How to kill drone

[Topless]

I will try extending the pipes a little. (I have cones made up, that when in place move the tips out another half inch.)

Oh, and I just placed the Dynaplate in the back loose, and it seems to help. I will just have to make time to pull the back apart to install it properly.

Yes, 3" is probably overkill, but I can use the cones to get additional backpressure if I need it. Compared to the stock exhaust though, the engine pulls harder at higher RPMs.

 

[Topless]

How heavy is dynomat?

Depends on how much you use!

Seriously, their website has the details. I am using "-plate" instead of "-mat" because it is lighter. Acording to their website, two layers of the plate is as effective as the mat, and weighs less.

 

[84Turbo]

I will try extending the pipes a little. (I have cones made up, that when in place move the tips out another half inch.)

Oh, and I just placed the Dynaplate in the back loose, and it seems to help. I will just have to make time to pull the back apart to install it properly.

Yes, 3" is probably overkill, but I can use the cones to get additional backpressure if I need it. Compared to the stock exhaust though, the engine pulls harder at higher RPMs.

When does one need more backpressure??????

 

[G Winter]

When does one need more backpressure??????

Back pressure has an effect on drone.

Glenn

 

[84Turbo]

Back pressure has an effect on drone.

Glenn

That's a very inefficient way of "effecting the drone".

 

[Topless]

Back pressure also effects the HP and torque curve. More back pressure will trade HP for torque.

 

[ken mohr]

Corsa. No drone, straight through exhaust.

 

[Topless]

Corsa. No drone, straight through exhaust.

Mine sounds better, and that is from Corsa owners.

I might even have the drone fixed... stay tuned.

 

[Tuna]

Mine sounds better, and that is from Corsa owners.

I might even have the drone fixed... stay tuned.

Even Corsa owners like 'loud, agressive' sounding exhaust when they are standing outside the car but take them for a road trip for a couple of hours and see what they say. Different story then after they endure the drone also.

Corsa exhaust gained 22 HP on my old '92 when I installed it - dyno'ed before and after - so I guess it depends on the level of modifications you have on your engine as to whether your exhast makes more HP difference than the Corsa. If the car is going to be used on road trips regularly and daily comutes, I'd rather live without the drone.

 

[tenaus]

exhaust drone

I have an 89 vert and have the same problem. I changed my catback to a "quieter" one and it got better. This weekend I put my hardtop on and the drone is back. It must come through the back where the softop resides because the hardtop is pretty well insulated and would allow less noise in. I'm probably going to try and put sound deadener in the back only and see what happens.

 

[84Turbo]

Back pressure also effects the HP and torque curve. More back pressure will trade HP for torque.

Uh, no. More backpressure just kills both horsepower and torque. Period.

 

[Topless]

Uh, no. More backpressure just kills both horsepower and torque. Period.

I know you have had this debate before with others on this forum, and frankly just don't feel like rehashing this just so you can justify your need to be antagonistic.

 

[bucket]

years of riding custom harleys with open exhaust has left my hearing challenged in my right ear..
quiet is good, sometimes

 

[Topless]

I have a sport bike with undertail exhaust. I can hear, but occasionally I am sitting on the hot seat.

 

[Hib Halverson]

I have a custom built 3" cat-back exhaust, with x-pipe and no mufflers. (snip)

With the above described exhaust, no amount of Dynamat or any other attempt at acoustic management for that matter, will solve your problem.

You're going to have to choose between an exhaust so loud that everyone within two miles knows you're coming and putting on a system which has mufflers adequate enough to make a noticeable reduction in drone yet not excessively reduce performance.

A C4 exhaust which works quite well at the 500 hp level but still quiets the exhaust such that the 1800 rpm drone will be greatly reduced is discussed at:Corvette Action Center Knowledgebase :: 1992 - 1996: Tech Article: Quietly Powerful: How to Build a C4 LT1/4/5 Exhaust that Gains 28 hp and...is Quiet

 

[84Turbo]

I know you have had this debate before with others on this forum, and frankly just don't feel like rehashing this just so you can justify your need to be antagonistic.

You're aware of the previous thread dismissing the myth of backpressure helping torque, and yet you go ahead and continue to try to propogate this untruth anyway???? Why??? There are new people coming on this forum, and they don't need to be misled by your fantasies about how an engine works.

I'm an engineer. I don't regard facts as "antagonistic".

 

[Topless]

Hib-
Nice write-up. I will follow your lead with the Thermo-Tec. (and get a little extra for the bike!) A question thought, are you running factory cats? And if so, does the ZR-1 have the same dimple after the cat on the passenger side as the LT1/LT4s? (no one ever seems to talk about that one)

As for being loud, mine is only loud went you open it up. Driving along next to it on the freeway (cruise), you cannot hear it. Now, if you down shift and pass, it is noticeable. In the neighborhoods, it is no more noticeable than any other system out there with mufflers (Corsa, Flowmaster, Borla, etc). Part of this, I am told, is where my X is in the system, and the other is how it was constructed.

The DynaPlate helped with noise at cruise (65+), in fact I hear more road noise than exhaust now. Holding a conversation is no longer a shouting match with the passenger. However, at 55 I still hit a drone that I know will never be solved with my system. I never did like driving double nickel anyway!

 

[Hib Halverson]

I run the stock cats...as the car is registered in CA, it's just easier to deal with the hated "Smog Check" by running OE rather than aftermarket cats. As for the "dimple"...right now, the car is stored elsewhere but I have a second set of LT5 cats in my parts room. I just looked. No "dimples" that I can see.

 

[Topless]

Hib-
I tried to get a picture of the spare set in the garage. Can you make out the indention in the pipe? (got home late, so best I could do on the quick) I have found this on LT1/LT4s I have been able to get a look at. Cat-backs would not solve the issue of the factory crimping the pipe. Just curious why I have not see this brought up in any exhaust threads.

-M

 

[CROOZ1N]

Nice nipple ... Uh i mean dimple. You think this is standard? I'll have to check mine.