OT: torsional rigidity in a u-shaped channel Options

[3liter914-6]

Hello 914ers,

I've got a question that has to do with a Volvo project I'm working on. V8 conversion, and because I'm doing an efan and the engine is a little farther forward in the chassis than standard (due to the t56 tranny), I'm having some issues.

The main issue is that I had to install the radiator 1" farther forward than standard. Not a huge problem, everything still fits, but the radiator is too tall and the cap extends above the slope of the fenders. When I get the hood back on, I'm going to have some problems. What I need to do is lower the top of the radiator crossmember.

It's a U shaped channel, probably about 3" deep. 18 gauge steel, and with a stamped piece of 18 guage steel spot welded to the top of the channel to close it off. I figure to put the radiator in a position where the hood will close comfortably I need to chop about 1.5" out of the legs of the U.

I bounced this off of a friend of mine who is an aero eng. grad student, and he confirmed what I thought--that the strenght of the crossmember is directly related to the height of the U. He couldn't answer my followup questions about whether seam welding and going with a thicker gauge of metal (16 or thicker vs 18) would make up for the lack of height.

He did suggest that filling the enclosed crossmember with a heat expanding foam would add to the torsional rigidity, but didn't have any specific suggestions on products. IIRC a couple of manufacturers do this on their frame rails. Is anyone familiar with this technique, and where I can obtain such a product? Would one of those home insulation spray expanding foam product work (sprayed after all the welding is done obviously)?

I have another question, which is related to cutting the 1.5" out. I'm not good at all with eyeballing a cut, and I can't get a ruler/t-square anything like that on there, as the crossember bows out in places, and I can't just measure up from the bottom as it's not a uniform depth.

I've levelled the car off side to side, and will level it front to rear, so I was thinking I could lay some saran wrap in the channel, and fill it with something like plaster of paris. Something that'll pour in, and setup hard yet still be removable. Assuming I have everything levelled off, I should get a pretty straight and uniform line that I can use as a guide for my cutting. Sound reasonable? Any suggestions on a good material to use? Any other suggestions on getting an accurate cut?

Thanks for any input/advice.

Adam

[smontanaro]

QUOTE (3liter914-6 @ Feb 19 2006, 10:24 AM)

... the radiator is too tall and the cap extends above the slope of the fenders. When I get the hood back on, I'm going to have some problems.

Why not recore the radiator with a shorter core?

[alpha434]

Estimating torsional rigidity is going to be EXTRA hard without pics!

Could you reinforce in front of and behind the radiator after you make those cuts? Are we most worried about securely holding the radiator or chassis flex?

[3liter914-6]

QUOTE (alpha434 @ Feb 19 2006, 11:55 AM)

Estimating torsional rigidity is going to be EXTRA hard without pics! Could you reinforce in front of and behind the radiator after you make those cuts? Are we most worried about securely holding the radiator or chassis flex?

Probably chassis flex. I really don't know what I should be worried about at this point. As part of the conversion process, I've added a second crossmember I think it's a 1 3/8" od tubular steel bar. It's a little bit forward of the engine crossmember, but still about 2 feet back from the radiator support. I'm not sure if this would help with any reduced rigidity of the rad. support, my guess is a little, but not much since it's so far back from the end of the frame rails.

I'll see if I have any pics.

[3liter914-6]

QUOTE (smontanaro @ Feb 19 2006, 11:48 AM)

QUOTE (3liter914-6 @ Feb 19 2006, 10:24 AM) ... the radiator is too tall and the cap extends above the slope of the fenders.  When I get the hood back on, I'm going to have some problems. Why not recore the radiator with a shorter core?

Well it's the plastic endtanks that are the problem. I could have the radiator recreated in Aluminum, but without the cap maybe? That'd be a last resort though, I think.

[alpha434]

Put a big "Z" behind the radiator. That should do it, as long as the radiaor won't fall out.

[3liter914-6]

QUOTE (alpha434 @ Feb 19 2006, 12:26 PM)

Put a big "Z" behind the radiator. That should do it, as long as the radiaor won't fall out.

Ok, now I'm going to need pictures. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif).

[3liter914-6]

QUOTE (3liter914-6 @ Feb 19 2006, 12:44 PM)

QUOTE (alpha434 @ Feb 19 2006, 12:26 PM) Put a big "Z" behind the radiator. That should do it, as long as the radiaor won't fall out. Ok, now I'm going to need pictures. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif).

Maybe this is what you're talking about, but would welding some cross bracing. Like a pair of X's inside of the U do anything?

Thanks.

[Porcharu]

What model Volvo? I have a 240 and can go out and look at mine for suggestions. I have a 351 roller cam short block sitting on a shelf for this car someday.

[bondo]

Check summit racing for aftermarket radiators. For $200-$300 you can find a nice amuminum unit that will fit. I'd hate to see you do all this chopping and then find that the stock radiator won't cool a V8 and have to swicth anyways. (aluminum radiators are MUCH more effective than brass ones)

[3liter914-6]

QUOTE (bondo @ Feb 19 2006, 03:14 PM)

Check summit racing for aftermarket radiators. For $200-$300 you can find a nice amuminum unit that will fit. I'd hate to see you do all this chopping and then find that the stock radiator won't cool a V8 and have to swicth anyways. (aluminum radiators are MUCH more effective than brass ones)

It's actually a modine radiator for a C4 corvette, so it should cool acceptably. It's a 3-row aluminum core with plastic end tanks.

