Twice Pipes

[mikewags]

What should I know about 3 to 2 header/twice pipes installation? Would I be better off taking this setup to my muffler guy, or doing this myself. I don't want to take on something that has been known to be a b*tch, and get stuck or caught up in a long drawn out exhaust overhaul.

Thanks guys!

[sblake01]

'Better off' is a relative term. For me, now keep in mind that this is not my car or my situation but if it were, 'better off' would mean putting everything back in the box and sending it back for a refund. I just wouldn't got through all of the hassle and expense involved to put dual pipes on a single bank engine. I could do it; I have welders, both gas and mig and tubing benders, expanders, etc. but just wouldn't have the desire. That being said, if you are set on doing this, having read what others have gone through to accomplish this installation, I'd take it to a good muffler shop.

[mikewags]

I haven't bought anything yet, i'm actually still deciding whether or not it's worth getting into.

Headers + Twice Pipes + Exhaust work = 400 - 500$.

Stephen, I appreciate your opinion on the subject. I'm aware that you think the dual exhaust setup is a complete waste of time and money; especially for the straight 6; but I'm curious why I have had several people telling me that the performance/sound gain would be worth doing this.

Are these people full of it, or just don't know what they are talking about?

Ideally, someone here that has a dual/twice pipe setup can give me some feedback on any performance gains/general review of doing this. I'm not about doing the dual exhaust, if it's just going to make a "sweeter sound" - To me that doesn't justify removing stock components/spending the money to get this done.

Thanks!

[Seppi72]

My title is a variant on the line that Ronald Reagan used about the Soviet Union; i.e., "Trust, but verify." It is probably the only thing on which RWR and I have ever agreed, but right is right, and he was right on that.

IMO, anyone who is selling some bolt-on performance part should be asked to "show me the numbers." (I guess I'm into paraphrasing today.:geek:) What I mean is that for about $200 they could get dyno runs of the car before and after the bolt-on installation and have them verified, witnessed, notarized and available for inspection. If a business isn't willing to invest that much money in a commercial product on which they expect to make many, many times that much in profits, you can pretty much write the mod off as crap.:sick:

[~KnuckleDuster~]

I installed the twice pipes set-up in my driveway. It's soposed to be easier to install in the 240's though. I did notice a bump in performance which I tested on my butt dyno. As for the sound its amazing. The sound alone is worth it in my opinion. Heres a vid: Please excuse the crap sound quality

<embed src="http://videos.streetfire.net/vidiac.swf" FlashVars="video=9d9c723a-f9e7-47b5-8b2c-9ae60179c8ab" quality="high" allowFullScreen="true" bgcolor="#ffffff" width="428" height="352" name="ePlayer" align="middle" allowScriptAccess="sameDomain" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer"></embed><br /><a href="http://videos.streetfire.net/video/Twice-Pipes-on-the-Z_174052.htm">Installed MSA Twice Pipes onto the 71 240z</a>

[Cutlass372]

Anyone else have any info on this system or even one for sale? I am also interested in this and looking for more opinions.

[Arne]

I can't see any reason that twice pipes would be better for performance than a single exhaust of adequate size tubing. Remember that twice pipes were used back in the '70s as "THE" performance choice. Why dual pipes? Because the large diameter pipes that we all use routinely these days were very hard to find. Two inch pipes were the largest your local muffler shop had available. These days we have larger 2.5" pipes available, which are much easier to work with, and have vastly better tuning ability.

[ozconnection]

Arne, I have reseached this topic myself for quite a while now.

What I have found is it's not just the diameter of the exhaust pipe that's important.

Exhaust system tuning can reap substancial power and torque dividends if done correctly. There are a number of textbooks that promote the idea of dividing the exhaust system into two separate banks for a six cylinder engine with a firing order of 1,5,3,6,2,4. Just like the intake side of things where there are dual plane, single plane, tunnel ram, individual runner etc type configurations, there should be insight given to these possibilities where the exhaust is concerned. There's lots of 'theory' on the topic. May I suggest you grab a book like "Scientific design of Exhaust and Intake Systems" by Smith and Morrison and have a litte read.

I haven't done this yet on my car, but I've already made the promise in another thread that as soon as my system needs replacement, this is the path I'll be taking.

[Nigel1943]

The Datsun works rally team in the 70's MUST have used dual pipes for a reason and it can't have been because they could'nt get hold of 2 1/2" tube:)

[Arne]

OK, I should have said, "I can't see any reason that twice pipes would be better for performance on a mostly stock street driven car than a single exhaust of adequate size tubing."

I'll concede that there are flow characteristics that may be advantageous if properly developed. I also strongly suspect that most exhaust shops do not have the knowledge to take advantage of this.

[darkstarrocker]

There was a post with pictures of an instal over in the tech section at zcar.com a couple of days ago.

http://www.zcar.com/forums/read/1/1975877/1975877#msg-1975877

[ozconnection]

I'll concede that there are flow characteristics that may be advantageous if properly developed. I also strongly suspect that most exhaust shops do not have the knowledge to take advantage of this.

