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12-13-2017, 05:55 PM #76
Before I forget , vnemous wants to see the "the show" at Gilligan's Island this summer ..
Yes that is true . If they were going to worry about one side being exactly like the other , that would be the place to do it .
As you move farther way from the base of the block , the size , shape , square inch's or exact volume changes . So 1 3/4" might get you closer , your still trying to correct the primary length by changing the collector ..
But then , if you consider that the primary length mismatch is worse than these POS headers . Well it would be like FMP winning the Special Olympics , even if he won , he (and these) would still be ******** ...
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12-13-2017, 06:15 PM #77Screaming And Flying!
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As long as it works for you. But nice work, the whole thread.
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12-13-2017, 07:18 PM #78
Actually offering up a "real world" response ... I'm impressed
I can tell you from personal flow bench time , that air doesn't like sharp corners . The two different apposing angles tend to build a large boundary layer against each other and the air column stalls out . The larger the corner radius , naturally , the less each wall works against the other .
Here's some cut and paste of my own ... Pppfffttttt
But it's from Jennings "so you want to build expansion chambers" so I trust the numbers ...!
I also included the "convergent" cone . I didn't want you to read about the "returning wave" in the "divergent" cone and think it was anything other than "more of the same evacuating pull" . The caboose of the train exiting the station , if you will .
I have also seen the 7* to 10* rule of thumb , while building shear plates way before you could buy aluminum one in any color you like .. I build quite a few sheetmetal tunnel rams and I can tell you air doesn't like to step out of a hallway and into a large room without getting lost . A little direction goes a long way ..
Header
Attachesto the engine and is the straight or slightly divergent (opens up 2-3degrees) section of the pipe. It helps to suck the exhaust gases outof the engine. The header pipe cross-sectional area should be 10-15%greater than the exhaust port window for when maximum output atmaximum RPM's is desired. In some cases the area of the header pipemay have a cross-sectional area 150% of the exhaust port area. thelength should be 6-8 of its diameters for maximum horsepower, for abroader power curve 11 times pipe diameter may be used. The part youtrim off to tune.
Divergent (Diffuser) Cone
Thesection of the pipe that attaches to the header and opens up at anangle like a megaphone. It intensifies and lengthens the returningsound waves thus broadening the power curve. The steeper the anglethe more intense the negative wave returns, but also the shorter theduration. The lesser the angle, of course, returns a less intensewave, but for a longer period of time (duration). The outlet areashould be 6.25 times the inlet area. 7-10 degree taper angle.
Belly
Locatedbetween the divergent and convergent cones, it's length determinesthe relative timing of the negative and positive waves. The shorterthe belly the shorter the distance positive waves travel and thenarrower the RPM range. This is good for operating at HIGH RPM only.The longer the belly the broader the RPM range. The diameter of thebelly has little or no effect.
Convergent (Baffle) Cone
Locatedafter the belly and before the stinger, reflects the positive wavesback to the open exhaust port and forces the fresh fuel mixture backinto the combustion chamber as the exhaust port closes. The steeperthe angle the more intense the positive wave and the gentler theangle the less intense. 14-20 degree taper angle. The taper angleprimarily influences the shape of the power curve past the point atwhich maximum power is obtained.
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12-14-2017, 10:11 AM #79
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12-14-2017, 02:24 PM #80Screaming And Flying!
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At the risk of sounding as ignorant as I am on the subject, what about the X ing of the tuner sides to let one bank pull out the gasses from the other? Anyone try this? It is said to work well on automotive systems.
Last edited by XstreamVking; 12-14-2017 at 02:26 PM.
83 V-King, 96 Mariner, 200 hp ff block 2.5 w/a 28p choppa
We gotta clean this liberal mess up, VOTE TRUMP TO MAGA!
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12-14-2017, 08:31 PM #81
All the Late model stock's and 410 WOO sprint cars run a 180* exhaust system that you speak of . I'm sure there is more to it than the "sports car" sound they have . It has to help being able to follow the firing order and have one primary vacuum the next one behind it .
I remember in the late 80's there were a couple of Comp gas dragsters that ran a diffuser tube about an inch larger in diameter and four or five inch's long over the outside of the collector exit , held in place by a few short pieces of tubing.
I don't know if it was to keep the air running along the outside from interfering with the exit , or if it was to use the air running between the tubes to help evacuate the collector . In any event , it was short lived .
It looked a little like this .. without the center ....
I was talking to one of my mentors a few weeks back about making both sides of the tuner equal and shortening the center divider . Thinking along the lines that one side would help evacuate the other ... he said , It's worth a try , but I would wrap an extension around the outside , that way if you don't like it you can zizzy wheel a couple tacks , and it's gone ..
