noob question about boxer sound

[nkx]

well i did a google search and found this:

 

http://www.drive.subaru.com/SubaruDrive-Sum02/Piston-Cranky.asp

 

the pic towards the bottom shows the crank in pretty good detail. it looks like an I-4 crank, but more compact.

 

i think im going to do a bit more searching, and maybe mock something up to see if i cant figure out why it sounds different...

 

another pic:

[TomRhere]

 

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!

 

I agree with the statement there. I'm not a Ford guy in the least bit, but the 302-351 engines are a prime example. It's in the firing order of the cylinder themselves, that help give an engine it's sound.

 

Yes, the exhaust has to do with it also, as you can change the sound by where you hang the muffler in the run of the pipe(s). The length of pipe between the engine and muffler,and the length of pipe after the muffler will change the exhaust note of the vehicle. Diameter of the pipe will have an effect on the sound also.

 

Both of these Ford engines are numbered the same as far as what cylinder is where on the engine. 1-2-3-4 on the left bank, 5-6-7-8 on the right. The firing order of those cylinders are different between the two engines. The 302 (non-SHO) firing order is, 1-5-4-2-6-3-7-8. The 351 & 302 SHO firing order is 1-3-7-2-6-5-4-8.

 

You can swap cams between the 2 engines, re-do the disty cap wires and run on down the road. Putting either cam in the other engine block, will make a difference in the exhaust sound of the vehicle. I have put the 351 cam in many 302 engines for various owners over the years. Most all of them have commented on the difference in the of the sound of the engine running and the exhaust sound changing.

 

If one could get the cam(s) re-ground for the EA-81/82 engines, so that the firing of the cylinders would change to firing a cylinder on one bank, then one on the other bank, instead of firing one bank then the other, you would get a different sound from the engine.

[Ru_]

ok this is rediculous! a new guy joins the board, probably doesn't know much about cars, (if he knew anything he would know that this convo would have turned into such a debate) and all he asked is why subaru's sound the way they do. HERE IS THE ASNWER! it's all in the exhaust header! AND NOTHING BUT THE HEADER! It is very uneven in legnth between the cylinders. EVEN THEN the older EA81 and 82 engines have siamese ports, meaning each cylinder exhaust port joins to one bigger one right in the head....hence only 2 pipes comming out. If you want your ru to sound like a honda, you first have to seperate the 2 ports in the head, then run EXACTLY EQUAL legnth pipes to a 4 into 1 collector....then you'll have your honda.

 

The sound of the engine comes from where?? the exhaust. It all boils down to where the sound pulses meet. If one pulse joins on top of another pulse, you get a loud pulse. It's like cars on a highway.....4 cars leave all driving the same speed each car leaves 180 seconds (degrees) after the other....but all have different distances to go....one car will probably run into the other when the highways join, and the other 2 will probably be WAY BACK somewhere close together...you make all those highways equal legnth....all the cars get in line...the same distance (time) apart.

 

V- engines are a different story and I am not going to get into that. Basically HO's and Inlines are the same engine, same crank (generally) and CAN SOUND THE SAME. But don't cause subaru uses uneven headers and honda's are closer to equal. ANd just cause it's a performance exhaust header doesn;t necessairly mean it's equal legnth....

[pattiandruss]

My OLD Honda Goldwing, flat 4, sounded like my 84 sub, which sounds like my wife's 93 Legacy. Maybe it's because they are all Japanese? Russell

[dave valiant]

A new guy? he has been on USMB since Dec. of 2003.

 

The only reason I brought up the Harley cylinder head was someone said the only reason one engine sounds different from another is the exhaust. That is a false statement. Period.

[zyewdall]

Here's some more info to throw into the mix... Old toyota landcruisers ('74) with the inline 6's sound exactly like my '61 landrover, with an inline 4, even though they have two extra cylinders. And neither sounds like most 4 cylinder engines in toyotas, hondas, etc. I'm thinking it might be due to the old L-head design maybe? I've never heard an old straight 8 run, but I suspect it would sound the same too....

