Best comob: 1st max QUIET with best flow for 360rwhp 2nd

[Modern Motorsports Ltd]

OK, what's changed/new since I last looked into this? I want a quiet (not kidding, stock corvette quiet or quieter would be sweet and make my chemo induced tinitus happier!) system that'll flow 350-360rwhp without great losses. Local shops I've talked to don't offer up any tried and true combo's. I'll have 1-5/8's primary new headers to replace my 1-1/2 set. Then plan is as follows:

 

2.5" pipes off of my header collectors which will then merge (very smooth Y, not sure if available Y's will be workable as it's a 90 degree bend that has to be done their...) into a 3" single just ahead of my transmission pan. Then this 3" single will lead into either a 'resonator' like this one

 

Their's a local Vibrant Stainless steel bottle with stainless steel wool with a straight thru 3" in/out and 5" overall diameter available in 12" and 18" lengths that might be suitable.

 

From the 'intermediate muffler/resonator (perhaps an oval borla small case)' 3" pipe on back to a muffler. At present I have a 14" case dynamax turbo..so I can fit in a 14-16" case and their is quite a bit of height/room available if required.

 

(present system is being replaced as it has too many imedances for my power jump of the last few years)

 

So any other suggestions on intermediate and rear mufflers or otherwise? Stainless steel (not a special desire of mine, but might last better?) Borla's seem quite reasonably priced and a few locally have said they're quieter and flow better than others they've played with (flowmasters etc).

 

Spintech feedback reccomended a sportsman XL in the back and a Pro Street as a resonator which is $175 in mufflers and the pro street wouldn't tuck up in the tunnel as high being 6" in width as the 5" bottle would......maybe not an issue but I don't want a clearance issue on my ride at all.

 

I'm quite fond of the Borla oval types for my intermediate muffler but they're pricey when I'm planning on using two, this one's $170US alone! (any deals to be had??)

Borla Oval case specs for picture below

 

I did look into the 'bell' connectors I mentioned in the header thread but exhaust shop felt they were best when you have a straight shot at them as they're sensitive to being bolted up at the correct angle/bang on.

 

Enough of my babbles....any and all feedback is welcome!

[Mike C]

From your 1 5/8' headers, I'd run the Flowmaster dual 2 1/2" into 3" reducer, a single 3" pipe back to the front of the diff, the 3" to 2 1/2" reducer cone from Flowmaster, then a welded mandrel bent combo of tubing into the back of a center in offset out 2 1/2" Dynomax super turbo, as long of one that would fit. I don't have any hard data, but in my head it seems running the cooler gases through a single muffler is better than running through 2 mufflers. With the single 3" under the car, the 2 1/2" should flow almost as well at the rear when the gas has cooled, it might even help keep the flow velocity up. I don't think you will EVER be able to get reasonable sound levels from a 3" muffler.

[Guest greimann]

Hey Ross,

 

I am running a 16" case X 3" id Dynomax Super Turbo, and twin cats under the floor. The sound is really nice, not too loud but not silent. It is louder than a stock Corvette.

 

The one thing that has a significant affect on the sound is the exhaust tip configuration. Originally I had a 3" turndown , and when I went to a twin 3" straight, the sound totally changed to a more resonant (better, little louder) sound. Consider using the tip to fine tune the sound!

 

When I built the car originally I had a 2 1/2 Dynomax out back and that was significantly restrictive. When I went to a 3" I picked up .4 sec in the 1/4 mile!.

[jeromio]

I'm very intrigued by this 3 to 2.5 inch idea. I too don't want an overly loud sound.

 

Does the exhaust really cool down that much in that 3 foot section? I've been planning on running 3 inch all the way back. I've been planning on buying a 3 inch muffler from Mac ( http://www.macperformance.com ). They look really well made and the price is very good.

 

There's too many options to consider!!!

[Lockjaw]

At the risk of pissing some people off, I am going to offer this as IMO.

 

Flowmaster's suck. To get it quiet, you should use a longer muffler with more sound deadening material. I had a 3 in dynomax cat back on my 95 Chev truck, and it was very quiet, and I picked up power with it. It used a super turbo muffler. IF you want to use multiple mufflers, use the straight through type, they won't kill your performance like a flowmaster.

 

A turbo will make one quiet....

[pparaska]

Lockjaw, that's not going to piss me off at all. Except for the magazines (which don't want to piss off their advertisers), if you look on the net for REAL test data, the flowmasters are known to have less flow capability (all that really matters for max power) than many other mufflers. We all know they're not too quiet (except for the larger 50 or 70 series I guess.) I personally like the sound of the flowmasters, but wouldn't want them on my car as they're too loud for my tastes.

