrong? LOL

UnderCover89TBI

iTrader: (25)

i know im buying UMI's i want red ones and i want them powdercoated and the spohns are 5 bucks less and not powdercoated. But I do like spohns products that is who i normally buy all my components from

CaysE

Since when are Spohns not powdercoated?

Al Hasse

Powder coating on Spohn SFCs is a $45 option, otherwise they are uncoated.

UnderCover89TBI

iTrader: (25)

so that would be 240 for powerdercoated spohns or 199 for powerdercoated umi's..

KYLE87

iTrader: (5)

Delete

TheScaryOne

iTrader: (3)

I bought and installed a set of black powdercoated Spohn SFC's. Can't tell you how the ride is though, can't drive the car. We pulled up the carpet and insulation, but we didn't even notice the thin black insulation that is on the firewall and travels up behind the dash. It went up. Took out the wire loom on the driver's side, some carpet, the door panel, the hood release cable handle, and probably my hush panel.

If you can, soak the inside of your car before you start welding. I'd rather live with a mildew smell for a few days than having to have my wiring redone. Thank god it was at a shop, and they're fixing it, but I miss my baby. :'(

KYLE87

iTrader: (5)

Delete

MrBrooks

The BMR units are the most impressive I've seen and definatly what is going under my car. These are the ONLY way to go for those of us with long tubes.
The units for stock route exhaust look VERY similar to the UMI's. And at the same price, These get my vote.

CaysE

Boy this isn't the TGO it used to be. I guess neither is Spohn.

TheScaryOne

iTrader: (3)

Fried about two feet of wiring. Just under the dash to the driver's seat. Should be all re-wired, but I don't have power door locks currently (relay went up in the blaze, and is en route) I dunno what's gonna happen with the carpet and stuff. If they just let me go with the free welding ($210 or so worth of welding) or if they charge me and I continue to press on for more interior.

KYLE87

iTrader: (5)

Delete

spurgeon76

Love my Alston's but I have no experience with the others.

Al Hasse

Only problem we had putting up my UMI's was a small carpet fire on the passenger side (and we had the carpet rolled back and spaced with pieces of 2 X 4). That was only because of the extra welding we did along the pinch welds. Had we done just the 3 weld points as suggested, there would have been no problems at all. BTW, the fire was doused before any damage could occur (advantage of welding on ramps and jack stands with me watching for smoke). I love my UMI's, the difference in the ride is night and day, even with stiff suspension.

Those BMR pieces look real nice. They also look like they might interfere with the exhaust y-pipe since they don't appear to follow the floorboard contour on the passenger side like the UMI's do. I could be wrong, but that's just the way they appear to me.

TheScaryOne

iTrader: (3)

Same here. We did a LOT of welding under the car. Six or seven inch welds along the pinch welds, with only three or four inches between each weld. We welded them to the floor pans, added in strips of metal to reinforce more. There was a lot of welding. And we looked in the cab for smoke after we welded where the fire started. It must have smoldered for a few minutes before it caught fire. Damage was worse because we had to lower the car and we couldn't locate a way to put out the fire. >.<

MrBrooks

The ones in that pic are for long tube "inside the frame rail" exhaust. They make a diffrent one for the stock route guys that clears also.

krisb410

iTrader: (9)

So you were welding without a fire extingisher nearby???????

TheScaryOne

iTrader: (3)

I didn't know there wasn't a fire extinguisher nearby. I was in a shop. I figured OSHA had come sometime in the last five years.

We ran around the shop like chickens with our heads cut off until he found a jug with "water" sharpie'd onto it. And at least it was water.

KJZ28/TA

iTrader: (1)

Which ones are good for both stock and dual exhaust. I have normal routed exhaust now, but I eventually want dual with long tubes.

Is there a sub-frame connector for both?

2fast4u92z

Without starting a HUGE fight. The tube vs. box is real interesting thread. As a dozen people will post there info (what they think). To end all the BS.

I have read all the post on this! And the REAL answer from a mechanical engineer is.... Each has its own pros and cons. But for SFC the best BOXED unless there are extra "tie-in". In tests to see the amount of force it takes to flex a 12" piece of tube-vs-box. Tube bends way easyer than box.

