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Discussion Starter · #1 ·
In looking at options for an engine upgrade for my 981 CS that's a dedicated HPDE track toy, I was told by a major engine builder that the PDK's in our cars cannot handle the additional power of a 3.8 bored and stroked to 4.0 or 4.2 with all the go-fast goodies installed. I know BGB and Deman both build for PDK cars and ZF states the 981 PDK (7DT-45) can handle 450FTLB of torque.

Shift rod sensor, valve body and other common PDK issues don't count in my opinion since that can happen to any PDK.

So I'm curious to know if anyone has had a more serious issue with the clutch, gearbox, or diff?

Thanks
 

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Discussion Starter · #2 ·
I'm wrong... the 7DT-45 is rated in N*m not ft-lb and depending on the source ZF says 450 other sites say 500. Which translates to 331 or 368 ft-lb. I'd say that's in the danger zone of a built engine. So, I think I answered my own question. Eventually, something is going to fail that close to the rating in a track environment.

But my question stands, does anyone have direct experience of such a failure?
 

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Discussion Starter · #4 ·
Thanks, Ed. I've been in contact with BGB and Deman, both great shops and they indicated no real issues. That's why I was surprised by the response from this very noteable engine builder. They stated that every build they had done on a PDK ended in failure.
 
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Thanks, Ed. I've been in contact with BGB and Deman, both great shops and they indicated no real issues. That's why I was surprised by the response from this very noteable engine builder. They stated that every build they had done on a PDK ended in failure.
Is this builder Flat6 Innovations? As they Do know what they are talking about..
 

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Discussion Starter · #6 ·
I didn't want to call them out, but yes, FSI told me this and I respect their resume of knowledge and experience. But, that's what I can't reconcile. Of three builders two say no real problems, one says, we won't even build you an engine for a PDK car. So my question of what are others experiencing is aimed at understand the risk $$ and if I'm willing to take that on in addition to a $$$ engine build.
 

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I didn't want to call them out, but yes, FSI told me this and I respect their resume of knowledge and experience. But, that's what I can't reconcile. Of three builders two say no real problems, one says, we won't even build you an engine for a PDK car. So my question of what are others experiencing is aimed at understand the risk $$ and if I'm willing to take that on in addition to a $$$ engine build.
Interesting, did FSI give you more details on exactly what would fail on the PDKs? I have heard debates about PDK tunes causing PDK failures, but have not observed any engine upgrades leading to failures. It is very interesting though as I am planning on engine upgrades after CPO.
 

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If I remember correctly, Flat 6 can increase the displacement of your 3.4 PDK to 3.8, but they will not go any larger to avoid compromising the health of the PDK transmission. Perhaps LN Engineering (Charles Navarro), can explain the limitations or if you can do something to beef up the PDK..?
 

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Discussion Starter · #9 ·
@thestuntdummy Hi... Nothing definitive, although I've been doing a lot of forum searches and reading and I'd bet on the clutch is the weakest link. That said I really have not found much in the way of failures due to HP and Torque. Lots related to heat and track use (shift rod sensors, valve body, solenoid, etc), especially on 987.2 & 997.2. As far as a PDK tune causing a failure. Yes, I think that's possible. I had a shift rod failure on a 987.2 two years ago and I feel it was a contributing factor. Porsche saw fit to add additional coolers for the 981/991 both on the PDK (automatic side) and the gearbox side. I was specifically interested in FSI's TrackPerformer, which apparently makes a lot of HP and Torque.

@Gilles, thanks... The size 3.4 to 3.6 or 3.8 to 4.0 or bigger is a function of the base engine on the 9A1 engines as I understand it, LN can bore 2mm over without the need to sleeve the cylinder. As mentioned, I was going for big power with a full engine build. So maybe I scale down some?

There are lots of ways to get to 4.0 or 4.2L with the 9A1. Maybe the shortest path is a used GT4 engine, bored to 4.0 or bored and stroked to 4.2. Throw on an intake refit from a 4.0 718 or x51 (intake and heads, but way more $$) and you end up with a nice bump in power and smoother delivery, especially in the 3-5K rpm range.
 
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Discussion Starter · #10 ·
I'm going to assume that this is an uncommon occurrence absent any posts to the contrary. So I think I will bit off much more than I can handle and see if an amateur with previous engine build experience can hack a 4.2L track engine together.
 
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