I finally got that new 3 ½” exhaust system done.

The old set up was 4” with a 4” H-pipe and Hooker aerochambers, = nice,but a bit too loud at low rpm for cruising, but I guess a 4” exhaust system aint gonna be quiet now is it. The car ran the same with the exhaust as without/uncapped (w/ 4” header extensions), meaning it slowed down 1/2tenth and 1/2mph with the exhaust, but the exhaust weights 60lbs, so the et/mph loss was from the wt. The new system is a 3 ½” setup, and similar to an X-pipe, but I built it to have some volume - around 500CID, about 8” x 18” (like David Vizard said). Then it goes into 3 ½” Magnaflow muffs (stick your arm straight thru). So the new system should flow just as good, if not better, then the old one, even tho it is a bit smaller, but a 3 ½” system is good for 750hp, so its still overkill, just the way I like it;) The good part is that the new setup is a bit quieter at low rpm (below 2500), so its nicer cruisin around town. I’m also experimenting with carpet/header wrap around the dumps/end of the pipes, to see if it helps to quiet things down some - with positive results. I’ll keep you guys up to date with that, as big cube motors need big exhaust systems to make power (same power as uncapped), and not choke the motor down. I'm gonna wrap the system with thermal wrap and stick it back up under the car, see if that makes a bit of a diff.

28_full.jpg[/img (http://memimage.cardomain.net/member_images/1/web/709000-709999/709320_28_full.jpg)]

29_full.jpg (http://memimage.cardomain.net/member_images/1/web/709000-709999/709320_29_full.jpg[/img)[/img]

Looks good.
That`s some X- pipe!!... Did you fab that up yourself ?
X-pipes really tame things down, well worth the effort.
3.5" is all you really need, I`m thinking you`ll really like the sound.

Interesting design. Looks good....keep us posted on the results.

What's your ground clearance at the closest point to the pavement?

It has about 4 1/2" ground clearance, more then the old 4" system (next to it)
which had about 3 1/2", which is a minimum when I do an exhaust system.
On the old 4" system the muffs were under the floor boards (seats) since they
exited before the rear tires makin for low ground clearance. The new system
is tucked up better, with the box being the lowest since you need driveshaft
clearance, when the suspension drops.
Sounds good, and the Magnaflows are quieter at low rpm, so its better for
cruisin. But I'm still gonna work on makin a bit quieter.
Plan on going to the track this winter and runnin it with and without the exhaust
for testing, but I still have a couple of changes to make.

Now that's my kind of exhaust system!
Was the Vizard article recent? He wrote one about 12 years ago about adding a resonant chamber after the headers....but not in an X configuration.

I'm running a full Dr. Gas 3" X system on my Nova, including tailpipes that exit behind the rear tires just like stock. I put Dynomax 12" bullets in the middle of the tail pipes to knock down the bark. It worked well. Main mufflers are Spin Tech. Measures 91dB at full song 50ft from the track. They check us......

Over the winter I plan to upgrade to a full 3.5" Dr. Gas X system. Was also going to use the big Magnaflows like you did. And include 3.5" tailpipes with the same trick I'm using now, small muffs in the middle.

The old system was 0 loss with 560hp, but probably not adequate with 700hp. Besides, building it all will be fun.

Got to try for that 9 second ET eh?

Nice work! I like it!

Ron

So, Is your box "X" chamber hollow inside? I was thinking of building something simular.

I'm going to change my exhaust too. I have 3.5 off the headers into a X with 3" out that feed into 2.5 Dyno Max super hemis, with full 2.5 tail pipes. It is very quite, which I like, but I removed the exhaust system last weekend and went .3 quicker and 5 mph quicker with a .1 slower 60ft at the 1/8 mile track. I dont want to uncap to race,but I dont want to give up .3, so a better exhaust is on my to-do list now.

Let us know how it works.

Hey kamero68,

The 2.5" stuff is killing you with that many cubes, as you already know. You are the guy with the hot wife...right? :beers:

Now,..... don't you just hate leaving 3 tenths and 5mph on the table?
I don't remember how fast your car is, but you can get where you want to be with a good system. And keep it reasonably quiet in the process. Not silent for sure, but quiet enough to not draw undue attention.
My car never seems to get looked at twice by the cops. And there are plenty here!

Despite what others seem to say, the X crossover is the way to go. It makes power over an H, and it makes the car quieter. Changes the sound for sure, but personally, I like the sound. Folks think I have a small block....until they see the numbers come up on the board.
An H, especially if the H section is long, just doesn't seem to make sense to me. The two sides won't share flow, just a pressure balance......I dunno, it's a mystery.

Dr. Gas makes a good setup. He invented the X afterall. You can use 3.5" to and through the X, and 3" out. Pick a good muffler, then maybe buy the Torque Tech 3" tailpipes. Or build your own with 3" mandrel bends. I used TA Performance 3" tailpipes, but I have no idea what they thought they ought to fit like, because I ended up modifying the heck out of them to get em on the car. The bullets in the middle that I added were after the fact.

I need to get some pictures up, but the whole system fits easy, and the exits are nearly hidden. I put a couple of these systems on Camaros, and with a bit of tweaking, they fit well.
I do have to admit that on my Nova, I removed the rear foot wells, they were rotted out, so I replaced them with flat plate, and that gives a ton of room for muffler clearance. But then, I don't have a back seat anyway. Seems even a good mod for a car with a back seat, because how often do you have passengers? The whole setup is very clean.

3 tenths and 5mph is very impressive....how much money do many folks spend to find that? And don't get there? Go for a better exhaust system....and be happy!


