something i've always wanted to know????

gtfpv · 23-12-2005, 12:25 AM

what makes a V8 sound like a V8?
QUEST 1 : why doesnt a straight 6 sound like a V8 ?
QUEST 2 : why doesn't a V6 sound like a V8 ? anyone know the technical reason ????

GTS_300_Coupe · 23-12-2005, 12:33 AM

My mates got a VU Commodore S ute with a custom dual exhaust setup, could almost pass as a V8 with its deep burbly note.

vztrt · 23-12-2005, 12:58 AM

Got a mate with a VR commo, changed his exhaust and it really has a V8 rumble. Better than any v8 commo I've heard.

klawsterfobik · 23-12-2005, 01:09 AM

its to do with the stroke cycle.

a v8 will have 2 cylinders on the exhaust stroke, with 2 on the intake, 2 on the compression and 2 on the combustion (power) stroke. Therefore its all symmetrical. And which is why they're also so smooth. And why you have such a nice exhaust note, because you have 2 cylinders pushing exhaust gasses out at the same time.

Not like with a 6 cylinder, where you will have 2, then 2 then 1 and 1 pushing exhaust gasses out.

Makes sense to me, and ive been at the pub!

Mind you i have heard v6 commies that have sounded very much like a v8, and my xy wagon i had people swearing that it was an 8 too.

Hunter · 23-12-2005, 07:57 AM

I was pretty sure it had a lot to do with the firing order as well...

Oh and I've heard *way* too many V6 dunnydores which sound like a cow taking a huge dump. Either that or they sound like a cow taking a huge dump into a vacuum cleaner.

Falcon 6s always sound good.

SunDrifter · 23-12-2005, 08:07 AM

I think klawsterfobik is on the money there. And seeing we're getting so many my mate stories.

My old XF had a Stage 3 COME cam and Mandrel Bent Pacemakers with a 2.5" system, and she really sounded like a V8 (lumpy!).

Lukeyson · 23-12-2005, 08:30 AM

yeah i find if a 6 exhaust is done on the cheap cheap or by a dodgy brother, it will sound like a tug boat. But if done well, they have some aspects of an 8 in the note, but still unique.
And i asked a mechanic that a while ago, and he gave me a similar story to klawsterfobik.

gww64 · 23-12-2005, 08:41 AM

Had an xa 6cyl that sounded like an eight. Couldn`t pick the difference. Till you drve it of course. Extractors and a twin system make all the difference. Depends on the mufflers you use as well.

**Raptor** · 23-12-2005, 08:46 AM

Quote:

Originally Posted by klawsterfobik

......
Not like with a 6 cylinder, where you will have 2, then 2 then 1 and 1 pushing exhaust gasses out.

Makes sense to me, and ive been at the pub!
......

WTF, it doesn't make any sense to me it sounds like you've been drinking.

A inline 6 cylinder (is there really any other kind) will have 1 on the exhaust stroke and 1 on the compression stroke every 120deg of engine rotation.

That other kind of 6 cylinder will have them split 60deg apart or some weird 90/30deg pattern if they are cut-down V8's

Common V8's sound the way they do because they have an exhaust pulse every 90deg of crank rotation, and this will differ depending on the firing order. There are also 2 different crank pattern, Flat-plane and Cross-plane. You'll find the Cross-plane in your everyday Ford and Holden while the Flat-Plane crank is more common in exotics such as Ferrari etc which sound quite different. Flat plane allows for lower weight (no counterbalance) and thus lower rotating mass (revs quicker) and thus more ultimate power but at the expense of harshness.

Pic's taken from here; http://www.autozine.org/technical_sc...dex.htm#Engine in the section on engine smoothness, I6 is best :voldar02:

I hope that provides some technical explanation rather than what me mates sisters uncles girlfriend car sounds like.

masters24 · 23-12-2005, 08:48 AM

VL Commy (boyfriends old work rig) sounded like a lumpy 8, although it was fully stock. The muffler/exhaust was a bit shagged and just sounded mean. His cousin who is a MAD holden nut hears it and goes "I didnt know a V8 would fit in a VL!" i was rather blown away...

YOOT · 23-12-2005, 09:02 AM

GO race a mate in his XR6 Turbo if you have something that will keep up and wind the window down while they are in front.

