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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by Shunyun
@69427 another question:
I just read your thread Exhaust System 4.0 and regarding the two 1.75” from the tee to a 3” collector, do you have any concerns over back pressure? I’m just guesstimating that the extra volume of the two (1.75 x 2 = 3.5) is enough. Or does the mismatch cause worse problems? Two 1.5”? One 3” flattened to 1.5” high (LOL!!!)?
You've completely lost me. Can you rephrase things, because I honestly can't picture what items of those dimensions you're talking about?
You've completely lost me. Can you rephrase things, because I honestly can't picture what items of those dimensions you're talking about?
OK, so I’m proposing to tee off of the side pipe header using two pipes that are the same size as the primaries of the header. Those will route to the 3” pipe of the under-car exhaust. I’m thinking two instead of one 3” because a 3” will reduce clearance further than what the header primaries already occupy.
But in the thread I referenced, you talk about how two smaller pipes are heavier and introduce more back pressure than one larger pipe of equal volume.
As others have mentioned, my challenge is that I’m trying to build a dual system using hooker style side pipes - long tube headers to 4” side pipes and a 3” under-car pipes - instead of a shorty header to two equally sized pipe systems. I think the systems you’ve built have been the latter, yes? My problem is that using a 3” pipe to connect the side collector to the under car pipe reduces ground clearance by 3”.
So maybe I should be asking how to calculate the required o.d. if I use multiple smaller pipes.
Respectfully, I think the way you're going at this is going to be a Grade A headache, but it's your time, money, and head.
As I said before, keep us updated with progress pictures.
I’ve come to that same conclusion. Seems that if I want to use long tube headers with side pipes then I’m pretty much stuck with a 3-4” od collector. And I just don’t see a practical way to do a dual system with that. And for that matter, I don’t see a practical way to add a cross pipe as well.
You don't have the room for all the piping. And if you tie into the collector you need to somehow shut off the flow to the side pipes otherwise most of the flow will take the path of least resistance. Works that way with electricity works that way with exhaust gas works that way with sewage.
How about working something out with a baffle type system for the side pipes that could be changed to muffle sound more in some conditions and allow free flow in others?
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How about working something out with a baffle type system for the side pipes that could be changed to muffle sound more in some conditions and allow free flow in others?
I can swap the side pipes (with inserts) in about 10 minutes. There are solutions that let you cap and uncap the straight-thru sections much faster (for example, spiralturbobaffles.com).
The very best part of sidepipes is the room they open up under the car. And the look. The sound, well, I can drive around in town, but I need earplugs for the highway. Any of the proposed solutions would add a lot of weight and complexity. But would be nifty if they could work.
For the pulse issue, you need headers that trade pipes from side to side (much like your distributor cap does with one pair of wires). Here's a link for that, though I don't know how you'd make that fit a C3, though you could convert your car to a flat-plane crank. https://www.motortrend.com/how-to/18...drange-torque/
In the achievable category, have you thought of exhaust cutouts that divert to a flat "NASCAR" style exhaust tips to fit under the frame rail? If you used a set of 69 side-pipe covers, no one would know that you didn't have actual sidepipes.
These are all really inventive ideas,,, but honestly, way too much effort and expense for no real gains other than “look what I did.”
Not really sure what your end goals are,,, more HP , less exhaust noise, or just cool effects. I think you’ve found your limits on this idea.
And for more HP there are way easier and less costly ways to get it from a SBC engine. But, truly entertaining reading,,
TBH it’s just that I want both. I already have a decent 3” system with a custom rear (see pic at top of the thread). If it was all about performance then I’d just stick with that. But I also want the side pipes! And I enjoy exploring “what if”. But I think it’s just too complicated, for now. So I’m just going to go for the side pipes and be happy with that.
