SSI 2k RPM Drone Is Horrible!

[David Inc.]

I think I'm going to try the car chemistry inserts in my GT3 style Dansk, and can record the difference. Mine drones a little higher--right about 2500--so I need to put something in place. I've used a cap before, which works, but it looks a bit ****.

[jhynesrockmtn]

This is a message I got from Brian about my M&K.

Jerry,
The muffler you have is an MKM26 dual out sport muffler. Either side can be capped. The only change in sound volume will depend on which side is capped. Cap the driver's side and all the sound comes out the passenger's side which of course will be a little less loud for you in the driver's seat. We have internal caps that slide inside the tailpipe stub-out and are then captured when the tailpipe is bolted back on. That also allows you to retain the dual out look.



I bought the car chemistry inserts and they do help. I don't have many miles on them yet. I did this toward the end of the driving season last year.

[scarceller]

Do not lug these engines below 3000RPM, it increases head temps tremendous amount. It's the primary reason for failed valve guides! Increased head temps from lugging these engines especial in hot summer climates will quickly destroy valve guides. Ever wonder why some engines need new valve guides at 40K mile while others can go 200K miles with minor guide wear? This is the primary reason.

Originally Posted by Jeff Higgins

I consider anything under 3,000 rpm to be "lugging" it. Unless I'm more or less coasting down a hill, or rolling to a stop. In other words, under little or no throttle. If I'm on the throttle at all, even light throttle around town, I try not to let it drop below 3,000 rpm, although I won't get upset if I let it go down to 2,800 or so very briefly. That means I'm shifting at 4,000 rpm or so any time I'm accelerating, even at a "polite" pace around town. These motors really thrive on this treatment, living long happy lives at a little higher rpm than you might be used to, if you are coming from other types of engines. These are not American V8's - they really like spinning up, even under light throttle. Try it for awhile and see how much happier both you and your car are, being a little more "playful", even when slogging through town.

[scarceller]

Have a picture of the muffler you are using? I was curious if the GT3 style muffler outlets droned, thanks for posting.

Originally Posted by s2k9k

Recently installed SSI heat exchangers with SSI GT3 center exit exhaust on my 1980 911SC. Sounds amazing on idle and highway speeds. No drone at all. But in town driving between 1800-2100 RPM, the drone is so loud its causing headaches. Is this with all dual exhausts? Might just have to go back to 2 in, 1 out if the droning is this bad with dual exit.

[pmax]

Originally Posted by scarceller

Do not lug these engines below 3000RPM, it increases head temps tremendous amount. It's the primary reason for failed valve guides! Increased head temps from lugging these engines especial in hot summer climates will quickly destroy valve guides. Ever wonder why some engines need new valve guides at 40K mile while others can go 200K miles with minor guide wear? This is the primary reason.

OP's situation is about running around town.
Downshifting from 2nd at 3000 rpm means 5500 in 1st at a leisurely 30 mph.

I would like to know who shifts our beloved 915 like that on the street !

[snbush67]

Originally Posted by pmax

OP's situation is about running around town.
Downshifting from 2nd at 3000 rpm means 5500 in 1st at a leisurely 30 mph.

I would like to know who shifts our beloved 915 like that on the street !

2nd gear at 1800 would be 20 mph. Op’s situation is town driving between 1800-2100 RPM, most likely in 3rd gear, when he would probably be better in 2nd gear at 3000 rpm.

And, you can probably only get one or two shifts from 2nd to 1st whilst moving faster than 10 mph before your 915 explodes.

[pmax]

Originally Posted by snbush67

2nd gear at 1800 would be 20 mph. Op’s situation is town driving between 1800-2100 RPM, most likely in 3rd gear, when he would probably be better in 2nd gear at 3000 rpm.

And, you can probably only get one or two shifts from 2nd to 1st whilst moving faster than 10 mph before your 915 explodes.

Yes, agreed.

At 30 mph, better off in 2nd above 3K than in 3rd.

2nd is the workhorse around town so there's no getting away from lower rpms than 3K but that doesn't necessarily mean it's lugging the engine, it all depends on the throttle.

[jadesculptor]

Originally Posted by scarceller

Have a picture of the muffler you are using? I was curious if the GT3 style muffler outlets droned, thanks for posting.

Sal, I have the M&K two in, two out GT3 style on my SC. It does drone, but after adding the baffled tips it is much better. Pretty much all of the 2 in 2 out mufflers drone to some extent.

[David Inc.]

Originally Posted by jhynesrockmtn

This is a message I got from Brian about my M&K.

I bought the car chemistry inserts and they do help. I don't have many miles on them yet. I did this toward the end of the driving season last year.

Did you pack the baffles with wool and use either of the restrictor caps? Mine are being delivered today and I'm not 100% settled on using the restrictor and wool.

[jhynesrockmtn]

Originally Posted by David Inc.

Did you pack the baffles with wool and use either of the restrictor caps? Mine are being delivered today and I'm not 100% settled on using the restrictor and wool.

I did use the steel wool. I want to say I put the cap with the hole in it on before install but can't remember for sure.

[RarlyL8]

Engine output needs to be considered when adding baffles. If adding packing material to the CC inserts you end up with dual 1-1/2" ID tailpipes. The object is to interrupt the pulse organization at specific RPMs that causes the drone. We typically add butterfly baffles to each tailpipe or internally cap one tailpipe for total elimination. Note that the louder the muffler the more drone can be an issue. Quiet mufflers include the padding or baffling to adequately disturb the annoying pulse organization.

[eastbay]

BTDT



popular at the car show

[Billthebuilder]

Quit messing with all the hi tech options just stuff a potato in one side

[dedyplay]

It's your muffler.

[David Inc.]

I've been thinking mufflers again and found this thread where I never followed up. I put two car chemistry baffles in my muffler, both with one restictor cap, and packed them with stainless but offset. On the left the packing is in between one baffle pair, on the right it's a different pair. The drone is totally eliminated and I don't get loud pops on the overrun, but it's about the same volume overall. They're easy enough to pull out when I get to the track, too, so I can go full noise.

If I didn't have a wife and a toddler I'd say job well done, but it's unfortunately still too loud to turn it on during nap time.

[Antomero]

I just ordered the new: SSI HOEING C3.2 PLUS EXHAUST, WITH TWO Ø70 MM TAIL PIPES, DUAL INLETS, Ø41/Ø60 MM HEAT EXCHANGERS.

It’s for my 84 3.2 Carrera. Should I expect any drone?

[Antomero]

This is the new setup!

[darrin]

Antomero -- while I have no personal experience with this particular setup, dual out mufflers are pretty notorious for droning when installed on our cars. Folks have had good success with mitigating the drone by blocking/capping one of the outlets. Single outlet mufflers generally avoid this droning issue.

[Antomero]

I’m hoping this new system was developed and designed to eliminate the associated drone.

[vanda]

Hi,

I also have an M&K 2 in 2 out sport, the drone was really bad. The performance of the system especially the headres is so good, that i am not even mad.

I found a solution for the drone, not a quick fix, but a major improvement, maybe brain will use it as the next iteration for the muffler.

The pictures are before and after.

Best
Jonas