[nkx]

My OLD Honda Goldwing, flat 4, sounded like my 84 sub, which sounds like my wife's 93 Legacy. Maybe it's because they are all Japanese? Russell

 

dont forget about the old beetles... not japanese, but it still sounds kinda like a subaru.

 

i actually took the time last night to make a crankshaft with con rods out of paper and tape last night. (gee, bored much?) i labeled the cylinder positions, and then wrote out each of the 4 strokes for each cylinder so i could see how each phase of any given cylinder corresponded to another at any give time.

 

now this isnt super scientific, but from the looks of my chart, there appears to be 540° (1.5 rotations) of crank rotation between each spark of the cylinders 3 times. then theres a dead spot. here, im seeing 1260° (3.5 rotations) until the next spark.

 

540°*3+1260°=2880°

2880°/360°=8

8 full rotations of the crank for a complete 4-stroke cycle for each cylinder.

 

someone please tell me they follow this...

[nipper]

This ca all easily be solved by turning up the radio and the 300 watt subwoofer

 

 

 

nippper

[MorganM]

The explosion in the damn engine makes the sound. The exhuast changes that sound. Net result is the sound you hear.

 

Different engines designs AND different exhaust designs systems = different sounds.

 

End of debate.

[dave valiant]

You win.

[rguyver]

:lol: :lol: I find this all amusing no one will all agree on this one but thats what message boards are for ................ :banana: just sit back and wach the bananas dance

[bulwnkl]

This statement from your post:

If you want your ru to sound like a honda, you first have to seperate the 2 ports in the head

 

makes this statement untrue:

it's all in the exhaust header! AND NOTHING BUT THE HEADER!

 

So are you uncertain, or suffering from multiple personality disorder?:-p

[WJM]

This statement from your post:

 

 

makes this statement untrue:

 

 

So are you uncertain, or suffering from multiple personality disorder?:-p

 

if you stick a divider plate onto the header flange effectively separating the ports...then you can do it.

[ausubaru92]

well i did a google search and found this:

 

http://www.drive.subaru.com/SubaruDrive-Sum02/Piston-Cranky.asp

 

the pic towards the bottom shows the crank in pretty good detail. it looks like an I-4 crank, but more compact.

 

i think im going to do a bit more searching, and maybe mock something up to see if i cant figure out why it sounds different...

 

another pic:

 

Look at the above pic

On a subaru crankshaft, the piston rods connect to the crankshaft at 180 degrees apart, (ie. cyl 1 at 0 deg, cyl 2 at 180 deg, cyl 3 at 180deg and cyl 4 at 0 deg.

Whereas a inline engine is at ( cyl 1 at 0 deg, cyl 2 at 90 deg, cyl 3 at 180 deg and cyl 4 at 270 deg)

 

So i believe that this may contribute to the boxer sound, but it is probably a combination of this and the header design.

 

 

Gannon

[jeffast]

i agree that sounds reasonable makes good sense but

 

i still want to hear some sound files

[bushbasher]

Part of the sound created by an engine is the explosion in the cylinder, the other part is the sound created by exhaust gasses blasting past the exhaust valve and port at extremely high speed. So head design, bore and stroke, and valve timing all have a huge effect. WJMs theory on unequal length pipes may have some merit when it comes to the boxer whump whump sound, though his explanation is a bit simplified. Subaru flat 4s DO sound way different compared to hondas, vws aircooled and watercooled when compared open head to open head.

[mikie]

So i believe that this may contribute to the boxer sound, but it is probably a combination of this and the header design.

 

 

Gannon

 

Thats a V8 crank youve posted a picture of, not a 4-cyl. A normal 4-cyl inline crank looks just like a subie crank.

 

Consider this. The reason a subaru has the distinctive note is due to the exhaust, which is the way it is because of engine layout. In a subaru each bank of cylinders is collected into one pipe. Becuase of the firing order BOTH left cyls fire consequetively, then both right, and because each time the second cyl's exhaust valve opens before the first is fully shut this means one BIG pulse from the left, then one from the right. Like a 2 cylinder engine. Then, due to the difference in header length left and right this effect is magnified in some applications, perhaps resonance, whatever. This is not good header design, which trys to collect the exhuast pulses in a nice interleaved fashion for better savenging effect, but to put the ideal exhaust system on a flat-4 would have the turbo dead centre under the sump, or a nightmare exhaust system.

