Would 2-1/2" siamesed exhaust be enough flow for my setup?

Already dual 2-1/2" all the way out, with H pipe. Still droning, so I am thinking of capping one side of the H and running 2-1/2" siamese setup to lose the drone.

Will this provide enough flow for me?

Not a permanent fix, so if still droning, I can hook from H back on that side back up.

 

weld in an O2 sensor bung so you can measure backpressure just before the crossover/X section. otherwise you'll just be guessing. 2.5" is ok for normal driving but full power, high RPM runs are going to be a restriction. My siamesed 2.5" into a single 3" was around 6psi backpressure at the torque peak(highest exh flow). It ran great most of the time but did seem to fall off early. Had great low end tho.

 

Great low torque would be nice. I need to check my truck's setup. I think it is 2-1/2" all the way out, and it has no drone and seems to work fine.

It is 5.7 hemi, 360 hp.

I may just try it out and see. I can always go back if it doesn't work well.

 

Experiment.

I will make a 2-1/2" cap, and cap off the driver side exhaust tip, leaving the entire left side exhaust to act as a resonator.

Then I will take that entire side off and cap at the H-pipe.

And compare seat-of-pants feel and drone.

Should be an easy and cheap experiment.

 

Have you tried dynomat or any other sound deadening?

 

Entire car's floor, trunk, and quarters are covered.

 

Found some calculators online. 330 hp needs 2.75" pipe, especially with the RPMs I am planning on running. But 2.5 is optimum for up to 5500 rpms, and should bump up my torque, as mentioned above.

I think I will just try it, and if it seems to work well, I may bump up the pipe size when I rebuild the setup.

By the way, i measured and my 360 hp hemi has a 2.75 outlet...for what it is worth.

 

Just remember that those calculated pipe sizes are with no additional restrictors, ie: crush bends, sharp bends, mufflers, etc. My 302 dyno #'s were 215hp @ 5200 rpm and 295ft/lbs of torque @ 4400 rpm to the tires, 3.00:1 rear, T5, and the measured backpressure was still just over 6psi at the junction with a 3" crush bent single pipe, flowmaster Y-pipe and 6901 hookers reduced to 2.5" before the Y. This was a stock 92 SEFI 5.0l with only an EGR delete and stock EFI system. Torque is great but top end I feel is restricted, but maybe it's just the heads...

...and it still droned.

Your idea of using the second pipe as a resonator tube is interesting tho, so I'll look forward to hear your results.

 

have you played with chaniging where the turn downs point?
ive heard that pointing them at 45 degree angels from the ground towards the center of the car is suspose make it quieter. the sound pulses are suspsed to hit each other and cancel some of the noise.

 

What about resonated exhaust tips or adding some weights on your exhaust?

 

I have thought of moving my tips, but they are welded on, and I can only twist the muffler/tip section so far.

I have thought of adding weights, but then you have to move them around until they hit a peak on the sound wave. At least I "think" that is what needs to be done.

My current thought is leave the exhaust the way it is, make one cap, slip on, with a quick-release mechanism so that I can pop it off if/when I go to the track and release those last few HPs, but keep it de-tuned and tamer on the street. Weld on 2 small nipples, and add a spring like you would use on a clevis pin to hold it on.

Like the spring portion of this...

 

Or you could just throw a set of turbo mufflers on it ?

 

I just might, but first, I am having fun trying playing with these!

 

i cant find the link but on a mustang forum there was a huge thread about puting a balance tube on the tail pipe. it basicly was a pipe that was teed into the tail pipe that just dead ended. the length of the pipe was 1/2 of the length of the tail pipe. the theory is that the sound pulse will go into the the dead end pipe and bounce back 180 degrees out of phase with the exhast pulses, canceling them out. multiple people on that board reported great sucess doing that.

now i know you dont have tail pipes but i would think the same theory could be applied to the pipes from the headers to the mufflers. they said if there was bends in the pipes that it wouldnt mater because its only sound going through the dead end pipe. so you could bend a 90 degree bend on the sound pipe so it will run parellel to the existing pipe.

i was considering trying this and even takeing it a step further by making the length of the sound pipe adjustable by useing two pieces of pipe that can be sliped over each other and clamped tight. this way it would be tuneable.

 

Just put some over the axle tail pipes on it. Even if you have to dump them behind the tires though the spring, it will change the sound and probably get rid of the drone....I plan on putting a set on mine this summer. Mine drones at 40-45 mph so loud it's hard to carry on a conversation in the car, but below or above that, it's fine. Just the added length behind the muffler will change the sound waves a bit.