Up, down, down, up FPC

[Nate22]

I've noticed if anyone changes the crank on a gt350 they go for a crossplane swap, due to vibration, reliability, and/or availability, I'd assume. But has anyone ever tried to do an up, down, down, up flatplane crankshaft. More like a traditional flat plane crank engine, instead of the up, down, up, down, that ford decided to do for whatever reason?

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[K4fxd]

But has anyone ever tried to do an up, down, down, up flatplane crankshaft.

Not that I have heard of. It would be a neat experiment. Hardest part would be sourcing cams.

 

[Nate22]

Not that I have heard of. It would be a neat experiment. Hardest part would be sourcing cams.

I would think a set of one off custom cams would be easier to make than a one off custom crankshaft. But idk.

 

[K4fxd]

I would think a set of one off custom cams would be easier to make than a one off custom crankshaft. But idk.

Ha Ha, yes that would also be difficult.

Need to find someone who is friends with Gene Haas.

 

[KJNVUDU]

I can't believe it! I just started an hour ago at the beginning of this forum to make sure this wasn't already discussed, and then I make it to the first page!
I have had the same question.
I have heard that the exhaust sound was their reason for the up down up down.
Switching may aid in reducing some of the longitudinal vibration (along the crank axis.) But not help with the second order vibration (? I can't think at the moment what it's actually called )
I must say I am in NO way an engineer. Originally, when i first got the 350, I was naive in the respect that I figured ford had exhausted most options for this engine. But now I realize the reality of compromises that must be made between all the groups within a big organization.
I am very curious to know how an up down down up crank would work. Even going as far as destroke a little.
I have spoken to a crankshaft manufacturer up in Wisconsin about this, and it seems like it would not be so astronomical of a price tag to try it. I know cams and other things come in to play here that would add cost. As well as stand alone engine control and tons of balancing work. And would probably try a dual intake setup.
I'm sure I will be told to just throw a cpc in it and let her eat, but I just can't help but wonder if there is a way to keep our beloved fpc and not have everything bolted to it vibrate to death.

Alright, let the flaming begin!!

Chris

 

[Nate22]

I can't believe it! I just started an hour ago at the beginning of this forum to make sure this wasn't already discussed, and then I make it to the first page!
I have had the same question.
I have heard that the exhaust sound was their reason for the up down up down.
Switching may aid in reducing some of the longitudinal vibration (along the crank axis.) But not help with the second order vibration (? I can't think at the moment what it's actually called )
I must say I am in NO way an engineer. Originally, when i first got the 350, I was naive in the respect that I figured ford had exhausted most options for this engine. But now I realize the reality of compromises that must be made between all the groups within a big organization.
I am very curious to know how an up down down up crank would work. Even going as far as destroying a little.
I have spoken to a crankshaft manufacturer up in Wisconsin about this, and it seems like it would not be so astronomical of a price tag to try it. I know cams and other things come in to play here that would add cost. As well as stand alone engine control and tons of balancing work. And would probably try a dual intake setup.
I'm sure I will be told to just throw a cpc in it and let her eat, but I just can't help but wonder if there is a way to keep our beloved fpc and not have everything bolted to it vibrate to death.

Alright, let the flaming begin!!

Chris

Yes ive heard it was mainly because of the sound too. Which is kinda crazy. But yes it should help with primary balance.

 

[K4fxd]

The main problem with the UDUD arrangement is the need for counter weights on the center cylinders. This adds weight which negates the benefits of the FPC.

Why they went for sound is beyond me. Maybe so people won't call it a Ferrari engine???

 

[JAJ]

I can't believe it! I just started an hour ago at the beginning of this forum to make sure this wasn't already discussed, and then I make it to the first page!
I have had the same question.
I have heard that the exhaust sound was their reason for the up down up down.
Switching may aid in reducing some of the longitudinal vibration (along the crank axis.) But not help with the second order vibration (? I can't think at the moment what it's actually called )
I must say I am in NO way an engineer. Originally, when i first got the 350, I was naive in the respect that I figured ford had exhausted most options for this engine. But now I realize the reality of compromises that must be made between all the groups within a big organization.
I am very curious to know how an up down down up crank would work. Even going as far as destroke a little.
I have spoken to a crankshaft manufacturer up in Wisconsin about this, and it seems like it would not be so astronomical of a price tag to try it. I know cams and other things come in to play here that would add cost. As well as stand alone engine control and tons of balancing work. And would probably try a dual intake setup.
I'm sure I will be told to just throw a cpc in it and let her eat, but I just can't help but wonder if there is a way to keep our beloved fpc and not have everything bolted to it vibrate to death.

Alright, let the flaming begin!!

Chris

So who's the crankshaft manufacturer is Wisconsin? Just curious - I'm having thoughts about building a "lower-case voodoo", essentially a regular Voodoo fitted with a custom crank and rods to deliver the magic 2.0 rod to stroke ratio. It'd displace 4.2 liters. The factory ECU could run it without a lot of changes. I figure that if Porsche can get 525 hp out of a 4 liter GT3 engine at 8500 RPM, what's the problem? I probably won't do it, but it's fun to think about...

 

[KJNVUDU]

So I'm not that crazy huh? Thank you.

I spoke with Moldex Crankshaft, and correction, they are in Michigan.

It was just the first place I called, but the guy started talking about one of the cranks he has built for an opel Kadett hill climber with an LT5.

https://www.enginelabs.com/news/video-on-board-a-high-revving-lt-5-powered-opel-kadett-hill-climber/

And a video of it in action.

 

[KJNVUDU]

And I respectfully challenge the counter weights.

I remember the first I read of the gt350. The author had made the comment that for being a fpc, ford didn't shave much weight. I think udud is partly why.

The 5.2 crank actually has counter weights opposite of all four rod journals. The LT5 crank below, appears to have half the weights. I'm sure there larger, but I bet you could lighten a bunch in there. And like said, get a good rod/stroke ratio.

 

[K4fxd]

And I respectfully challenge the counter weights.

Here is a Ferrari crank. Counter weights are small compared to Voodoo or the GM offering.

https://www.ebay.com/itm/2940482289...MIlsSepbb_hgMViEb_AR320Q4zEAQYBSABEgIsVvD_BwE

 

[Bitten in '69]

Dan, At least part of the size difference could be explained by the Ferrari being a much smaller displacement.

 

[K4fxd]

Dan, At least part of the size difference could be explained by the Ferrari being a much smaller displacement.

The smaller displacement is also why they don't have all the problems with vibration Ford and GM are having. I think the F1 V-8's had 1.5 inch strokes? IIRC they had no center counter weights.

 

[Nate22]

Dan, At least part of the size difference could be explained by the Ferrari being a much smaller displacement.

The voodoo being up down up down is 100% why they need so much counterweight vs a up down down up. Basically makes it being fpc almost useless.

 

[KJNVUDU]

And I found the other thread containing a lot of info.

https://www.mustang6g.com/forums/threads/ford-out-gm-in-with-fpc.139646/

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