From what I read box is best for SFC but everything else tube is fine. Cuz in other apps. Say roll-cage you are trianglating the chassis. Now one could get away with tube SFC if the car also had a rool-bar or cage.

Think about it then have you seen a building made out of tube steel? It is I beam,C beam, or box. Same on cars all production cars are box frame. I know there are tube chassis cars but that is apples N oranges. As I have never seen a tube chassis car with only a huge square shape. No there are more tubes!

Any input would be great.

TheScaryOne

iTrader: (3)

Well, I see it this way. IIRC box tubing is resistant to being along any of it's flats. It's *really* hard to do. But not so hard on it's angles. Tube is difficult to bend along the whole thing, but not nearly as difficult as bending box at the flats. So I think it depends on the forces the tubing will see. I have no idea where the different forces all effect SFC's.

This is based entirely on stuff I remember reading, and not any degree of first hand knowledge.

Gaccett32

iTrader: (3)

I am going to end the tube vs. box debate once and for all. After extensive research (engineering books and askinging actual engineers to help explain) round is stronger than square in almost all respects. Square is also stronger than rectangular. Interstingly triangular is stronger than square(but I don't believe it is stronger than round) of course this is based on all having the relative same dimensions. This is not debatable, it is physics, its not it looks like its stronger or some website trying to SELL their products says so. The most important strength test for a sub frame is tortional strength, contrary to the popular belief on this website a round design is stronger than a square one. The simple explanation is that a round design places stress equally on all areas while a square design has areas of no stress and areas that have greater stress(compared to a round design) when applying the same stress to both designs(while the dimensions are equal). In order for a square design to be stronger it needs to be bigger and heavier. Also the materials that can be used in making a round design are better than those avaible to make a square one(which deosn't mean that a round is always made with better materials). There are several examples of round constructs being used because a square one would be weaker, aquaducts, the ST Loius arch(the McDonalds arch just kidding), roll cages, pressure chambers(buildings are square and use square materials for other reasons however when design permits they use round for max strength, the underground columns of many buildings are round).

online170

Thats all fine and good, except up till now, its just alot of "he said, she said, i read" . You cant end an argument with that, its hardly a proof. Why dont we put some numbers to the hear say and REALLY end the debate?

But as mentioned before in this thread, both designs are excellent, and can be used because of their pros and cons. Different types or stress, cost, materials availability, tools availability, etc....

I agree that the most occuring stress IS torSIONAL stress, but that doesnt mean we can ignore the others. Its usually common practice to test the item in all scenarios, sometimes what you THINK is the worst case, isnt. Also, someone mentioned the square design has areas of no stress. Thats not necessarily a bad thing. it doesnt mean that area of the SFC isnt doing anything, it just means that part is not being "stressed out". Stress is usually bad, and we use design and materials to counter act it.

So you cant "end" the argument because of title, or you spoke to some one, or read something by someone who has a title. Lets put some dimensions and numbers to it and find out WHAT IS, rather than WHAT IF.

But its kind of pointless, because the yield strengths, or the ultimate strengths, or safety factors we are talking about for failure rates are far beyond what the cars can actually induce on the SFC, unless your car pulls twisting wheelies consistently. So the bottom line is, they look beefy enough to be SAFE, and im sure ANY SFC that has earned a rep, is just for that reason.

2fast4u92z

What you said is true. But the key words where of same size and materal! As boxed are about twice the size.
My boxed are 4" by 1"+

On my car I have 1/8" steel plate cut to the curves of the floor pan then welded to the floor and the SFC. Then on a 45* angle of the SFC there is more boxed to the trans cross over. Then I have a tubed bar from insides of the SFC. For my x-treme BMR torque arm.

The 1/8 plate is for a clean stock look and so there are no pockets for future rust. Also I use the SFC for my jack/lift spot rather than the floor pan.

This is plan take but it take about strength.

http://www.homebuiltairplanes.com/fo...ead.php?t=3372

Gaccett32

iTrader: (3)

[QUOTE=online170;3633596]Thats all fine and good, except up till now, its just alot of "he said, she said, i read" . You cant end an argument with that, its hardly a proof. Why dont we put some numbers to the hear say and REALLY end the debate?




