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Single to dual exhaust cats/sensor??

scotts90ranger

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But dual on a V6 will still sound like a V6, a crossover like an H or X pipe would help...

I didn't read through all of the long posts, but to note on the two cats inline, they have different mesh size, the first is likely more coarse than the second, one more to burn off excess hydrocarbons and heat the mix before the second trying to convert the CO and NOx into CO2 and other inert stuff...
 


1990RangerinSK

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Dual tailpipes on a single exhaust is the equivalent of taping a sausage to your leg under your polyester pants before going to the disco.
Is that a sausage under your pants? Or are you just happy to see me?
 

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Dual tailpipes on a single exhaust is the equivalent of taping a sausage to your leg under your polyester pants before going to the disco.

This was a radio program out of Chicago when I was a kid.... funny stuff, and the first one in that video is hilarious

AJ
 

cbxer55

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I didn't do it, but my 4.0 Mustang came with a dual exhaust. Yes, the factory Y is still there, and there are two 3 inch pipes welded to a second Y for the two pipes. I intend to replace the entire thing with a Borla True Dual catback with an X pipe next year. The original owner of this Mustang put on a GT rear bumper and it has two Ford Performance mufflers. Along with a CAI that has a cold air tube feeding the filter, and a 93 octane tune, it runs FANTASTIC! With an automatic transmission, it spins the NItto NT555R 265/35 tires easily.

There's a guy on the Mustang forum that says six cylinder engines make more power with a six-into-one-into two, than they do with a true dual. But the true dual will always sound better.

I think the stock exhaust had a third cat behind the Y. It doesn't now. No rear o2 sensor either. My Lightning is the same, original owner deleted the two rear cats and the rear o2 sensor when he installed the Borla catback. .
 

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gw33gp

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🤔 Hmmmm. Not convinced, but I have to think about that one....
Think about this too. If scavenging didn't exist, two stroke engines would barely run without it. Scavenging is mostly due to gas velocity and momentum of that gas.

Even in a 4 stroke engine scavenging improves horsepower. It helps to increase flow and helps to clear the combustion chamber of combustion gasses and replace it with fresh correct ratio intake gasses. It also is bad for emissions. The momentum of the intake gas can also help to increase dynamic compression ratio but not nearly as much as turbo or supercharging.

You mentioned earlier about dragsters not having much of a tail pipe. They do have exhaust pipes, but they are just shorter ones for each cylinder. They actually help with internal scavenging in the engine. If those pipes break or didn't exist, it would result in a loss of power. It is not uncommon to hear about a F1 or Indy race car that has cracked a header and has lost power. That has a terrible affect on the scavenging.

I am an old Chemist too that has been in the hobby of road racing with SCCA for over 30 years. I build my own engines and have learned a lot about how to make more power by managing intake and exhaust flow. Believe me, scavenging is a real thing.
 

cbxer55

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Of course scavenging is a thing. That is what headers are for. That is why expansion chambers make the most power on two stroke engines. If scavenging didn't work, there would be no headers for sale anywhere. They may not add a huge amount of power, and what they do add is usually top-end oriented, but they do add power. Same with expansion chambers, what power they do add is in a narrow rpm range. The range the power is improved can be fiddled with by doing such things as 4-into-2-into 1, which lowers the rpm band the power increase occurs.

My Suzuki B-King has a 4-into-2-into-1-into-2. It is a very rideable bike around town for a high strung inline four. Makes great power at low rpms, and still goes north of 10 grand with ease.

My M109R picked up noticeable power increase when I put a 2-into-1 on it, but it lost some low rpm power as a trade off.
 

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MikeG

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I thought two-stokes pressurized the intake? Or is that only some of them?
 

scotts90ranger

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2 stroke diesels don't run without forced induction, 2 stroke spark ignited are a different animal and the tuned pipe thing is a science all in it's own... I used to know more than I remember anymore... port timing plays a big deal with the exhaust on 2 stroke, it gets complicated...
 

cbxer55

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2 stroke diesels don't run without forced induction, 2 stroke spark ignited are a different animal and the tuned pipe thing is a science all in it's own... I used to know more than I remember anymore... port timing plays a big deal with the exhaust on 2 stroke, it gets complicated...
I've had two Suzuki GT-750 Lemans (Water Buffalos) in my time. liquid cooled three cylinder two smokes. And smoke they did, big time, like three chain saws on crack cocaine. On both I installed 3-into-3 expansion chambers on them. There was a company that made a 3-into-1 chamber, but for the life of me, I don't understand how that would work. Since the triples have a 120 degree crankshaft, and each chamber works with the cylinder it's attached to, how in the f*ck does a 3-into-1 work? I know how chambers work, reflecting the exhaust back at the cylinder, and the fact it only works at a narrow rpm range, hence why two smokes are so "peaky". Below that rpm range, the exhaust doesn't get back enough to put all the air/fuel into the cylinder that escaped through the piston port. And above that narrow range, exhaust starts getting back into the cylinder. Maybe the 3-into-1 smooths it out, gets rid of the peakiness, at the expense of some power?

Two stroke motorcycles, just like lawn appliances, don't pressurize the cylinder. Normally aspirated. I imagine trying to pressurize a cylinder with giant holes in the cylinder walls, would be complicated. I don't believe diesels today use piston ports. I believe they use disc valves or the like. Motorcycles were starting to go there before two strokes were outlawed, due to really bad emissions.

I sold my last Water Buffalo in 2006. At the time, whenever I rode it, it never failed that someone would tell me my bike needed to have the engine rebuilt since it was smoking so bad. Or I'd depart a stop light and hammer it, leaving a YUGE blue cloud in the intersection. Then someone would catch up to me and give me the single-digit-salute. LMAO!!

I have pics of the bikes, but they're either hard photos or on floppy discs. LOL!
 
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cbxer55

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On my Suzuki street bikes, you have an intake port on one side of the cylinder, down low on the cylinder wall. The exhaust port is higher up on the other side. The carburetors on the back, feed the air/fuel into the crankcase, where the oil is injected, straight onto the crank bearings. Oil is also direct injected under the pistons to directly oil the bearings on either end of the connecting rod. The air/fuel/oil mix in the crankcase is then drawn into the cylinder as the piston goes down.

It's complicated. As the piston comes down after combustion, the exhaust port is exposed first. Out goes the exhaust, which the evacuation of the exhaust sucks the intake in when the intake port down lower is exposed. Thus, when the piston starts rising, it closes the intake port first, but the exhaust is still open. The outgoing exhaust pulls some of the intake out with it, but the exhaust design causes a reversion, the exhaust flowing back toward the cylinder, pushing the fuel/air/oil back into the cylinder before the piston closes the exhaust port off. It makes for a very peaky power band. If you elongate the widest portion of the pipes to try and smooth out the power band, you end up losing some peak power. It's why two stroke pipes have that funky look they do, fat in the mid section, with stingers on the back.

My dad needed to borrow my first one, a 74, back in 79. It had J & R Power Pipes on it. I told him, do not, under any circumstances, grab a handful of throttle from a dead stop, expecting to take off like a bat out of hell. If you do, it'll just lug and you will end up with the front wheel in the air around 4500 rpms or so. He did it anyways, and came back rather quickly, shaking a bit. "Don't ever let me ride that beast again!" LOL!!
 
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