Leon,

I am running twice pipes(2" each) from a header. It is cool seeing you do all this data work with the dyno. I have only dynoed my L24 once at Zcon and made 150/150 roughly with badly tuned SU's. I found that out after installing my wideband. I was running lean when I thought I was running reach, so I think the tool is a necessity for fine tuning. I am getting ready to re-dyno my car since I have cleaned up the tune on my SU's. I will be doing kind of the opposite as I will be going for timing parameters -primarily.

I can say for a FACT, you will love the sound of the duals on the L engine. I was actually attempting to make an in-car video the other day to share the sound, but it will have to take some tweeking. I can't wait to install my Mikunis and compare dyno sheets.

Keep us updated!!!

Hey Steve - get ready to put a big :classic: on your face with those Mikuni's!!

Leon,

I am running twice pipes(2" each) from a header. It is cool seeing you do all this data work with the dyno. I have only dynoed my L24 once at Zcon and made 150/150 roughly with badly tuned SU's. I found that out after installing my wideband. I was running lean when I thought I was running reach, so I think the tool is a necessity for fine tuning. I am getting ready to re-dyno my car since I have cleaned up the tune on my SU's. I will be doing kind of the opposite as I will be going for timing parameters -primarily.

I can say for a FACT, you will love the sound of the duals on the L engine. I was actually attempting to make an in-car video the other day to share the sound, but it will have to take some tweeking. I can't wait to install my Mikunis and compare dyno sheets.

Keep us updated!!!

I've followed your posts as well Steve, your duals are awesome! You and Chris have definitely helped convince me to go with duals. I'm also using 2" pipes along with 2 glasspacks per pipe. Believe me, I've just about looked up as many twice pipe videos as possible, but I haven't heard any in person yet. Your exhaust sounds great, get the wife to film a driving video!

I hope the car will be ready tomorrow. I'd also be really curious to see the differences an X-pipe makes with the duals, as I know you have an X-pipe. As far as comparing dyno results, it's really tough to do with different dynos especially if they are different types of dynos. You really want to use the same dyno every time you test so that the results are comparable.

However, we can make a valid comparison of the torque curve's shape. Basically, different length and diameter manifolds will create peaks at different rpm. These peaks are also dependent on cam specs, cylinder bore, and combustion chamber volume. If you have dyno sheets, post them up, and from there we can make comparisons of the effectiveness of different intake and exhaust manifolds, along with different cams and compression ratios.

I'll keep you guys updated.

If I ever get back to the dyno I will post up results!

I was actually using a small step ladder with the camera mounted to it in the hatch, but it needs some stability improvements.

I was hoping the X pipe would have helped the drone issue with these cars, but I don't know if it helped. It is pretty damn loud to start with-especially under load around 2300rpm.

I am also running a cheapo MSA header that has unequal lenghts, so I know affects things also.

Warning: two glass packs only will be very loud. I also have two magnaflow mufflers and it's still pretty loud

Did I mention that it sounds freakin awesome:cool:. Can't wait for them Mikunisssssss

Edited August 24, 201113 yr by madkaw

Believe me, you are really going to enjoy the Mikunis! The sound and performance is as good as it gets until I go EFI with ITBs.

It would be great to see how the X-pipe affects the torque curve, be sure to post results if/when you get them.

Repost from HybridZ on 9/10/12:
 

Dyno Testing a 260Z - Part 2

 

This is an analysis based on my dyno testing from yesterday (9-8-12).

Test Parameters

 

The reason behind testing was to baseline the Nissan Motorsports header/dual pipe exhaust against the stock manifold/single 2.5" that I baselined on page 2. Also tested was the same setup with advanced (from stock) timing, then with air cleaners removed, and finally with EDIS/Megajolt controlling ignition.

 

The settings are as follows:

 

 

• early 260Z with 1972 L24/E88 that was installed by the previous owner
• stock cam and internals
• triple 40DCOE-18 Weber carbs with K&N-style filters (no heat shield)
• Cannon long-runner manifold
• Nissan Motorsports header with crush-bent true dual 2" pipes
• Mobil1 synthetic 10W-30 in engine, Redline 75W-90 in transmission (GL-4) and differential (GL-5)
• Stock 260Z distributor or Ford EDIS run by Megajolt for ignition

 

Testing was done at Dito's Motors in South San Francisco on a Dynomite load-bearing dyno. Robert and David are great guys to work with!

 

 

Test Settings: Same as page 2, but with a Nissan Motorsport header and 2" twice pipes

 

 

 

 

 

 

Results:

 

SOLID lines are the initial baseline

DOTTED lines show the new exhaust

 

 

The new setup made a peak of 130.5lb-ft @ 3350rpm and 115.8hp @ 5600 rpm, compared to the initial baseline of 136.3lb-ft @ 4100rpm and 120.8hp @ 5150rpm.

 

Analysis

 

The results are not unexpected, the single 2.5" did better than the separate duals. It is worth to note that the Nissan Motorsport header brought the torque peak down by about 750rpm when compared to the stock manifold and 2.5 pipe setup! This is caused by the header's very long primaries. The powerband feels like a mini-V8, gobs of torque down low, but still likes to rev. However, mid-range torque took a definite hit.

Final Thoughts

 

The twice pipe system does not have a merge collector, which would give gains across the board. Integrating a merge collector can also shift and improve the torque peak. The next iteration of the engine will be jetting the carbs (more for partial throttle cruise, WOT AFR is 11-12), putting in a more aggressive cam to take advantage of the header and to let the engine breathe better at higher rpm. I'd also like to build a single-pipe system utilizing this header. Eventually, I will build up an L28 to drop in.

 

Other Notable Data (not exhaust related):

1. Advancing distributor timing gave peak gains of 2.1lb-ft (132.6lb-ft) and 4.3 hp (120.1hp)
2. Removing the dirty air cleaners gave additional gains of 3.4lb-ft (136.0lb-ft) and 4.2hp (124.3hp)
3. Using EDIS/Megajolt to tune the spark curve gave another additional 4.4lb-ft (140.4lb-ft) and 3.6hp (127.9hp)