True dual straight pipe?

*Broaner* · 06-01-2005, 11:09 AM

Well, this may sound odd to some of you and possibly could be quite a bad idea. I'd like your opinions. I'm currently in the process of making a VQ 240. That isn't the point of this thread. Recently I had the pleasure of starting the VQ in my Max for the last time. This was right before I pulled the tranny. I had the y-pipe off. The experience was very pleasant. Open headers were much quieter than open y-pipe. This has brought me to several hypothesi and ideas. First, I'm thinking that a true dual exhaust setup is much quieter. Second, I'm thinking a true dual is much more refined sounding. I'm think of running and wondering if straight piped(AKA: non muffled true dual) will be rediculously loud. When I started it in the driveway and did some reving and low speed driving it sounded really good. Certainly quieter than it was with open Y.

What do you guys think this will sound like? I know I'll be able to test it for a while on just open headers but I don't want to have to wait two weeks if its rediculous. Also, I'm thinking that the actual manifold may be doing some muffling. Since the Z manifold flows more is it going to do less muffling?

With all that said, is there a downside(power wise) in going with true dual? I often hear of domestic people preaching about x-pipes. What is the purpose of those?

*95CustomMaxima* · 06-01-2005, 12:17 PM

X pipes balance the exhaust gases between the two pipes, making better power. If you decide not to run an X pipe, the exhaust is going to crackle and pop and sound pretty horrid. Alot of company's use an H pipe on their cars exhaust system (Mustang, Corvette etc..) vs. the X pipe to keep production costs down, thats why you hear alot of domestics switching to X pipes (better flow and nicer sound). The H pipe just connect the two pipe via a horizontal pipe to balance the exhaust and the X pipes flows both in smoothly, being an X not a horizontal pipe(H).

-Nick

**Kevlo911** · 06-01-2005, 12:26 PM

Do it, it will prob sound pretty nice using the Xpipe and all. 1.5in-2in pipeing.

*Terran* · 06-01-2005, 12:45 PM

wouldn't you want 1.25 maximum since each pipe would be flowing half what our exhaust is and 2.5 is the max before an NA 3.0 will lose power?

eckohb · 06-01-2005, 12:52 PM

who says he's staying N/A?

*Terran* · 06-01-2005, 01:01 PM

Quote:

Originally Posted by eckohb

he says he's staying N/A?

I suppose

eckohb · 06-01-2005, 01:03 PM

hehehe, broaners car will be crazy fast.

*96sleeper* · 06-01-2005, 02:12 PM

Quote:

Originally Posted by Terran

wouldn't you want 1.25 maximum since each pipe would be flowing half what our exhaust is and 2.5 is the max before an NA 3.0 will lose power?

Deosn't work like that, use the area equation for a circle. A=PiR^2

2.5 inch pipe
pi(1.25)^2= 4.909

1.25 inch pipe x 2
pi(0.625)^2*2= 2.454

two 1.75 inch pipes would be closest to one 2.5 inch pipe.

.

*japmaxSE* · 06-01-2005, 03:41 PM

Damn you beat me to it I was also thinking of the same thing true dual exhaust when I was doing my swap. hmmmm..

*Broaner* · 06-02-2005, 11:15 AM

Thanks for the thoughts guys. I'm worried about how I'd run an X-pipe. I'd have to put it after the tranny since the Z33 tranny is so fat. And then I'm going to run out of space as I'm going to be using like a 3 foot driveshaft.

Yeah, this car will only be NA for about three months. Once the swap is done I'm going to focus on suspension then its 8lbs for me and eventually upping the boost I'm sure. All I need to get the blower on is $300 worth of fuel stuff.

I think I'm going to order these mufflers. My goal is to get close to 300WHP on the 3.3" pulley. So the 2" muffs should match pretty well. The dual 2.25" will be way too big for the few NA months. It'll dog like no other. Or maybe I'll just get it running and see how loud it is then match the muffs acordingly.

3 inch single
=(3.14)(1.5^2)
=7.065

2" dual
=2(3.14)(1^2)
=6.28

2.25" dual
=2(3.14)(1.125^2)
=7.95

Quote:

Originally Posted by eckohb

hehehe, broaners car will be crazy fast.

Hehe... I worked out the power/weight. Current race weight is 2300lbs. Supposing 350 flywheel HP It'll be in the 6.6lbs/hp range. That should be fun with a close ratio 6Spd.

***Jeff92se*** · 06-02-2005, 11:20 AM

Duals might be interesting. But the purpose of x-h pipes are for balancing (yes) but to help torque (ie.. scavenging from each side). I don't know if duals without a h/x pipe would sound all that great. (ie.. two little 3 cylinder engines haha). We all know how stupid 4 banger sound on straight piple. I guess imagine a Geo Metro with a straight pipe. haha. So if you go duals, DEFINATELY run a x/h to help.

*SPiG* · 06-02-2005, 11:56 AM

Magnaflows are really loud when used by themselves. They are also very raspy. Great flow but very little noise reduction. I would only use them as a resonator.

*Broaner* · 06-02-2005, 12:08 PM

Quote:

Originally Posted by h2kSPiG

Magnaflows are really loud when used by themselves. They are also very raspy. Great flow but very little noise reduction. I would only use them as a resonator.

I have a monster Magnaflow now(3"IDx6"CaseODx30" length). I have no resonator and no cat. The volume is loud but that is expected. I'm very happy with it. I can live with volume but I cannot live with rasp. There was absolutely no rasp in gear on my system. Local people or people that were at the GLD meet will testify to that. Thats why I'm so stuck on Magna as my next exhaust setup.