289FIA undercar high-performance exhaust
 

As my build inches closer to reality, some practical considerations need to be addressed. During the summer, I plan to park the car in an underground garage near my apartment; off-season, it will be at a friend's house with a steeply downhill driveway. Looking at the ground clearance of the side-pipes, I think they are going to get massively hung-up upon entrance and exit at both locations. Pragmatism may force me to switch to an undercar exhaust, exiting in front of the rear wheels. What experience does anyone have with high-performance pipes and mufflers that will fit snugly under a 289???

Thanks!

Jeff

You will only be able to get 2.25" pipes under the car with some 2.5" mufflers -- similar ground clearance issues apply --

I'm doing an undercar exhaust on a 289 right now. It has the CR drag headers. I cut off the two 2" elbows turning out and replaced them with 1 3/4 going back as that is all you can fit between frame rails and footboxes. Then a 2 into 1 with a 2" exhaust. I'd link to CR but there catalog isn't working right now. I've used Thrush oval mufflers from Summit as they are very flat and barely hang below the frame rail at only 3 1/4 deep. http://www.summitracing.com/parts/WLK-17704/ The 2" is more than adequate exhaust with twin pipes on a small block. The centre in muffler gets the 2" under the cowl hoop just outside the gusset and it's slightly above the frame. It's coming together really well right now and I can't wait to hear what it sounds like. I'll post some pics when I'm back on the shop computer.

Nick is a master, he knows the game and does great work.

Shhhh BTW: it's an original 289...

Hey Jeff,
I really don't see how any under car exhaust other than side pipes will fit under a ERA FIA car. Especially if you use their jag based set up. Now, I have seen it done and you have to sacrifice some power to do so AND I really don't like seeing the muffler from the side. It is quite visible and rather ugly. I choose to "notch" my supports to get the side pipes a little closer to the body/ frame. The previous exhaust when done was only 2 1/2" off the ground and scraped over everything and anything. I do like Jim Holdens new car but I haven't seen how they did the exhaust. I do believe ERA has changed the chassis brackets under neath since my car to accommodate the exhaust better. I ended up making mine from 3" tubing and loback inserts in the pipes. I had to modify my headers and it took a while but the end result was a very tight fit. I did notice in your pics a shot of the drivers door. What are those new round tubing pieces in the interior? Keep up the good work.

Hey Jeff, I can try and round up some photos if you need. My exhaust is no lower than my frame, so unless the frame doesn't scrub I'm OK. I personally don't like the how a lot of the FIA's out there side pipes where done. They have way to much space between the body and the pipes. Thanks, Matt.

I ran under car exhaust on my Midstates but i ran it outside the frame and it seems to work well and have not had any clearence problems( so far).look in my photos.

I'd love to see more pics, especially of the finished (I hope!) build. What's in the gallery is a little dated.

Jeff

Those are intended to be additional protection in the event of a side impact...

Jeff,

When I click on the camera to look in your gallery, I don't see any photos ... am I looking in the right place? Thanks.

- Tim

Jeff / Matt,

Following this with interest ... looking for a similar setup on my FIA, which should be underway soon. Will be very interested to see what you guys come up with in terms of pipe size and muffler selection.

What I am looking for is essentially the under-car exhaust, but that exits in front of the rear wheel.

These may be questions for Bob at ERA, but how close can the exhaust and mufflers be to the body? Is there heat shielding that goes on the underside of the car?

Thanks.


- Tim

No; that picture is in my posting in the "For Sale" folder.

Jeff

I've been looking at mufflers for my SBF swap into my Austin-Healey, which has minimal ground clearance. Saw these on spintechmufflers.com:

Cruiser Street- 7000 (Round) List Price: $130.50
Online Price: $129.50

Inlet Size: 2 1/4 Inch Center
Outlet Size: 2 1/4 Inch Center
Case Size: 2 1/4 X 9 X 16

Description:
You asked for it - you got it. The lowest profile muffler available today. Only 2 1/4 inches thick. An excellent muffler for those who like to cruise. Excellent flow rates,great sound and plenty of ground clearance. Description


Might be of use to you guys.

Hey Tim/ Jeff,
I will try and get some better pics tomorrow. Plus I have to get my wife to re size the photo's for me, I know I know! I've noticed from other FIA owners pics that the side supports for the chassis have a notch in them some what (on the newer chassis). Mine is an old chassis and they have made some good improvements. Basically what I did was positioned where I wanted my side pipes and used a 4" hole saw and cut through the support. Now just wait a minute Bob, I did box the support back together and welded it all tight. I used tight mandrel bent elbows and header clamps that are really pretty trick. They have two 90 degree bends and then a single clamp that tightens them up together. I used a rubber mounted support studs two per side (one for vertical and one for horizontal loads). They where actually used on Harley Davidson motor cycles to rubber mount the gas tanks! I of course used some over sized washers to help disperse and heat build up. They are at the back so they should be fine. The over all package is A LOT tighter to the floor and bottom of the body. When you look from the side they are pretty much did even with the frame rail so if I scrap I'm hitting other stuff too. I just didn't care for the look of a few others, too close to the ground. Now it does get really tight around the brake box area! I mean really tight but it's more than fixable. Again, pics are worth more than words so I will try and posts some. Thanks, Matt.


There are a few pics in my gallery but I really stink at this computer stuff!

How about Dr. Gas Oval tubing???

https://www.drgas.net/catalog.php?catid=3