SBC Flat Plane Crank - NMNA

Not mine, no affiliation...It just seemed like something a GRM'er or two might appreciate.

Crower SBC flat plane crank - $600

Interesting. Crower doesn't list a flat plane crank on their site, I wonder if he knows what a flat plane crank is. 

Crower does have some rather pricey cranks, $3k or more. Yikes!

 You need a custom cam shaft too.

Right?

Yeah someone explain like I’m 5. Never heard of that retrofit. 

81cpcamaro said:

Interesting. Crower doesn't list a flat plane crank on their site, I wonder if he knows what a flat plane crank is. 

Considering the same seller has listings for a forged Crower SBC crank, forged Crower SBC flat plane crank, and Bryant BBC forged crank, with only the one making any reference to being flat plane, I'm guessing yes he does.  Just because they don't offer one in their catalog doesn't mean they haven't made them.  I've also found multiple references to Crower specifically (and others) having made flat plane cranks in years past. On the face of it, seem plausibly legit...And if so, looks rather GRM priced compared to what (few) other references I've found for similar. But if true, also still definitely a very small niche item for sure.

RossD said:

 You need a custom cam shaft too.

Right?

Yes, another thing Crower is supposed to have produced in the past, which I'm sure they could easily dig up the specs on for a 'semi-custom' grind...Or any other SBC cam manufacturer could probably do the same almost as easily.

cdeforrest said:

Yeah someone explain like I’m 5. Never heard of that retrofit. 

This crank + associated camshaft + fuel/ignition that supports non-standard firing orders = SBC having a 'Ferrari-esque' identity crisis.

Emailing.

cdeforrest said:

Yeah someone explain like I’m 5. Never heard of that retrofit. 

Common V8s have a "cross plane" crank, where the crankshaft throws rotate from the front at 90-180-90 degrees.  This makes for a smooth running engine but has the downside that every possible firing order will have an uneven sequence on every bank.  No matter what you do, one cylinder on each side will be 90 degrees out of phase relative to the other three.  This is the source of the characteristic V8 "warble" or "rap" which gets pronounced on engines with completely separate dual exhausts.

A flat-plane crank is essentially a four cylinder crank.  Firing sequence on each side is even.  The firing order literally becomes two four cylinder engines, joined at the crank 90 degrees apart.  Downside:  The engine shakes like a four cylinder engine.  Twice as bad, actually, since there are twice as many cylinders.  But it sounds SO glorious.  Not like a pile of crap, which some ears (mine included) appoximate the sound of a crossplane V8.

Almost (all?) Ferrari V8s have flat plane cranks.  Ford famously made the 5.2l V8 in the new GT350 a flat plane crank.  From this outside observer, they did it strictly for the aural experience, as they had to do some funky things with the firing order to make a flat plane work with a plenum manifold (Ferraris have IR type manifolds).  Crank throws on the 5.2 are up/down/up/down rather than up/down/down/up like every four cylinder or flat plane V8 ever.

  What they seem to achieve is a higher RPM Range. the Crower crank sold for 2600 new, Cam is just a Grind away.  You could build a pretty Trick Engine For 5 grand, but it deserve's good parts, stroke is a little long , few years back there was one W/ 3 1/8 stroke on the H.A.M.B.

GTXVette said:

  What they seem to achieve is a higher RPM Range. the Crower crank sold for 2600 new, Cam is just a Grind away.  You could build a pretty Trick Engine For 5 grand, but it deserve's good parts, stroke is a little long , few years back there was one W/ 3 1/8 stroke on the H.A.M.B.

From discussion on Speedtalk, they tried flat plane cranks in Pro Stock but it lasted until the first actual drag run when the driver noted that he couldn't see the tach because his eyeballs were shaking so bad!

It's strictly a sound thing.

I really did e-mail, and will seriously persue if he's willing to ship.  My goals are not for high RPM, especially not with a 3.48 stroke, unless I started with a 305 block to keep the piston weight down.

Driven5 said:

81cpcamaro said:

Interesting. Crower doesn't list a flat plane crank on their site, I wonder if he knows what a flat plane crank is. 

Considering the same seller has listings for a forged Crower SBC crank, forged Crower SBC flat plane crank, and Bryant BBC forged crank, with only the one making any reference to being flat plane, I'm guessing yes he does.  Just because they don't offer one in their catalog doesn't mean they haven't made them.  I've also found multiple references to Crower specifically (and others) having made flat plane cranks in years past. On the face of it, seem plausibly legit...And if so, looks rather GRM priced compared to what (few) other references I've found for similar. But if true, also still definitely a very small niche item for sure.

