Magnaflow Mufflers are installed

[vms4evr]

Well I got my Magnaflows installed last night. These are the ones for the 92-96 LT1/4 cars. Not a catback. No resonator. Mufflers are all polished stainless steel with a single 3" inlet and 2 twin tips coming out. They look great. Welded in place.
Initial feeling is they sound really good. At idle you can tell they're not stock. Nothing obnoxious though. Give it a little gas and they have a deep rumble from off-idle to about 2Krpm. After 2k the bass goes way down and they have that racey sound. There is some resonance between 1200-1600 that I have to cure. But I'm pretty sure our buddy Redbob is going to help me address that.
I have a couple of pics I snapped last night before it got dark so I will post them as responses. As soon as I can get my daughters laptop for a few minutes I'll give a shot at recording some sound files. Later.
Graham

 

[vms4evr]

Rear view

 

[vms4evr]

Rear 45deg angle view.

 

[Drewser]

SHARP!

If those sound as good as they look, you have a winner!

 

[intruder9]

Shiney! Looks gooood!!!!

 

[vms4evr]

Thanks. Yes they look awesome on the car. At idle there is a slight rumble. From idle to about 2000rpm they have a deep powerful sound that smoothes out. Above 2000 they sound really sweet and racey.
The only catch is I have a coupe and the resonance is there at 1200-1800rpm on accelerate and decelerate. I can live with it but my wife can't. She got out of the car and said it is too loud period and won't get back in it until i FIX it... ie, take them off. And it looks like I'm going to have to do just that. We swap cars so the Vette doesn't get hit with all the mileage. I have a long commute and she has very little commute.
Kinda sucks cause I love the way these mufflers look on the car. So at the end of the week they come off and the factory mufflers go back on for the lovely Buick sound...
So next week the mufflers will be up for sale. I'll post them in the parts for sale section if anyone is interested.
Graham

 

[Edmond]

Graham,

stinks to hear about the wifey not liking the new sound. But I'm sure you'll get something that will look just as sharp and with a tone that you will both agree on.

 

[c4ever]

They look sweet Graham. Any chance of some mod to eliminate the resonance?

Carlo

 

[vms4evr]

These have to be the best looking mufflers I've seen to date (personal preference of course). I've gotten lots of compliments at work with it sitting there in only 2 days. Even had a guy in a green 94 chase me down the highway waving at me to pull over. We happened to get off at the same place so I talked to him for a bit. He may buy them from me if I don't get a buyer soon. He's younger and single. I took him for a ride in it tonight and he loved it. So maybe I can recoup some of my money.

If not they will go back in the box until I can figure out how to quieten them down. I thought about a muffler plug or whatever it is called stuck in one of the dual tips on each side so it would tone them down. Not sure if that will work or not. Right now money is getting tight so playing with an H or X pipe is out of the question. Later on it is doable if i don't sell them. I'm sure my buddy Redbob can come up with some good ideas. Just can't afford to redesign it right now.

I'm really bummed out about this and hate to take them off ad

Graham

 

[Topless]

Exhaust shops will usually make and install an x for $100. It would be cheaper to have this done that to pay to have the mufflers welded two more times.

just a thought.

 

[vms4evr]

Topless,
you're absolutely right. this guy has an X-pipe. he only charged me $50 to put these on and won't charge me to put my originals back in. he owes me a favor because i got him a handful of people who are now customers.
here is the problem. where are you going to put the X-pipe and assure me that the resonance will go away? no guessing. he isn't sure and neither am i. that is the dilemna. if i keep them then i will remove the resonator and run new pips from the cats back to the mufflers and put 1 or more X,H whatever it takes pipes to cancel the resonance. that is where redbob comes in. he has the engineering background and knowledge to help place them properly. problem is i need this fixed this week. so it is easier for the moment to just take them off.
Graham

 

[davesredvette]

I just had some magnaflows on my 94 Torch Red with the polished stainless steel, wow is it hotttt. Mine sound good allround. I had the old factory muffs, cut off and just put the magnaflows right on. Did you change anything else? I have a K&N air filter and that's all. Is your car auto or stick?

 

[Topless]

Graham-
From what I read from Redbob, without using the mathematical formula, you would put the x as far back on the car as possible. Basically, just before the pipes split to go around the spare.

I would love to know what an X does for you. I have been contemplating it on my 92 for a while now. As soon as I get it back (and fixed!), I will probably experiment.

Let me know if you find out how the x works on the vette.

Best of luck.

Mike

 

[vms4evr]

Dave,
Did you put the exact same magnaflows? They have a bunch of different ones you can put on. These actually fit excellent. All we did is cut the pipe and weld new ones on. I have the SLP cold air setup with 3 K&Ns and a cut shroud. That definetely changed the breathing habbits. Other than that the usual small mods. TB bypass, chip, air foil. No serious stuff.

Mike,
They're off tomorrow and a guy down in Charlotte is buying them from me. He wants that exact muffler and the louder the better! So this will resolve my immediate problem that I recoup most of my money and will put it towards plug wires and maint stuff I need to do. It'll be a few months before I have the money to play around with this again. In the meantime I'll do my homework and holler for Redbob. I'll be under that car the next couple of weekends so I'll get everything measured up and get him the info. At some point I want to go back to these mufflers. The guy buying them from me will be experimenting with an X-pipe. He has the materials and a mig welder. He said he'd keep in touch and give me some ideas on X-pipe placement. His engine is no where near stock though and he is on his way to 400HP.

Graham

 

[-=Jeff=-]

Graham-
From what I read from Redbob, without using the mathematical formula, you would put the x as far back on the car as possible. Basically, just before the pipes split to go around the spare.

I find this interesting.. Reason is the LT4 exhaust has an 'H' crossover right before the bends outward from the center to the mufflers.

