Tech articles back in the day said that, when splitting a stock manifold and welding in a baffle, a solid baffle would rap loudly. Putting a hole in the baffle would smooth out the tone. Headers sounded more like the solid-baffle split manifold. All of this seems very much like an H-pipe or X-pipe in principle.
Originally Posted by Paul View Post with the typical Chevy six firing order 153624 and dual headers like the Fentons you get an imperfect pulse order the front manifold goes: pulse, pulse, pause, pause, pulse, pause and the rear manifold goes: pulse, pulse, pause, pulse pause pause so exhaust scavanging is broken, and intake pulses can be affected too but when heard side by side they do make a unique kind of music *********************************************************** Huh? 153624.... The front header has positions 1,2 and 3. The rear has positions 4,5, and 6. Sooo, aren't you really getting out of the first header: Pulse, Pause, Pulse, Pause, Pulse, Pause. Out of the second aren't you getting the same but off one, Pause, Pulse, Pause, Pulse, Pause, Pulse. I don't think you could get any better for scavenging...
Well, if I had bothered to read a little more closely it has already been answered to death. Can we get a "retract your last post" button for these situations?
So Ive read a few posts here saying they they split the manifolds by welding in a block off plate between the three, or 2-4... and said they drilled a 3/8 hole in the plate. They said it was the best sound they ever heard. Whats the sound? More mellow than a regular split manifold? Rappier? Louder? Deeper? Why was it cooler than just welding in a solid block plate to split it? Thanks
These pics of my 230 Mopar show the split exhaust manifolds....these were done using a pair of stock exhaust manifolds with the heat riser cut from both and the manifolds welded up by a local blacksmith.......eventually this engine will end up in my 41 Plymouth Coupe......oh....and the weird, to US eyes water pump is an Oz Holden 6 pump adapted onto the mopar block.......the carbies are also single barrel late 60's Holden 6 strombergs.....much easier to rebuild here & get parts for.......andyd
My dad has 41 studebaker commander with a 245 truck engine. He had new pipes installed. No muffler, and split behind the axle to make 2 pipes exit the rear. It sounds like crap. I mean like a raggy sounding old pulp wood truck. Will splitting the manifold make this thing sound better?
I have been reading through this thread trying to follow it. The piece that i don't see discussed here is the pressure pulse echos scavenging the exhaust valve at opening. The length of a header primary tunes the rpm range that the pressure pulse which is echoed from the end of the primary to pull the gasses out of the exhaust valve when it opens. Longer primaries give you a power band at lower RPM, and shorter primaries give a higher power band, due to the pulse frequency of the pressure wave which gets reflected at the opening of the primary (the collector). Splitting a straight six into separate dual exhausts does a couple of things. You will get effectively a pair of three cylinder engines so you get half as many pressure pulses, So a lower frequency of pulses (by half) so that has the same effect as longer primaries (twice as long), pulling the rpm range of the power band down lower into a more usable range (more torque). dual exhausts also gives you twice as much pipe area so less back pressure. that means more power because the engine doesn't lose as much power pumping out the exhaust. A big (like 3" or 4") single exhaust will give you the same low back pressure as a pair of 2" exhausts, so then the duiscussion goes back to pressure pulses. What you get by re-combinging the two primary collectors into a secondary collector is a second set of pressure wave echoes at the pipe length of the second primary (measured from the valve). this has the theoretical effect of giving you a second power band, because from a pressure point of view you get one set of pressure waves at one RPM range from the primary length (first collectors) and a second set of pressure waves tuned in at a second RPM range giving another power band. It is like having headers with two different lengths at the same time. Short primaries all joined into a single large diameter pipe should have the effect of a single power band high up the rev range and may give more absolute peak power, but a lot less down low in the rev range, which is the same reason you see open pipes on drag engines - primary only, no secondary. Remember when you are reading this that the pressure wave I am talking about is only helpful because the low (vacuum) part of the wave, hitting the port at the right time, gives low pressure, which tends to pull the exhaust out through the valve instead of there being back-pressure which the engine would need to pump against. So all of this splitting has the effect of more power over a broader range. I don't want to take anything away from all of the people here who have done the work and run the different setups. My comments are all very theoretical and I know I am setting myself up for a barrage of comments, but a few people have asked the question, so I thought I would take a stab at starting the theoretical discussion.