I guess that's the value of forums like this. With our collective and shared knowledge we could probably go to the exhaust shop and tell them what we wanted on our cars.

Knowledge is power:geek:

[ozconnection]

There was a post with pictures of an instal over in the tech section at zcar.com a couple of days ago.

http://www.zcar.com/forums/read/1/1975877/1975877#msg-1975877

There was a comment by one of the posters that all the pipes merged into one pipe and then split again into two pipes and this was a good thing. Wrong!! This is pointless and isn't a true twice pipes setup. The interaction of the exhaust pulses at this point will negate any advantage the system could have provided the engine with.

Group cylinders 1,2,3 and 4,5,6 together and keep them separate all the way through...no interconnecting pipes or any form of merging. Check out the attachment to see what I'm talking about.

[geezer]

I have never heard of anyone doing any dyno testing to determine any appreciable power gains, one way or the other. I don't have a leg to stand on as far as proof, but I don't see how going from 2 into 1 and back into 2 would be any different than using an H or X pipe on a V8 to equalize pressure. Granted, with a V8 the pressures are equalized between banks and not just cylinders, but I can't see how it would be detrimental. It would seem to serve as a means to even out wave pulses would it not? I am planning on using a true twice pipe system also, but only for the sound I hope to produce and the nostalgic value.

[ozconnection]

I have never heard of anyone doing any dyno testing to determine any appreciable power gains, one way or the other. I don't have a leg to stand on as far as proof, but I don't see how going from 2 into 1 and back into 2 would be any different than using an H or X pipe on a V8 to equalize pressure. Granted, with a V8 the pressures are equalized between banks and not just cylinders, but I can't see how it would be detrimental. It would seem to serve as a means to even out wave pulses would it not? I am planning on using a true twice pipe system also, but only for the sound I hope to produce and the nostalgic value.

Unfortunately nor do I have any 'proof' with the L series as yet. As soon as my current single system expires, I'll be doing some dyno testing to establish differences.

V8 engines are a different kettle of fish. Different number of cylinders, different firing order and therefore work to a different 'tune' to our sixes.
We cannot compare what works on an eight to what works with our engines however much we try.

I'm curious, why don't you throw your machine on the dyno now and after the pipe change? Give us all a taste of things to come for those who are going to do this to there cars in the future. :D (and post an "on the dyno" sound clip too, please!)

[geezer]

I'm curious, why don't you throw your machine on the dyno now and after the pipe change? Give us all a taste of things to come for those who are going to do this to there cars in the future. :D (and post an "on the dyno" sound clip too, please!)

Unfortunately I won't be able to do the before & after dyno, as the car is already being built from the ground up. The after will be of little help to anyone without a point of comparison, but I will one day post a sound clip of it here. There does seem to be an increased interest in twice pipes lately.

I have most of an original twice pipe system that I am using to duplicate a new one. This is the closest pre-muffler I have found so far. I plan to use only these stacked megaphones out back. The header is a Trust. Notice how crude the bends are in the factory pipes. My new mandrel bent pipes will be somewhat of an improvement.

[ozconnection]

Yes please Ron, you must post the sound of your machine here once it's done....it looks superb. :cool:

I'm wondering if there is flow mixing (ie completely separated chambers or not) with that magnaflow pre-muffler you have? Do you know, can you tell?

[Cutlass372]

Anyone have any pictures or videos of a modified twice pipe system (True 2 pipes all the way back)? I would love to hear/see it.

[geezer]

I'm wondering if there is flow mixing (ie completely separated chambers or not) with that magnaflow pre-muffler you have? Do you know, can you tell?

The Magnaflow 11378 is the best replacement I have found so far, but I have not bought one yet, just in case something better suited is found. I doubt the chambers are totally isolated, as it isn't stated in the product description. With a straight thru design, and the limited expansion of the exhaust within the muffler I don't imagine there would be much flow mixing or pulse shaping taking place anyhow. I understand your reasoning, running two totally isolated branches all the way and am curious to know if there is a benefit doing so, but it really isn't important for my intended use. I'm going to connect my leaf blower to the OEM twice pipes to see if the pre-muffler has isolated chambers or not.

Brand: MagnaFlow
Product Line: MagnaFlow Performance Mufflers
Part Type: Mufflers
Part Number: MPE-11378
Case Shape: Oval
Inlet Diameter (in): 2.250 in.
Inlet Quantity: Dual
Inlet Location: Center
Outlet Diameter (in): 2.250 in.
Outlet Quantity: Dual
Outlet Location: Center
Internal Construction: Perforated stainless tube with packing
Muffler Material: Stainless steel
Muffler Finish: Natural
Case Length (in): 11.000 in.
Overall Length (in): 17.000 in.
Thickness (in): 4.000 in.
Width (in): 9.000 in.
Outlet Style: Standard, without tip
Quantity: Sold individually.

