SuperTrapp SuperMet 2 to 1 exahust, how to dyno

[Thumper Buttercup]

Here are two 2011 FLHRs with stock 103 motors and HQ500 cams. One has the SE air cleaner, and the other has the SE Heavy Breather. The lower curves are with 20 discs and a closed end cap, and the higher curves are with 26 discs and closed end cap. In each case increasing the disc count improved the torque curve. Throttle response and driveability is also better. I realise that different combos will behave differently, but Supertrapp's tuning guide needs updating for the modern era. We're not working with 80" engines any more.
14 discs is a butt plug once we bring cams into the equation.

OK, I guess I resemble the "butt plug" remark .

So lets talk our setup

95 .010 over SE flat pistons
Original heads reworked by larry, Stage one & squish grooves
bee-hive springs 84 cc's measured
(Valve sizes were not changed)
48N Andrews cams
HPI 51mm intake and HPI Back-plate and breathers
Exotic air filter
OEM injectors 8 degree 4.35
Cometic .030 head-gasket with checked zero deck height
SuperTrapp SuperMeg 2 to 1 exhaust


Now the way she pulls and runs our dyno butt is saying it
is doing great here, we do listen to our stereo all the time
riding, and when on the road we have rode as much as 650
miles given the right day.

Now lets talk MPG, am I killing that here also???

So should I keep where we are and try the timing to cool this
down or should I open the pipe up a couple more disks???

Or should I just get this close and plan on having to go true dual
pipes for better flow and keeping her quiet??

[Sonny S.]

No less than 18 discs...IMHO.

[Sonny S.]

oh...and DO NOT over tighten the mounting screws. You will reduce flow by flattening out the discs

[mayor]

Mayor can post my dyno sheet showing more torque at 3000 RPM's with more discs

Cool. That would resolve my original question on disc count and mid torque.

[strokerjlk]

24 disks and a closed cap. Is where i would start
14- 16 disks and open cap. If noise wasn't a issue.
18 and closed is the least amount Imo as well

[Thumper Buttercup]

24 disks and a closed cap. Is where i would start
14- 16 disks and open cap. If noise wasn't a issue.
18 and closed is the least amount Imo as well

OK, we loaded her up with 18 disks and a closed endcap.

I'll take this back to the post on tuning.

[Thumper Buttercup]

OK,

   I jumped the gun last year, we thought the bike was way loud
and went to pull disks, I remember two of the bolts breaking and
having to pull the whole chamber out to get to the bolts.

When we pulled the chamber the packing was messed up and burnt
on one end, we repacked it and taped it into place and pulled the disks
and kept riding.

We'll last night we pulled the disks off and looked through the bolt holes
and the packing looked good and we added the disks and got back
to 18 and a closed end cap.

The bike is not loud like it was last year, it is great with all the disks back
in and it made a huge difference in the bike today.

Thanks for all the input guys.

[Powerglides]

I appreciate the position that you find yourself in regarding noise level versus performance with the Supermeg. What you may wish to consider, as an experiment, is to add more discs (my guess is that 24-26 with a closed cap will give optimum performance), and see if you can tolerate the extra volume. Once you get to the point that enough noise is enough, accept it, and tune from there.
Personally, I wish Supertrapp would bring out a 5" muffler for the baggers, like they have for the V-Rod, so we can have the power that our parts combinations give us, without having to tolerate too much additional noise.

[msocko3]

I appreciate the position that you find yourself in regarding noise level versus performance with the Supermeg. What you may wish to consider, as an experiment, is to add more discs (my guess is that 24-26 with a closed cap will give optimum performance), and see if you can tolerate the extra volume. Once you get to the point that enough noise is enough, accept it, and tune from there.
Personally, I wish Supertrapp would bring out a 5" muffler for the baggers, like they have for the V-Rod, so we can have the power that our parts combinations give us, without having to tolerate too much additional noise.

I'm running 25 disk with a closed cap for my HQ120 with the 0033 cams, it is only a touch louder than my previous HQ95 with 0039 cams was with 18 disk and a closed cap. One of the things I love the most is I can get decent torque and not make a bunch of racket, I can still hear the stereo.

[Sonny S.]

24 disks and a closed cap. Is where i would start
14- 16 disks and open cap. If noise wasn't a issue.
18 and closed is the least amount Imo as well

I had said I went from 22 to 18 and a closed cap to quiet mine down a little. Well I hadn't put but about 20 miles on it. After a few rides the mid to top end power was noticeably....Less !
The bike didn't run horrible...but was noticeable.
I went back to 22 and the power was back, and the noise level wasn't much different.
22 is no problem with stock mounting bolts.
I believe your pipe came with 20. I would put them in if it were me.
Stock heads would be a different story. Larry's heads flow very well.

[Thumper Buttercup]

We'll add the last two and see how it goes tomorrow with the new
tune.

Check the General forum, I fixed our Supermegg with a John Deere
clamp and went back to the original 04 transmission mount for the
header pipes.

This clamp they had was really beefed up where it goes though the
tranny mount.

[Thumper Buttercup]

We'll Guys,

   We added the last two disks to give us 20 + closed end-cap, it
was a hot one today but the exhaust was not.  There was a drone
with the 18 disks and end cap that went away with the extra two
installed, the exhaust is actually quieter so all is good.

    Also a noticeable increase in power on the bike so we are happy.

[Winston Wolf]

Here is the difference in the curve a few discs can make. These are with an open end cap, which is equal to about 10 discs.



You will see on a dyno that there is a point where adding more discs doesn't change anything and midrange starts to suffer quite a bit, in my case it was 20 and open (so about 30 closed).

[mayor]

interesting.  was there any jet changes before run 15?  It looks like the afr went richer, which likely indicates the the air may have been stalling.  Did you try advancing the timing at 3k and 3.5k to see if you could burn some of that fuel? 

[Winston Wolf]

interesting.  was there any jet changes before run 15?  It looks like the afr went richer, which likely indicates the the air may have been stalling.  Did you try advancing the timing at 3k and 3.5k to see if you could burn some of that fuel?

Same jetting on each run. I didn't adjust the timing this session either. Thats only changing discs. I've taken a lot of timing out of my timing map to get rid of detonation in that range.  Could be a little improvement to be had...