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Fabbing a 3" exhaust-s130-pics and ??'s


madkaw

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Well I am finally getting around to fabbing up the 3" exhaust for my daughter's 81 280zxt. Anyone that has done this project that wants to share some helpful hints -PLEASE chime in here:)

I am planning on a 2&1/2" downpipe transitioning right into 3" the rest the way back. I have purchased 2 bungs so I can reinstall the O2 and later installal a wide band. I do not plan on running a cat. I purchased my mandrel stuff at http://www.mandrel-bends.com/catalog/. They seemed to have the best pricing and a sweet transition piece. I am using all 16 guage aluminized to a dynomax 3" inlet to twin 2.5's.

I have started the project-starting from the rear. I think the "over the hump" part around the diff will be the most difficult. Infact, my first ? is the clearance in that area. I tried to take level pics to show how the pipe hangs around the diff area. The bend is maybe one inch below the lowest point-being the sway bar---do you think I have this up tight enough? I am worried about getting to close around the CV.

I am planning on using 2 exhaust band clamps(butt type) to make the exhaust removable as needed. One band clamp will be near the front,probably right after the down pipe and the other will be wherever I have another set of factory pipe ends that I know will butt up squarely-probably around the diff somewhere.

It looks like I will be able to use all of the original hangar hardware-atleast the rubber hangar parts are still good and I can modifly off of that.

 

Any comments on the band clamps? I know the V style are better, but these are 8$ a piece. I used them on my duals for my 240 and they tightened up nicely, but I have no actual run time on them.

 

I need to find some exhaust tips for the muffler. I was hoping to find some cheapo chrome tips for now instead of the high dollar SS. I know I am sounding like a tight ass here, but I have spent 2k in the last 3 months on this car and my daughter is attending IU right now and you know who is footing the bill. She absolutley loves this car though and I need to get it back to her soon.

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Well I hit my first bump in the road since the flange I got does not fit the turbo. I ordered it with the pipe but the bolt pattern is square instead of rectangular like on the stock turbo. So off to the machine shop I ran and I am having one made. This will slow things up since I need to tie the front with the back part of the exhaust so I can check clearance. I'm not happy with the back half and I am going to shoot for more clearance. I almost forgot how much this is a pain in the back to do-I said almost:)

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...

I have started the project-starting from the rear. I think the "over the hump" part around the diff will be the most difficult. Infact, my first ? is the clearance in that area. I tried to take level pics to show how the pipe hangs around the diff area. The bend is maybe one inch below the lowest point-being the sway bar---do you think I have this up tight enough? I am worried about getting to close around the CV.

....

It looks like I will be able to use all of the original hangar hardware-atleast the rubber hangar parts are still good and I can modifly off of that.

 

Any comments on the band clamps? I know the V style are better, but these are 8$ a piece. I used them on my duals for my 240 and they tightened up nicely, but I have no actual run time on them.

 

I need to find some exhaust tips for the muffler. I was hoping to find some cheapo chrome tips for now instead of the high dollar SS...

 

Hi Madkaw, I did a 3" on my ZXT http://forums.hybridz.org/showthread.php?t=124360&page=2

 

EXa_6.JPG

 

I used six(?) v-band clamps so you can easily take it apart. Those were ~$35 each.

 

I welded 38 pieces together, counting all the brackets :mrgreen: Then I ground down all the welds and wrapped the pieces in Thermo-Tech and coated with their 2000F paint.

 

You can see where it goes up and over the rear crossmember, then the 45 next to the muffler nearly touches the CV boot at full droop. Under compression the boot is out of the way.

 

I got my dual 4" SS tip for ~$80 from my friend that owns a muffler shop.

 

Hope this helps, -hughdogz

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I Have been following your thread on the members projects and you do nice work. I went with just 2 disconnect points using the band clamps. I'm going the cheaper route with two 8$ clamps. Now I need to come up with the flange for the turbo since the one I ordered is incorrect.

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  • 2 weeks later...

Well after hours on my back and a lot of cursing(wasn't really that bad) I got the exhaust done. I had the flange made by a local machine shop out of 3/8" steel. Nothing fancy, just a rectangular flange with 5 holes punched in it-40$.

I managed to utilize the 2 band clamps to have 2 seperation points. Of course the use of band clamps meant that the ends had to butt up square. Getting it all the come togther was the hard part. I had to remake the joints on the downpipe twice.

My welds aren't the best, but they should hold just find.

After driving the car I am a true believer of the added HP from this upgrade. Definite improvement all the way around. I actually timed the car before changing the exhaust. I did some "passing gear" runs timing the car from 50-70mph. Now this car is an automatic, so I let the car downshift on its own.

Before 3" 50mph-70mph 6.5 seconds

after 3" 50mph -70mph 4.9 seconds

 

I think that is very respectable improvement for the little investment in time and money, especially since I needed a new exhaust anyway.

The exhaust tips were chaepies from autozone.

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It sounds deep and throaty and just better all the way around. My daughter even liked the way it sounded-of course she was just glad to get her car back:) I am still really impressed by the bang for your buck with this improvement-especially since I had to do the job anyway.

Now I need to start shopping around for an intercooler setup.

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