JBrady

I have been planning some more mods to my LS400 and the exhaust is high on the list. The following are some points to consider and reference.

Here is a picture of the drivers side catalyst outlet including the O2 sensor.

JBrady

Y pipe to center resonator detail showing neck-down from 60mm to 50mm at inlet.

JBrady

Hand drawing of stock system parts and dimensions. This is for reference and the dotted line paths through the resonators and mufflers are not the actual paths, just to show there is substantial redirection. It is actually done with baffles, chambers and perferatored tubes.

JBrady

Drawing of suggested new system

JBrady

My current exhaust, picture of pre-mufflers without rear mufflers attached showing where the pipes exit right now.

Lvangundy

Cool Glad the pictures are up!

Your plans look well written out, although I think where the 2nd resonators are the pipes bend differently (just to be picky)

I'd like to get better shots of my exhaust system also, just to make some comparisons.

JBrady

Yeah, the drawings are just to show the components general size and layout.

JBrady

I have done some calculation on pipe size and square inch area for flow. Ideally, you want enough area so that backpressure will be kept low but not so much that flow slows and you loose flow energy.

Something else to consider, 2 smaller pipes have LESS flow capacity than the equal sq/in larger pipe. This is due to the total wall area. Wall area = surface area and there is always drag induced at the surface. Therefore, equal area with less surface area flows better. Additionally, gas flow in a tube is greatest at the center as the walls induce drag so the speed is slowest there. One large pipe has the best combination of surface area to cross section area.

Here are some pipes listed first by Outside Diameter "OD", then Inside diameter "ID" (less due to pipe wall thickness) and Cross Section Area "CSA".

50mm OD = 1.96" OD = 1.85" ID = 2.69 sq/in CSA
2.25" OD = 2.10" ID = 3.46 sq/in CSA
60mm OD = 2.36" OD = 2.21" ID = 3.83 sq/in CSA
2.50" OD = 2.35" ID = 4.34 sq/in CSA
3.00" OD = 2.85" ID = 6.38 sq/in CSA

So, the 3.00" should flow as much as 2 x 2.25" pipes.
A 2.25" pipe has 28% more area than a 50mm pipe.
A 2.50" pipe has 25% more area than a 2.25" and 61% more than a 50mm.

SilverFlare

hey, i don't know is this useful???

http://www.junction-produce.co.jp/ht...1/CELS_all.htm

u can click the last 4 four icons for hearing the sound..

here is the translation;

The all stainless steel intermediate straight pipe has become setting of volume concern.
* Because it is the same form as all genuine flanges, to step-up from of the installation, and the other companies muffler only of the straight stainless steel pipe and only the all stainless steel rear muffler of junction produce.
* The catalyst * intermediate straight stainless steel pipe, the muffler for competition please refrains the use on the general public road.

keep it up..

JBrady

Thanks Silver, I liked the sound of the 1st and last best. Of course I have no idea what I am listening to

The first sounds like a full system with resonators.

The middle two are harsher and louder...

The last just the mufflers?



The images look like both systems include a Y-pipe. If so these are the first true cat back systems I have seen. Do you have any actual pictures? It looks like each section of the system has its own price. Using the currency conversion here http://moneycentral.msn.com/investor/market/rates.asp
the Y section on the second system which looks to include a resonator would be 74,000 yen or $604 dollars. Plus shipping/handling ext. This may be resonable depending on the construction. Again, any specifics you can provide would be nice.

The second Y section with 2 resonators is 92,000 yen or $751 so that may be interesting as well. As far as final mufflers go, the ones shown are way to VIP for me. I would go with Super Turbos or something similar that are hidden but sound nice. I am not into show, just go, and deep quiet sound... like the last one.

Another observation on the diagram is the junctions. At the cat areas it shows flanges and all others look like neck downs... curiously, in one of the JIC systems pictured from the GS forum there are slight neck downs at each flange.

https://www.clublexus.com/forums/att...&postid=417830

In reading the linked Overboost article the system shown for the GS does not have neck downs.

http://www.overboost.com/pix.asp?ima...l/DSCN1051.jpg

Since the section one pictured is definitely the GS system I must guess the 1st is the LS, but for what years???

Notice that neither system is a true cat back as they both start AFTER the center resonator.

retrodrive

I have a full exhaust so I will take a pic next week when I would be putting in the new alternator.

JBrady

Good deal. What system do you have? Were the parts available seperately? How hard is it to get in the states? Please post the front Y section as detailed as possible from a couple angles or more. Thanks again.

SilverFlare

some quick shots from HyperRev magazine,

SilverFlare

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