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CK5
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'72 K5 - Greg's @MightAsWellK5 Build
- Thread starter Greg72
- Start date
This is the build description. I will improve this later. (GB)
If you're concerned about the clearance on the sides of the tank, lift the truck by the end of the framerails and try to twist the frame up a little. May not be accurate but it will give you an idea of how much flex is in there. With all the tubing you have in there from the cage it shouldn't be bad.
2016.02.24 - UPDATE! - PRESSURE WAVE TERMINATION BOX...???
Say whaaaa?
I have to be honest. When I bought the David Vizard book "How To Build Horsepower" a few weeks ago, I thought I'd get a lot more detail on exhaust design and optimization. It turns out to be the VERY last chapter in the book and other than learning to scale muffler flow rates at 2.2CFM per HP of engine power, it didn't tell me much about how to plan for resonators or size them, or what truly qualifies as a "resonator" in the first place.
From what I can tell, a resonator is nothing more than a volume of air inside a container... which sounds a lot like a typical Flow-through muffler design. In fact, he even mentions that a "gutted" muffler housing can be used as a resonator if you want.
He did make mention of something called a Pressure Wave Termination Box, which sounded cool... but the only thing he really showed was this illustration:
So basically in my application, it needs to be 500 in^3 of displacement, and should be somewhat "triangle-shaped" to match the photo.... Does that mean truly conical in real life? Or can it be flat on the top and bottom as long at the sides have a taper to them? What about the proportion of the triangle itself? Looks to be about 50% longer than it is wide.... so if I'm dumping a 3" collector into it, maybe 9" wide and then 12" long???
It looks like the incoming pipe needs to overhang by maybe 1/2 of it's diameter as well (Approx 1.5")... if the diagram is really drawn to scale.
Anyway, it's kind of annoying. If a resonator / PWTB is such a valuable way to maintain low-backpressure while effectively reducing noise.... you'd THINK he would have spent a bit more time talking about the basic criteria for building one.... and which characteristics can be modified to move the resonance points around....
Has anyone seen a decent article on Pressure Wave Termination Boxes? This will ultimately get built and installed inside my torsion box area, so I've got a VERY flexible space to build whatever I want / need.... I could buy an off-the-shelf resonator from Vibrant or whoever... but if I could build what is basically just an "exhaust expansion tank" for my specific engine size and HP, that would be way cooler and would probably work better too.
-G
Say whaaaa?
I have to be honest. When I bought the David Vizard book "How To Build Horsepower" a few weeks ago, I thought I'd get a lot more detail on exhaust design and optimization. It turns out to be the VERY last chapter in the book and other than learning to scale muffler flow rates at 2.2CFM per HP of engine power, it didn't tell me much about how to plan for resonators or size them, or what truly qualifies as a "resonator" in the first place.
From what I can tell, a resonator is nothing more than a volume of air inside a container... which sounds a lot like a typical Flow-through muffler design. In fact, he even mentions that a "gutted" muffler housing can be used as a resonator if you want.
He did make mention of something called a Pressure Wave Termination Box, which sounded cool... but the only thing he really showed was this illustration:
So basically in my application, it needs to be 500 in^3 of displacement, and should be somewhat "triangle-shaped" to match the photo.... Does that mean truly conical in real life? Or can it be flat on the top and bottom as long at the sides have a taper to them? What about the proportion of the triangle itself? Looks to be about 50% longer than it is wide.... so if I'm dumping a 3" collector into it, maybe 9" wide and then 12" long???
It looks like the incoming pipe needs to overhang by maybe 1/2 of it's diameter as well (Approx 1.5")... if the diagram is really drawn to scale.Anyway, it's kind of annoying. If a resonator / PWTB is such a valuable way to maintain low-backpressure while effectively reducing noise.... you'd THINK he would have spent a bit more time talking about the basic criteria for building one.... and which characteristics can be modified to move the resonance points around....
Has anyone seen a decent article on Pressure Wave Termination Boxes? This will ultimately get built and installed inside my torsion box area, so I've got a VERY flexible space to build whatever I want / need.... I could buy an off-the-shelf resonator from Vibrant or whoever... but if I could build what is basically just an "exhaust expansion tank" for my specific engine size and HP, that would be way cooler and would probably work better too.
