Making a 6 cyl cross flow sound like a v8

[TICKFORD220]

Only straight six I ever heard that remotely sounded like a v8 at idle was a fairly hefty 265 hemi,at revs they sound mean but nothing like a v8.

[Falcon Coupe]

It can be done. I was once fooled by a HX premier back in the 80's. The idle was similar to this:

https://youtu.be/mlfASIX0s9E?t=57s

[slowsnake]

Originally Posted by Falcon Coupe

It can be done. I was once fooled by a HX premier back in the 80's. The idle was similar to this:

https://youtu.be/mlfASIX0s9E?t=57s

Hello,
Lovely..

Cheers Billy

[slowsnake]

Hello,
It was pointed out to me earlier that I added another website to the wrong thread.
So I will put it here where I meant to in the first place!

http://www.soundracer-australia.com.au/


Cheers Billy.

[Sar4890]

Extractors a big exhaust and a mild cam usually makes an old crossy sound v8ish at idle its when you step on the loud pedal that illusion disapears and they make a distinct sound that 250's make. Imho i would either embrace the sound of the 6 or go for a V8.

[solarite_guy]

Originally Posted by Sar4890

Extractors a big exhaust and a mild cam usually makes an old crossy sound v8ish at idle its when you step on the loud pedal that illusion disapears and they make a distinct sound that 250's make. Imho i would either embrace the sound of the 6 or go for a V8.

Absolutely agree with you. Everything plays a part in the sound quality, yet, the fact of the matter is, an I6 with a 120* cross plane crank will give an exhaust pulse based on that 120* crank journal separation.

In all honesty I think is is a beautiful sound note.

A 90* cross plane crank in a 90* V8 will give a pulse note based on that.

These differences ensure neither will ever sound the exact same as the other.

The 250 Chevelle sounded sweet and to be honest I have a soft spot for GTOs, Chevelles, Cutlass/442s and GSs. My first car was a '65 389 GTO convertible 4 speed car and my Mom drove a '66 Chevelle then a '72. BTW, she is the one who introduced me to drag racing at a very young age with her '50 Chevy fastback.

Yet, you caught that the earlier vid did not record high revs. Had that happened, what you described would happen. The sweet symphony of an I6.

To try to approximate the rumble sound at song, looking at the very good picture of the Chevelles headers paints the picture. Based on the firing order of that engine, a 120* separation, ensuring a sweet symphony will come from that engine at full song.

Take 1 pipe from the rear 3 and move to the front 3 then match with taking 1 pipe from the front 3 and move to the rear 3 and rumble separated by a 240* offset from each of the 2 exhaust banks will occur at song.

Not exactly like a V8, but a rumble.

[falcon fg]

Thanks solarite guy. Where the engines that you are talking about pre cross flow?

[slowsnake]

Hello,
Are you sure you want a 6 or do you really want an 8?
You will not get a V8 sound right through the rev range on 6 cylinder engine,on idle of slightly higher,but you have to remember you can run low rpm in each gear at different speeds.
Like I said the Liverpool Command traffic cops had my Reg Number in all their Charger patrol cars, follow,pull over and lift bonnet,the cops freaked out to see a grey 138 motor that they said sounded like a 302 F100?
I was over Fairfield pits every Friday,every week because I told one of them jackbooted bastards to **** off,and I ripped my tickets up and threw them at him!..I got a defect sticker every Friday.

Two piece extractors,mild cam and I also took the counterweights out of the dizzy and just run it advanced 15° or so,it was by ear,it was a beast!
Ended up cutting it in half with a 9" grinder,made my brother an EK Holden box trailer,put the running gear into a EJ van I picked up with a piston through the side of the block.

One Liverpool Command Highway Patrol dog gave me 32 speeding tickets in 10 months, I had a real ball in the 70's, I had to move to Qld to get my Qld licence before they cancelled my NSW brief.

Cheers Billy.

[solarite_guy]

Originally Posted by falcon fg

Thanks solarite guy. Where the engines that you are talking about pre cross flow?

Looking for some vids for you.

[mick taylor]

I will say that no 6 cyl sounds like a V8
You could get an old log ford 6 to sound not all that bad with dual exhaust.

