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Flat plane crank summary again from Enginelabs


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#1 mariner

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Posted 06 December 2021 - 19:12

A nice summary on flat vs 90 degree cranks from , of course (!)  Enginelabs

 

Enough graphs to help without getting too much into heavy maths.

 

https://www.enginela...ne-crankshafts/

 

The oil flilter  problem mentioned by GM reminds me of the struggle to get a Cosworth DFV to be an endurance engine.

 

They do miss the obvious flat crank problem   - no more off  beat V8 Detroit rumble! 



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#2 Magoo

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Posted 09 December 2021 - 08:49

Thanks!



#3 Canuck

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Posted 09 December 2021 - 15:25

Thanks!

Well that begs the question...Mr. Smith?



#4 Magoo

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Posted 09 December 2021 - 16:15

Well that begs the question...Mr. Smith?

 

My good friend Jeff Smith, formerly of Hot Rod and Car Craft magazines. He took the long way around on this one, which is probably good. 

 

I would have mentioned the difference between the Shelby and Corvette single-plane cranks. The Shelby throws are up-down-up-down, while the Chevy is UDDU. 



#5 Canuck

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Posted 09 December 2021 - 23:13

It's interesting that something as mundane as the timing chain was the death knell for the Voodoo engine. Even more interesting that the solution was to shutter the production and walk away from it. The politics and (often lazy) decisions that lead to issues in the future in engineering projects never cease to amaze me.

 

The current group I work with went out of their way to hire fresh, relatively inexperienced engineering grads from outside our industry in an effort to break out of the same-thing/different flavour paradox that hiring industry-experienced people tends to bring. However, one of the side-effects of the lack of experience and the young age (the average age in the eng department was early 20s) laid the groundwork for things that, a decade later are coming back to haunt us. One that I was dealing with recently was brought about by a large transaction, requiring a substantial review and update of our documentation, both drawings and procedures.

  • QC and Docs - "Hey, we need to update sub-assembly XXX to Rev B"
  • Eng - "That sub-assembly is up to date"
  • QC and Docs - "Yes, but one of the parts in the BOM is Rev C now and the drawing lists the part as Rev B in the table"
  • Eng - "We can do a drawing sheet increment, but it doesn't need to be up-rev'd".
  • QC and Docs - "But the process requires that we up-rev the sub-assembly."
  • Eng - "Why don't we remove the revision level from the sub-assembly BOM table all together, that way when we make minor improvements, we don't have a bunch of sub-assembly drawings to adjust".
  • QC and Docs - "Because sometimes you make part revisions that should be new part numbers, and they aren't backwards compatible".
  • Eng - "What about fit/form/function criteria? Why are there parts that aren't backwards-compatible sharing part numbers?"
  • QC and Docs - "Because you thought that was easier in the beginning. You wrote the process that way".
  • Eng - "The process doesn't prevent that? What the hell?"
  • QC and Docs - "You were all living at home in your mom's basement when you wrote the process".
  • Eng - "Fine. We'll do a drawing increment then".
  • QC and Docs - "No, the process  requires a revision, not an increment. Please up-rev the document to Rev B, and make sure the BOM table show the new rev status of the updated part".
  • Eng - "Right...the process. We're on it".
  • Eng - "Here's your new sub-assembly XXX revision B showing part YYY is revision C".
  • QC and Docs - "Perfect. Thank you".
  • QC and Docs - "By the way, sub-assembly ZZZ needs a drawing increment, because you up-rev'd assembly XXX".
  • Eng - "But you just said a sub-assembly with an up-rev'd component, needs to be up-rev'd."
  • QC and Docs - "Different situation".
  • Eng - "What? What do you mean different? Part YYY was up-rev'd, so you made us up-rev sub-assembly XXX!"
  • QC and Docs - "Yes".
  • Eng - "And now you have sub-assembly ZZZ, which contains sub-assembly XXX, with part YYY, and you want a drawing increment?"
  • QC and Docs - "Obviously, yes."
  • Eng - "What the hell is wrong with you guys? Why is this a drawing increment".
  • QC and Docs - "Because it's not the first sub-assembly."
  • Eng - :confused:
  • QC and Docs - "The first sub-assembly requires an up-rev, but the next higher-level assembly only requires a drawing increment."
  • Eng - "WTF? Why? Why are you doing this to us?"
  • QC and Docs - "You wrote the process, we just follow it".
  • Eng - "And what about the next level assembly above the drawing increment?"
  • QC and Docs - "No updates required at all".
  • Eng - :mad: :confused: :mad:
  • QC and Docs - "It might seem completely arbitrary. Well, it is completely arbitrary, but we didn't make it this way, you did".
  • Eng - "Fine, we're removing the revision status from the BOM tables".
  • QC and Docs - "No".
  • Eng - "But!"
  • QC and Docs - "NOPE!"
  • Eng - "We're doing it!"
  • QC and Docs - "Yeah, no. Now give us our drawing increment".