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12-14-2017, 09:14 PM #82Screaming And Flying!
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in a NA 2 stroke its all about the reverse pulse I thought?
Who cares about reverse pulse in a 4 stroke as the piston pushes the gas out?Last edited by powerabout; 12-14-2017 at 09:21 PM.
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12-14-2017, 09:25 PM #83
No I wouldn't exactly say that , but the outboard exhaust system is definitely stuck in the "Fonzi" era ...
More from Jennings :
These aspects of sonit wave behavior are employed in the expansion chamber exhaust system to help scavenge the cylinder-and then to prevent charge loss. To illustrate this, let's watch in slow motion the activity in a typical chamber through a single oper- ating cycle: When the exhaust port opens, exhaust gases still under considerable pres- sure are spilled out, and a wave-front starts its march down the exhaust system. After moving a short distance in a parallel-wall tube, this wave reaches the megaphone, more properly called a diffuser. Here, the surrounding walls diverge, and the wave re- acts almost as though it had reached the end of the pipe-except that the diffuser is a much more efficient converter of wave ener- gy. In the diffuser, a lot of the positive-wave energy is inverted-to a negative wave-and is promptly reflected back up the tube to ap ply a vacuum at the exhaust port. This vacu- um is stronger than one might suppose, hav- ing a value of about minus-7.0 psi at its peak. Obviously, it can be of great service in clearing exhaust gases from the cylinder and in hauling the fresh charge up from the crankcase through the transfer ports- which is precisely how it is used in an expan- sion chamber. Now if the exhaust system ended there, as was the case back in the days of the super- charged DKWs and "blooey-pipe" Greeves, this vacuuming effect would be a mixed blessing: anything that will pull exhaust products out of a cylinder will pull the fresh charge right after them. Horsepower being very directly related to the weight of the air/ fuel charge trapped in the cylinder at ex- haust-closing, this side of the megaphone's activity is undesirable.
The angle given the baffle-cone, and that of the diffuser, are selected with an eye toward engine output characteristics. My own preference in angles of divergence, for diffusers, is a low of 6-degrees and a high of 9-degrees. Diffusers tapered at less than 5- degrees, included angle, are almost impossi- ble to accomodate within the available length; those with angles greater than 10-de- grees are inefficient wave inverters and wave energy recovery with them suffers. Re- searchers have shown that maximum diffus- er efficiency occurs with a divergent angle of 8-degrees. However, if you want maximum horsepower and are not concerned about power range, a 9-degree diffuser returns a very strong wave of short duration that will help. Conversely, if you want a broader power range, diffusers having a slower taper will spread the power at some expense to maximum.
So as far as "tuning" goes .. we are limited to either a high strength signal for a short time or a less aggressive signal for a longer duration .
For all practicle purposes , the stock 3.0L "tuner" in nothing more than a straight pipe . So in my eyes it could benefit with a shallow angle divergent cone . Not enough to kill a bunch of bottom - mid range torque ... but just enough of a compromise to kick it on top a little . That's my plan anyway ...
The Greeves "blooie pipe" looks all to familiar ....
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noli liked this post
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12-14-2017, 09:40 PM #84
Old hodaka dirt squirt?
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12-14-2017, 09:43 PM #85
Never be closed minded to any technology . Everything under the sun is related and intertwined in one way or another .
NA 2 stroke ... the only time I hear that term is in reference to a GMC diesel . It obviously means something different to you .. ???
Reverse .. ???
Positive = in
Negative = out
So , a farmer has his water well by the road . he has one sprinkler 100 yards away and the other 500 yards away .
When the pump is activated , which sprinkler will spray first .. ???
How does he get them to fan the same amount of water ..???
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12-14-2017, 09:43 PM #86Screaming And Flying!
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I guess you need in cyl pressure sensor to mod an exhaust then you get the answers
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12-14-2017, 09:50 PM #87
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12-14-2017, 09:54 PM #88Screaming And Flying!
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NA? same to me as you but lots of 2 stroke turbo sleds out there now
happy just to say 2 stroke, yes its all connected from the air in front of the induction to the air at the end of the pipe
Farmer has to get the same pressure to the spray nozzle on both sprays when they are working
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12-14-2017, 09:56 PM #89
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12-14-2017, 10:46 PM #90
So nobody has played with tuners on a dyno? Or is the amount of gain just not worth the effort?
I CAN ALWAYS MAKE ANOTHER DOLLAR, BUT I CANNOT MAKE ANOTHER DAY
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