 

The Dynomax Super Turbo has a really good mix of sound absorption, flow, low frequency output, and price, IMO. Borla is excellent too, but expensive.

 

One thing to keep in mind is if you leave all the muffling until last in the system, it's going to be somewhat loud unless you put a restrictive muffler on it. A pre-muffler or resonator in the tunnel is a great way around this. I may someday hack my system up and put in resonators, as it's too loud for my tastes, even though it's a dual 2.5" system with the larger, longer Hemi Super Turbo mufflers.

[Guest JAMIE T]

Ross, FWIW, I'm going to run long tube headers into 3" dynomax Bullets(one per header), then into a Y pipe, into 3.5" single the rest of the way back into an Edelbrock Victor Stainless rebuildable 3.5" straight through muffler(it should look like an Import style muffler/tip). It will still flow plenty(my motor makes over 500RWHP) and should provide much reduced noise over other set-ups.

[DavyZ]

Ross, I did buy a good used system from Rick Johnson that is mandrel bent all the way from a Y-pipe to a Borla Stainless, then to a Dynomax Super-Turbo. He assured me time & time again that the system was relatively quiet. It won't be hooked up for a while, but I'm hoping by the end of summer. Is this a 'now' project, or will this be finished by summer's end? Just curious.

 

Davy

[Guest Anonymous]

Ross, I have 2.5" dual, to a custom y-pipe, to a 3" x 16" dynomax race bullet, to 3" flowmaster out the back. IT'S TOO FREAKING LOUD!!! I set off car alarms just idiling by!!!. Maybe a Dynomax straight oval muff with "roving" fiberglass??? I might try that next. MAybe a downspout tip?? A turbo is my last resort cuz of the restriction. Maybe I'm wrong here guys, but a turbo seems restrictive to me. HELP, I need a solution too!

 

[Modern Motorsports Ltd]

Thanks for the info and responses to date guys

 

I should've mentioned my dad's 240Z LT1/T56 has a 2.5" Y to a 3" single -> BIG Bottle (long and large OD, inhibits ground clearance somewhat) and then some 3" muffler out back. His sound is PERFECT for me.....at idle nothing different from a stock L6 and at cruise quite pleasant with some gain on throttle as per normal. They've done a number of trips now and it's 'fine' in my Mom's opinion so I know it's quiet besides my own trials. But I had some concerns the bottle he has or muffler might not be ideal (not saying his is choked, although that could help me , his was done by local shop with local/non big name parts). His setup/cam etc isn't same power output of my own setup although close so I don't want to just copy his setup without some extra research. But his did prove to me a 3" can be done quietly.

 

I had a look at Dave G's exhaust pic and I'm not sure that cat setup would clear under my ride comfortably? The cats look like they're right under or just rearward of the transmission? I've got a large/flat trans pan that's not too high in my trans tunnel... I do like the idea of moving the 'merger' rearward as dual 2.5's have 9.8 square inches of area vs. 6.1 for the single 3" (38% more area!). A little further rearward and the gas is a lot cooler (particularly in duals with greater pipe area/convection/transference etc). I did query the exhaust shop about merging my Y behind my trans pan instead of in front of it and he wanted to do it in front, don't recall why in particular, perhaps geometry of the Y transition and fitting the intermediate muffler before it goes into the upbend over the rear crossmember towards rear muffler etc as seen in Dave's setup their isn't that much length to fool around with.

 

Here's Dave setup to have an idea of length's available.

 

I like the idea of stuffing THE largest reasonable muffler in the rear location as it just seems the larger case can do more dampening with minimal loss (correct?).

 

Dave, I'm planning to do this as soon as I've decided on components and have my header mods (or header spacer mods, see other thread) complete.

 

Mike, thanks for the differing 3->2.5 input. I'm not feeling so adventurous having already done two exhausts that could've put money somewhere else by now......I don't disagree with your suggestion in any way and it may very well work fine. I've just had enough of any 2.5" components at present...had them loud and/or restrictive in various combo's and seen a couple 3" combo's in V8Z's that sounded quieter. Another sides my dad's was Dustin's setup in Oregon in his 280Z V8....he had a huge bottle, purple hornie perhaps, I don't recall exactly but quieter at lower throttle/rpms and a distinctive growl at WOT.

[Lockjaw]

Well I am glad I am not alone in the to loud exhaust category. That was fun when I was young, but I hate that junk now.

 

I have a Hooker Max Flow 3 in on my turbo L engine, and it does not set off car alarms that I know of, and it really pretty quiet, with a really deep tone, until you hit it. Then it sounds good. It was cheap too. 50 bucks.