The future is apparently bringing SAP and a complete abandonment of our current part numbering scheme in favour of the currently in vogue sequential numbering style. Perhaps we can get this ridiculousness fixed before then.



#6 Greg Locock

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Posted 10 December 2021 - 00:12

Probably in the most boring off topic diversion ever, our design engineers recently got fixated on the idea that if two bushings shared common OD ID and length, they could have the same part number, and were differentiated by the rev letters, ie AA for the front bush and BA at the rear. Then of course we decided we'd rather fit them the other way round. They also swapped the part numbers, so what was a BA was now labelled and AA and vice versa.

 

This meant that if you picked up a bush with a part number on it you couldn't tell from the part number which bush it was.



#7 Magoo

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Posted 10 December 2021 - 14:18

The General Motors ignition switch debacle comes to mind. 



#8 Almag

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Posted 10 December 2021 - 20:36

I would have mentioned the difference between the Shelby and Corvette single-plane cranks. The Shelby throws are up-down-up-down, while the Chevy is UDDU. 

Yes, and explained that, as a consequence of its UDUD crank (and unlike a UDDU layout), the Shelby has ginormous counterweights at either end.


Edited by Almag, 10 December 2021 - 20:37.


#9 Almag

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Posted 10 December 2021 - 20:49

The article claims that timing chain issues doomed the Voodoo. I don't know that that's correct. Yes, there was a timing chain issue. It was a TSB for improperly installed tensioner that applied only to certain VINs of the 2020 GT350 AND the cross-plane variant of the Voodoo that resides in the GT500.

 

More accurately, after five model years, the car the Voodoo was created for (GT350) reached the end of its lifecycle. The GT500, however, continues.



#10 Bikr7549

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Posted 10 December 2021 - 22:06

It's interesting that something as mundane as the timing chain was the death knell for the Voodoo engine. Even more interesting that the solution was to shutter the production and walk away from it. The politics and (often lazy) decisions that lead to issues in the future in engineering projects never cease to amaze me.

 

The current group I work with went out of their way to hire fresh, relatively inexperienced engineering grads from outside our industry in an effort to break out of the same-thing/different flavour paradox that hiring industry-experienced people tends to bring. However, one of the side-effects of the lack of experience and the young age (the average age in the eng department was early 20s) laid the groundwork for things that, a decade later are coming back to haunt us. One that I was dealing with recently was brought about by a large transaction, requiring a substantial review and update of our documentation, both drawings and procedures.