Best sounding V8 has to be a 351 Cleveland but I have herd some that were rubbish esp single exhaust not to mention some VB to VL V8 Commodores with single system they had a blub blub noise just a shocking sound, one would drive past my place and I would cringe.

In 1980 I had a single exhaust on my HG 253 stock to were the 2 pipes come into one and then 2 1/4 into a Hills sport straight through muffler sounded good, but I don't know what they were doing with the commodores system, it must of been in the point that the 2 pipes joined was in the wrong spot.

Like Solarite says, you could mess with the extractor pipes order and length to get some type of sound, but could loose power in doing such.

There is a VX Commodore V8 Single exhaust getting about around here and it does not sound like a V8 at all, he flogs the crap out of it all the time and it's bloody quick.

[snowcone]

Back in the 70's when I was an apprentice mechanic, one of the other apprentices had a 250 XY with a lumpy cam, solid lifters and a twin system back from the extractors and it sounded like Allan Moffets' GTHO

[slowsnake]

Originally Posted by snowcone

Back in the 70's when I was an apprentice mechanic, one of the other apprentices had a 250 XY with a lumpy cam, solid lifters and a twin system back from the extractors and it sounded like Allan Moffets' GTHO

Hello,
Snowcone eh!..cool name!..lol..

Cheers Billy ( bent head )

[solarite_guy]

Originally Posted by falcon fg

Thanks solarite guy. Where the engines that you are talking about pre cross flow?

Alright, it is not just a matter of a couple vids. Need to start out with some pictures and commentary. It will be a couple posts or three or four or maybe more.

You may already be aware, but up front, something I want to make sure is clear for everyone is a separation of terms.

Cross flow vs port configuration/layout.

What makes the cross flow make the sweet 6 cylinder song vs a rumble is not the fact air/fuel come in one side and the exhaust goes out the other. Rather how the exhaust ports are configured, i.e. their physical layout, regardless of what side of the head they are on, relative to the intake ports is more significant.

I'll lay out a few Ford 250 cylinder heads and an Austin Healey 3000 head right here.

In this pic, we see 2 versions of a 250 cylinder head. The bottom has the old log style intake and #3 and #4 exhaust ports siamesed. The top is a modern alloy replacement where the #3 and #4 exhaust ports are no longer siamesed.

In this 1st pic, pay careful attention to the bolt pattern around the siamesed #3 and #4 port opening.



Now I have a series of 3 pics showing a 250 2V head going through a conversion to separate the center siamesed center exhaust ports.

Again, I ask you the pay attention to the bolt pattern.







Now an Austin Healey 3000 head port layout.



Give you a chance to study that a little then I'll add some thoughts, and you or anyone else can ask questions along the way.

[mick taylor]

Originally Posted by solarite_guy

Alright, it is not just a matter of a couple vids. Need to start out with some pictures and commentary. It will be a couple posts or three or four or maybe more.

You may already be aware, but up front, something I want to make sure is clear for everyone is a separation of terms.

Cross flow vs port configuration/layout.

What makes the cross flow make the sweet 6 cylinder song vs a rumble is not the fact air/fuel come in one side and the exhaust goes out the other. Rather how the exhaust ports are configured, i.e. their physical layout, regardless of what side of the head they are on, relative to the intake ports is more significant.

I'll lay out a few Ford 250 cylinder heads and an Austin Healey 3000 head right here.

In this pic, we see 2 versions of a 250 cylinder head. The bottom has the old log style intake and #3 and #4 exhaust ports siamesed. The top is a modern alloy replacement where the #3 and #4 exhaust ports are no longer siamesed.

In this 1st pic, pay careful attention to the bolt pattern around the siamesed #3 and #4 port opening.

image

Now I have a series of 3 pics showing a 250 2V head going through a conversion to separate the center siamesed center exhaust ports.

Again, I ask you the pay attention to the bolt pattern.

image

image

image

Now an Austin Healey 3000 head port layout.

image

Give you a chance to study that a little then I'll add some thoughts, and you or anyone else can ask questions along the way.

Yes there is a cast iron peace that you can just shove in that stupid dual port that I have seen and sure it is what would change the note.