-G
It seems to me that is very similar to a hemholtz.. With regards to the setup and sizing it properly I'd be more inclined to get it running and tune from there, you are likely to end up with some strange resonance that could be deafening.. I was not sold on resonators until recent, I removed the intake resonator on my 6.2 and just about went deaf, it still has an audible resonance but it's much more reduced and live able.. The funny thing is those black widow mufflers use what looks to be similar to the principle he suggests, they are triangular inside the case.. I wonder if pairing one of those with a nice large case magnaflow or dynomax would eliminate any drone.
Yeah, I've seen the Helmholtz resonators before....kind of like a big "J tube" hanging off the side of the exhaust pipe... but from what I remember they are mounted a LOT further back in the exhaust system. Not sure if they go before the actual muffler or after... I'll have to read up on that one again.
-G
I wouldn't know how effective they would be before.. It's sure to be a tuned type of deal.
That resonator behaves as an exhaust tip as far as the engine is concerned - in that it's not really controlling as a wave at that point. the only reason I could see to make them triangular like that would be to help w/ flow - trying to get around that 90 after all the gas has expanded would be turbulent.
I have a feeling that an overly large muffler may do something similar.
I have a feeling that an overly large muffler may do something similar.
If you wanted to get really into it, run that thing on a dyno and put resonators or hemholts's in the hotter sections of the pipe - that's where youd have a standing wave.
That sounds like fun.. I wanna go if you do that..
Vizard doesn't have that much detail because they don't install resonators on dynos. In fact, many of his recommendations (particularly for valvetrain) aren't very practical for real world applications and wouldn't last very long on a street driven vehicle.
I think where you put the resonator (distance from the collector) is going to be more important than shape of the inlet, assuming the inlet shape(or the whole resonator) doesn't restrict flow. I think you should use some of the Flowmaster "outlaw" mufflers as resonators. (the ones that don't have any packing in them, but several stepped wide open chambers) They make them in stainless, they have no packing, and could give you a little of the flowmaster rumble without the reduced flow of a typical chambered flowmaster. They are usually a slightly larger tube with steps inside of it, like these...
If you want to you could probably make something just like them out of 304 instead of 409 if you want it to look nicer.
http://www.flowmastermufflers.com/?page_id=451&partno=815430
http://www.flowmastermufflers.com/?page_id=451&partno=815430S
They filter out some of the higher frequencies and give you a lower tone.
Also, I've seen first hand where that 2.2 cfm/hp doesn't work in real life, so I wouldn't put too much emphasis on it. Just stick with your dual 3" with high flow quiet mufflers (like the Borla XS) and add some "resonators" if you want, but don't get too carried away with the resonator and spend 2 months designing a custom one that does the same thing as something you can buy for $80 or whatever they are. Also, just an empty chamber is going to lose flow as it expands and contracts, creating turbulence, I think you want more control than that, which is why they have angled ends and perforated through tubes on most mufflers with higher flow.
You can always contact Burns stainless, they have a lot of experience and software programs that can recommend an exhaust size and diameter and also header collector size, length, primary tube length, etc.
I think where you put the resonator (distance from the collector) is going to be more important than shape of the inlet, assuming the inlet shape(or the whole resonator) doesn't restrict flow. I think you should use some of the Flowmaster "outlaw" mufflers as resonators. (the ones that don't have any packing in them, but several stepped wide open chambers) They make them in stainless, they have no packing, and could give you a little of the flowmaster rumble without the reduced flow of a typical chambered flowmaster. They are usually a slightly larger tube with steps inside of it, like these...
If you want to you could probably make something just like them out of 304 instead of 409 if you want it to look nicer.
http://www.flowmastermufflers.com/?page_id=451&partno=815430
http://www.flowmastermufflers.com/?page_id=451&partno=815430S
They filter out some of the higher frequencies and give you a lower tone.