While were at it, if you dont mind me askin....would this work for 4 bangers too? Im runnin duals already buit its kinda weird....i mean, it goes 2 pipes to 1 and then the 2 pipes go into one bigger that splits towards the end into 2 again. Wouldnt it be better if it never get back to 1 making it only split once? Do i make sense? pretty hard to explain, maybe pics would help. Thanx and sorry if its kinda O/T
A friend ran true duals on a mid '60s Triumph TR-something years ago. It had a dual outlet exhaust manifold from the factory, so we made dual pipes for it with glasspacks. Very distinctive sound.
Hard for me to say this but I have a '49 1/2 T w/ a '56 235, Fentons, 2" out to an "X pipe" then two 24" cherry bombs. Low rumble, no rap on deceleration. I miss some sound, the x-pipe really mixed the flow so now I'm thinking of removing the cherry bombs. Some run the pipes straight out the same side, mine are straight out the back evenly spaced under the bumper, kind of traditional split 8 style, thinking of bringing them together.
The X pipe kills it for the same reason that a split manifold has to have a divider plate inserted between the two outlets.
Why a split manifold. Because it was cheap, and worked good. Back then you could not just go by headers where I lived, and most of us did not have much money. The manifolds from a Co corvette worked great, but cost big money for us poor boys. I have used both back in the day. Also made my own 3 carb intake back then, for my 261 engine. I had the fast's 6 in Flint.
We use to put a plate in the exhaust to separate exhaust. We used a 3/4 block and a full block. The 3/4 block is the best. Full block is real loud. Another way to make it sound good is to use 3/4block and two different kinds of mufflers.
I'm running a header on my 235 that splits 3 and 3 ran them to 12 in steel packs(there 2 1/4) and then dumps-sounded like crap and the fumes were unbearable.I pulled the dumps off and ran pipe to the back.So it goes 1 3/4 header(split) to the 2 1/4 steel packs then back down to 1 3/4 then to 1 5/8 from about midway to over the axle to the bumper.True split the whole way.Now it sounds wicked.Deep rumble and raps like crazy at mid to high rpm.When the motor is backing down it raps but a Little different.At idle it even has a nice Little rumble.Its LAUD-Turns heads now.It raps like a 01 mustang GT I had w/ no cats magna flow magnapacks(steel packs) and a set of comp cams.Its just not as deep a tone.And actually lauder but only at high rpm.At idle it cant touch what that car sounded like.I still cant get over that a strait 6 can sound so wicked
Be sure to punch a small hole in the plate (1/4--3/8--1/2), because a SOLID block will dang near break out windows!!! Back in 1949, my '41 Chev. had a great rrraapppp when backing off in 2nd gear!!! The Porter mufflers were a great aid too!-------Don
"Fentons and 22" Smittys on my 235." Boy, does this bring back memories of the Sat night my '57 283, 3-speed got wiped by something like a '52 Convert w/ a hopped up 261 Gimmie in it that had the splits and "smitties" on it walking away from me going home! To this day, a split-6 with glasspacks will raise the hair on the back of my neck, it is that GREAT a sound! pdq67
That's basically what I did out of necessity on my 63 Belair. Initially I wanted to run duals straight back and keep them both on the left side, but the 63 "X" frame would'nt allow it. One would be tucked in between the frame and floor pan while the other would be hanging down under the floor. I ran two 1 7/8 pipes from the Fenton headers to dual Smithy's then to a homemade Y pipe that blended into a single 2 1/2 homemade tailpipe. It's got a much deeper tone and still raps a bit when I down shift. Before, with the stock 1 barrel carb and single exhaust it would go into a lean surge and be quite sluggish on hills. Now I barely have to tickle the throttle and it will accelerate while going up the same hill and pulls pretty hard. I barely have to give it any throttle when I let out the clutch now as well. I think the 2 barrel Weber helps alot too.
sound mostly because in most states you will have to run heater lines on the manifold because The heat generated from the stock manifold helps atomize the fuel in the intake. With split manifold its hard to atomize. But it all depends if you live in wyoming or texas. Performance is not much of a gain unless you have 3/4 race cam intake with carbs milled head etc. Also naturally aspirated engines need about 3 to 4 pounds of backpressure to help the scavenging affect of the cylinders but it all depends on personal preferance.
i did it to my dads 41 stude flthead 6. i used the outlets from chevy ram horn manifolds. it sounded like a tractor before. now it sounds sweet with dual cherrybombs. he went back to the muffler guy and had resonators installed, pop said it was way to rappy! the piece in the middle is what was removed.
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