Muffler, Dual 2.25 in. Inlet/Dual 2.25 in. Outlet, Stainless Steel, Natural

[ozconnection]

Ron, great idea with the blower! :bulb: When do you think you'd get one of these mufflers?

A very comprehensive list of features supplied by the manufacturer. Too bad it doesn't mention what happens inside the thing!

I wouldn't mind getting one of the magnaflow mufflers myself if it is truely split. I still think that if you're going to all this trouble, you may as well do it 'properly' and get the most 'bang for your bucks!' :classic:

I will go to their website and ask them. Perhaps you could too if you wanted to. They might be more inclined to respond if there are two people asking?!

[ZDemon]

Here's a few of the vids of my old stockish 2.4L with the twice pipes.

The first vid only goes up to 3K Valves werent set and carbs werent sync'd.

The second one, I had done the valve adjustment, but i dont think I had sync'd the carbs yet.

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/Tbb9mzHPxZo&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><embed src="http://www.youtube.com/v/Tbb9mzHPxZo&hl=en&fs=1" type="application/x-shockwave-flash" allowfullscreen="true" width="425" height="344"></embed></object>

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/rZT9wXzHof0&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><embed src="http://www.youtube.com/v/rZT9wXzHof0&hl=en&fs=1" type="application/x-shockwave-flash" allowfullscreen="true" width="425" height="344"></embed></object>

I love the set up, such great sound, much better in person. If I thought i could keep the set up with a turbo, I would.

[ozconnection]

Got this from Magnaflow today. They were really quick in their response too. Thanks Magnaflow!

It's the internal workings of the 11378 muffler.

Seems to me that the two pipes are not separated but allow the mixing of gasses. What do you guys think?

I like the sound of the twice pipes ZDemon! :smoke:

[geezer]

It's the internal workings of the 11378 muffler.

Seems to me that the two pipes are not separated but allow the mixing of gasses. What do you guys think?


I expected this to be the case. Likewise, testing the OEM twice pipes with my leafblower, revealed that both thru pipes share a common expansion chamber. Without the use of magnehelic pressure gauges while under running conditions my crude test is hardly conclusive, but I would estimate there is about a 15-20% transfer rate from the pipe being supplied air to the other.

ZDemon, thanks for the videos, NICE!

[jtl260z]

I haven't bought anything yet, i'm actually still deciding whether or not it's worth getting into.

Headers + Twice Pipes + Exhaust work = 400 - 500$.

Stephen, I appreciate your opinion on the subject. I'm aware that you think the dual exhaust setup is a complete waste of time and money; especially for the straight 6; but I'm curious why I have had several people telling me that the performance/sound gain would be worth doing this.

Are these people full of it, or just don't know what they are talking about?

Ideally, someone here that has a dual/twice pipe setup can give me some feedback on any performance gains/general review of doing this. I'm not about doing the dual exhaust, if it's just going to make a "sweeter sound" - To me that doesn't justify removing stock components/spending the money to get this done.

Thanks!
I custom made my dual exhaust for about $200.00. Love the look and the sound.

[ozconnection]

I custom made my dual exhaust for about $200.00. Love the look and the sound.

Can you post a sound clip???

Cheers :classic:

[ToXIc]

hey ZDemon hearing that exhaust note made my ears cum...
its awesome...

Hey OZCONNECTION where can i get a set of the twice pipes you posted? (post # 13)

ZDemon are those the same ones you got... or do you have the MSA version that goes from 2 to 1 the 2 again?

[mikewags]

I custom made my dual exhaust for about $200.00. Love the look and the sound.

How did you get the exhaust to come out on the right side? Isn't the gas tank in the way?

[Arne]

hey ZDemon hearing that exhaust note made my ears cum...
its awesome...

Hey OZCONNECTION where can i get a set of the twice pipes you posted? (post # 13)

ZDemon are those the same ones you got... or do you have the MSA version that goes from 2 to 1 the 2 again?No longer made. I saw an NOS set of the exhaust itself (no matching headers) offered here in Oregon a short while back, but I know for certain that they sold to a guy who has the correct header to go with them.

[ToXIc]

^^^

:cry::cry::cry: i want one... doesn't anyone clone them?

[Arne]

^^^

:cry::cry::cry: i want one... doesn't anyone clone them?Nope. A user here (70z4fun) was trying to find a clone of that system for years. He gave up looking, and then recently bought the NOS system I was talking about.

[ZDemon]

hey ZDemon hearing that exhaust note made my ears cum...
its awesome...

Hey OZCONNECTION where can i get a set of the twice pipes you posted? (post # 13)

ZDemon are those the same ones you got... or do you have the MSA version that goes from 2 to 1 the 2 again?
they're the MSA, I'm probably going to eliminate the small section where it is one pipe when I put them on the '77

[JonnyRock]

ZDemon -

What did you do to fit both pipes out the rear valence? I'm getting mine installed soon, but am unsure of what to do about the fittiment at the very back. I don't think the pipes would fit vertically stacked, so I guess I'll have to have the cut-out enlarged.
Should I just have the exhaust shop do this?