Exhaust Backpressure

[Dray]

I am thinking about building a custom exhaust for my 2017 F3L
and the question of backpressure or lack thereof raised its head.
I would cut off the oem header pipe about 2" in front of spring
hooks and run exhaust pipe back to a 2" inlet x 18" long bullet
style glass pack mounted pretty much where the oem muffler
was mounted. There would be 45 degree "S" curve in the pipe
to get it outside of the frame. I would also use the oem muffler
heat shields on the new muffler. So, would this create enough
backpressure to keep everything happy? I did a temporary
mounting of the muffler and this gives me a deeper exhaust
note that I am happy with.
Feel free to jump in here with experience/opinions.

Dray:yes::yes::yes::yes:

 

[BLUEKNIGHT911]

BACK PRESSURE

IMHO , if you guess what your back pressure was ... it's going to be very difficult to get a new one that mimics your Old back pressure. I think you should have your current Back pressure tested ( to verify what it is ) before you proceed. Back in the Day, folks were putting straight exhausts on all types of combustion powered vehicles and would swear it was now Faster than a speeding bullet :roflblack: .... But a dyno test usually proved they actually LOST Power.....good luck with this .... Mike :thumbup:

 

[Dray]

Hey Mike, My muffler guy says used automotive cats have about 6 ozs.
of backpressure. Thinks mine should be about 1/2 of that. I do know that
the cat material in my cat is about 4" or 5" deep and the width of body
at inlet pipe. I will probably play and see how it works out.
Thanks for your input!

Dray:yes::yes::yes::yes:

 

[BLUEKNIGHT911]

back-pressure

Hey Mike, My muffler guy says used automotive cats have about 6 ozs.
of backpressure. Thinks mine should be about 1/2 of that. I do know that
the cat material in my cat is about 4" or 5" deep and the width of body
at inlet pipe. I will probably play and see how it works out.
Thanks for your input!

Dray:yes::yes::yes::yes:

Here's the important statement " muffler guy SAYS used auto Cats have ABOUT 6 oz of B-P " ..& .." Thinks yours should be about 1/2 of that " ..... I think SEAT of the Pants testing is going to be a long process..... good luck ....keep us posted ........... Mike :thumbup:

 

[Dray]

Yep, I think you are probably right. Muffler guy said come by and we would
do a before and after check for a baseline. I will probably take him up on it.

Dray:yes::yes::yes::yes:

 

[Wildrice]

I am thinking about building a custom exhaust for my 2017 F3L
and the question of backpressure or lack thereof raised its head.
I would cut off the oem header pipe about 2" in front of spring
hooks and run exhaust pipe back to a 2" inlet x 18" long bullet
style glass pack mounted pretty much where the oem muffler
was mounted. There would be 45 degree "S" curve in the pipe
to get it outside of the frame. I would also use the oem muffler
heat shields on the new muffler. So, would this create enough
backpressure to keep everything happy? I did a temporary
mounting of the muffler and this gives me a deeper exhaust
note that I am happy with.
Feel free to jump in here with experience/opinions.

Dray:yes::yes::yes::yes:

After I installed the Cat bypass with Big city Thunder I lost some power from a dead stop & couldn't burn rubber anymore--then I found out if I took it up to 10-15 mph I could spin the rear tire. I'd like to tone down the sound a bit--I've considered taking the standard stainless steel baffle that came with the by pass pipe---cutting it in 1/2 installing it along with the Big City Thunder baffle to add a touch of off the line power & tone down the sound level. It won't fit in it's entire length thus the reason for cutting 1/2 off. & installing it at the pipe just prior to the muffler.