Inline 6, why not 8?

[Road_Warrior]

Originally Posted by Raptor

How about VW groups W12 ;)

Similar size to a V6 but with 12 cylinders :

That engine still makes my head explode, I can't comprehend the concept of a W motor or even how it works.

[gunner]

Originally Posted by Road_Warrior

That engine still makes my head explode, I can't comprehend the concept of a W motor or even how it works.

The "W" is a bit of a misnomer and probably causes peoples' confusion. Think of the W12 as a normal V12 engine ie two inline 6 engines connected at the crank. The only difference is that VW didn't use two inline 6 engines, they used two VR6 engines.

So what's a VR6 engine? It's a very, very narrow angled V6 engine. On a normal V6 you have two separate cylinder heads. Now imagine a normal "V" angle is 90 degrees. What happens when you start reducing this angle? At 45 degree, say, you'd still have two separate cylinder heads but if you reduce the angle further the cylinder heads will eventually touch. So VW basically just made a very, very narrow V6 engine that had both its cylinder heads connected into one.

Hope that made sense...

Otherwise:
VR6 Engine

and

W12 Engines

[Kamshaaft]

The conrods come in at slightly shallower angles for the lower banks of cylinders and IIRC the two cylinders that are paired together fire at different points in the firing cycle. It's a neat piece of engineering to get it to run as well as they have, but it's still bound to be less smooth than the Barra, or a Jag V12, or etc.

I don't know what the firing order is though. I'd hate to have to put a new dizzy in, as everything would be in Italian. If it came from VW in German, I might be safe.

[geckoGT]

Originally Posted by Kamshaaft

The conrods come in at slightly shallower angles for the lower banks of cylinders and IIRC the two cylinders that are paired together fire at different points in the firing cycle. It's a neat piece of engineering to get it to run as well as they have, but it's still bound to be less smooth than the Barra, or a Jag V12, or etc.

I don't know what the firing order is though. I'd hate to have to put a new dizzy in, as everything would be in Italian. If it came from VW in German, I might be safe.

Its german for a start, and as if it is going to have a dizzy.

[CPOCSM]

Here is an Alfa with a straight 8

http://www.youtube.com/watch?v=9UyChWMbl_A

Bloody awesome noise!!

[Kamshaaft]

Originally Posted by geckoGT

Its german for a start, and as if it is going to have a dizzy.

You got me.
Figure of speech.

[Yaw]

Probably a bit late in the thread for this, but anyway.
The car that Duston Hoffman was rabbiting on about in "rainman" was a straight 8
1949 Buick Roadmaster. Straight 8. Fireball 8.

[joolz]

My Grandfather used to work on them years ago and were common for breaking cranks as they were so long.

[Franco Cozzo]

With the breaking crank issues, couldn't you just make them out of a stronger material? I'd imagine it'd be a similar issue the 20B rotory engine has, they have problems with snapping their eccentric shaft when you start hitting certain power/torque figures which can be resolved by spending up on better quality stuff.

[Wally]

Originally Posted by Big Damo

I was just thinking the other day, we've got an I6 right? Why don't we have I8s? Obviously it isn't just going to be as easy as slap on an extra 2 cylinders but how come we don't have them?

I'm guessing it would be a tad bit too long, but would it offer any benefit over a V configuration?

I must be getting bloody old, because it used to be common knowledge why the V8, but for the youngsters: the longer the crankshaft the more prone it is to whip at high revs. Not an unknown phenomenon even in today's supa dupa I6's. Having said that, common knowledge in auto circles is usually baseless.

[Road_Warrior]

Originally Posted by Big Damo

With the breaking crank issues, couldn't you just make them out of a stronger material? I'd imagine it'd be a similar issue the 20B rotory engine has, they have problems with snapping their eccentric shaft when you start hitting certain power/torque figures which can be resolved by spending up on better quality stuff.

Well, I'm sure back in the day when straight 8's were all the rage they could have made the cranks out of a stronger material, if it existed then and if the know how existed along with it.

[jpd80]

Originally Posted by melon466

5 cylinder is the best balanced engine you can get

Far from it, they have terrible NVH.
I-6, V12 and horizontally opposed engines are the best balanced engines.