 

To make a boxer sound like an inline 4 you need to run one equal length header from each cylinder to a collector mimicking the inline 4. To make a inline 4 sound like a subie you need to collect cyls 1&2 and cyl 3&4 each into a runner at the manifold(so that consequtively firing cyls are together - the reverse of a good header design) and then run these with 2 different lengths into another collector.

[WJM]

Thats a V8 crank youve posted a picture of, not a 4-cyl. A normal 4-cyl inline crank looks just like a subie crank.

 

*BUZZZZZZZZZZER*

 

Wrong. Looks just like a Yamaha motorcycle crank. The sproket in the middle is to drive the chain for the cams up top.

[mikie]

*BUZZZZZZZZZZER*

 

Wrong. Looks just like a Yamaha motorcycle crank. The sproket in the middle is to drive the chain for the cams up top.

 

It has extremely wide big end journals for a 4 cyl, and 2 oiling holes for each extra-wide journal. It looks suspiciously to me like you could attach 2 conrods to each of those. Anyway. a normal 4 inline crank DOES look just like a subie crank.

[WJM]

It has extremely wide big end journals for a 4 cyl, and 2 oiling holes for each extra-wide journal. It looks suspiciously to me like you could attach 2 conrods to each of those. Anyway. a normal 4 inline crank DOES look just like a subie crank.

 

agreed...but, ive never seen any v8 USDM design like that...i would believe a Porsche/Ferrari/Lambo/*insert exotic here* crank like that...but again, ive never seen one. Ive only seen that type of crank in a Japan Motorcycle engine.

 

subie cranks do look like normal I4's...but, shorter of course.

 

It's all in the header design. PERIOD.

[mikie]

agreed...but, ive never seen any v8 USDM design like that...i would believe a Porsche/Ferrari/Lambo/*insert exotic here* crank like that...but again, ive never seen one. Ive only seen that type of crank in a Japan Motorcycle engine.

 

subie cranks do look like normal I4's...but, shorter of course.

 

It's all in the header design. PERIOD.

 

Agreed x 3. While discussing it, that thing in the middle of the crank is way to large to be a cam drive sprocket - given that the cam sprocket has to be twice the size again for the appropriate reduction, and the teeth look like a pickup for a crank position sensor. It has the snout and flywheel bolt pattern for a normal v8. WHy its like that i dont know either.

[WoodsWagon]

Part of it is in the head. The head off of the EJ22 has a different pitch between the two exhaust ports, even though they are not siamesed. One port is longer than the other, hence having a lower sound. Next time you have the heads off, tap the valves (with a spring on) with a plastic hammer. Two differen't notes. Firing order plays a big part too. The EJ without exhaust behind the cat sounded like a V8 at idle. It has to do with the pulses overlapping. Any engine with straightpipes sounds like trash to me. Loud pipes just make your tresspasing more obvious and the cops have an easier time finding you.

[bulwnkl]

agreed...but, ive never seen any v8 USDM design like that...i would believe a Porsche/Ferrari/Lambo/*insert exotic here* crank like that...but again, ive never seen one. Ive only seen that type of crank in a Japan Motorcycle engine.

 

subie cranks do look like normal I4's...but, shorter of course.

 

I agree, too. The only way I can see this being a 4-cylinder is if it's a 2-stroke; the throws are only 90 degrees apart.

 

It's all in the header design. PERIOD.

 

Wrong. Over-simplified and only partly true. PERIOD.

[PopsicleMud]

I'm still reading this thread because it's fun watching everyone get all worked up about it. PERIOD.

 

[nkx]

It's all in the header design. PERIOD.

 

old bugs have 2 exhaust pipes, but they still have that signature flat 4 sound... how do you explain that? :-p