From a performance only stand point, which is going to be the better power enhancer:

3" mandrel Y, 4" pipe back.

or

Dual 3" mandrel with X pipe?


Too many factors to consider in mufflers and styles for a custom setup! I can't make up my mind!

It all depends on the motor and application. dual 3" will obviously process more volume of exhaust but that may not be necessary. You also have to consider the availability of 4" mandrel bent piping. For most trucks it's readily available off the shelf. What are you working on?

Going to throw dual exhaust on my '87 IROC with engine in the sig. Most places I've researched say that dual 3" and single 4" are about equal when it comes to flow. My concern is flow characteristics and pulsing, which I would think is used more in the dual xpipe setup rather than stuffing it all in one pipe.

I was surfing summit racing, and can't seem to find much for 4" piping so It may just be 3 period!

A 3" y-pipe won't fit in the stock location. You'll have to hang it low to fit it in there. 2.5" is the biggest you can squeeze between the pan and crossmember. Of course you can always run it across after the transmission as well...

For your setup I can't see you needing more than a single 3" or dual 2.5" pipes. Anymore and I think you'd really notice a significant loss in the lower end. If you're going to be running with cats then for sure have a dual cat setup made as well. Lots of space for it. If you really want the flow of dual 3" or a single 4" exhaust then just have cutouts made up before the cats.

At TGO you should be able to find some pics of a couple good dual setups.

You're part of the Cascade Crew no?

Oh, another, but expensive, option would be to run an oval tubing intermediate pipe to keep your ground clearance if that matters.

I've got 3" Y pipe between my pan and cross member right now, it's just not mandrel bent. The intermediate pipe I have right now, is 3". I've got a cutout on and gain 4-5 tenths in the quarter mile with the cutout open. Single 3" IS a restriction for me.


Of the research I've done, the consensus is:
300-400HP 3 1/2"Single 2 1/2" Dual
375-450HP 4"Single 3"Dual

While I am thinking I'm around the 360 mark, I'd like to leave that room to grow.


Though no one seems to state if those numbers are rearwheel or flywheel..... But my 360 is rear wheel.

Got lots of pics of routing and I've been down there many times trying to play. Just been jumping between the 4" 3" hurdles. I'm part of the Cascade Crew yep redface.gif )

Ahhh not manderal bent, no wonder you can fit it! I put a Moroso street/strip pan on when I put my new motor in which is turning out to be a big mistake. Not only did I lose some space between the pan/k-member but it's hanging about 1/2 lower as well(I needed more oil capacity tho) AND the hedman y-pipe anything but fit properly with it.

I'm still surprised the single 3" is that great a restriction! I honestly wasn't expecting that... or could it be your current muffler and/or cat(s)? I'm actually asking this now as I run the Hooker 3" catback and wasn't thinking it'd be holding me back any. Making me worry now tho!

Does anyone run oval tubing or is it hard to find?

Lastly, if you run all the piping down the passenge side do you plan on y-ing the duals back together again to go over the axle?

I asked about the crew as I spend alot of time yapping with John aka Dewey. That 305TBI he keeps working on is becoming quite impressive sounding.

The dual 3 inch has a area of 14.13 square inches and the single 4 of 12.56. So the dual 3 will flow about 12% better and should have a slight edge in performance. But I would think either would work well in your application.

Where the pipe actually parallels the cross member, its full size. My friend Mike has a Moroso pan and we are going to put dual on his also (383), I'm glad you bring up the crossmember and pan because we'd forgot about his pan!

Right now I have no cats, and the 40 series flowmaster crossflow out the back. On my previous engine which was an unbalanced smaller cammed version of this one, the cutout gave me 12HP and 14-15lb-ft on the dyno. With the cutout open I didn't notice any improvement in seat of the pants.

Quite large seat of the pants improvement with the cutout now, and the actual butterfly on the mccord powerplate seems to be smaller than 3" even.

Can't find anywhere that sells straight ovalized pipe. What about 4" pipe squished in a vice? You'd need someway to check and make sure the area is still about 7.07sq"

Thanks for the info '68! I'm glad to run the dual 3"! Gotta get that little edge, and hopefully it will sound better too!