 

RossD said:

 You need a custom cam shaft too.

Right?

Yes, another thing Crower is supposed to have produced in the past, which I'm sure they could easily dig up the specs on for a 'semi-custom' grind...Or any other SBC cam manufacturer could probably do the same almost as easily.

 

cdeforrest said:

Yeah someone explain like I’m 5. Never heard of that retrofit. 

This crank + associated camshaft + fuel/ignition that supports non-standard firing orders = SBC having a 'Ferrari-esque' identity crisis.

Good news is that a single plane intake under a carb and some swapped around plug wires on a distributor should have fuel and spark covered.

Daylan C said:

Good news is that a single plane intake under a carb and some swapped around plug wires on a distributor should have fuel and spark covered.

From Ford's testimony on the development of the "Voodoo" engine, no.  An up/down/down/up crank does not work with a shared plenum manifold, as there is air-starvation issues with any firing order you'd care to pursue. 

You'll need either a gaggle of Webers or a Hilborn. 

I am more than okay with this.

In reply to Knurled. :

Ok gaggle of Webers or Hilborn fixes everything anyway.

Knurled. said:

I really did e-mail, and will seriously persue if he's willing to ship.  

If you need any local assistance, let me know. Kent isn't that far out of the way for me.

How to turn your V8 into a pair of four cylinder engines  Has anyone ever built a cross-plane crank for a Ferrari or Voodoo motor just to piss people off? 

I've heard stories about the flat plane Ford breaking all sorts of exciting things due to the vibrations. It's supposedly the reason why that engine isn't available as a crate.

In reply to Keith Tanner :

Wouldn't a cross plane for a Voodoo 5.2 just be a Coyote crank?

Then I guess the answer is yes! 

Keith Tanner said:

How to turn your V8 into a pair of four cylinder engines  Has anyone ever built a cross-plane crank for a Ferrari or Voodoo motor just to piss people off? 

I've heard stories about the flat plane Ford breaking all sorts of exciting things due to the vibrations. It's supposedly the reason why that engine isn't available as a crate.

From what I have read, the problem with the Voodoo is that it has a manual transmission.  The shifter is either mounted to the chassis and completely isolated from the drivetrain, which makes the shifter feel awful, or it is attached to the transmission, where it transmits all the NVH directly to the cabin.  Because Ford wanted to re-use parts common with the regular manual trans Mustangs, like the transmission and floorpan and interior (minor items), they went with option B.  As such, they had to work with eliminating NVH in the drivetrain itself, which is where the exciting new failure modes come into play.

If they'd made it automatic-only (regular or DSG type trans), they could have done a better job isolating the drivetrain from the driver without having to resort to some of the things they did.

I hope you get this, pete, I’ve always wanted one but other than the belair and Wartburg i’m into ls stuff now.  

Sooo.. doesn’t sound (heh) it’s a real performance mod, then. 

Keith Tanner said:

Has anyone ever built a cross-plane crank for a Ferrari just to piss people off? 

Maserati

In reply to Knurled. :

Stroke is going to play a part in any vibes from the engine, and to get 500 inches for a pro Stock motor ,I bet.

if 1 came up at that price with 3.0 stroke i would be gettin' Freaky. 

Dart has an aluminum Block 4.125 Bore (400) with small Mains

we somehow once put a 400 Flywheel on a 350 Race motor Gary said It looked like swimming with his eyes open at 7000 but couldn't see the Tach.

In reply to GTXVette :

If I recall correctly, when they tried a flat plane crank, it was during the days of displacement/weight/wheelbase juggling so it was probably a small block.

Either way, I have plans to mitigate all those problems.  If the guy responds to my e-mail.  Which he hasn't.

Sometimes it's better to call a plumber than a blacksmith.

Dirt track guys have been doing this for years.

180° headers.

​​​​​​In reply to Knurled. :

You could always try calling... After all, he did put his direct contact info in the body of the ad.

bentwrench said:

Sometimes it's better to call a plumber than a blacksmith.

Dirt track guys have been doing this for years.

180° headers.

I Want A Set for A Big Block chevy almost any condition.. so please If You know Of A Pair, useable ?  Schoenfeld !