[3liter914-6]

QUOTE (Porcharu @ Feb 19 2006, 02:19 PM)

What model Volvo? I have a 240 and can go out and look at mine for suggestions. I have a 351 roller cam short block sitting on a shelf for this car someday.

The windsor is doable but a tight fit, owing to the taller deck height. I'm working with a .030 over SBC. The car is a '90 240DL. I have some pics on my laptop of the crossmember, but they're not at the right angle. I'm going to go and grab some later this afternoon. I really appreciate all the input.

Here's where I'm at so far BTW:

(IMG:http://iesforums.org/engcomp.jpg)

The flat shelf in the front is the piece I need to modify.

[bondo]

QUOTE (3liter914-6 @ Feb 19 2006, 01:36 PM)

QUOTE (Porcharu @ Feb 19 2006, 02:19 PM) What model Volvo?  I have a 240 and can go out and look at mine for suggestions.  I have a 351 roller cam short block sitting on a shelf for this car someday. The windsor is doable but a tight fit, owing to the taller deck height. I'm working with a .030 over SBC. The car is a '90 240DL. I have some pics on my laptop of the crossmember, but they're not at the right angle. I'm going to go and grab some later this afternoon. I really appreciate all the input. Here's where I'm at so far BTW: (IMG:http://iesforums.org/engcomp.jpg) The flat shelf in the front is the piece I need to modify.

Is that an LT1 with a belt driven water pump? (looks like an LT1 intake manifold/throttle body)

[neo914-6]

I would modify the body as a last resource. I agree with Royce in finding a radiator to fit perfectly so when you replace it you won't need something too custom.

If your commited to this radiator and it's just the filler cap, try to seal it (rubber plug, epoxy, or cut the filler spout and plastic weld it.) Then add a filler tee with cap inline on the hose where it clears.

[Porcharu]

I looked at my car a few minutes ago. I wouldn't cut up that crossmember and modify it. I would get a radiator that fits or just cut the whole thing out and replace it with some rectangular tubing - it's all nice and flat in that area and should be easy to do.

[alpha434]

Can you cut the whole piece out and weld it in a lower position? An "X" or a "Z" set of cross bars right in front of the engine should be more then enough to keep the chassis from twisting.



And everyone else should aknowledge that he WANTS to do this, and even if it seems unreasonable to one of us, or all of us; he's asking for help on HOW not IF. Right? Sorry. I'm defensive on the subject. Ti rods and all.
(IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)

[3liter914-6]

QUOTE (alpha434 @ Feb 19 2006, 05:47 PM)

Can you cut the whole piece out and weld it in a lower position? An "X" or a "Z" set of cross bars right in front of the engine should be more then enough to keep the chassis from twisting. he's asking for help on HOW not IF. Right? Sorry. I'm defensive on the subject. Ti rods and all. (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)

Right. I appreciate everyone's advice, I may end up having to have the radiator modified--but ideally I'd prefer to make this one fit. I know if works from a cooling standpoint. This is going to be a daily driver, and I rack up a ton of miles. It'd be nice to have a off-the-shelf radiator so that I can just slap it in. I'm not really sure how I'd go about finding a radiator with similar dimensions W/O a cap. Here's the relevant measurements of the rad I'm suing:
[img]https://shell7.tdl.com/~jags/Pages/images/Volvo-V8-Radiator.gif[img]

The picture I posted earlier was a little on the old side, unfortunately I'm a little more commited to modifying the x-member than it let on. Here's where I'm at as of Friday:
(IMG:http://iesforums.org/crossmember.jpg)

I've already drilled out the spotwelds, and junked the 18ga. shelf. Now I can replace the piece, but it'd probably take just as much work as properly modifying the xmember (assuming it's possible).

Would something like this, in addition to adding a heavier gauge shelf at the top of the U be of any benefit?

(IMG:http://iesforums.org/xmember.jpg)

Thanks!

[3liter914-6]

QUOTE (alpha434 @ Feb 19 2006, 05:47 PM)

Can you cut the whole piece out and weld it in a lower position? An "X" or a "Z" set of cross bars right in front of the engine should be more then enough to keep the chassis from twisting.

I'll have to check it out and see if there's room.

[3liter914-6]

QUOTE (bondo @ Feb 19 2006, 03:45 PM)

Is that an LT1 with a belt driven water pump? (looks like an LT1 intake manifold/throttle body)

It's actually an L98 block. I need to run EFI for emissions, but it's got AFR heads and a few other goodies that would be crippled by the TPI, so I modified an LT1 intake to fit. Management is via MSnS.

[MecGen]

Hey Man

Let start by saying thumbs up on the choice of conversion (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) I have always been a fan of Volvo V8 (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)

That Xmember does look salvagable (sp). and the cross bracing would help, but not as much as we would hope. It would only be affective in one dirrection, and the V8 pulls in a twisty dirrection. I am "fine tuning" a 400+hp G-Body, and this rad Xmember is a hot topic.

I thing you are going to have to spend some time thinking this out. You could go to a metal supplier and inquire about a 4X1/2 box tubing, change it and be done, or if you are dead set on modifying this one, I will see if I can find a pic on how my Monte is crossed brace, bet it would help... (IMG:http://www.914world.com/bbs2/html/emoticons/cool.gif)

Later

(IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)