LT1-LT4 Modifications 1993-97 Gen II Small Block V8

4" exhaust questions

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Old 08-25-2007, 11:29 AM
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Default 4" exhaust questions

Who here has 4" exhaust? I'm curious what you used for the ypipe, I hear there is a kit out there that has the piping for dual 3" to the single 4" collector for the ypipe? I'm just going to run a dumped bullet right before the axle to cut down cost as the mufflex systems are crazy expensive to go over the axle.
Local shop is only $8 for a foot long piece of 4" pipe so it would def. be way cheaper than buying a catback, seeing as I will just dump it.

So I'm mostly wondering what to do about the ypipe, I would need something that works with pacesetter longtubes, thanks. -Corey
Old 08-25-2007, 01:11 PM
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Flowmaster merge, go to the local 18 wheeler store order you some bends and fab it up. Also a 4 inch bullet turned down under the car is gonna be BRUTAL! I would take a hammer to the floor and put a round regular muffler there, Aero, Borla, Magnaflow, Ultraflow, Dyantech...something other than a Bullet.



David
Old 08-25-2007, 02:05 PM
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its not that brutal..its what i had on mine before i switched to gmmg..its nice and deep...its loud too but you know it aint stock..not as bad as you think it would be
Old 08-25-2007, 03:58 PM
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I went from 3" catback to 4" Mufflex catback and loved the sound but lost 60' at the track. With the 3", I could cut 1.70 60' and was running 8.2s at 81-82. I installed the 4" and cut 1.75-1.77 and ran 8.1s at 84...I installed roller rockers, better valve springs and a 52MM TB along with the exhaust. and was told that the 4" killed my 60' and I should've been in the 7s which was my goal. I think I should've left the 3" and went with the other bolt-ons. My opinion: Don't go 4" if you have a bolt-on car, but if it's built, go for it. I loved the sound, but didn't want to sacrifice ET.
Old 08-25-2007, 04:09 PM
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Its a hotcam motor that is going in, and will be getting hit with a 200 shot.
Old 08-25-2007, 11:58 PM
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I have the mufflex 4" stuff. It sounds like no other but the fit and finish could be better. I started with the Mufflex ypipe but ont of the box it was wrong. The only reasone Mufflex could give me is Hooker cant makes good headers. Now I have one I fabed using the Flowmaster merge.
Old 08-26-2007, 02:56 AM
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I have the setup you are talking about. I am getting ready to go over the axle with it To loud for me with it dumped at the axle
Old 08-26-2007, 02:57 AM
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BTW I built my own 3in to 4in merge. it takes up a 1/4 the space the Flo does and looks better IMHO
Old 08-26-2007, 05:21 AM
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Can you post up some pictures and what you used? Getting the ypipe made up will be the hardest part here for me. thanks.
Old 08-26-2007, 09:58 AM
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Honestly, if you are not going over the axle then why not do true duals? Cheaper and it will make more power. Hell, a x pipe or h pipe will even be better than true duals alone.
Old 08-26-2007, 11:16 AM
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Originally Posted by ZONES89RS
Honestly, if you are not going over the axle then why not do true duals? Cheaper and it will make more power. Hell, a x pipe or h pipe will even be better than true duals alone.

Why send the extra money and add the extra wieght just to loose ground clearance? My Four inch stuffs up in the stock routing. The only way the car made more power was with open headers

I know my car is slow and doesn't make much power but I am kinda picky
Old 08-26-2007, 12:20 PM
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Well, i have seen some that have great groung clearance. I guess you want to be able to say you got 4"? I would go out the rear of the car with it if it was my daily, you annot talk on the phone when it is dumped.
Old 08-26-2007, 01:04 PM
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Originally Posted by ZONES89RS
Well, i have seen some that have great groung clearance. I guess you want to be able to say you got 4"? I would go out the rear of the car with it if it was my daily, you annot talk on the phone when it is dumped.

You have me beat then. I have installed many of them and none came close to my 4in system that goes in the stock location
Old 08-26-2007, 08:52 PM
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Originally Posted by ZONES89RS
Honestly, if you are not going over the axle then why not do true duals? Cheaper and it will make more power. Hell, a x pipe or h pipe will even be better than true duals alone.
I've got SLP subframe connectors, Spohn T/A thats mounted on their cross ar deal, there is no way in hell I'm going to get away with running duals. I've seen one car with my setup with true duals, he never got back with me on how he did it.

