Understanding L-Engine Exhaust

[ksbeta]

Having scoured the exhaust forum and reading up on twice-pipes, pipe diameters, etc., I'm hoping to get some insight on the Pros & Cons of a few setups, and get some advice for the new build.

I've got three setups:

1) What's currently installed on my '70

2) New setup purchased locally on Craigslist

3) What's currently installed on '71

Forgive the crude drawing, but it's a notional sketch of the three setups:

#1) Headers run into ~2" pipes until about the center of the car, where they come together into what looks like a 3" pipe for about 2 feet. They then split back into two ~2" pipes and head to twin 'resonators' at the rear of the car. This setup came with the car, I know almost nothing about it, and sounds absolutely fantastic:

Resonators:

#2) Setup purchased on Craigslist, guy had stored for awhile. Three parts: (a) Nissan P/N# 20010-N3000, twin 1.75" pipes coming from the header, combining into a single 1.75" pipe, where it attaches to ( single 1.75" pipe, through a 'resonator,' and continuing down a 1.75" pipe to © an Ansa-style exhaust. No header included here.

a:

b:

c:

#3) Setup currently on the car. Older headers, connected to what appears to be a 2.5" pipe that goes uninterrupted to the rear of the car where there's a more traditional looking muffler. I heard this setup while connected to the motor briefly (L24, light-Cam, twin Weber DGV's), and it sounded okay. Nothing to write home about.

Short clip, not too helpful:

http://www.youtube.com/watch?v=V9q7RirnZzg

- - - - - - -

So, the whole point? The '71 is getting a new L28, matted to 44phh Triples, with some camshaft work done. The exhaust that's on there currently is new from the headers-back, but since I have setup #2, I was thinking about putting it on. I'm worried the pipes are too small, but like the resonator/ansa-style combination.

Would #2 be too small for this new motor (e.g., limiting?). Is there an 'ideal' for these cars? I've never worked with exhaust before, and want to make sure this is done right. I guess I could always try and re-create the setup of the '70 (#1), but thought I'd solicit some help first.

Long Read, sorry. Thanks in advance for whatever bits of wisdom you've got.

Bill

[John Coffey]

Any of these exhausts will work on your car. #1 and #3 will give you better performance with #3 being the better choice because its significantly lighter.

[LeonV]

Any of these exhausts will work on your car. #1 and #3 will give you better performance with #3 being the better choice because its significantly lighter.

Agreed.

Performance-wise, #3 has an edge (weight & packaging) but #1 should work just as well. #2 is more restrictive and you will lose power (and torque) compared to the bigger pipes.

You can find an extensive exhaust discussion here, with both theoretical and empirical data: Exhaust Thread

That thread pertains not only to the L-series, but to most any other 2- and 4-stroke engine.

[ksbeta]

That thread is great, thank you both. I'll keep reading, cheers!

[LeonV]

Glad to help!

[madkaw]

I would stay with 1 since you said it sounds the best- who cares about the weight- really.

[ksbeta]

Steve, that exhaust is staying on the '70, but I might consider trying to get a shop to recreate it. Can't figure why they made the pipes come together for that short section, but it seems to work.

[madkaw]

There's been a ton of threads on the exhaust for these cars, but not much in hard dyno proof of the advantage of one over the other-except it's given that mandrel bends and bigger than stock is better for the performance engine.

The possible idea of the center section might have been for scavenging-loosely based on an X-pipe configuration. It might be for packaging reasons-it's really hard to tell. It might have a more profound affect on sound of your exhaust than the actual performance. I don't make light of the advice that has been given, because weight is always good to avoid. For me, the experience of driving a sports car involves a good sound. Will I get more enjoyment knowing I saved a few pounds with a lighter exhaust or a constant smile from the sound of my motor singing thru a great sounding exhaust.

I have a similiar exhaust on my car, and for me, it is one of my favoriye parts of the car. I just love the sound of this motor with duals.

http://youtu.be/NGh6urUlzcQ

http://youtu.be/yo2M0F0DCVI

[LeonV]

I've got dyno evidence and analysis in the exhaust thread linked earlier.

The dual pipes didn't perform as well as the single BUT I changed the exhaust manifold when I went to duals so it's not exactly apples-to-apples. I plan to do a single down the road and test it against the duals, keeping the manifold constant. I suppose I could also re-install the stock manifold and mate it to the current pipes...

[ksbeta]

Leon,

I've finally had time to dig through that entire HybridZ thread. I had to read it about six times to understand all the big words you guys were using, but it was definitely worth my time. How'd you go about building your twice pipe setup?

[LeonV]

Leon,

I've finally had time to dig through that entire HybridZ thread. I had to read it about six times to understand all the big words you guys were using, but it was definitely worth my time. How'd you go about building your twice pipe setup?

Glad you found it useful! Feel free to ask questions if you need clarification.

As for exhaust fabrication, that was easy.

Step 1: Install header

Step 2: Print out photos of Fairlady Z432 exhaust

Step 3: Take the photos and Z to exhaust shop of choice and toss them a few hundred bucks

I told the exhaust guy how big I wanted the pipes, what kind of mufflers to use and where, and had him put in a couple O2 sensor bungs and exhaust tips to finish it off. When I replace it, I'll be going to a single (2.5-3") with either the stock manifold or header and quieter mufflers.

[EuroDat]

Hi Leon,

Thats a really good thread on Hybridz. I have been reading it all morning (again and again). A lot of info to absorb.

Cheers

Chas