 

It does not resonate (which I hate with a passion), and it really pretty quiet on the interstate. I bet a race magnum bullet muff or two in the tunnel would quiet things down alot, and they won't really affect your flow since they are straight thru.

[Guest Anonymous]

I'm not fond of the car being loud either anymore, it's cool for a while, but I can't but keep wondering how cool it would be if the exhaust wasn't the only thing I heard. I like the looks of that little bullet to knock things down a bit.

 

Could another one be put maybe in the straight piece between the differential 90 and where it makes the other 90 to the muffler out back (early Z I'm talking here) seems like a pair of resonators and a quiet muffler would finally get it quieted down where I'd like to see it (I think).

 

Regards,

 

Lone

[Owen]

Had my car running for a little bit and it is pretty damn loud!

 

I have Hooker ceramic block huggers into 2.5s which upstep into two 3"s then into a single 3" Random Technology Cat then 3" all the way back. I'm using the Apex Dunk muffler cuz I liked the looks.

 

The muffler is a big can with wool or whatever wrapped inside and it has no sound deadening capabilities whatsoever. I would recommend a muffler that is properly chambered, but I would also recommend a pre-silencer like my cat or like those bullet mufflers.

 

Car isn't properly tuned yet so we'll see.

 

Owen

[Guest greimann]

The front flange of the cats are even with the end of the tailshaft, but remember I have a T5 and a 2+2, so I have a about 9" extra to play with under there.

 

Yea baby! another case for the 2+2! Comes with an R200 stock and can fit a full sheet of plywood in the hatch!

 

I am with you guys on the sound thing. I want a "real" car that is smooth, powerful, reasonably quiet, reasonably loud... an all around GT.

[danj]

Ross

 

You mentioned about Tinitus. I also have Tinitus, although mine was induced by using firearms at a young age without ear protection. Just wanted to say that I hope this condition corrects itself without having to compromise the sound of a deep-throated exhaust system, but especially, and I know I speak for everyone on the HybridZ forum, I hope your treatments go well and that you will be as healthy as your Z-car before long.

 

I appreciate all the help and advice you have given me during the on-going fabrication of my ZX over the past year

 

Dan H

[Guest Tom Scala]

The info about the exhaust gasses cooling as they travel rearward is correct. I saw an independant test done in a car club mag that had a 455 Pontiac Lemans street car use 3" headpipes with 2.5" mufflers and tails,then 2.5" mufflers and 2.25" tails. All mufflers were Super Turbos. 1/4 mile times and speeds were virtually the same varied no more than .05sec. and .5MPH between the quickest & slowest (very consistent high 11 sec car) and backpressure measurements taken at 3 points in the system were also nearly identical. The 2.25" tailpipes were noticeably quieter both to the ear and on a db meter. The 2.5" mufflers were replaced with 3" and no practical difference was noted,except in increased sound levels.

The tester determined as long as the mufflers are placed as far back as possible(the test car was a station wagon) smaller pipes/mufflers can be used with no performance penalty and lower sound due to the cooler condensed gasses displacing less volume. Another 455" car (67 Lemans coupe mid 10 sec ET's) was tested and the performance did fall off some with the smaller pipes/muffs but not that much. That motor was making 600+HP though.

[Tim240z]

Tom,

That was very interesting, thanks for posting. It makes sense I guess, but I have been programmed (maybe brainwashed ) for so long that bigger is better, I have a hard time swallowing this concept. I don't know if I would be brave enough to try this on my car. Do you know where I can find the original article on this?

Tim

[Guest greimann]

I think the operative word in Tom's example is mufflers, as in two. A lot of guys are running a single muffler and a single 2 1/2" unit is just too restrictive for a V8.

[pparaska]

Dave, I'd agree. A typical 2.5" muffler won't handle enough flow to get much above 200-250 hp.

 

I went with two huge Hemi Super Turbos to fight flow restrictions as much as possible, hoping all that muffler volume would help bring the noise down. Boy, I was mistaken on that second part. Too loud for my taste, but my Harley riding neighbors think it sounds great and not too loud .

 

Someone on HybridZ had obtained a full-up Dynomax catalog that had flow ratings (cfm) for a certain amount of pressure for each muffler. Who was that? Tom Scala?

[Mike C]

As you've found Pete, it's all about tailpipes. I have a pair of the 2 1/2" Hemi turbos on my Jimmy, and it is QUIET! The loudest thing on it with the 'vette 2 1/2" rams horns is the failing alternator bearing . It would be interesting to see a direct comparison on somebody's car with all else being equal but muffler size and outlet.