  • QC and Docs - "Hey, we need to update sub-assembly XXX to Rev B"
  • Eng - "That sub-assembly is up to date"
  • QC and Docs - "Yes, but one of the parts in the BOM is Rev C now and the drawing lists the part as Rev B in the table"
  • Eng - "We can do a drawing sheet increment, but it doesn't need to be up-rev'd".
  • QC and Docs - "But the process requires that we up-rev the sub-assembly."
  • Eng - "Why don't we remove the revision level from the sub-assembly BOM table all together, that way when we make minor improvements, we don't have a bunch of sub-assembly drawings to adjust".
  • QC and Docs - "Because sometimes you make part revisions that should be new part numbers, and they aren't backwards compatible".
  • Eng - "What about fit/form/function criteria? Why are there parts that aren't backwards-compatible sharing part numbers?"
  • QC and Docs - "Because you thought that was easier in the beginning. You wrote the process that way".
  • Eng - "The process doesn't prevent that? What the hell?"
  • QC and Docs - "You were all living at home in your mom's basement when you wrote the process".
  • Eng - "Fine. We'll do a drawing increment then".
  • QC and Docs - "No, the process  requires a revision, not an increment. Please up-rev the document to Rev B, and make sure the BOM table show the new rev status of the updated part".
  • Eng - "Right...the process. We're on it".
  • Eng - "Here's your new sub-assembly XXX revision B showing part YYY is revision C".
  • QC and Docs - "Perfect. Thank you".
  • QC and Docs - "By the way, sub-assembly ZZZ needs a drawing increment, because you up-rev'd assembly XXX".
  • Eng - "But you just said a sub-assembly with an up-rev'd component, needs to be up-rev'd."
  • QC and Docs - "Different situation".
  • Eng - "What? What do you mean different? Part YYY was up-rev'd, so you made us up-rev sub-assembly XXX!"
  • QC and Docs - "Yes".
  • Eng - "And now you have sub-assembly ZZZ, which contains sub-assembly XXX, with part YYY, and you want a drawing increment?"
  • QC and Docs - "Obviously, yes."
  • Eng - "What the hell is wrong with you guys? Why is this a drawing increment".
  • QC and Docs - "Because it's not the first sub-assembly."
  • Eng - :confused:
  • QC and Docs - "The first sub-assembly requires an up-rev, but the next higher-level assembly only requires a drawing increment."
  • Eng - "WTF? Why? Why are you doing this to us?"
  • QC and Docs - "You wrote the process, we just follow it".
  • Eng - "And what about the next level assembly above the drawing increment?"
  • QC and Docs - "No updates required at all".
  • Eng - :mad: :confused: :mad:
  • QC and Docs - "It might seem completely arbitrary. Well, it is completely arbitrary, but we didn't make it this way, you did".
  • Eng - "Fine, we're removing the revision status from the BOM tables".
  • QC and Docs - "No".
  • Eng - "But!"
  • QC and Docs - "NOPE!"
  • Eng - "We're doing it!"
  • QC and Docs - "Yeah, no. Now give us our drawing increment".

The future is apparently bringing SAP and a complete abandonment of our current part numbering scheme in favour of the currently in vogue sequential numbering style. Perhaps we can get this ridiculousness fixed before then.

 

Very early in my career I once saw our engineering manager open up one of the drawing flat file drawers, pull out a drawing, use his eraser (vellum drawings), write something on it and then put the drawing back and walk away, without even looking at me. Probably he revised a wrong dimension, using his method of changes to avoid embarrassment, or the hassle of doing it right. Not out of his character, he was never wrong.



#11 MatsNorway

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Posted 07 January 2022 - 23:04

One reason mentioned for flat plane is the pulses. Unless i missed something why not run a hot V NA engine and get them spagetties tied together on old school/bigger stroke engines that has to run cross plane. Your not running a single carb anyway.


Edited by MatsNorway, 07 January 2022 - 23:16.


#12 gruntguru

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Posted 08 January 2022 - 00:28

That's certainly an option although getting a serious set of headers to fit in the vee and down the firewall would be a challenge.

There are plety of hot vee turbo engines around - two obvious benefits. Shorter runners improve response and reduce heat in the engine bay. Plus - pulses can be timed evenly to four turbine runners, with either crankshaft type.



#13 Wuzak

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Posted 08 January 2022 - 05:56

One reason mentioned for flat plane is the pulses. Unless i missed something why not run a hot V NA engine and get them spagetties tied together on old school/bigger stroke engines that has to run cross plane. Your not running a single carb anyway.

 

Like these?

 

https://www.museumof...m/foytdohc.html