Flowmaster crossover pipe

[LT4John]

I just had a set of Flowmaster's (2 chamber) installed on my 96 LT4. Problem is that the resonance between 1500-2000 rpm is way too loud, sounds great pass 2K. The shop that did the job is willing to install a X pipe or a crossover (h) pipe.
Question, which is the best way to fix the resonance, a X or crossover pipe? and where exactly should the pipes connect to the exhaust?

Thanks for any help

 

[Ken]

I'm running the 40s series Flowmasters on 3-inch duals with an X-pipe, and the resonance is bad; so bad that it's almost unbearable. My engine is built, and it sounds to me like the windows are going to blow out at +/- 2 grand! Reminds me of the TV commercial for the car stereo company where the guy is blowing out windows, and bus shelters and eyeglasses, etc. as he's driving down the street. :L

_ken

 

[LT4John]

When I bought the car it had muffler elimantors, and I don't know where the original crossover pipe was installed. I have two sets of pipes, one on each side coming out of the cats, they meet at the center resonator and then branch out to each muffler. All the pictures of exhaust systems I have seen in parts manuals, I don't believe I have ever seen a crossover pipe. But I am a newbe at this, and that's why I am asking.

Thanks again

 

[Hotred94]

I have a Flowmaster 40 series with 3" duals, and midrange noise is nasty. I've fiddled with things here and there-more rubber, tighten up the bolts, lower the mufflers, add sound insulation-I've even tried stuffing the rear chamber with fiberglass. I didn't do the crossover pipe but people tell me that won't make much difference. I've pretty well decided that if I want to keep my hearing I better change the mufflers. I'm thinking about getting a Delta Flow or a nice stainless system.

 

[Mad-Mic]

i can't remember who posted this but this was posted about 6 months ago and what i remember there was this person had a measurement that came off the Y pipe and spliced in behind that i believe the crossover pipe was 18 inches long? not sure i know this isn't much help but might be able to help out your muffler guy.

 

[vms4evr]

You need to keep the resonator in there. Removing it will just compound your problem. I tried using the Magnaflow SS mufflers because they looked great. Straight though design 3" in to dual 2.5" out tips. They sounded awesome at idle. Sounded like a racing car above 3Krpm. Problem was you didn't want to be in the car between 1500-2000+rpm. It was only liveable closer to 2500rpm.

An exhaust engineer that used to visit this forum told us that the X-pipe would go as close to the cats as possible. So you could try putting an H or X pipe between the cats and the resonator if it will fit. Otherwise you're stuck putting it right behind the resonator. The closer it gets to the mufflers the less it will do for resonance from what I understand.

I'll be surprised if a crossover of any type will help. That's why those factory mufflers are the way they are. Resonance...

I'm considering the Delta Flows also as an experiment. They at least have restrictions that are supposed to address resonance. They just don't look very good. Just another plain looking can like the factory ones.

Graham

 

[3 Deuce]

Put the MagnaFlows on last weeek and the resonance from the Flowmasters is gone like the wind...finally got the Corvette sound I wanted and those four 3" horns out back look outrageous....

 

[LT4John]

3 Deuce,

From all the great responses, I am going to forget about the crossover pipe and I am thinking about Flowmaster 50's (info from other posts), or the MagnaFlows.

Could you tell me more about the MagnaFlows you installed last week. Is there a model number or type I can reference? The shop I am dealing with is also a MagnaFlow dealer.

Thanks for all the help

 

[3 Deuce]

The Magnaflows are '91-'96 Corvette specific. They're polished mufflers with two 3" rolled round tips on each one. These are also highly polished. I wanted the B & B tips (the ovals) which are 4 1/2" each, but these fill the space just as well and compliment the rear lights equally well....:s

 

[vms4evr]

3 Deuce,
It sounds like you are using the exact Magnaflow that I had all the problems with. The 92-96 specific ones. Look beautiful! Resonated like mad in my car. Actually gave me a headache just driving it to work. Had to take them off. I'm wondering if running the SLP cold air kit with a cut shroud doesn't cause some of this. My factory LT1 mufflers even have a little grumble to them now.
Here are the mufflers I'm talking about that drove me crazy...

http://corvetteactioncenter.com/forums/showthread.php?threadid=13745

Graham

 

[3 Deuce]

Those are the ones...no problem at all and the Flowmaster were unbearable at 2000RPM. especially trying to cruise on the freeways in 6th, the area of resonance was fairly wide, usually had to drop to 5th to get rid of it...not a concern with these. I have a K & N but no vortex box or ram-air box so I can't help there...

