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noob question about boxer sound


nkx
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WOW thats a lot of replies!

 

the exhaust note is aided by the plumbing after the engine, but the source is the internal engine design. thats why you can always tell a mustang from a comaro. mustangs always sound like they are drowning, no matter what headers style they use, its all in the design of the heads and the compression and the cams, ect...

 

ok, so what makes the internals so special? wouldnt the source be the crank, as everything else on the motor references its position to the crank?

 

ack, i think im going to have to make a small model to try and figure out the positioning on the crank.

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WOW thats a lot of replies!

 

 

 

ok, so what makes the internals so special? wouldnt the source be the crank, as everything else on the motor references its position to the crank?

 

ack, i think im going to have to make a small model to try and figure out the positioning on the crank.

 

Cam timing has alot to do with exhaust note. Designers cant really fiddle with when TDC is, as it is always in the same spot. The can fiddle with calve lift, tming, duartion, and overlap/.

As far as engine internals on ANY boxer engine, since cboxers arte flat equal and opposit forces cancel each other out so there is usually almost no mwear on the pistons, connecting rids, and crank.

Boxer engines tend to breath pretty well due to design. The intake runners are of equal length. SUbaru exhauts systems are already fairly well free flowing (hence the lack of alot of headers on the market). THis goes for almost any boxer except VW as they used the exhaust for a source of passenger heat.

 

 

nipper

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er27s are wierd stuff, cuz they were just carved out of an ea81. they took the two cylinders that share the same port, enlarged the exit port that they both share, then stuck one more port on there for the extra cylinder.

 

two cylinders(on each side) share one port, and the last one gets its own...

 

japanese bigblock sound!

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Speaking of ER27 exhaust sound, I don't happen to like mine. It's still a 6 cylinder, but it's not that great. So, exhaust tuning people, what would need to be done to get it to sound like a Datsun 240Z? Strictly exhaust work, or also head and port work?

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I think its three things #1 fireing order 1.3.2.4. , one head fires first then the other 1,3 then 2,4 , #2 VW's fireing is diffrent but have a simmler sound so part of it has to be the shape of the engine 3# the large piston bore VS the short stroke , this is common on all subaru engines of all years H6 or H4.

 

i can still tell a Subaru engine apart from a HONDA or any other engine no matter what exhost system it has .

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WJM is correct. And what honda motrocycle has a boxer? Newer goldwings have a small v-6 (1800cc).....sorry, thats another forum........

 

He's talking about Honda bikes with a straight 4 in them and V-twin Harleys. You put open pipes, like a Harley, on a Honda and it will NOT sound like a Harley. You put Honda style pipes on a Harley and it will NOT sound like a Honda.

 

Point is the sound comes from the engine; not from the exhaust system. Take the pipes off and set them on the ground.... they dont make any noise. Yes, the exhaust can alter the sound but the signature sound engines have is created from the engine. The design of the engine yeilds that signature sound; not the pipes bolted on to the engine which mearly masks the sound.

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So my 2 cents..

My exhaust guy He drives an L-series wagon just like mine he has a carbed ej18 in it, my car has a carbed ea82 in it

My car has stock ea71 headers going for about 8-10 inches then mated to 1 7/8 that merge offset unequal length like stock into a y pipe then into 2" out through custom straight through eliptical barrel resonator to custom phart can at the back

 

My muffler guy has stock ej18 collector mated to 1 7/8 merged equal length into a y pipe then 2" through straight through center resonator into phart can at the back..

 

My car sounds like a subaru and his sounds like a toyota so much so that people ask him if he swapped a 20 valve 4age into his 'roo..

 

It is the unequal length headers and ONLY the unequal length headers that give subaru flat fours their distinctive sound..

 

the pulses from left and right head combine into a larger pulse, because of the delay of one pulse taking longer to get to the merge, so in effect two pulses merge into a larger single pulse so instead of the engine sounding

brum_brum_brum_brum_brum_brum

it sounds

BRUM_____BRUM_____BRUM_____BRUM

as you accelerate the pulses in the headers lengthen and the sound alters slightly as it does when the engine revs higher..

 

Harleys sound different because their firing order is messed up because of the angle between the pistons and how much of a crank rotation it takes for each piston to rotate twice to top dead center relative to when the last firing takes place..

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Harleys sound different because their firing order is messed up because of the angle between the pistons and how much of a crank rotation it takes for each piston to rotate twice to top dead center relative to when the last firing takes place..

 

Engine design; just like why H4s sound different from I4s from I6s from V8s. They will even sound different from one another in the same catagory.

