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Senior Porsche Financier
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Discussion Starter · #1 · (Edited)
When I last posted, my '06 CS w/ 38K miles had died @ a DE w/ what sounded like a bad crank or rod bearing. Given the conditions under which it happened and my 230 grade-4 over-revs, porsche declined any warranty coverage.

Post Mortem:

Before I go forward w/ this I'd like to ask that any discussion / speculation about the failure conditions, porsche's response or the price of fish be conducted in other threads.

I'll have my take on the whole thing and then I want to focus exclusively on the rebuild going forward.

One single rod bolt was found to be loose, the main crankshaft bearing was damaged as well as the rod bearing farthest from the oil supply. The crankshaft and carrier need to be replaced but my case can be re-used. The dealer's mechanic thought it was the over-revs which broke the engine - as did Charles w/ LN Engineering. These guys know more than I do. The mechanic also said there was enough collateral damage that he couldn't definitely point to one cause.

Some of the over-revs were due to hitting / blowing thru fuel cut @ the raised redline of my reflash [7800 rpm]. I missed one shift and that's where the grade-4 over-revs came from. @ 3 ignitions / crank revolution, 230 overrevs is a small fraction of a second.

I generally agree I abused the engine, but if over-revs killed the engine, I'd expect > 1 rod bolt loose. Likewise I'd expect valve stem damage w/ over-revs. loose rod bolt aside, I'm struck w/ the similarity of this failure to those others have seen.

Also, the M97.21 started it's design life as a 911 engine to be installed w/ the oil scavenge points 180 degrees opposite from where they are in the cayman. Probably sufficient oil scavenge in the 911; in the cayman not so much.

Never underestimate the power of denial.

My 0.002: Yes, the M97.21 can be abused. Porsche should reduce the redline further and warn that the CS should only be used for carriage to picnics if warranty coverage is to be expected.

The CS is a terrific car w/ some weaknesses. As to porsche - I can distinguish between the car and the company.

As I said above - This thread is for the rebuild going forward.

Going forward:

I crunched the numbers and found either of two paths to be similarly priced:

1) Rebuild the engine w/ stock components to a 3.4 and then TPC turbo it.
EDIT: This is wrong - swapping in a good used stock 3.4 and then turbo'ing it was generally the same in cost to #2.

2) Rebuild the engine w/ stronger internals and key internal fixes to a 3.6 w/ 12:1 pistons and stay normally aspirated.

Since the engine is apart now is the time to strengthen it.

One thing - I'm going to mention conversations I've had w/ mechanics & vendors. I'm going to do my best to report them accurately. If anyone thinks I've mis-represented something - that's not my intent; please correct me.

I spoke w/ Mike @ TPC (the man himself!) and he's of the opinion that the 3.4 is a great engine of itself. He suggested rebuilding it to stock and if I wanted more horsepower to turbo it.

While I can't argue with the success of the TPC turbo packages (and I *really* want one) - I did break my engine and so decided to rebuild it stronger.

[I'm aware that one of the biggest 'fixes' to be implemented will be to my driving.]

I have been impressed w/ Charles Navarro's products [LN Engineering] and he spoke w/ me at length -- several times -- about my options, for which I'm grateful.

He offers cylinder liner rebuilds, displacement upgrades and select stronger internals to overcome the stock M96/M97 weak spots.

To work w/ LN I'd still need a dealer to tear the engine down, diagnose it, submit a warranty claim and rebuild it. That degree of coordination was important enough to me to head for Chicago instead of a closer mechanic although Charles mentioned he does business w/ other shops familiar w/ his products.

Charles suggested Joe Rizza Porsche of Orland Park, IL. Charles is also located in the Chicago vicinity and so I took my CS from Montana to JR Porsche, dropping it off at 5:30 on the Friday which started memorial day weekend. They were open until 7:00 that night.

Charles mentioned that JR's mechanic, Marc, has rebuilt engines w/ his products and was suggested to rebuild mine. I needed a shop which was both familiar w/ LN's products and would coordinate w/ LN on the whole repair process.

As of today, Charles and Marc are going to meet to go over the whole package and put an estimate together. Both have made suggestions as to where I can save money -- and where to spend it to go stronger.