I have had this pleasure with my best friend who has a sedan, we raced back from my girlfriends house after State of Origin, since the sedan is a little quicker he was always in front from 100km/h upwards and believe me, there is nothing more spinetingling than a Barra240T at WOT from 10 feet away at break neck speeds!!! :thebirds: Sounds meaner, louder, and almost like the engine will explode than any other stock performance car in Australia :Reverend:

Casper · 23-12-2005, 09:38 AM

Quote:

Originally Posted by gww64

Had an xa 6cyl that sounded like an eight. Couldn`t pick the difference. Till you drve it of course. Extractors and a twin system make all the difference. Depends on the mufflers you use as well.

My XD I6 sounded like a V8. Now, of course, we all like to think this but in this case it sounded so much like a V8 that a mechanic who owned a V8 XE insisted I pop the hood as he thought the 4.1 badges on the side were "sleeper badges" and he didnt believe me that it was only an I6.

As for modern I6's (4.0l etc), they just dont sound the same, its a totally different sound. No idea why.

OLDFORDNUT · 23-12-2005, 10:01 AM

the old ford 6cylinders sound like a v8 with a twin system yet holden red and blue and black 6 cylinders never do,i always put it down to the stroke length as i could not think of any other difference as we all used the same 3 or 4 muffler types back in the 80's.
funny thing is an old hot Holden grey motor with cast iron headers and a twin system made a lot of the v8 guys want me to lift the bonnet as it sounded like an 8 when going past on the hiway.

gozza · 23-12-2005, 10:08 AM

my mate had a vh 6 cyl
slow as all buggery but it sounded like a v8
best sounding thing ive heard

23-12-2005, 10:09 AM

Quote:

Originally Posted by Casper

My XD I6 sounded like a V8. Now, of course, we all like to think this but in this case it sounded so much like a V8 that a mechanic who owned a V8 XE insisted I pop the hood as he thought the 4.1 badges on the side were "sleeper badges" and he didnt believe me that it was only an I6.

As for modern I6's (4.0l etc), they just dont sound the same, its a totally different sound. No idea why.

Unmuffled modern i6s sound like a truck at low rpm under load... There could be a way to modify the exhaust headers and lengthen some cylinder's headers so it sounds like a V8?

klawsterfobik · 23-12-2005, 10:46 AM

its not hard to get a 6 to sound like an 8, until of course you get higher up in the revrange.

Reading back through my original post, it doesnt make sense. And Raptor has pictures!

Steffo · 23-12-2005, 11:24 AM

You can get a 6cyl sounding pretty close. Where my best mate used to go to school, one of the guys there had an AU XR6-VCT ute, it sounded like a V8. It sounded awesome.

Ryan · 23-12-2005, 11:36 AM

I've heard alot of 202s that sound like 8s and even a few RB30 VLs.

But for some reason ive never heard a V6 Commy sound like a 8.

I know for a fact that my dad's uncle's I6 XD bushbasher with no exhaust sounds like a 351. :hihi:

Even my VL sounds a bit like a 8 because of it lumpy exhaust note.

XRated · 23-12-2005, 12:11 PM

The note on my I6 is really thick and deep, I've had plenty of people ask if "it's a V8?" I know nothing can imitate a real V8 though..... I'll try and get a recording of my note.

Hunter · 23-12-2005, 04:28 PM

My cousin's XY with non-crossflow 250 6 in it idles so lumpy that it really does sound like a V8. So much so that the car nut mate of his down the road whos bigtime into valiants asked him what V8 he had under the hood when he first heard it.

23-12-2005, 04:46 PM

Is the same prinicpal for the sound the same for a boxer engine like a WRX?

If you want to make a 4 cylinder sound like a WRX, take out a spark plug lead.

rob_liss_lms10 · 23-12-2005, 06:26 PM

quoting Hunter "My cousin's XY with non-crossflow 250 6 in it idles so lumpy that it really does sound like a V8"
the pre crossflow 6's imo are the only 6 that can come anywhere close to the sound of a V8.How-ever,in saying that....a 6 is a 6,a 8 is a 8.if you want the sound of a 8 that bad,get 1.