EDIT: http://www.burnsstainless.com/OvalTubing/ovaltubing.html

Have you looked at www.spintech.com (http://www.spintech.com) ? From what I know of, they're the ones who pretty much started the whole oval pipes "business." Just a suggestion.

I've seen a spin tech oval 4" dual system (with some custom mods) on a 163mph(- note I am pretty sure thats what it was, blown 383(?) mopar) blown street car (Scott @ SD Concepts in RI), but he is making 1300+hp on a very conservative dyno. I would *think* dual 3", esp with some sort of crossover, would work fine for you. But, I have spent alot of money and my car still bites, so take what I say with a grain of salt, or a spoonful of old bay...
The 4" oval looks incredibly evil, sits very tight if you are low to the ground, and is almost obscured by the asbestos wrap on *some* parts and the kevlar tranny diaper that prays the 4L80E never explodes...
I run a dual 3" with x pipe, sounds VERY quiet compared to a true dual with the same mufflers. But I like the quiet, so... I've gotten a ton of comments on the loudness difference though. I have some older true-dual exhaust sound clips I should post for comparison later.
BTW, I test ran a pair of spin tech (tiny by small, very loud, nascar-esq, maybe 4" top to bottom, 8"? wide, 12-14" long mufflers vs my 20" case 3" offset/offset dynomax hemi super turbos and saw no difference in power.
but, do note I blow the filler out of the dynomax's every 3 years or so, but I don't like magnaflows and think the ultraflows and/or race bullets are too loud, so I will stick with replacing my aluminzed mega-mufflers with a sawzall and some jack stands when they blow out.. torque tech carries them, I'm sure they can be had for cheaper, but they are friendly folks who make sure I get what I need..

Matt

After some more research, the X pipe wont work with my setup. I'm running the pipes along the stock routing, which means both pipes down the passenger side of the car. For the X pipe to be effective it needs to be in the right spot, and the right length of pipe behind each header or the exhaust pusles could run smack into each other.

So it will be a dual 3" with H pipe, and two Hooker Aerochamber or Dynomax Ultra Flo mufflers.

Not sure which muffie yet!

Twilight- I'd go with the Dynomax Ultra Flo's. Great sound and flow and not that expensive. Check out Scott's car at http://www.sd-concepts.com/ This thing is a MONSTER! He could probably hook you up with oval pipe if you want to go that route. I would think that a single 4" pipe would be much easier, and use a cutout for the track if exhaust restriction is a concern. I had an 88 IROC-Z with Nitrous and ran a single 3" Flowmaster with a single outlet (not the restrictive crossflow) that ran pretty well for a street car. For a motor with the hardware you have listed, I would bet a 4" single would be OK, but a dual 3" might be overkill. There are plenty of much nastier motors on this site that run 2 1/2" exhaust and run great numbers (not to say your motor isn't nasty, I'm sure it is). When you run whatever you are going to use, post some pics, because I know how tight it is under that car and I'd be interested to see how it all fits.

Originally posted by caru68:
When you run whatever you are going to use, post some pics, because I know how tight it is under that car and I'd be interested to see how it all fits. I agree! I've got a '91 Z28 Camaro that I've been trying to "resurrect(sp?) for the past 5-6 years now. I still haven't made up my mind as to how I want the motor, and if it'll pass smog. I gone from wanting a daily driven 383ci:
-11-sec car, all motor
-mid to low 12sec car all motor
-mid to low 12 sec all motor, 10s with nitrous
-10 sec motor with a ProCharger
-single turbo or twin turbo running 10s

LOL, I think that's it tongue.gif The stupid thing on my part is, I don't have the money to do any of that, except maybe building a daily driven 12sec 383ci, but that'd still take a lot of saving! tongue.gif I guess it's one of those...I wish my car.... :confused: :D

It will be something similar to this:

http://mysite.verizon.net/vze84hud/duals/thirdgen1.jpg

Looks good to me! :D Since you did say "similar", what are you going to do that is different?

Use larger pipe graemlins/thumbsup.gif

Originally posted by Twilightoptics:
Use larger pipe graemlins/thumbsup.gif LOL...Sweeeeet...That'll work! ;) graemlins/thumbsup.gif :D