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

[3liter914-6]

QUOTE (maf914 @ Feb 21 2006, 03:34 PM)

SBC in a Volvo. That's cool! I wish those slow lame-ass Volvos driving in the left hand lane while we are going in to work in the morning had small blocks! (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

Thanks. I'm pretty excited about it, as once the radiator issue is sorted, it's just a little bit of plumbing, and then mounting the MS and attaching the wiring harness to the relay board. Oh, and tuning and exhaust. With the parts I used in the build, I'm hoping for 430hp. I can live with less, but I'd be disappointed if it's not at least 400. 400hp in a 3000lb Volvo, should make for one quick brick.

My goal for the project is to triple the hp while maintaing an visually stock vehicle with stock drivability. The real icing on the cake is going to be doing all this and actually increasing fuel economy. With some good tuning, efficient heads, and the 2 overdrives of the T56 I'm pretty sure I can pull it off. Despite the tiny, understressed I4 the car originally came equipped with, the best I could every pull off was 25mpg, and I'm really good with squeezing out the MPGs.