 

[vms4evr]

I'm glad they are working out for you. They do look great from the back and side view of the car.
But I'm confused. You have the factory base but a K&N filter in it. The difference I have is the SLP which is steel tube. That maybe what caused me the problem. But I like the SLP setup so I want to keep it.
If it isn't too much trouble when you get a chance could you do a small test for me and let me know what happens? Could you pull the air filter and just run it for a few minutes with an open breather and see if the exhaust starts resonating inside the car between 1400-2200rpm somewhere?
This really has my curiousity perked now.
Graham

 

[3 Deuce]

1st chance I get...we're doiing some remodeling here so it may be awhile....had it up for some 100+ runs last night and it sounds so sweet up there....

 

[Vintagevetter]

Flowmaster Drone

Hi Guys,
I bought a 94 LT-1/6-Speed coupe about 4 months ago, that came equipped with Flowmasters. When I test drove the car, I loved the way it sounded, at idle and going through the gears. It wasn't until later, when I got on the Freeway cruising in 6th gear that I discovered the dreaded "2000 RPM drone" The problem is that this happens right in the cruising zone. 65 to 80 mph. You either have to drive 60 or keep it over 80, or go back to 5th gear.
I thought only my car had this problem, until I found this website. I love the sound of the exhaust, but I would like a "fix" for the drone. I haven't crawled under the car to see what size Flowmaster are on the car. If someone has come up with a solution for this problem, I would loved to hear about it.
Jeff:confused

 

[vms4evr]

1st chance I get...we're doiing some remodeling here so it may be awhile....had it up for some 100+ runs last night and it sounds so sweet up there....

Cool. Thanks. Just post it in here or send me email. Mine sounded bad-a** up at the high end and the resonance went away. Either that or the exhaust note was so strong I couldn't tell

Graham

 

[3 Deuce]

A further thought might be...that there could be a difference between the sound of the LT 1 & the LT 4 due to pipe diameter, flow, etc...?

 

[LT4John]

I just had a set of Flowmaster Delta Flow 50's installed today. The resonance is gone. :Twist The 50's are a three chamber muffler and are a little quieter than the 40's, but I could not feel any performance difference between the two. Sounds good on the highway in 6th gear at 2K, but have not taken it on a long trip yet. (I won't for a while, when the car was up on the lift, they found that my rear spring was starting to splinter) Now I have a new project:Silly

 

[vms4evr]

Glad to hear it John. Those are the ones I was going to try next to see what happens.
Can you pass on the part number you got. I was looking at one that was 3" center input to dual 2.5" or 2.25" tips. I was thinking they would need some nice polished tips installed them to improve the look.
Do you feel any difference over stock as far as hp/tq? sotp?
Graham

 

[LT4John]

Flowmaters gave me this info; DeltaFlow 50's, center in, center out 2 1/2'" part number 942550.
Because the fit was so tight, my muffler guy ordered the 2 1/4" in so he had more metal to make a flange with, not sure why:confused
I don't know the part number of that one. Hope this helps.

 

[LT4John]

vms4evr,

To answer your second question "Do you feel any difference over stock as far as hp/tq? sotp?" I never had stock mufflers on the car, it came with muffler eliminators. I felt a little difference after installing the 2 chamber Flowmasters, but do not feel any difference between the 2 and 3 chamber mufflers. I don't race the car, so could not give any performance numbers. The Engineer from Flowmaster said the performance is the same from both (if you can believe what the vendor saids)
:eyerole