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I will be installing a 400 SBC next year along with a 2.25" dual exhaust system on my 240Z and have a question about muffler clearance and spare tire well mods. I have read all the posts I can find about this subject but could only find mods done to the well rending it unusable for a spare tire. Has anyone installed a 280Z space saver (inflatable) spare tire and associated well in a 240Z and then installed duel mufflers to the left side of well? I started this mod the other day and looks like I should be able to gain 4" to 5" of extra clearance if I install a custom well as far to Right as possible without having to modify the fuel tank. My new well will be around 21.5" in diameter compared to the 26.5" stock well.

 

 

0c85a040.jpg

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One thing to think about (and a lot of this depends on your horsepower levels) is that a single 3" exhaust doesn't limit power as much as some think. I just finished a 3" single exhaust on a 1995 SCCA T2 Camaro 1LE and it picked up 15 whp over the dual 2.5" exhaust that was on the car. It puts down about 315 whp with a basically stock LS1.

 

One of the keys was a properly designed merge collector that brings the factory 2.25" pipes together in a 6" merge with a 12" cone going from the 2.5" collector end to the 3" exhaust piping.

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I agree John. I actually looked at doing that until I saw what it would do to my ground clearance. That half inch became quite critical for my goal for the car to be a daily driver. As it turns out, I've even scraped the 2 1/2" pipes a couple times. My car does not have lowering springs either. It is riding on the Nissan euro spec springs and the ride height actually increased an inch over the old "sprungs" when the new ones were installed. I can't imagine trying to get around if I were 1 1/2" lower.

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Hey a fellow Idahoan. Good to hear from you. I live in Idaho Falls (SE corner of state).

 

I never considered a dual inlet single outlet muffler? Wonder what the flow rate difference is compared to a dual muffler setup? I'll have to e-mail Magnaflow and ask. I was thinking of something like these sitting vertical side by side with the outlet being on the bottom so I can gain more ground clearance. 0ca59cf0.jpg

My car will be a daily driver and I need as much ground clearance as possible, which lead me more toward a dual 2.25" setup vs a 3" single. Magnaflow also makes a dual inlet - dual outlet muffler? Again concerned about decreased flow rates. I'll be running around 400hp and want something pretty mild sounding / quiet as not to attract attention. I would also would like to hear my stereo when cruising down the freeway.

 

I also plan on installing a crossover pipe behind the tranny. I like the exhaust system shown on pages 14-3 and 14-10 of the JTR manual (17th addition). Just need the clearence on the left of the spare tire well.

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My LS1 dyno'd at 311 RWHP which maths to about 365 at the flywheel - not far from your stated goals. Magnaflow recommended 2 1/2" exhaust (dual) for that HP range. The muffler is quiet at idle and not bad at cruise although I do intend to install sound deadening material in my car when I redo the interior - after I get the windshield leak fixed. It really wakes up when the throttle is punched. Keeps the car stealthy when I'm behaving myself but advertises something other than an I6 when exercised a bit.

 

Idaho Falls - nice area - lots of winding mountain roads around there - lot nicer than Pocatello. Good Z country except in the winter.

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Guest tony78_280z

Car Chemistry Header Inserts are the answer to your problems. I too wanted 2-1/4 DUAL exhaust for my 350Z the only way you'll fit that under there is with their product. Me, I just bent my pipes after the headers out behind the front tires. I don't have imissions where I live :) I love it and think it looks way cool. They claim better performance over turbo mufflers and glass packs. Even better flow than strait headers.

 

Mine are a bit raspy right now, but as I get my carb tuned the closer it gets to a good sound. Beats me as to why, but proper air/fuel is necessary for the inserts to work properly. I'll be installing smaller jets by this weekend and I can update on how much quiter it gets, but it is already pretty good.

 

Their instructions or webpage did not describe my problem with the air/fuel and I was conserned about that noise so I emailed Ken from their webpage. I immediatly got a response with suggestions and help. VERY GOOD technical support I must say.