[The Yeti]

Originally Posted by cosmo20btt

From what I remember straight eights had a common problem of breaking cranks, that is one of the reasons v8s replaced them.

thats not entierly true, braking cranks isnt a real issue this can be adressed with adding extra main bearings but the reason was simply real estate, to get cubic inches you need bore size X stroke so to get the size engine you eaither had a really long bonnet or went wit ha V configuration

theres still plenty of healthy straight 8's arround in the nostalgia seen

pitty classics.com are such tools about posting images on other forums perhaps if they did more people would see the image and follow it through to find more and they would get more traffic :

[buggo]

Originally Posted by melon466

5 cylinder is the best balanced engine you can get

XR5 owner/fanboy?

[Quicksand]

Originally Posted by CPOCSM

Here is an Alfa with a straight 8

http://www.youtube.com/watch?v=9UyChWMbl_A

Bloody awesome noise!!

That sounds HOT AS!!!

[aussie muscle]

Originally Posted by lofty

What I want to know is, is it theoretically possible to design a V8 crank to replicate the balance factors of a straight 8? In case that makes no sense, consider that you can make a parallel twin sound and feel like a 90 deg V twin by phasing the big end journals 90 deg apart. Yamaha did it with the TDM and TRX. So why wouldn't the reverse be possible, giving the character of a straight motor with the benefits of a V?

There's a bit of that stuff in the last Australian Muscle Cars magazine about the old F5000 engines. relating to how the angle of the big ends and crank were made in them.

as for straight 8's, it helps when you have a bonnet longer than half the car's length, like a Cord or Dusenburg. :

[[CaSeY]]

who cares about a straight 8, how bout barra v12 with 2 turbos

[jpd80]

Originally Posted by lofty
What I want to know is, is it theoretically possible to design a V8 crank to replicate the balance factors of a straight 8? In case that makes no sense, consider that you can make a parallel twin sound and feel like a 90 deg V twin by phasing the big end journals 90 deg apart. Yamaha did it with the TDM and TRX. So why wouldn't the reverse be possible, giving the character of a straight motor with the benefits of a V?

What you're suggesting is a flat plane crank, beautiful balance
and no counter weights required on the crank...

Sounds like two four cylinders, check out the Ferrari:...LINK

[388cube_edxr8]

who cares about a straight 8, how bout barra v12 with 2 turbos

Waaaaay ahead of you mate - already got one in the works. The hardest part is finding the money to fabricate the crank and the passenger side head (manifolds are on the other side)

Should have about 700kw (960hp) when done but its a loooong way off.

[Stattic]

Originally Posted by 388cube_edxr8

Waaaaay ahead of you mate - already got one in the works. The hardest part is finding the money to fabricate the crank and the passenger side head (manifolds are on the other side)

Should have about 700kw (960hp) when done but its a loooong way off.

what lol have you got a link to a build thread or something or are you joking

[388cube_edxr8]

Nah mate serious but suffering from a severe lack of funds. I need to spend more time at work and less time in the shed.

[Saraco]

Originally Posted by lofty

What I want to know is, is it theoretically possible to design a V8 crank to replicate the balance factors of a straight 8? In case that makes no sense, consider that you can make a parallel twin sound and feel like a 90 deg V twin by phasing the big end journals 90 deg apart. Yamaha did it with the TDM and TRX. So why wouldn't the reverse be possible, giving the character of a straight motor with the benefits of a V?

And YAMAHA have done it again! The new R1(2010 MODEL) is an inline 4cyl but has a 90 degree i.e. two plane crank (all other inline 4cylinders have a single plane 180 degree crank) this thing is the most V8 like sounding inline 4 I have ever heard! Sounds even more V8 like than a V4!

[The Yeti]

a mate of mine owns Pauls Old Skool Only, he's currently doign a hart transplant on an old Buick



theres plenty more here if you are interested http://www.facebook.com/?ref=home#!/album.php?aid=197364&id=334269315675

http://oldskoolonly.com/default1.htm%20index1.htm

[lofty]

Originally Posted by The Yeti

a mate of mine owns Pauls Old Skool Only, he's currently doign a hart transplant on an old Buick
http://oldskoolonly.com/default1.htm%20index1.htm

Meaning what, replacing the I8 with a V8? If so, what's happening to the oldie?

[lofty]

Originally Posted by 388cube_edxr8

Waaaaay ahead of you mate - already got one in the works. The hardest part is finding the money to fabricate the crank and the passenger side head (manifolds are on the other side).

Casting up a V12 block no biggie then?