Ron

When you guys change exhaust configurations, are you playing with jetting between?

I found out this after swapping from a full street exhaust with a Dr. Gas X-pipe to a race setup. With the race muffler setup, the car wouldn't run the second half of the track...lean miss from 1000' on. I jetted up two sizes front and rear which helped, but still a bit lazy. Went up another two front and rear and the car continued to pick back up.

What surprised me is the car being lean with race mufflers vs X-pipe setup. My thinking originally was with the supposed improved scavenging of the X, that the open system might be rich, not lean, but that was not the case with my setup.

Anyway, my point is that you need to go through your jetting completely when swapping exhuast components.

I think my test was unconclusive between the two exhausts. The street system weighs 75 lbs total vs 9 lbs total for the race setup. I'd like to go back to the street system as I do not care for the loudness or harshness of the race mufflers. I think a true at the track swap test will have to wait till spring next season.

Rafel,

Your new setup looks real good...keep us posted on how it does on track compared to the old system.

Dog gone this 16 gauge exhaust tubing is heavy.

http://memimage.cardomain.net/member_images/1/web/709000-709999/709320_28_full.jpg
just looks like a little man waving and shouting to us:" im the man! He! look at me! im a noisy little bastard!"

LOL..... This is funny Robert!!

http://memimage.cardomain.net/member_images/1/web/709000-709999/709320_28_full.jpg
just looks like a little man waving and shouting to us:" im the man! He! look at me! im a noisy little bastard!"

And exactly "WHAT" were you "ROLLING" Robert when you came up with that one ??... that was funny really... I`m still laughing too......!!!

67RS502

Have you run the car yet?
I'm wondeing how well the new exh worked out for you.
Ron

How did you construct the resonator box? I'd like to do the same.

Yes the chamber is hollow, I wanted to make some small baffles inside, and
maybe do some kinda sound deadener, but it was enough work as is, so I just
wanted to finish it...

Kamero68
I'm surprised that you only lost 5mph with a 2 1/2" exhaust, I would have expected
7-8mph. Stick a better exhaust system on that thing. Big mph is what make
it fun on the street - its what you can really feel from a roll, like hittin it at 50mph.

Yea, I thought about stickin a basketball on top with a smiley face:)

Nope, havent run it yet, car aint ready, plus I gotta wait for good weather, its still
upper to mid 80s, at least the humidity is dropped some.
I still gotta do some things with the car to get it track ready. I cut the traction bars
off, so I need to make a new set - extended to hit under the frame connectors, about
4"-6" longer. I did stick in some new Calvert Racing split monoleafs, and relocated
the shocks (again). After I redo the T-bars the rear will be done for now. Then I still
need to pull the pan and stick a windage tray in it. Then it will be track ready, by then
it should be Jan. or Feb. and we'll have some good weather.
Other things have been keepin me busy - like my Luv truck, which I need to take to the
track this winter also, gear change (373s) and uncapping it are 2 things I need to do.

Also my new ride - the 69 chevelle I just picked up is keepin me busy, I need to have
a 200-4R built for it, do a front disc brake setup for it, and will eventually pull the 383
out of the Luv and stick it in the chevelle, this will give me an excuse to build a 400sb
for the Luv;) The camaro has kinda been on the back burner lately, but I will have it
track ready by winter time.

Todd,
No I havent done any jetting when uncapping, but with the old 4" exhaust there was
little need to I believe, since the exhaust was big enough as to not be a restriction.
Like I always say - a car should run just as good with an exhaust as uncapped, if
the exhaust is done right - this is where size does matter, especially on big motors.

RickD
I just cut a 3 1/2" pipe in half - then welded some 16"x4" flat plate on top and bottom.
The hard part was makin a directional baffle inside to direct the exhaust to each
exiting pipe smoothly.

Nice job on the exhaust. I do have a question (or two): What exactly is the "resonator box" supposed to do? What I mean is; Is it supposed to quiet the system down or increase performance? Reminds me of an "expansion chamber" used on 2 stroke engines.

I'm surprised that you only lost 5mph with a 2 1/2" exhaust, I would have expected
7-8mph. Stick a better exhaust system on that thing. Big mph is what make
it fun on the street - its what you can really feel from a roll, like hittin it at 50mph.

This was in the 1/8. I havent been able to try it in the 1/4 yet. My car picks up pretty good on the 2nd half of the track so it might still make 7 or 8 mph. It MPHs much better than it ETs, but I,m working on getting it to hook better. But, we got rained out last weekend, so no runs on the new changes yet.

Have you ran the 1/4 mile yet?
if so what has your mph been?
if not what mph in the 1/8?

67RS502,

See my post on the summit racing mufflers sight You'll find it interesting

Have you ran the 1/4 mile yet?
if so what has your mph been?
if not what mph in the 1/8?

No, have not made it out to the 1/4 track yet, we got rained out last weekend.

with exhaust ran 1.77 60ft<><><>7.56<><><>93.83

no exhaust ran 1.82 60ft<><><>7.29<><><>98.75

Then I shimmed my ssm bars and moved the battery to the trunk and went

<><><><><><> 1.71 60ft<><><>7.19<><><>98.93

Ive put some adjustable shocks on but have not had a chance to run it yet.

still thinking of making a single 3 inch exhaust with 2 spiral moroso mufflers in line...

Man...all this big exhaust talk makes me want to step up to 3" soon...

Here is my 3.5" system.

http://home.centurytel.net/40Coupe/images/misc/exhaust4.jpg

http://home.centurytel.net/40Coupe/images/misc/exhaust1.jpg