 

Research their product on their webpage

http://www.carchemistry.com/ccexhaust.html

 

They are not much more expensive than mufflers.

 

Let me know how they work out.

 

-Tony

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My car will be a daily driver and I need as much ground clearance as possible, which lead me more toward a dual 2.25" setup vs a 3" single.

 

I plan to run a 3" single exhaust on my LS1 240Z. I have not worked out all of the details of this but I would like to have duals merge into one behind the trans. My car is lowered and I plan to use oval shaped tubing to save on clearance. The oval tubing in a 3" size says the height is only 2 1/8" and the width is 3 1/2". It is expensive but it should do the job to allow more clearance.

 

See it here: http://www.burnsstainless.com/OvalTubing/ovaltubing.html

 

Any pros or cons to this?

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That oval shaped SS tubing would work great. Kinda pricey though. I think I will talk to the local hot rod exhaust shop and see what they are capable of doing, as I am not convident enough to make my own exhaust system. Thanks everyone for your imput.

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I looked into the oval pipe and it was rather expensive - especially the elbows - and much more difficult to fabricate. If you calculate the cross-sectional area of an oval 3" pipe it is not much more than a single round 2 1/2". I ran dual 2 1/2" to an 'X' pipe right behind the tranny then dual 2 1/2" again - out the normal path on the drivers side but used a http://www.drgas.com "frame clearance tube" to pass under the differential mount on the pasenger side and still maintain ground clearance. Once behind the differential both pipes swing over to the drivers side to a dual inlet, single outlet muffler in the stock position.

My dyno numbers are from when I had the duals combining into a single 2 1/2" pipe after the tranny.

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I have a pair of Borla flow-through mufflers up in the original position, and did have to beat the spare tire well a bit, but the original tire fits in there just fine. It's offset a bit to the right, but the original hold-down still does its' job. The muffler does not touch the well. Something that might have made a difference is that I mocked-up the exhaust and wedged it into position to see where the interference was - I didn't move any more sheetmetal than absolutely necessary.

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http://www.carchemistry.com/powersqueeze.html

 

That's funny! These kind of things have been around since the 1930s and I thought they had fallen off the map. Like WC Fields said' date=' "There's a fish born for every hook."[/quote']

 

They seem to have joined merge collectors at the foreskin of exhaust technology...

 

http://www.burnsstainless.com/BTEC/btec.html

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The oval shaped tubing has been intriguing to me for some time. It is the stuff that stock cars (NASCAR) uses. There are several suppliers, one might do some Google searches. I had a brochure from a 'race supplier' that I grabbed at one of the races locally, and had the pages dog-earred; but, for the life of me I can't find it. For interesting side exit exhaust (which I'd NEVER do), they have 'boom tubes' if I recall correctly. Just seems that it would make the resonance in the cabin unbearable.

A while back I had the local muffler shop talking about clearance solutions, and they said that they just lower the car hoist down on the tubing and make their own 'ovals'. Seems kind of 'hoaky'; but, I have seen some of the cars that they do, and their work is pretty slick. Can't comment further on their 'smash' technique because I haven't seen it.

 

Final note: I just found the brochure... http://www.bsrproducts.com did someone mention them already?

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do yourself a favor do not waste your money on the car chemistry inserts they are horrible They are the worst sounding muffler in the world. I had them installed at the muffler shop started the car, jacked it right back up and cut the whole exhaust out. I used a Magnaflow 2.5 dual in dual out set up that is mounted under the car up in the drive shaft tunnel its about 1.5 inched below the driveshaft but does not hang down under the car at all. I have never rubbed my exhaust yet. But I am running 18" tires which makes the car a little taller but not much. I have about 4" under the car. It sounds great as well people alway tell me that it sounds bad as especially under full throttle it screams but isn;t bad a cruising speeds. Highly recommend the Magnaflow.

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