Ryan · 23-12-2005, 07:02 PM

Quote:

Originally Posted by rob_liss_lms10

quoting Hunter "My cousin's XY with non-crossflow 250 6 in it idles so lumpy that it really does sound like a V8"
the pre crossflow 6's imo are the only 6 that can come anywhere close to the sound of a V8.How-ever,in saying that....a 6 is a 6,a 8 is a 8.if you want the sound of a 8 that bad,get 1.

Yep I agree.

While alot of 6s do sound tough like V8s their still 6 cylinders,if you want the genuine V8 rumble then buy a V8.

smoo · 23-12-2005, 07:13 PM

Quote:

Originally Posted by rob_liss_lms10

quoting Hunter "My cousin's XY with non-crossflow 250 6 in it idles so lumpy that it really does sound like a V8"
the pre crossflow 6's imo are the only 6 that can come anywhere close to the sound of a V8.How-ever,in saying that....a 6 is a 6,a 8 is a 8.if you want the sound of a 8 that bad,get 1.

Hmm I dunno. A few 265 Valiants come close from what I've heard. But yea, a V8 is a V8, even an old original '34 Ford Coupe will tell ya that, or an LS1, even if it does need the revs piled on haha. Most Subarus have aftermarket exhausts which make them louder, drifting away from the similar sound to a V8 (less appealing imo, a stock one sounds much better)

buickman · 23-12-2005, 07:50 PM

Quote:

Originally Posted by rob_liss_lms10

quoting Hunter "My cousin's XY with non-crossflow 250 6 in it idles so lumpy that it really does sound like a V8"
the pre crossflow 6's imo are the only 6 that can come anywhere close to the sound of a V8.How-ever,in saying that....a 6 is a 6,a 8 is a 8.if you want the sound of a 8 that bad,get 1.

Have to agree with you there the log type Ford 6 from XK-XB with twin extractor system would be the closest I've ever heard to sounding like a V8.

The X/flows & ohc & any other 6 still sound like a six to me. Having always owned a V8 cars and still do as a hobby car I can pick the sound easy

gtfpv · 23-12-2005, 08:10 PM

Quote:

Originally Posted by Raptor

WTF, it doesn't make any sense to me it sounds like you've been drinking.

A inline 6 cylinder (is there really any other kind) will have 1 on the exhaust stroke and 1 on the compression stroke every 120deg of engine rotation.

That other kind of 6 cylinder will have them split 60deg apart or some weird 90/30deg pattern if they are cut-down V8's

Common V8's sound the way they do because they have an exhaust pulse every 90deg of crank rotation, and this will differ depending on the firing order. There are also 2 different crank pattern, Flat-plane and Cross-plane. You'll find the Cross-plane in your everyday Ford and Holden while the Flat-Plane crank is more common in exotics such as Ferrari etc which sound quite different. Flat plane allows for lower weight (no counterbalance) and thus lower rotating mass (revs quicker) and thus more ultimate power but at the expense of harshness.

Pic's taken from here; http://www.autozine.org/technical_sc...dex.htm#Engine in the section on engine smoothness, I6 is best :voldar02:

I hope that provides some technical explanation rather than what me mates sisters uncles girlfriend car sounds like.

thanks to all who replied . i think i now have some idea . just read in wheels also that the boss verses the ls2 sound vastly differant due to log stroke verses short stroke and differant firing order . obviously it is just not one factor but i geuss the 8 cylinders harmonics are a base to start from. cheers.

chippa6 · 23-12-2005, 08:48 PM

personally I don't I have heard any 6 cyl that could pass for an eight. I had a six in my xb then slotted an eight in an there was no way you could mistake it. some crossflow motors can get a nice burble at idle butstill not the same as an eight.

Cheap AU · 23-12-2005, 09:58 PM

what is the ideal set up to get the best note exhaust wise from i6 AU? out of 2 1/2 sport system straight through, 2 3/4 or 3 inch

does it sound better as they get bigger or does it tend to start to drone out n sound crap

stockstandard · 23-12-2005, 10:08 PM

I have to laugh at all these "my/mates 6 sounds just like an 8" comments. Anyone who knows anything about cars can pick the difference in 0.1s

Casper · 23-12-2005, 10:10 PM

Quote:

Originally Posted by stockstandard

I have to laugh at all these "my/mates 6 sounds just like an 8" comments. Anyone who knows anything about cars can pick the difference in 0.1s

Normally I'd agree with you except I've been fooled a couple times myself with some of the older I6 engines.