Installed Borla Quad-tip Stingers a couple of weeks ago. My neighbor has single-tip Stingers on his Z06 and a friend let me drive his convertible with the quad tips.

Car ran good but the overall noise level was very high compared to the other two cars I was familiar with and there were two very nasty resonance points at 1500 and 2500 rpm.

So, I set out to tune the Stingers.

First step was to buy some "3 "test plugs," part # 33422 down at your local speed shop-Home Depot. These consist of two large metal washers which sandwich a rubber "donut" which expands when you tighten a wing nut and bolt that goes through the center of the plug. If you want to try this, you need four of them because the washers are not the same size and you will need two of the smaller washers on each side of the "donut."

First I plugged one inner and one outer outlet on different sides. Quieter but the resonance was still there. Then plugged the outer outlets on each side. Quieter but the resonance was still there. Next I plugged the two inner outlets. Wow, quieter and all the resonance was GONE. Very smooth sound all through the rev band.

A little calculation showed plugging two outlets reduced the cross-sectional area of the combined four outlets by 20%. But, this reduction only occurred over about the last 8 inches of the exhaust system--the distance from the "Y" after the little mufflers or resonators--and the two outer outlets. Figured this reduction probably isn't a problem

But, not having enough to do, I set about modifying the "test plugs" to leave a hole in the middle. A 1/2 inch hole left me with no resonance but an odd "whistle" at idle which went away above about 1500 rpm.

So, I made a 1" hole in the plugs. Problem solved! Good sound, nice rumble at idle, and no resonance peaks. I figure about a 5% reduction in overall cross sectional area with the 1" hole. I think a 7/8 inch hole would be better but a bi-metal hole saw is about $10 and another set of plugs goes for $10 and it takes about 45 minutes each to modify them so you can have a hole in the middle.

The point of this whole thing is you don't have to be satisfied with the sound of your quad-tip Stingers!

If you'd like to try this send me a note and I'll provide more info.

In summary, I suspect the Stingers are tuned to a stock C5 and anything and everything you do to the air flow through the engine from the air filter to the Stingers themselves affects the overall sound and resonance points. Even a cam would make a difference because of the overlap between the intake and exhaust lobes.

My car has a Donaldson air filter, ported throttle body, stage II heads and cam, Z06 intake, long-tube headers, free-flow cats and x-pipe, and the Stingers, of course.

Been a fun project.

 

 

Where's the pics???

So basically you made the 4 tips stingers sound like the 2 tip stingers?? This is good information to know, save a few buks and buy 2 tippers...

 

You have too much time on your hands! :bb

 

I agree with your statement that even a cam will affect the sound. I installed the stingers then two months later installed my cam. The car was noticably louder after the cam install.

 

Not actually since there is still some exhaust flow. I have heard the 2-tip Stingers can have the same piercing resonances Ray had. So it's not that simple. I actually drove his car yesterday, and have to admit the car is much "louder" than his previous exhaust (not sure which B&B - Route 66 I believe) but with his "tuning" I didn't notice any resonances which I'm very sensitive too.

Of course the top was down and the world always looks (and sounds) better in a vette with the top down on a beautiful day. But from short test drive they had a split personality, semi-civil at low RPM's but go WOT and any NASCAR fan would recognize the sound.

I think Ray is on to something here folks.

Tom

 

I had the Quad Stingers bolted up to my stock engine and they were perfect as far as tone and db level. Then I had a cam and LG headers w/o cats added and the car was loud at idle and sounded good but, at WOT you could forget even hearing your conscience talk.
I had to take the Stingers off b/c they were too loud.
I'm going to add the cats and put the Stingers back on and see what it sounds like. Hopefully that combination will be quiet enough for everyday driving.

 

Maybe, but I don't think so. One of my points was that my quad system before tuning didn't sound like at least one other quad system. That said, I can't think of any reason my system should sound like someone else's dual tip system. But maybe you're right.
I do know that the size of the tubing from the x-pipe to the Stinger mufflers and from the mufflers to the dual tips is the same size. On the quad tips, the tubing from the mufflers to the quad system's tips is a smaller size. So, I don't know but suspect that a dual tip system with the big tubing would sound different from my "dual tip" system with smaller tubing. All this is guess work on my part. My acoustic engineering training was a long time ago. :flag

 

I had some concerns about the Stingers being to loud, so before I installed them I wrapped the over the axel pipe with exhaust wrap(also to keep heat out) Keep in mind that I have no point of reference except the Corsa Indy that was on the car previously but the Stingers do not seem all that loud. I also noticed when one of the clamps was loose, (not really loose, just enough to move) I had a nasty resonence at idle. I have intake and exhaust + 2 cats.

Pete

 

I wonder how much partially blocking off those two tips increased backpressure. And did it cost you any hp? I guess a few hp for no resonance is a fair trade off.
Just a thought.

How did you keep the plug in the pipe after you drilled out the center?
Can you post a close up pic of your current setup?

 

A good tech solution to an annoying problem. However there are products out there that do the same thing, albeit they cost. I myself installed some CC inserts in the 3" back pipes before my Borla stingers, to change the sound wave that my system was creating. Great performance sound but awful cabin resonance, especially at low speeds. Witout opening a can of worms, there was those that claimed Restriction, Restriction. Well stock exhaust is 2 1/2" and two sets of catalytic convertors. Has anyone seen a catalytic convertor internals, talk about restriction!!. At any rate I have the sound I want without 90% of the unwanted resonance. Its called tuning.

 

Here are the pictures:
First, the plug as it comes from Home Depot.



Second, the first modification. Make the two washers the same by taking the small washer from a second plug assembly.


Third, the plug as installed.



I used four 1/4 inch machine screws to replace the center bolt. Smaller screws would work fine. I used what I had on hand. Drill and tap the inner washer.

Final step will be to paint the installed plugs with high temp flat black paint.

[Modified by raylat2002, 11:43 PM 6/27/2004]


[Modified by raylat2002, 11:46 PM 6/27/2004]


[Modified by raylat2002, 11:48 PM 6/27/2004]

 

Glad you worked it out. I solved my stinger resonance problem by replacing them with GHLs. Your fix sounds much cheaper than mine.

 

hmm so how easy is it to takes these out then? also is there any chance of them falling out?


what section at home depot would this plug be located in?

thanks

 

Takes maybe 11 seconds to remove each plug. I use a 7/16 socket on a 6 in extension held in my battery-powered drill. You just back the machine screws out until the rubber donut is no longer compressed and then reach in and pull them out. Using something with a hook or bend on the end and sticking it through the hole first helps.
When you tighten all four screws evenly the donut expands evenly against the surrounding tailpipe. It's held pretty tightly.
Can they fall out? Don't know. I'm watching to see how the rubber donut holds up to the heat.
But this is a cheap, cheap solution. The test plugs go for $2.87 ea. You'll need four of 'em and 8 machine screws. If you get self tapping machine screws--they go for about 10 cents each, you don't even need a set of taps.
You can find the test plugs in the plumbing section of Home Depot or Lowe's.
Let me know if you need more specifics.

 

I think this is going to be the key problem with this fix...

 

Quote:
I think this is going to be the key problem with this fix...

Oh, yeah, I think you're right. I'll just have to see how long they last. Replacement donuts are cheap but if they only last a week then this not a good fix.

This began as a "proof of concept" project rather than a long-term fix. I had never heard of someone trying to tune an exhaust. So I thought I'd give it a try.

A long-term fix might be to have a stainless steel washer cut and tack welded in place.

:flag