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Flat Plane Crank

 
Old 02-02-2019, 04:18 PM
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UKKid35
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Default Flat Plane Crank

Insane costs aside, would it be possible to fit a flat plane crank to a 928

I presume the current cams would still work

Would it shake itself to pieces?

I seem to remember some Ferrari engines existed in both cross plane and flat plane versions, or am I mistaken?
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Old 02-02-2019, 04:37 PM
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change the crank, change the cams.
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Old 02-02-2019, 04:55 PM
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UKKid35
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If there is anyone who knows about insane costs...

Thanks SG, I get it now, piston movement would be totally different on each bank, not just relative to the other bank
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Old 02-02-2019, 05:47 PM
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944 cams? It's the flat-plane-crank half-a-928 engine. Seems like they should work, ASSuming the torsional vibration of two didn't shatter the crank.
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Old 02-02-2019, 06:01 PM
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UKKid35
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Originally Posted by dr bob View Post
944 cams? It's the flat-plane-crank half-a-928 engine. Seems like they should work, ASSuming the torsional vibration of two didn't shatter the crank.
They have balance shafts don't they?
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Old 02-02-2019, 06:41 PM
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Originally Posted by UKKid35 View Post
They have balance shafts don't they?
Yes, 944 engines have balance shafts.
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Old 02-02-2019, 06:49 PM
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Do a search on the Ford GT350 Voodoo engine development - a flat-plane-crank engine. It took Ford with all its resources and expertise, quite a bit of development time to get it right.

With that said, it would be much easier and cheaper to buy the Voodoo with its computers and harnesses, than to attempt what you propose with the 928 engine.

Not only that, the Voodoo is completely debugged.
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Old 02-02-2019, 06:54 PM
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I thought this had been brought up before.

I don't have the engineering background to fully understand all the issues, but many are covered in this thread:
https://rennlist.com/forums/928-foru...28-engine.html
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Old 02-02-2019, 06:57 PM
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Definitely not proposing - just idle pondering, having spent all day working on my AJP8
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Old 02-02-2019, 08:22 PM
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Just whip one out of a lotus v8. Comes with twin turbos apparently. See Top Gear Patagonia special...
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Old 02-02-2019, 09:21 PM
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ALL Ferrari V8s are flat plane, except one model made for Lancia. At least up to around 2000. They dont seem to have a bad name for vibration AFAIK. Just put a 2 plane forged crank in a press, flatten it, heat treat, good to go. Chevy have sold flat plane cranks for years, last I looked.
jp 83 Euro S AT 57k
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Old 02-03-2019, 06:17 AM
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Originally Posted by Wisconsin Joe View Post
I thought this had been brought up before.

I don't have the engineering background to fully understand all the issues, but many are covered in this thread:
https://rennlist.com/forums/928-foru...28-engine.html
Great thread - thanks
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Old 02-03-2019, 07:19 AM
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Originally Posted by SwayBar View Post
Do a search on the Ford GT350 Voodoo engine development - a flat-plane-crank engine. It took Ford with all its resources and expertise, quite a bit of development time to get it right.

With that said, it would be much easier and cheaper to buy the Voodoo with its computers and harnesses, than to attempt what you propose with the 928 engine.

Not only that, the Voodoo is completely debugged.
Spot on!

Not sure how many of you have heard one in action, but the Voodoo engine sound is amazing! Flat plane cranks are also part of the reason that Ferraris engine sound is so intoxicating!

Add full throttle to the V12 flat plane configuration and it seems that the sky is tearing open!

Last edited by 928 GT R; 02-03-2019 at 01:20 PM.
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Old 02-03-2019, 10:00 AM
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Originally Posted by jpitman2 View Post
Chevy have sold flat plane cranks for years, last I looked.
Did you really?

Please show just one example.
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Old 02-03-2019, 12:50 PM
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Originally Posted by jpitman2 View Post
ALL Ferrari V8s are flat plane, except one model made for Lancia. At least up to around 2000. They dont seem to have a bad name for vibration AFAIK. Just put a 2 plane forged crank in a press, flatten it, heat treat, good to go. Chevy have sold flat plane cranks for years, last I looked.
jp 83 Euro S AT 57k
flat-plane V8 has the same imbalance as straight-4 in that the rod/piston accelerates at a different rate at BDC vs TDC so the crank is a big torsion bar...

as with I-4 it can't be cured but can be managed by keeping rod/piston mass low and using longer rods....or using balance shafts.

the biggest F-V8 is what, 4.5L, with baby 94mm pistons that you just know are micromanaged into minimum weight spec.
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