The Plan:

1) LN Nickies cylinder liners, displacement increase to a 3.6. going to 3.8 wasn't an option w/o a complete 997 3.6 donor engine.
2) upgraded JE pistons, 12:1 compression ratio.
3) R&R Connecting rods, ARP rod bolts.
4) IMS ceramic bearing upgrade.
5) Low temp thermostat.
6) LN Deeper sump kit. [adds 1/2 qt capacity].
7) Billet chain tensioner and oil pump drive.
8) Some sort of additional oil-safe -like supplemental oiling apparatus and an oil cooler. <TBD>
9) If I can contact Softronic Scott I hope to have my SRP flash reworked to return to the stock 7200 rpm redline - and compatible with the displacement increase. Or I'll return to stock flash.

I'm hoping the 3.6 w/ 12:1 pistons will turn out to be a very special combination.

Stay Tuned !
 

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I like the plan. A little more hp/torque and a lot more robust. I was going through the same decision process with my NSX. Unfortunately I sold it. However, I had decided on keeping it NA with a small increase in displacement.
 

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Boxster Enthusiast
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What kind of HP are you looking to get from the rebuilt engine?
 

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I'm not mechanically inclined but will follow thread with much interest. Please explain it all as you go along so I can try to understand as much as possible.To enhance my enjoyment of my Cayman I'm trying to understand some the more technical aspects of the car. So, please keep up the posts and explain as much as possible the how and the why.:thanks:
 

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Senior Porsche Financier
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Discussion Starter · #5 ·
just by the displacement increase - maybe 5 - 7 %. I'm looking for a broader flatter torque curve - more torque at lower rpm.

What I'm hoping for here is the combination of 3.6, SRP, borla and 12:1 compression is a very responsive engine.

Thanks for your interest.
 

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VLAGER
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I think that you can really trust the folks at LN Engineering.
Hope that you update your post with some costs as you continue.
 

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Cayman The Destroyer!
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What will you actual CR be with the bigger bore & 12:1 pistons? Definately no turbo in your future.

I agree that over rev's are the quick way to the scrap heap. My DME is set at stock redline & I added a shift light string on the top of the dash right in my line of sight.

Accusump or TTP is a must as well. A strong engine with no oil pressure goes boom too! TTP is much easier to install with the engine out of the car & apart.
 

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Discussion Starter · #8 ·
Where did you get the shift light string ? - I've been looking for one of those.
 

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How about going with the Nickies liners to 3.6, then use JE pistons with a CR of 9.5:1, and installing a TPC turbo dialing up to 0.8bar sound ?
 

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Discussion Starter · #11 ·
How about going with the Nickies liners to 3.6, then use JE pistons with a CR of 9.5:1, and installing a TPC turbo dialing up to 0.8bar sound ?
only if I win the lottery.
 

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Cayman The Destroyer!
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Was thinking about doing the same thing but Mike L at TPC talked me out of it
 

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Discussion Starter · #13 ·
Was thinking about doing the same thing but Mike L at TPC talked me out of it
I don't want to pit one vendor against another -- both have great products. I was unable to reconcile the apparent positions of TPC & LN - and I understand that both have product to sell.

One treats the M97.21 as solid enough to turbo to +100 - +150 hp. Another views it as weak in spots; to be fair, most of LN's work began on reinforcing the weak spots in the M96.

I can even make a case for a TPC turbo'd car not necessarily being as hard on the engine as as staying normally-aspirated: even wide-open on a track, it won't be wide-open for long -- the raw capability of a turbo'd CS to build speed will mean that after a short run at WOT it's likely that the engine will get some coast-down rest.

A normally aspirated car may be pushed harder / longer @ WOT ...

I don't want' to stray too far afield of the rebuild -- I responded because I faced this choice. I came down on the side of building the engine stronger internally because I *did* break my engine as others have done. The M97.21 isn't uniformly solid.

The other thing which factored into the decision was that I wanted to build a car which would stay within my capabilities. I love turbocharged cars; I felt a turbo CS could have been too much for me.

Who knows - the next rebuild I may just pull the 12:1 pistons, go w/ 11:1 and 4 - 5psi boost and see what a turbo 3.6 feels like.
 

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Cayman The Destroyer!
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I respect your choices. I've spoken to Charles at L&N quite a bit and he knows his stuff. I'm sure you will be pleased with the engine. Besides the real fun is going around the corners anyway!

looking forward to your reports on the build progress. Planning to dyno after?
 

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It would be cool if you could post pictures at various stages of the rebuild...
 

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Discussion Starter · #19 ·
It would be cool if you could post pictures at various stages of the rebuild...
sorry - I'd love pictures but I'm 1100 miles away !
 
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