CFR Comparison

[Tom O.]

I've never been a big fan of CFR but WOW what a difference in usable power.

From the GMR Performance Facebook page:

"Here is the same build with the two runs showing the Fulsac DX pipe with CFR mufflers vs the DD zilla. Now to be clear the Fulsac pipe is NOT the issue. Those mufflers are. Look at the loss of low end TQ . That is over a 66% loss of tq at 2500 rpm. the mid dip on the CFR run was corrected by 2 ftlbs but that was as good as I could get it. SO however you want to look at it. That is back to back data." (See attached dyno sheet)

 

[hulkss]

I've never been a big fan of CFR but WOW what a difference in usable power.

The CFR's are a big, loud, open muffler that is not working well at all in this case. Two big diameter mufflers drop the exhaust flow velocity too low and cause the loss of torque at the bottom end.

Here's a plot showing the difference with a stock cam and 1.75, 2.00 and 2.25 inch diameter muffler cores with the Fullsac headpipe.

 

[CousinKAP]

interesting data...

my take....

these bikes are slow and will always be relatively slow unless you invest a ton of money... Worrying about 5-10 hp and x amount of torque seems silly to me.

maybe I'm jaded because I grew up riding sport bikes and went pretty fast and I came off a v-rod and that was slow to me.

 

[Tom O.]

I guess if you're going to run consistently on the top end of the RPM's that type of muffler would be beneficial.

My main reason for posting is that I see quite a few people that run this type of set up. CFR seems to be a popular name. I know its all subjective, sound, performance and so on but I was actually shocked to see such a big loss in power where it matters most for the average rider.

 

[Tom O.]

interesting data...

my take....

these bikes are slow and will always be relatively slow unless you invest a ton of money... Worrying about 5-10 hp and x amount of torque seems silly to me.

maybe I'm jaded because I grew up riding sport bikes and went pretty fast and I came off a v-rod and that was slow to me.

You're right. It takes a ton of money to make these things even close to being fast.

There's about a 40hp and 61tq loss on the low end. That's pretty dramatic in my book. Looks like it doesn't catch up to the D&D until around 5K. I am guessing this would be a little less on a smaller engine. I think this one was a 113.

I guess I just expected better from CFR. Seems to be pretty popular on the forums from what I have seen.

 

[CousinKAP]

i understand. I have CFR but I personally went for sound over performance for the above reason. I figured I'm not trying to zoom everywhere super fast and the sound was just too good to pass up when matched with dresser duals. just my opinion. I think even if i spent a ton of money on motor work it will never be where I want it to be. Once you are exposed to sport bikes yamaha r1's and the like these are like scooters...

The info was interesting ....maybe if i would of known this i would of went a different route...there was a brand i was interested in but it was a solo setup...i would of needed to buy the ghost pipe.

 

[OldMike]

interesting data...

my take....

these bikes are slow and will always be relatively slow unless you invest a ton of money... Worrying about 5-10 hp and x amount of torque seems silly to me.

maybe I'm jaded because I grew up riding sport bikes and went pretty fast and I came off a v-rod and that was slow to me.

These are good points, I rode mostly Harley but recently a ZX10R and Vrod, the Vrod is fun but slow. Touring bikes are fun but slow, they are more fun when you concentrate on torque. Have to go easy on the large, open exhaust and long duration cams. You are rarely going to use the upper RPM's, but be careful with too short of duration cams with high cylinder pressure and pinging. Find a balance.

 

[BluesBelly]

These are good points, I rode mostly Harley but recently a ZX10R and Vrod, the Vrod is fun but slow. Touring bikes are fun but slow, they are more fun when you concentrate on torque. Have to go easy on the large, open exhaust and long duration cams. You are rarely going to use the upper RPM's, but be careful with too short of duration cams with high cylinder pressure and pinging. Find a balance.

Pretty much trickles down to three categories of scooter, Road racers, Touring bikes and Bar Hoppers. Buying one style and trying to make it something it's not seldom works. Expecting a touring bike to live at high RPM is as unrealistic at taking a cross country ride on a bar hopper. So yes I agree that when Harkey engine modification exceeds a so called stage two it's fun but unrealistic at least in my experience.

Blues

 

[Tom O.]

Buying one style and trying to make it something it's not seldom works.

Kind of like when I tried to squeeze some more hp out of my old Honda VTX 1300 so I could keep up with my Harley riding buds. Didnt work out so well, I ended up buying a Harley instead. lol

 

[15StreetGlideS]

Go with the Bassani DnT pipes. Sound like CFRs but have a 3 stage baffle to help with back pressure. They sound great.

 

[14 FLHX]

My stage one with CFR slip ons.



My stage 2 ( wood 222 cams) crusher slip ons

 

[Bafflingbs]

Go with the Bassani DnT pipes. Sound like CFRs but have a 3 stage baffle to help with back pressure. They sound great.

I know, old post, but, this is fantastic advice.

 

[Mojo]

Good numbers 14 FLHX !