QUOTE]
http://www.abc.net.au/science/experi...pisode22_1.htm


This is just a simple example, you want proof, my father is an engineer, I workerd at his company over the summer drafting, I posed this question to him and he confered with other engineers just for accuracy. His company builds high pressure dryers, which are cylindrical, all the tubing is cyclindrical, the reason being the the round design can handle the pressure stress better than a square one design could, if the square was better they would use that instead. Posting the equations would confuse most people even more, they confused me, but the simple consclusion of testing done by actual engineers and stated in their books so that most anybody could understand is that round is stronger than square.
If you require more proof than I will post links to the complex equations and the explanations. But Im busy right now and Im responding because Im taking a break. When I have time and if you require, I will link to the complex explanations.
I agree that actual number testing or field testing would answer the question, however there are more factors that are required, such as quality of material, quality of manufacture, etc. So only answering the simple question of is round better than square(which is all that is posed by this debate) a simple answer is yes all things being equal.

2fast4u92z

in the example you posted has nothing to to with anything a SFC would see. A f-body would have to be hit in the front or rear to make that example right. Again there are many examples that don't work in are setups. Like a buildings supports being tubed. we need to look at the flex in the tube or boxed in the middle or at the ends. Good example is like a 2500Hd truck bed frame is C or boxed but uses tubed bar to go from frame rail to rail. B/C each materal has a better load strength. In fact is any production car a tubed frame?

I could have used tube as mine is supported every 24". But as I removed my cage and this is my only support i used boxed.
Read the link I edited in my last post.


And if the debate is "if all is equal length,thickness,and materal" the answer is Boxed. As far as tube being circle so there are no higher stress areas you are right but that only matters when the applied pressor or load is on the edge. Fact is a 10ft tube and a 10ft box are supported at the ends and stack weight in the middle the box is way better.<--the real numbers for that teast are in the link.

Here is more reading
http://www.pro-touring.com/forum/showthread.php?t=33252

KJZ28/TA

iTrader: (1)

To end this argument someone needs to buy 2 sets of SFC, one square and one round. Install it on there car, cut it off, and put the other on. Drive it, slalom, skidpad, etc. see if there is a difference..until then I dont think anyone should even worry about it.

My question still goes unanswered though...is there a SFC that has space for the stock and dual exhaust configuration?

Gaccett32

iTrader: (3)

[QUOTE=2fast4u92z;3633698]in the example you posted has nothing to to with anything a SFC would see.


Fact is a 10ft tube and a 10ft box are supported at the ends and stack weight in the middle the box is way better.<--the real numbers for that teast are in the link.

[QUOTE]

1st, that was a simple example designed to show principle. 2nd your example is as bad as mine, for yours to work there would have to be massive amount of weight in the middle of the car, then the square would be stronger than the round. I did state in most repsects that round is better than square, you have stated the one area where square is stronger than round, but it is just as irrelevant as mine to the application for cars.

http://www.factoryfive.com/table/ffr...ecs/frame.html

Scroll down to the section title ROUND TUBE VS. SQUARE TUBE
Again torsional strength or round is better than square, your point is also mentioned which I have admitted. But round is still stronger in more ways than square.
Round Stronger-1)torsionally
2)vertically
3)pressurally (ie pressure chambers outward and arch's inward)
Square Stronger-1)horizontally

And your proof is again just talk in on a message board, while mine is based on actual engineers work. Tortianal strength is pretty much all that matters in SFC applications since they are supposed to stop the twisting motion(torsion) of the motor on the body/frame of the car.
All racing sports use as much round tubing as possible(on the role cages designed to provide the best protection for the safety of the driver), the reason frames of cars are square is because first they need to support the weight of the car, and secondly they are cheaper and easeir to make, and thirdly they provide a much easier mating surface for the rest of the cars parts(the body etc.). It is harder to mate a flatish surface to a round one than it is to another flat one.

2fast4u92z

First to answer your quesstion yes there are just do a search. Second we have tried this and that is why all my buddies shops push Boxed unless the car is geting heavy cage or added support.