[slowsnake]

Hello falcon fg,
On my way back from the Territory in 1981 I stopped in at Townsville Qld,had a mate who invited me to call in on my way back to Sydney, he said he may have a bit of work for me with a Townsville Engineering company,he was right into his Ford V8's,he had an old XA Coupe,street car cum drag car.It was a filthy beast of a thing to ride in too,it scared me.

Anyway he and his mates had a clubhouse,I forget what they called it but the club ran the local Townsville Dragstrip.
There were a lot of folks I met there and from memory a dude called Bob Krogdahl,he was a designer/builder.

I was just looking through my ( stuff ) and his name popped up,so that's why I looked him up on the net!
Lo and behold I find him!..and what a surprise too,so I have a link for you falcon fg,make sure you play the video of the engine in the link.
Hope you like it...

http://www.aussiespeed.com/tag/krogdahl-head/

Kind Regards Billy.

[slowsnake]

Hello falcon fg,
As you can see the engine is twin ohc,sans Jaguar style,I had some spare time today and spent it looking for some additional info on these beautiful bits of Aussie genius.
Got a few links for you and the other members,hope you mob enjoy reading about Bob and his heads!

http://i1106.photobucket.com/albums/...21946930_n.jpg
Cheers Billy.

[slowsnake]

Hello falcon fg,
I can't do this computer stuff very well,am using a 7" tablet, its a no-name jobbie, have nearly zero signal on wireless modem,it makes it very hard to manoeuvre my way around these things,but will persevere!

Krogdahls story is worth following, I am surprised he has not been mentioned on this forum,or maybe he has and I just haven't found it yet,his heads are/were quite rare,the last one he had advertised 4 yrs ago was $65 grand!
Not sure if motor was included?

Hope you enjoyed reading about him!

Kind Regards Billy.

[solarite_guy]

So, for what you are pursuing, if we look at this older iron head in the picture:



Then the newer iron 2V head getting prepped for the port divider:



It is obvious that both heads from the factory have a compromised center port as they came from the factory. However, for what you are after, maybe not so much of a compromise.

Now take a look at these extractors:



and these shorties:



We can see, though there are individual pipes for each cylinder, the center siamesed port allows both #3 and #4 cylinders to hit those same 2 center extractor pipes. This includes both the exhaust gasses and the sound wave pulses.

From a sound perspective, this situation is almost the same as a set of extractors with the 2 center pipes crossed and the 2 center ports in the head being separated, either by the divider in an old head or a newer head like the alloy shown at in the top pic. The difference being, crossing the center pipes with a head where the #3 and #4 are separated will be better for performance. The sound might meet your rumble requirements a little better too.

Does that make sense?

Back later with more.

[solarite_guy]

Then, using a head like this with NO divider between the 2 center exhaust ports a fella ran a good test for our purposes.



In the fist test, the extractors funnel all 6 pipes into a single exhaust.

The second test the collector was cut off to create dual exhaust in 2 pairs of 3 into 1 systems.

In watching this keep in mind what we discussed earlier about those 2 center ports even with individual extractor pipes for the 2 center ports.



The first test produces a note like the typical sporty 6 cylinder exhaust note.

The second test, without change of cam, produces more of a rumble. Really wish he had rev'd it more.

So even though the exhaust dumps into the 2 center pipes through a siamesed center port arrangement through a gasket like this:



We can get variations in the exhaust note depending on how the exhaust is configured during the 2 tests.

Why?

In the first test, the sound waves of each pulse get re-combined into their natural 120* separation as they are funneled into the single pipe.

This is a similar sound effect as an X-pipe installed in an exhaust system for a 90* V8 with a 90* cross plane crank. The typical V8 which normally gives a rumble. Put the X-pipe in and the result is a symphony based on 90* pulse separation between left and right bank, fooling the ear into hearing what sounds like a 180* separation between each left bank pulse and each right bank pulse. A sound much like the earlier V8 example with 180* headers.

Think about that and any questions.

More later

[Junkyard-Dog]

In some ways, I prefer the sound of a straight-six... probably because of E-series XR6s.

V8s are nice but there is nothing like chopping them at the lights with a 6 cylinder car.