4" isn't going to be extremely costly for me, I'm kinda hoping Ellis can give me some advice how to run a 4" in my stock location.....especially what I need to make this y pipe. I'm not going over the axle with this, it shouldn't run me a whole lot to do this.
Its also going to start shying away from being my daily as I fix my truck up. I picked the truck up to cruise around town with. Oh yeah and currently I have a company work truck, the car mostly gets driven to the weekly car show or out to the store real quick, its not driven every day as is anyway. I was driving around for the longest time with my cutout open when I had it also, loud is fine by me.
Old 08-27-2007, 12:01 AM
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Originally Posted by camar0corey
I've got SLP subframe connectors, Spohn T/A thats mounted on their cross ar deal, there is no way in hell I'm going to get away with running duals. I've seen one car with my setup with true duals, he never got back with me on how he did it.

4" isn't going to be extremely costly for me, I'm kinda hoping Ellis can give me some advice how to run a 4" in my stock location.....especially what I need to make this y pipe. I'm not going over the axle with this, it shouldn't run me a whole lot to do this.
Its also going to start shying away from being my daily as I fix my truck up. I picked the truck up to cruise around town with. Oh yeah and currently I have a company work truck, the car mostly gets driven to the weekly car show or out to the store real quick, its not driven every day as is anyway. I was driving around for the longest time with my cutout open when I had it also, loud is fine by me.
Then it sounds full proof, i hope with the time and research you put into it you get what you are looking for, i personally on my toy(89RS) have LTs with 2.5 inch into a Y pipe, but i have dual cutouts before it Ys in, makes it perfect for track use or just enjoying noise.
Old 08-27-2007, 01:15 AM
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Damn 2.5 would choke my engine



The 4in to 3in neck is gone now
Old 08-27-2007, 02:19 AM
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The only thing better than 2 1/2 dual dumps is dual 3 inch. If you ever run across a exhaust size schematic there is one that calculates the minimal exhaust size for HP and it breaks it down to duals and single. Pretty good to use as a referance, ill post it if i can find it.
Old 08-27-2007, 04:01 AM
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A 2.75” (stock) single system is good for a 310hp engine with zero loss…
A 3” Single system is good for a 370hp engine with zero loss…
A 3.5” Single system is good for a 503hp engine with zero loss…
A 4” Single system is good for a 657hp engine with zero loss…
A 2.25” dual system is good for a 457hp engine with zero loss…
A 2.5” dual system is good for a 513hp engine with zero loss…
A 3” dual system is good for a 812hp engine with zero loss…

Now these numbers are assuming that everything else is set up perfectly. The muffler must flow as much as the open pipe or more to get zero loss at the listed hp levels.

Ive been kicking the idea of getting the 4" mufflex or 3 inch true duals for my setup. I feel id have HP to gain over the 3" corsa/cutout. Ellis i take it you like ur mufflex alot? Do you have anymore pics of your setup?
Old 08-27-2007, 09:33 AM
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The one i saw was nothing that high for 4 inch single. Think it was 550-575 maybe.
Old 08-27-2007, 10:25 AM
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I have the 4" system and the Spohn T/A. Because of the T/A mount Mufflex built the Y-pipe on the car ( I'm lucky enough to live near Mufflex ). The T/A mount sits right where the normal Y would be so they had to do allot of bending to get the Y pipe to fix properly.

I have Jet hot headers into 3" pipes.3" in/out cats, that merge into the flowmaster collector then into the mufflex 4" system. The driver's side cat is in an odd location, but it got thru state inspection just fine. My real concern was the exhaust being so close to the fuekl lines. I wrapped them in the head shielding tubing, then also make a metal plate that I covered with the sheets of heat sheilding. Eventually I want to go with braided hoses and will reloate them.

I'm traveling for work this week, but will be home on the 28th. I can post a pick of the Y-pipe, it's off the car right now as my engine is pulled due to spun bearings!


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