I knew when I posted the car frams being Boxed you would say cobra. Two of my friends have Factory Five cars. And when you see that frame in person you will see that it may as well be made of aluminum as it takes very little(compared to a 3400lb camaro). I mean the frame is like 3ft apart, where the people set is off the frame and the car weights 1/2 of 3rd gens. EVERY APPLICATION HAS A BEST MATERAL AND DESIGN! I would bitching to my friends if it didn't have a tube chassis.

I guess I could break out my old school books or post up the math to show you but it real isn't that important. Yes there is better metal available in tube But how many people on here even know what they are buying now from companys.

I am not mad or starting a online fight as i am not like that. But what does your dad do build washing machines? I would take the word of a person with a Masters degree, a major chassis fab guy that has bend both materals infront of me and people that have these cars and have done these mods or a general "what is stronger tube or box".

Look into Giakoumelis G, Lam D. or American Institute for Steel Construction.

These are building information but they will cover in more detail than this board can handle this issue.

I will call Brent and get the wall thickness and sizes of there SFC and do ou the math again and if anyone wants to post up specs of other companys i will do the math on those too. This way the math will speak for itself and people can just makeup there own mind. So lets just lay off tell real numbers can be posted up. And please if you see REAL SFC posted up have you dad to the math and post up to. I like this thread as long as it stays productive and on topic.

Gaccett32

iTrader: (3)

Here is some links to engineers with engineering degrees who specialize in automotive design who state that round is better than square, not "buddies shops". I have yet to meet a mechanic with no degree who knew what they were talking about. Also do you have an engineering degree, what are you refering to by books. Also my father is an engineer for industrial dryers. Think of giant compressors, like you can buy at sears, except much more complicated, he definetly knows more about engineering than any one else here. I asked him while searching this forum and I ran into a debate on round vs. square, seeing as how he is an engineer and nobody on the boards could claim that, I asked him.

http://www.rorty-design.com/content/tube_work.htm
http://www.dragracingonline.com/tech...rks/iii_3.html
http://www.hansracecraft.com/faq/index.htm#1c

For the last one you may need to select general questions.

I also do not want to start an online fight, I simply imparting my knowledge. I will continue to post more sites with more proof to make my point. Also could you put links to specific info, I couldn't find anything at AISC.
Could you be more specific as to how this applies
http://books.google.com/books?id=lcm...FcMo#PPA496,M1
I dont want to read an entire book to find one paragraph that supports you argument. Feel free to do the math.

2fast4u92z

Ok first these examples well very interesting are way different and a Tube chassis car is very different to a stock body f-body car with sfc. Oh and as far as driveshafts go.. Come one a twist is way different than what a sfc sees.

I fact lets sum up

Tube standing on end with weight on top. Tube wins
Tube is a twist or torqued setup tube wins
Horrizonal position or measuring flex horrizonal boxed wins

My buddies own major car shops and build $200,000+ tube chassis cars. i have seen pics of these cars crashing and your tube main hoop is sheard 6" off the lower horrizonal tubes. And when i asked "why not use boxed at least where the door jam/stock sfc would be. He said on these type cars there is no need for support there the hoops and center of the car are the large support areas.

yes I have a degree. and am still is college. But my info comes from two very close buddies that have degrees in this and one works at GM and the other did work at Delphi. both with boxed sfc on F-bodies.

Look Tube wins in everything but Horrizonal and key words or size for size.
Question why don't people use boxed in custonm bent frame apps?
Answer b/c it's so hard to bend and even harder on the thin side.

How about this would it end this debate if I go to my buddies fab shop and get to pics.
One of a 10ft tube bar supported on the ends and me standing in the middle.
And one of me doing the same on a boxed 10ft long piece.

I already know the answer they both flex some but he tube does twice as much.

I have a Physic book that gives the way to measure, given you have the specs of the materal. I have another buddy that is a professor at a major college, realy good with physics and math. I will see monday. I know he will be up for this test. So by next week end i will have Brent get me the specs on his SFC tube and boxed, then get two same size pieces and set up a in garage test. To measure horrizonal load on the "sfc". they don't need to be the same size as sfc but it helps to show the aplied load.