Also, I've seen first hand where that 2.2 cfm/hp doesn't work in real life, so I wouldn't put too much emphasis on it. Just stick with your dual 3" with high flow quiet mufflers (like the Borla XS) and add some "resonators" if you want, but don't get too carried away with the resonator and spend 2 months designing a custom one that does the same thing as something you can buy for $80 or whatever they are. Also, just an empty chamber is going to lose flow as it expands and contracts, creating turbulence, I think you want more control than that, which is why they have angled ends and perforated through tubes on most mufflers with higher flow.
You can always contact Burns stainless, they have a lot of experience and software programs that can recommend an exhaust size and diameter and also header collector size, length, primary tube length, etc.
Better get Engine Masters on You Tube involved with this discussion. They just tested 2 1/2" vs. 3" exh with the exact same system and bends and guess what the 3" made more power and it was louder, imagine that.
Was that the one that Freiburger (HOD ROD) was involved with?
I saw that YouTube video and I was really disappointed in the test setup. It's pretty common knowledge that the first couple of feet past the collector is a critical spot to maintain flow.... an 18" collector extension (minimum) can add lots of power and TQ. It looked like they came off the header collector and IMMEDIATELY choked the exhaust down to the 2.5" diameter (didn't even taper gently from the 3" collector to the 2.5" pipes over 18" or whatever).... creating a huge reversion point (my guess) and then laughed at how poorly the 2.5" system did..... By comparison, the 3" system came cleanly off the collector and didn't neck down at all (IIRC) so it shouldn't surprise anyone that it ran better.
I think they also refused to re-jet the carb between tests to try to get equivalent A/F ratios.... they just let the 2.5" system run "fat" which certainly would have killed more power too. A self-learning EFI would have at least compensated for the exhaust change A/F and made the testing more fair...
Too late for me now anyway.... I just got off the phone with Cone Engineering (So Cal) and have another 30 feet of stainless (3" straights, 90s and U-bends) headed my way....
-G
the systems they used were off the shelf for camaro i believe.
A 2.5" system is too small for that engine, to be honest I was suprised it was less than 30 hp, as at the track you might see a worse difference than that at that level. I can pick up 20 hp on a little 425hp 388 SBC by uncorking the 2.5" exhaust to 3" open collectors, surely a 550 - 600 hp motor needs more than that. Heck at your level, if you have a 3.5" collector I wonder how much you would pick up with that vs a dual 3". But I think a dual 3.5" would be way too loud for little gain. A 3" is a good compromise.
And although it's fun to measure the dyno numbers, I would rather see 60 ft times, ETs, trap speeds, etc. That is a measurement of what you feel, not what a dyno feels. That system was also extremely long, like limo long. And it had two 45 degree bends for tailpipes, thats it. It looked like a mock system that wouldn't actually fit in anything. They both may have peformed slightly better in a better length.
One other thing you can't hear on a dyno is the sound when you let off under engine braking. It can sound real nice and smooth or sound like barky popping crap. Small long tailpipes exaggerate that.
And although it's fun to measure the dyno numbers, I would rather see 60 ft times, ETs, trap speeds, etc. That is a measurement of what you feel, not what a dyno feels. That system was also extremely long, like limo long. And it had two 45 degree bends for tailpipes, thats it. It looked like a mock system that wouldn't actually fit in anything. They both may have peformed slightly better in a better length.
One other thing you can't hear on a dyno is the sound when you let off under engine braking. It can sound real nice and smooth or sound like barky popping crap. Small long tailpipes exaggerate that.
I remember the good ole days of high school when burned out glass packs that popped and cracked on deccel were badass!!! My old '82 chevy 3/4 ton would back fire once in a while with dual exh that dumped before the rear axle and spit out a big fire ball at night. So much fun when you didn't give a shit about noise and drone and all that crap.
My old Suburban did a lot of that deceleration popcorn stuff....
Starting at around 0:17 in this video:
-G
Check this episode out for a surprise...
Yeah...saw that one. Left me feeling conflicted....
On the one hand, it made me feel like primary tube routing and shape is pretty forgiving after all... So the fact that my primary tube lengths are sometimes almost 6" different from each other (worst case) my engine will still start and idle properly.
But is also left me feeling like I spent 100 hours building "eye candy" that won't perform any better than if I'd screwed together a bunch of black pipe and cast iron elbows from Home Depot.
-G
yeah, but if it looks pleasing that's it's own reward.
