Belly Pan Build with pics - '97 Civic

[PaleMelanesian]

watching with keen interest... looks good!

[brucepick]

Thanks guys.

I put in the middle section yesterday (Sunday) but no pics yet. It's very tight working under there. But I can tell you a bit. Correction - more than a bit - this got long!

When you start this project, make sure you have on hand your preferred healing ointment and hand lotion. I must have picked up a dozen small scratches, some more uncomfortable than others. Also be ready to replace some small drill bits. Working in those cramped quarters, it's easy to press on the drill slantwise and - - - oh, s**t!, there went another one.

The partially built belly pan is already helping fuel economy. The car was getting about 46 mpg ever since the head rebuild, with one exception where the EGR got clogged and I had to learn to deal with that. But last week (front section of pan only) I had commutes around 50 mpg, with this morning's fill at just about exactly 50 for the tank. And this morning's run, admittedly with a nice 7 mph tailwind, it got 55 mpg ! - with the recently added 2nd section to the belly pan. Coming home in the rain with a headwind varying 10-15 mph, it still got 47.5 mpg. So I consider the pan a win already. (MPGuino numbers used here)

I'm pretty sure the '97 generation's exhaust path is different from what basjoos encountered on his '92 Civic. On the '97 it runs down the middle (or close to it) till about 15" before the end of the rocker panel length, where it takes a major jog over towards the passenger side.

That info is a lead-in to the fact that I had a heck of a time molding an upside-down exhaust tunnel under the exhaust. Going straight back from the engine was pretty doable. You screw the sheet to the framing members that run lengthwise, about 6" to 10" from the pipe (the framing runs at a slight angle, not dead straight back). You form it to sag in the middle. I found a much bigger challenge dealing with the nearly right angle bend about 15" before the rear wheel well cutout. I didn't get it right, and the aluminum tunnel buzzes at startup rpms because it's touching the exhaust system. So I'm going to have to revisit that area next weekend.

Just to be sure you know, I'm using 24" aluminum flashing under the exhaust system. Otherwise, it's coroplast.

My plan is to Dremel-cut the aluminum wherever it touches the exhaust. Easy to find the places by poking the sheet. Split it like you'd split the skin of a cooked chicken - without gouging the pipe of course. Split lengthwise, and maybe also at an angle, so it can open up. Then form a small sheet of flashing to cover the new gap, and rivet it into place. It's just a few words, but I wouldn't be surprised if it takes half a day or more to make it happen.

Or I could rip it out and start that section over. But that would want a whole new sheet of coroplast, and maybe new flashing too. And a 55-mile trip to work and back in the old Volvo to get the big coroplast sheet. So I think instead, I'll mod what I built yesterday, and push it into shape.

Next time I work on the middle section I'll jack up the rear more than the front, for better access in the problem area. And I hope to take some pics too.

Back earlier in this post I described how I built the main tunnel below the exhaust. I left the flashing the full 24" width, extending a few inches beyond the car's framing runners. Then I screwed the coroplast to the framing runners, and to the underside of the rocker panels. That's all it needed, for about half the length of the run.

In the rear half of the 74" run the coroplast didn't quite reach to the frame member. Next to the frame member was a run of four (?) parallel fluid lines - probably 2 brake + fuel + return. Anyway, no drilling there! So I cut some flat 1" wide plated steel I had into about 4"-5" strips. Placed the strip against the frame member (below the flashing actually), with the long direction reaching over to the coroplast and holding it up in place. One sheet metal screw through one end of the strip, and the other end of strip presses up on the coroplast. I put in about 5-6 of those, they seem to work great.

There are a zillion little problems to solve on a project like this, and not always the same on different cars. And there are probably 20 ways to deal with each of them. When I'm laying on my back with drill in hand and the flashing or coroplast doesn't want to go where I want it - I look for the first easily workable solution I can think of, and it pretty much has to be no cost or low cost.

[BamZipPow]

Something you might want to consider is using the semi-rigid dryer ducting fer yer tunnel. They come in 3", 4", and 6" diameters.

[brucepick]

Civic was hit in rear going to work on Tues. a.m. Not too bad, and I seem to be OK - but it needs a new bumper cover. Shop should be doing the work this week.

So - because the next work on the belly pan is the rear (not built yet), which will attach to the rear bumper - that work is on hold till next weekend.

Meanwhile, I've been getting 51-52 mpg tanks, as long as I behave myself. Right now, it's better between 50-55 than it is between 65-70 mph.

[PaleMelanesian]

[euromodder]

That's a serious spike & thus a great improvement.
That valve job really seems to have helped.

[brucepick]

Accident damage fixed; got the car back this past Thurs. I only lost one weekend I could have worked on the belly pan but it was so COLD I was happy to stay inside!

Anyway, this weekend I built the third major section of the belly pan - from the end of rocker panels to the rear bumper. Took pics but they're not uploaded yet.

This was the only section where I found I needed stiffeners or framing. I used (2) 1" x 1/8" x 6' aluminum stock from hardware store. Paid about $10 each, probably would be less at Home Depot. Stiff enough to stay put, but bendable so you can make the panels curve up/down a bit to scoot under exhaust components.

[brucepick]

OK, as promised here are some pics of the continuation of the belly pan project. I'm short on time now, so I'll drop in some pics of the middle section and add notes when I'm able to come back.



http://i188.photobucket.com/albums/z...ingforward.jpg

[jedi_sol]

Keep us updated if any exhaust fumes enter into the cabin, or anything related to covering the entire exhaust pipe.

[Bill in Houston]

Great detailed write-up and pics. You are helping me to think through the details on my future pan.