As far as the books I would have to scan and post pics but they show that is many controled tests tube wins in (CTF) over boxed by more than twice the load. However it's higher MPa rating is due to not the triangler strength. As the thickness of the tube is the major factor.

I will see I can find a PDF or doc of the math equation. But I don't think anyone would be able you use them as they are 10 variables and each is another equation.

KJZ28/TA

iTrader: (1)

I did a search I only could find that Spohn wont fit both full dual and stock configured exhaust. So the search did not help very much.

This thread is very entertaining......I hope it keeps going.

87 formy

I probably shouldn't be getting anywhere near this argument since I chose a business major as opposed to engineering and missed out on some fun; however, I have some ideas to contribute.

What if, hear me out, the choice of SFCs depends on the use.

For the examples below we'll assume the size/material to be identical.

Example #1: Drag Racing
Scenario: lifting front end (assuming use of an anti-roll bar)
The front end gets lifted, the force tries to bend the subframe connectors. Boxed are stronger.

Example #2: Off roading
Scenario: Front passenger side wheel going over a large rock
The car wants to twist and puts torsional forces on the SFCs. Tubed are stronger.

I'm just stirring things up a little. One last thing to consider is the passenger side SFC. The tubing typically has a bend in it, which would make it weaker; the boxed are in some cases welded together and in others one straight piece (BMR). Who wants to take that one on?

2fast4u92z

the SSM (discontinued), BMR,ect... But the real question is what are you looking to do? You said stock exhaust with cats then you said dual exhaust. For stock the passenger side needs to be a one piece design so the passenger tubes can fit the caved in floor pan. On most dual exhaust or long tube headers the exhaust is down the center then the cross member is more of a problem.

87 Formy

You are very close with what you said about the two different apps drag vs twist. However in our setup a car would have to bend to the point of a totaled car to even have a boxed SFC damage or not work. In fact the sheet metal would rip or break away from the subframe first. As far as the BMR I would say that is the weekest link but there are ways aroung that by using different wall thickness or with a better bending ways. Another good question for Brent over at BMR. I was there test mule on the 4gen stuff as I had a full list,every product they have on my car, and before it was even for sale. We helped out on one of the first LSX tube K-member mainly.

Oh NOTE: in both cars I would hope there is a good cage as no matter if you even had a tube or box mad of any materal they (IMO) can't handle that load. In fact my Enginering buddy droped the nose on his 6second firebird hard after a wheel stand and riped apart the sheet metal on the stut tower! Oh and there was a CM tube welded about 4" away from the rip. Fact nothing can stop forces in surrounding areas.

don't worry there is no fighting going on just some enginering and physics talk. So post anyone input or ideas.

Gaccett32

iTrader: (3)

So we pretty much agree as to the strengths of each style.
Round tube being stronger torsionally and standing vertically
While the square tube is stronger laying vertically
So is this argument then about which is more important for a car, or do the square SFC available may actually be stronger or equally as strong as round SFC because they are 'beafier'
Then that adds to the debate, weight issues, fitment issues(ie exhaust) and even ground clearance it would seem.
So then waying all the variables, it would still appear as though round SFC are superior to square SFC, I believe the torsional strength factor is the most important for automotive applications, round SFC usually weight less, they have better clearance than square, and have better ground clearance. Then their is the issue of quality of material and construction, which is could be imposible to tell, unless you felt the need to run various materials tests and trials to determine construction quality which would require sampling many different SFC of each type throughout production.
The complexity of this makes it impossible so we should just rule this out and assume all are made with the same quality of material and construction.

Is it just me or this turning into something of a philosophical debate of which there is no end.

Guest

This argument comes up a hundred times, and its always wrong answers. I haven't even read it all to see if there's anything right at all up above but most of what I saw isn't.

I'm going to quote something from above I see quite often thats a totally off base statement
You should leave the engineering to your father. As a simple explanation why, what stress is the SFC itself in under most conditions? The SFC's are not connected to the motor or the rear axle, and the body of the car is MUCH larger than the diameter of the SFC (dont forget these cars are not body on frame) so in an INSTALLED condition, the SFC's are not going to see much if any torsion at all. Thats where most people fail in trying to determine whats best, they forget what the SFC is attached to and what actual forces it will be subjected to.

