Making a 6 cyl cross flow sound like a v8

[falcon fg]

I know a 6 cylinder pre cross flow with twin exhausts can be made to sound like a v8.
Can a steel head 6 cylinder cross flow be made to sound like a V8??
Has anyone done it??

[solarite_guy]

First, I don't think what you stated about the straight 6's mentioned sounding like V8s is exactly possible, but with specifically designed exhaust relative the the firing order can be somewhat approximated.

Assumptions:

90* V8 block with 90* cross plane crank
I6 blocks blocks mentioned with 120* cross plane cranks

What makes the typical V8 sound is the combination mentioned above mixed wih conventional 4 into 1 exhaust. NO 180* headers. NO X-pipe.

This combination results in each bank firing 2 cylinder sequentially on each side during their firing sequence.

To approximate this, you want a similar effect from the I6 headers. That is, force 2 sequential cylinders to fire on each side of a 3 into 2 system with a single out pulse 240* out of sequence on the 3rd pipe of each pair of the . 3 into 2 system.

A similar effect will occur, but not exact.

[falcon fg]

Thanks, I will take you advice to an exhaust shop this week. You are correct when you say the pre cross flow exhaust sound is not exactly the same as a V8 but it does sound very similar and with twin pipes most "non expert" people don't recognise the difference. I have spoken to an exhaust shop previously who said pre cross is easy to do to get the required sound but a cross flow is very difficult. I'm hoping some one on here has had it done and therefore I can tell a shop what I want. Please keep comments coming.

[ozpacman]

I reckon I know the sound you're seeking falcon fg!

Certainly back in the day there were a lot of six cylinder falcons running around that I always considered had either the 'right' or 'wrong' sound when it came to modified exhausts.

Dependent on the style of extractors used, one had a kind of throaty sound reminiscent of a V8, and the other sounded like a bad fart!

I remember one mate had a 250 three on the tree ute that he put pipes on and it sounded really nice. Another mate liked it as well and thought he'd do the same with his 4.1 4 speed XC panel van, and it sounded terrible.

Don't know if that was due to the wrong style of extractors or something to do with the cross-flow head design.

Russ.

[falcon fg]

Thanks for your comments Russ. I agree with what you said. Hopefully someone has got a 4-1 with the right sound.

[Mercury Bullet]

Back in the 70's I had a mate with an xb pano that you would have sworn had a v8.
I couldn't believe my eyes when he popped the bonnet and there was a 250.

Unfortunately all I know is it was a combination of extractors, Lukey mufflers and twin 2 inch pipes. How it was configured I have no idea sorry.

[eb2fairmont]

The trick is to run dual pipes and a set of extractors with long primaries in a 321 format.

The secondaries need to be long cut the pipes and flange and run dual exhausts.


The set up I have on my xf runs back to a single for the cat, but splits after into dual hooker aerochambers and a couple of hotdogs.

[Itsme]

Make sure you add a balance pipe/tube to help to achieve the required sound.

[falcon fg]

Thank you eb2fairmont. I have a few questions you may be able help me with.
1. Are your extractors a brand name off the shelf or are they custom made?
2. I notice you have a cat in your system and the two pipes go single into the cat then two out. I don't need a cat due to the age of the engine (1976). Do you think that I need a cat in my system to achieve the V8 sound?
3. What size are your pipes?

[falcon fg]

Thanks Mercury Bullet. I believe 250's are easy. The 4.1 crossflow is different and difficult.

[Nu66et]

My understanding was the pre crossflow sounded better because of the siamese 3-4 cylinder port. Maybe if you ran a balance pipe between the 3-4 primaries on a crossflow you could replicate it.

[slowsnake]

Hello,
Back in the 70's my 62 EK P/van had a set of speakers just inside the top tailgate,run my tapedeck through a small amp,always drove with tailgate up,we would play very loud V8 cars revving their heads off at the lights,guys next to you didn't know what you were running,lol,.that's a true story too.

Cheers Vilhjalmur.

[dunga]

Must have a lumpy camshaft, twin exhaust ,6 into 2 extractors will be as close as you are going to get.

[falcon fg]

Yes slowsnake I've heard of this before.

[pottery beige]

twin system

hot dogs

no mufflers

[falcon fg]

Thanks Dunga. I appreciate your comments (noted)

[TICKFORD220]

In the 90s i had an xd with a warm cast x flow with the second largest off the shelf crow hydraulic cam available,stupid people that weren't into cars all thought it was a v8,250psi static compression may have helped that...
The exhaust was nothing special,motivator extractors and a single 2.5 with a lukey straight through,drone city......
Id say a decent sized cam for a start.

[futura]

If you want v8 sound, just buy a V8. All the money in the world will not make a crossflow 6 sound like a cleveland.

