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I am in the process of putting in a new engine, hopefully this weekend. I had some time to work on the exhaust by putting in a 3" collector and exhaust pipe to the muffler. It can be done though it is tight. I have seen Pat Miacal's system and he has a small dimple in the system where it crosses the sway bar. Hopefully I have eliminated it. I also am putting a flange connection right before the muffler so that I can attach a straight pipe for track days. I'm learning to weld so its functional.

If someone is going to do this they will need 2 180 U bends and a couple of feet of straight pipe. I don't think you could go more than 3" OD. The other alternative is to use some oval tubing under the axle. Just a bit more complicated to do.

Mark
I'm pretty sure I have the big bore headers, what is the primary size on these headers? I'm thinking about just having an exhaust fabricator cutoff the collector and re-work on a bigger collector and then run the 3" from there instead buying another header. This may very well be my best and most affordable option. I'm pretty sure I would gain a significant amount of power as the motor sits now and would see even more after I did the cam swap. But with all that would need to be done I may have to pull the motor making that a better winter project.

Here is another article I found on gutting the Ansa exhaust, so I will probably do this and have the 3 inch piple mated to it if I can cutout the old pipe.

http://www.spacecitypanteras.c..._the_GTS_Exhaust.htm
Last edited by hustler
If you are going to go through the trouble of modifying your headers to add a 3" collector, I would also add 3" ball flanges instead of the standard 3-bolt flange for a leak-free seal without a gasket that blows out. The other advantage is you can reposition the exhaust pipe to center them on the cutout easily. I never liked the Hall Big Bore exhaust because what they called the 'Venturi Effect' collectors which choked their 2.5" collector to a 2" flange. Look at them and you'll see what I mean.

Here's a pic of the ball flange. These are from Flowmaster.



FYI - I have considered 'engineering' a tuned exhaust myself and I gave up after reading up on the theories and applications from better men than I. The best read I have had on exhaust theory were those written by David Vizard.

I made up an exhaust for fun using Flowmaster 40 mufflers (3" single in/ 3" dual out) and they sound great with solid cams. I can really feel them working when I am going through the gears. But, they are loud. I only put them on when I go to the local cruise ins. Attached are pictures of the Flowmasters on my car:




Good luck with your build.
I went home for lunch and did some measuring. The primaries are 1 3/4" and I think you are right as it tapers from a 2.5 into a 2.25" pipe back to the mufflers. I've also decided that hacking into the stock muffler and doing all that work will be for little gains. Thinking about getting the mufflers from PIM with the 2.5 inlet and cutting it out to accept a 3" inlet. The tips are 3.xx so that should provide way better flow than th stock units.

I'm just not excited about doing a mechanical or electric cutout, they go south quickly and I don't want to wire some goofy setup or run a cable for them.

I like those flowmasters, always have had a great sound to them, but I think personally I want the polished stainless look since my car still has the chromed bumperettes. Think they would compliment the car.
here's two pictures of 180s that exit traditionally. I personally like the ansa look and thought this might be something to do, maybe capturing the best of both worlds. I would think that with that setup you'd be able to keep the A/C too. I do also like the hexagon Lambo exhaust too, decisions decisions.
http://p400sv.at.infoseek.co.jp/GT5.13-06.jpg
and
http://p400sv.at.infoseek.co.jp/GT5.13-04.jpg
and
http://p400sv.at.infoseek.co.jp/GT5.19-06.jpg
A little update, I got a call back about doing the Pantera exhaust from a guy whos done a few local Panteras and he seemed doubtful a 3" exhaust could be routed through the factory path.

As far as the camshaft, I plan on doing either a hydro or solid roller swap this winter since I'll probably be pulling the motor to change out the springs etc.
A 2.5" exhaust pipe will route fine thru the factory path but requires you flip the halfshafts to gain some clearance. A 3" pipe will definitely have a clearance problem unless you use 3" oval pipes inbetween the halfshafts and lower A-arms. Even then, you need to check your clearances to verify interference with the rear suspension travel.

Have fun


Aloha
I talked to the guy this afternoon and he was willing to take a look at it to see what we could do. I may just take it down there and talk about either getting an oval piece, but the problem is I need to get the lowering springs on before we do anything because that will change how high the a-arm sits in relation to the halfshafts as well.

Does anyone have any real world gains doing back to back dyno testing going from a 2.25 or 2.50 to 3" exhaust with a cleveland? Chassis or Engine Dyno?
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