KJZ28/TA

iTrader: (1)

I have stock routed exhaust with Flowmaster cat back right now. Would like SFCs but in the Future I want true dual exhaust.

2fast4u92z

Yes but you have mis-typed it "square is stronger laying HORRIZONALY"
Clearance isn't a real issue on 3rd gen (is more on 4th). Yes tube is light or could be as there are better metals used in tube.<--But that doesn't mean that is what companys are doing(more cost=lower profit). In reality Other than the boxed or tube SFC the mass majority of the buys don't know or care about he materal used or the wall thickness. When BMR built my pieces I picked out the materal and spec out the tube sizes.
As I stated in my last post even though tube is better at twisting are cars would never is that much flex. At least not more than a boxed can easly handle.
The thing you have to think about is why do boxed work better horrizonaly and also hold about twice the weight? And if you know boxed is the strongest in a horrizontal then it is the best per the design and app. That would flex less. so when you floor it,hit bumps,lock the breaks,ect and the car is sifting weight these are trying to stop the front of the car and the back from flexing. Also the sfc should have a 1" bend weld every 10" on both sides off the SFC. And if this boxed or tubed sfc realy saw all this twisting it would rip the 1" weld (well not the welds but right around them).

It is not impossible(very hard) Just ask the manufacture what the product is made of and the thickness. The you find the strength of the metal and the find out the weight that is breaks at. Most people don't know how to do this!
But the fact is SFC are good it is a bandaid to slow body flex. It works great but as one pushes the car more and more i.e. big tires,gears,shift kits,lowering springs, and lots of horsepower. the body is seeing way more than it was designed for.
The key in any design is to trianglulate the structure. so a cross brack from SFC to SFC or angled pieces of the SFC to the tran cross brace. You where saying that without even knowing it when you said tube is better due to no edges for stress.

If the differences in the horrizontal load in bowed vs tubes wasn't so great in the boxes favor I would hve used it. Fact is 99% of people won't see the difference in tube vs boxed. So heres to everyone buy what ever you like just please install them right!

I think we rapped up this "philosophical debate". It's been fun but I'am out of beer!

2fast4u92z

You can go with the bmr as it will not mount in the way of your stock style exhaust. However you will see the driver side is better cuz it has more support pieces. so when you do duals if the pipes are away from the SFC I would take the time to add some more meat over there.


MADMAX

Yes you are very right. In fact dead on! But just to amuse the possiblity I started to say "what if" but the fact is the amount off twist the body would be even if it jumped a curb, isn't anything a boxed can't handle. I realy Like the imput thanks.

Gaccett32

iTrader: (3)

I think you are underestimating the amount of twist an fbody experiences even with the stock motor. From my own experience, (I have t-tops) and all the mods I currently have, when I floor it, I definetly twist the body, pretty badly, so much so that my center console twists and then pops when the tranny shifts out of first(this may be due to something being broken or loose allowing more body flex than usual but I havn't found it yet), but it still is body flex by twisting. I would even suggest that the conditions where the flexing occurs bewtween the front and rear(which you suggest is more common and more important) is not as common. Who in and fbody takes dips, and such head on, I take them at an angle which again twists the body of the car. Cars with full frames(far superior to fbody design) and too much power always end up twisting the body first(there aren't any cases that I've heard of where short of slamming the front end after a hard launch would you bend the car at the middle), why because they have a square frames. Correct me if I've misconstrued your arguments as to why the square design would be better because of the forces it sees.
So I guess every automotive engineer(which pretty much covers all of racing) who uses round over square, stating one of the reasons is torsional superiority over square designs is completely wrong.

Couldnt you just do a simple experiment to test this. Take a thin sheet of metal, say two feet by 1 one foot. Twist it like an engine would a car's body and observe. Then place a square tube on either side (say about 1/4 inch sides) and twist. Then take a round tube (about 1/4 dia) and twist. Then you could also bend at the middle. Would this experiment be a valid means of testing the basic premises of both arguments.

KYLE87

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krisb410

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I'm going to have to unsubscribe to this thread because of the "boxed vs square" thing. There are already enough threads on that top topic, continue in one of those threads.

This WAS an interesting thread, until now