[solarite_guy]

Now we have seen the pre crossflow head with the open, siamesed center exhaust ports in combinations of 6 into 1 and 2 pairs of 3 into 1 produce 2 different sounds even though the camshaft remained the same.

Now let's look at the Austin-Healey 3000 straight 6 with individual exhaust ports down the length of the head. Reference picture:



Each of these are in performance states of tune with the 2nd one having noticeably more cam than the first.





The factory exhaust manifolds are like 2 shorty 3 into 1 extractors but cast iron.

Nice cars.

The only way to turn that exhaust note into a rumble would be to cross a couple pipes between the front 3 and back 3, such as #3 and #4.

Questions?

[Junkyard-Dog]

Can we make my 4G54i Magna sound like a V8?

[solarite_guy]

You would have your work cut out. Here is the head.



There maybe some chance for some exhaust side grouping, but I would have to scratch my head a little about this with the I4 block and flat crank. I almost think some odd angle cross plane crank would be needed.

[98TLS]

Looking back i kinda cringe when i think of it ie why would ya but when a much younger fella i had a nice XW ute and paid good coin to have an exhaust bloke do his thing he actually did a good job and it sounded sweet much to my XW V8 Fairmont owning mates annoyance

[XByoot]

Originally Posted by Junkyard-Dog

Can we make my 4G54i Magna sound like a V8?

Don’t mess with perfection!

[Sar4890]

If you shoe horn another one in there we could go straight eight at least.

[XByoot]

Originally Posted by Sar4890

If you shoe horn another one in there we could go straight eight at least.

You won’t believe this but there was an old rwd Sigma wagon that they fitted an LS into. What a waste of a sigma. The old 4G54 and all its “character” isn’t a bad old bucket of bolts, I’d rather that I think.


As for sixes, you know, I like the six sound,remember the old XU1? They weren’t a bad sounding bit of kit, don’t try and pretend it’s a V8. I’m relating it to the scene in Spinal tap where he has the cucumber down his pants. Moral of the story is don’t pretend to have something you don’t ..... you’ll end up embarrassed

[mick taylor]

Originally Posted by XByoot

You won’t believe this but there was an old rwd Sigma wagon that they fitted an LS into. What a waste of a sigma. The old 4G54 and all its “character” isn’t a bad old bucket of bolts, I’d rather that I think.


As for sixes, you know, I like the six sound,remember the old XU1? They weren’t a bad sounding bit of kit, don’t try and pretend it’s a V8. I’m relating it to the scene in Spinal tap where he has the cucumber down his pants. Moral of the story is don’t pretend to have something you don’t ..... you’ll end up embarrassed

The old XU-1 sound at idle was ok, but a mate had a G pack Torana with a worked 202 with dual exhaust that was chevy style pointing down both sides to the road, she was quite but would rump thump noise at idle, when he dropped off another mate at his mum and dads place they hated that noise and could not understand why it did that, so he would have to drop him off at the start of the driveway 100m away.

If I hear a nice big cam late at night I love it, not to mention some ***** flat to the boards going past my place, it's music to my ears if it sounds good.

A mate who lived on the Bundaberg highway who would jump out of bed to watch some ***** fly by flat to the boards, you could hear them coming up the hill, sounded great !

Even them old 2stroke diesels could sound good, when I lived on top of a hill I would listen out for it coming around about 10.30 at night but I could not hear the cars from home much at all.

[XByoot]

The old 2 stroke diesels certainly had an awesome sound. The old Driptroit Diesels were in everything!
Yeah, I always picture the XU1 with a normal single exhaust , those twin down pipe exhausts...

[mick taylor]

Originally Posted by XByoot

The old 2 stroke diesels certainly had an awesome sound. The old Driptroit Diesels were in everything!
Yeah, I always picture the XU1 with a normal single exhaust , those twin down pipe exhausts...

The GTR had a single pipe coming out at the rear muffler but the stock Holden XU-1 rear muffler just has 2 little pipes coming straight out at the rear of the muffler.

I don't like the droop down tips look.

What I am on about is called a Chev type pipe style that comes down at the rear of the back wheel to the ground and you can only see a inch or 2 of pipe, they can not be destroyed like some can hanging out the rear.
1960 and 70's Chevy had such.