Twice Pipes

[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. (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. (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.

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?

Edited October 12, 2008 by ozconnection

[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.

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.

Edited October 14, 2008 by ZDemon

[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!

[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.