 

Sure you can change the sound by the exhaust system; but thats not what made the sound what it was originally. The engine gives you its signature sound and the exhaust system changes it from there.

 

It's all speculation and opinion anyways; were all talking about different engines, exhaust systems, and pure opinion on what it 'sounds' like. I don't think anyone here is right or wrong :-p

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er27s are wierd stuff, cuz they were just carved out of an ea81. they took the two cylinders that share the same port, enlarged the exit port that they both share, then stuck one more port on there for the extra cylinder.

 

Are you sure about this? Not to go off-topic but an ER27 engine with 2 less cylinders is just about equal to an EA82 N/A engine.

 

1987 Subaru

Horsepower: 97 at 5200 RPM

Torque: 103 at 3200 RPM

 

1989 XT6

Horsepower: 145 @ 5200 rpm

Torque: 156 @ 4000 rpm

 

(145/6) * 4 = 97hp

(156/6) * 4 = 104lb-ft

 

You didn't say they enlarged the ports to make power though but I figured if they did, they did it for some reason.

 

And, I agree with Will. Both my XT6s and my RX turbo no longer sound like a Subaru anymore. My OBS with the Borla header on the other hand. :brow:

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UGH! it's all in exhaust....Only V- type engines make the funny noises. Inlines and H- engines have the EXACT same rotation between firing, thusly a horisontally opposed and an inline engine will sound the same with the exact same exhaust and engine building spec's. LOL and yes....an XT-6 is the same engine as an EA82....just 2 more cylinders welded on....lol one more way to carry on a blunder eh? lol

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Are you sure about this? Not to go off-topic but an ER27 engine with 2 less cylinders is just about equal to an EA82 N/A engine.

 

1987 Subaru

Horsepower: 97 at 5200 RPM

Torque: 103 at 3200 RPM

 

1989 XT6

Horsepower: 145 @ 5200 rpm

Torque: 156 @ 4000 rpm

 

(145/6) * 4 = 97hp

(156/6) * 4 = 104lb-ft

 

You didn't say they enlarged the ports to make power though but I figured if they did, they did it for some reason.

 

And, I agree with Will. Both my XT6s and my RX turbo no longer sound like a Subaru anymore. My OBS with the Borla header on the other hand. :brow:

 

the most reasonable explaination for this is that the two cylinders that share one port, flow the same as the cylinder with its own port, because...

the one that is shared only sees one one exhaust puff at a time, so its basically like it has its own port....

i measured the cams between ea82s and er27s... same stuff.

the only place they got fancy was the intake manifold.

that could be why they wanted bigger exh ports.

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make the math work like its a 240Z header.

 

Well, which math? I guess in part I was trying to demonstrate that the sound is generated inside the engine, and is merely resonated by the exhaust. When I pull the exhaust off my XT6 (2.7-liter flat 6), it sounds absolutely nothing like my Z-car (2.4-liter inline 6) without its exhaust, and it never will without different cams and heads, and maybe even a significantly different ratio of bore to stroke.

 

This is very analogous to a musical instrument like a trumpet. You can alter the tone, you can make the noise more or less "brassy," or other similar things by switching between a trumpet and a coronet or a flugelhorn (changing rate of taper of the tube, size and flare rate of the bell, diameter of the straight portion of the tube, etc.), but the base sound is the same between them because the instrument is not generating the sound, the player is. The instrument, which is analogous to the exhaust of a car, simply resonates the sound and can augment certain qualities of it.

 

Exhausts are normally much simpler than musical instruments in that they are typically constant-diameter pipe from the lead-pipe to the muffler (at least) and are all made with basically the same construction and material-type.

 

I don't disagree at all that you can "smooth" or "even out" the sound by tuning to make the exhaust pulses reach a certain point at a certain interval, but as I said in the example above, even when you do that some engines just sound completely different.

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If it is all in the exhaust, then why don't the jap bikes with v twins and loud pipes sound like Harleys. If you say they do you are completely tone deaf. I have been told that the reason for the distinct Harley sound is the angle that the valves are in the head. If this is true it the sound it makes would have absolutely nothing to do with the exhaust that is on the bike. I have heard Honda and suzuki v twins with straight pipes and they sound loke crap. Harleys sound so nice.

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What do you mean finally? Are you saying that a Harley and a Suzuki v twin sound the same? If you are you are out of your mind.

 

I understand the question is about how a boxer gets its sound. You are saying that all engines with the same number of cylanders sound alike if they have the same exhaust. I am giving the most obvious example of that not being true.

 

Finally!

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