 

[Redbob]

I find this interesting.. Reason is the LT4 exhaust has an 'H' crossover right before the bends outward from the center to the mufflers.

Redbob here!
You're both right: The calculations that I did (back around '92), and the space available, dictated the crossover pipe location just where the LT4 cars, and the Export cars, have it.
Theory says that location should work, and my experience says it does work, although the reason it was done was not to reduce interior noise but to reduce Exterior ("passby") noise, so Export LT-5 cars could meet the European noise test requirements. (Even with the "noise test" power-reduction feature in the ZR-1 engine ECM, those cars couldn't meet the Euro noise law.)

Graham! Your idea of a "muffler plug" would also work quite well to reduce the noise!
We did that also early in our development program for the ZR-1.
BTW, when I say "our', I mean Calsonic, not GM!

Anyway, we took a variation on the early 2-outlet muffler, but redesigned internally to make both outlets functional. We got a huge reduction in muffler backpressure (big surprise, eh?) and a corresponding huge increase in noise, inside and out. Not pleasant at low RPM, but it really would sing at high RPM. Then we plugged one of the tips with a block of wood, with a screw through the side of the pipe to hold it in place, and another screw into the end of the plug so we could grab it to pull it out. With the plug in place, it sounded just exactly like stock.
That was so successful we got the actuators and controls from a Nissan Skyline (Japan-only twin-turbo car) "dual-mode" muffler (also produced by Calsonic), and we made a pair of butterfly valves, just like throttle butterflies, to go in the inboard pipes. We got the controller recalibrated to about a 3500 RPM start-to-open point.
That system was dang near perfect - low restriction at high-RPM, low-noise around town.
GM didn't want to spend the money, about $100 additional per car.
If I had a way of making an mpeg from a VHS tape, I could show you what the car looked/sounded like on our chassis dyno as it revved. Of course, that was a '90 model LT-5, not your LT-1.
Anyway - Graham: before you give those mufflers away, try a plug in one of the pipes on each muffler. You could whittle a piece of hardwood - belt-sander might be better, actually - and anchor it to the pipe with a very unobtrusive screw. I'd suggest the plug be at least 2" long; it doesn't need to be a perfect leak-tight fit In fact, if it is you'll be hard-pressed to ever pull it out. You could for that matter make a sheetmetal plate to cover the outer end of the plug, for better appearance. Although I think that just painting it flat black would work fine. You *might* find the inner end of the plug turning to charcoal over time... but another sheetmetal plate should solve that also.

But d*mn those mufflers look good on your car, Graham! Try the X-over, try the plugs - then if all else fails, sell 'em to me! I'll make 'em work!
Regards,
- R

 

[vms4evr]

Well... I have to sell them. I don't have the time or money right now to continue with experiment. They came off the car this morning. Almost cried watching them come off... :cry

-=Jeff=- Neal is buying them and is close by so we're going to meet Sunday and he's going to use them on that custom exhaust system he is building. It's going to sound intimidating!

Redbob,
Yes they do look damn good! I'm holding on to this idea of making a setup that works using those mufflers. I'll just have to buy a set later on when our money issues get resolved. I'll have them ship them to you and you can fix them up for me :eyerole

The idea you mention about the Nissan is very appealing. I looked at PowerEffects in the past. Their system has a lever on the side of the muffler that you set. Their flow control is inside the muffler and acts like a cork screw. Check out their website. Or you can get it rigged up to control it from within the car. But to have them work based on engine rpm would be really cool! With of course, an override, so you can just leave them wide open when you want that stop light intimidation factor A set of motor controlled butterflys over the openings that are buried inside the tips so no one can really see them. Much like the throttle blades on a carb. That would be cool :cool

Graham

 

[Edmond]

Redbob,

Just curious about the development of the LT5 exhaust system. Why would GM go to an outside developer for that? Wouldn't it be cheaper to keep that in house? Afterall, GM would know the Corvette best right?

 

[Topless]

RedBob-
On those adjusting mufflers, are there prototypes available, or an ability to recreat them? What would happen if you straight swapped a set designed for a Skyline?

-Mike

 

[Redbob]

Redbob,

<snip> Afterall, GM would know the Corvette best right?

BWAHAHAhahahaha.....
Oops, excuse me! Sometimes I just...
Anyway: The short answer is: GM gets all their exhaust system work done by suppliers. (There are at best one or two engineers at GM that actually have a corner of a clue as to how exhaust systems work - and I'm speculating here; I never actually met one.)
In the case of the C4's, including the ZR-1, that supplier was Arvin, in Columbus, Indiana - a good company with very knowledgeable engineers.
Calsonic, the company I worked for, was trying to get "in the door" at GM, to become a GM supplier, and there's no better place to showcase your technical capabilities than on the Corvette.
Ultimately, we were successful, and designed and developed the C5 exhaust system; our work started, though, in '90 as a ZR-1 improvement program, and later as a program to develop an Export exhaust system for ZR-1's, which at the time did not meet European noise standards.

RedBob-
On those adjusting mufflers, are there prototypes available, or an ability to recreat them? What would happen if you straight swapped a set designed for a Skyline?

-Mike

Mike:
There are no "dual-mode" mufflers available in the aftermarket to my knowledge. Calsonic does not produce aftermarket exhaust systems, and any such muffler you could find (like from a Skyline, or from a Mitsu 3000GT VR-4) would NOT work, since they're desinged for very specific vehicle and engine combos.
If you were fairly good with machine tools, you could make up such a thing, manually-controlled, as I outlined to Graham; the tricky part would be making the throttle butterflies. You don't just want a round flat plate with square edges, you want a flat plate with beveled edges so it will seal the tube before it is completely square in the tube.
Regards,
- R