[slowsnake]

Originally Posted by dunga

Must have a lumpy camshaft, twin exhaust ,6 into 2 extractors will be as close as you are going to get.

Hello,
You are pretty well spot on there,I know you are talking Fords but my Grey sounded just like a 302 F100!
Especially to the cops,every time I was pulled over around Liverpool/Cabramatta it was "lift the bonnet", every time,

Had mildish cam,2 piece extractors,(3 into 1) twin 1-3/4 DIA exhaust and just 22 inch Lukeys,the head was ported and polished with near 30 thou shaved off it,run triple 1-1/2 SU carbs!
Yes you are spot on!

Cheers Ulick

[falcon fg]

Thanks for your comment futura but I have problem caused by another so I am stuck with the six probably forever. I just trying to make the best out of a bad situation but still get the sound I want.

[eb2fairmont]

Originally Posted by dunga

Must have a lumpy camshaft, twin exhaust ,6 into 2 extractors will be as close as you are going to get.

This - just make sure the two pipes are as long as possible.

[eb2fairmont]

Originally Posted by falcon fg

Thank you eb2fairmont. I have a few questions you may be able help me with.
1. Are your extractors a brand name off the shelf or are they custom made?
2. I notice you have a cat in your system and the two pipes go single into the cat then two out. I don't need a cat due to the age of the engine (1976). Do you think that I need a cat in my system to achieve the V8 sound?
3. What size are your pipes?

1. genies. However 1.75" primaries are the cuts nuts on these which pacemaker make.
2. No.
3 2.5" although 3" is better.

[solarite_guy]

Originally Posted by Nu66et

My understanding was the pre crossflow sounded better because of the siamese 3-4 cylinder port. Maybe if you ran a balance pipe between the 3-4 primaries on a crossflow you could replicate it.

You know, I think you are on to something there. The way the exhaust manifold really does not have an effective separation between 3 and 4, this would result in 2 and 4 going off in a seeming side by side 120 sequence as if 2 and 3 went in sequence, giving a rumble.

It is easier to find full sequential firing separation examples on a V8 with 180* headers vs conventionally grouped exhaust.

Keep in mind pipe cylinder displacement, pipe diameters, pulse separation in degrees, muffler types, resonator types, valve timing all play a role in overall sound quality or lack of.

Here is a V8 with 180* headers. This gives full 180* firing pulse separation for each bank and produces the symphonic sound:



Here is the typical V8 with 2 instances of non separation of firing sequences per bank firing. Nice rumble. No symphony.



Without knowing the exact specks of each engine I would guess the race car with the 180* headers is in a more modified state of tune. Just looking at the tiny exhaust on the Mustang tells me it doesn't have a whole lot under the hood, yet gives the sound of the tougher hombre.

[solarite_guy]

Forgot to mention 5 and 3 would have the same effect as if 5 & 4 fire sequentially.

[OzJavelin]

Make it sound like a hot six ... I'm a V8 fan, but there are plenty of great sounding 6-cylinders out there. Personally I'd look at the British/Europeans for a better note to replicate (if possible)

[solarite_guy]

Originally Posted by OzJavelin

Make it sound like a hot six ... I'm a V8 fan, but there are plenty of great sounding 6-cylinders out there. Personally I'd look at the British/Europeans for a better note to replicate (if possible)

That is my favourite. The sweet symphony of an I6. I loved the sound of my Austin Healy 3000 MkII.

Not sure how familiar you are with the exhaust system but it had a split 2 of 3 into 1 exhaust manifold with twin head pipes feeding into a single muffler and then twin tail pipes out of the muffler. No resonators. Sang beautifully.

Of course when it comes to V8s I want the rumble.

[solarite_guy]

Originally Posted by solarite_guy

That is, force 2 sequential cylinders to fire on each side of a 3 into 2 system with a single out pulse 240* out of sequence on the 3rd pipe of each pair of the . 3 into 2 system.

The bolded needs correction. It is 2 of 3 into 1 systems.

[Vesper Martini]

Originally Posted by dunga

Must have a lumpy camshaft, twin exhaust ,6 into 2 extractors will be as close as you are going to get.

Probably needs to run Carbs too, EFI smooths out the bumps..

[OzJavelin]

Originally Posted by solarite_guy

That is my favourite. The sweet symphony of an I6. I loved the sound of my Austin Healy 3000 MkII.

Not sure how familiar you are with the exhaust system but it had a split 2 of 3 into 1 exhaust manifold with twin head pipes feeding into a single muffler and then twin tail pipes out of the muffler. No resonators. Sang beautifully.

Of course when it comes to V8s I want the rumble.

Healy 3000 was exactly what I was thinking ..
.. or some of the Jaguars ..

[falcon fg]

Thank you eb2fairmont for the additional info