Flat or single plane cranks ....????

[gwood]

Originally Posted by afterburn 549

Ok
Now if i had an old V8, right about now I would be wishin a vendor would start selling a Flat plane crank and cam kit for it.
Will this ever happen?

Stevie's Crazy Garage. (Good name.)

[afterburn 549]

Thanx for the name drop!

Ahem 27 grand?
cough.
sputter.

[Jeff Higgins]

Originally Posted by cockerpunk

every inline 4 ever made has a flat plane crank.

Yamaha has built cross plane in-line fours for a number of years. They started with their Moto GP bikes and now use them in street bikes as well. Their big advantage is that they do not accelerate/decelerate all four pistons at the same time.

[afterburn 549]

Thanx!
Now there is something I did not even think of !

[jcommin]

Originally Posted by tcar

Cross plane cranks need counterweights.

Flat plane cranks don't have counterweights.

Ford uses a harmonic balancer to smooth out the vibes.

Going back to my college days in the early 70's, I remember learning that the inline six is naturally balanced. 8 cylinder engines , straight or v designed are not - they need external balancers.

[Jeff Higgins]

Originally Posted by jcommin

Going back to my college days in the early 70's, I remember learning that the inline six is naturally balanced. 8 cylinder engines , straight or v designed are not - they need external balancers.

That's true - inline sixes are the only engines that come up all zeros. Used to be about the most common engine made because of that. Packaging has kind of hurt it, though - it's just so darn long. Lots of crank twist in the more powerful ones, too.

Mercedes, however, have developed a new I-6, variants of which will power all of their cars in coming years. Everything old is new again...

[afterburn 549]

https://www.svtperformance.com/2015/09/22/news-flat-plane-crank-conversion/

[afterburn 549]

I am always a little bit surprised that the ford six with the exhaust and intake all on one side was not promoted as a turbo version.

[pavulon]

Originally Posted by Jeff Higgins

That's true - inline sixes are the only engines that come up all zeros. Used to be about the most common engine made because of that. Packaging has kind of hurt it, though - it's just so darn long. Lots of crank twist in the more powerful ones, too.

Mercedes, however, have developed a new I-6, variants of which will power all of their cars in coming years. Everything old is new again...

I believe any V-12 angle satisfies the "all zeros" criteria too as it is essentially two inline 6's on one crankshaft.

[Bill Verburg]

Originally Posted by afterburn 549

Ok
Now if i had an old V8, right about now I would be wishin a vendor would start selling a Flat plane crank and cam kit for it.
Will this ever happen?

There's really no need
the F/O on the modern Chevrolet LSX series motors and the Ford Coyote reduce the consecutive side firing issue to just 1 pair on one side. The LSx fires #2 and then #6 consecutively on the right side while the Coyote fires #8 & #6 consecutively on the left side. There is still 90° o crank rotation between them. You can use the same TriY headers as the NASCAR boys do to mitigate even that. My personal favorite is the DOHC Coyote 5.0, though the LSx have their charms, its really hard to top the cam timing variability of a DOHC motor, The LSx substitue displacement and otherwise excellent design for the sophistication on the Ford motor.

The older V8s will have 2 consecutively firing cylinders on each side, crank torsion and vibration is up over that in the modern V8s but you can still live w/ it just not rev as high or as often. here the Tri y exhaust really shines.

The irregular firing pulses do have their benefits, among them is the ability to put power to the ground, HD V twins were notoriously good at powering out of a corner on dirt, The Yamaha V4 w/ crossplane crank does the same on pavement, not sure that this is applicable to 8 cylinders though but it sure does sound good.

[Jeff Higgins]

Originally Posted by Bill Verburg

The irregular firing pulses do have their benefits, among them is the ability to put power to the ground, HD V twins were notoriously good at powering out of a corner on dirt, The Yamaha V4 w/ crossplane crank does the same on pavement, not sure that this is applicable to 8 cylinders though but it sure does sound good.

One of the older tricks in the H-D flat track arsenal is to re-set the cam timing (very easy on the XR750/Sportster platform) to make it run as a "Twingle". The Triumph, BSA, and Norton guys did this as well on their parallel twins. The parallel twins were turned into a "split single", or "twin single" ("Twingle") wherein both jugs fired together. The H-D's necessarily have a 45 degree split, but the idea is the same. Better traction on really slippery clay. I saw Chris Carr running this setup on his XR750 in Sturgis one year, when he was riding the local half mile while recovering from a broken leg. Very easy to pick his bike out of the crowd.

[yetibone]

Originally Posted by cockerpunk

every inline 4 ever made has a flat plane crank. there isn't any particular magic to them.

the sad things is the engineering that makes the GT350s motor rev so high isn't the fact that its a flat plan crank, but very good valve train engineering. if i was on the valve train team, id be pissed the marketing guys keep trying to say the engine is magic because its flat plain

Detroit Diesel 4-53 had a 90 degree crank because it was a 2 stroke.

[scottmandue]

I have nothing to add but would like to thank afterburn for posting this and all you brainy guys for posting.

I have heard the new Mustang and was wondering how they got that sound.

Carry on.

[afterburn 549]

I have a rudimentary skill set, but others with more understanding have helped.
Plus, all this has made me study the homework they have posted, plus some I have found.
Thanx guys .

[Bill Verburg]

Originally Posted by Jeff Higgins

One of the older tricks in the H-D flat track arsenal is to re-set the cam timing (very easy on the XR750/Sportster platform) to make it run as a "Twingle". The Triumph, BSA, and Norton guys did this as well on their parallel twins. The parallel twins were turned into a "split single", or "twin single" ("Twingle") wherein both jugs fired together. The H-D's necessarily have a 45 degree split, but the idea is the same. Better traction on really slippery clay. I saw Chris Carr running this setup on his XR750 in Sturgis one year, when he was riding the local half mile while recovering from a broken leg. Very easy to pick his bike out of the crowd.

Originally Posted by Jeff Higgins

One of the older tricks in the H-D flat track arsenal is to re-set the cam timing (very easy on the XR750/Sportster platform) to make it run as a "Twingle". The Triumph, BSA, and Norton guys did this as well on their parallel twins. The parallel twins were turned into a "split single", or "twin single" ("Twingle") wherein both jugs fired together. The H-D's necessarily have a 45 degree split, but the idea is the same. Better traction on really slippery clay. I saw Chris Carr running this setup on his XR750 in Sturgis one year, when he was riding the local half mile while recovering from a broken leg. Very easy to pick his bike out of the crowd.

The HD 'twingle would still sound odd
HD does use a 360° cranks like Dudacti but the cylinders are 45° out of phase
Norml HD firing pattern is 315-405-315, 'Twingle' is 45-675-45-675


Ducati and British vertical twin will be an even fire 360-360-360, 'Twingle version is the same

[vmax]