964DJM

About to embark on engine rebuild for my otherwise immaculate 40,000km 2002 996 GT2.

It runs EVOMS turbos, 1.1-1.2 bar boost and dyno sheet from PO shows 480rwhp. Unfortunately a bent conrod exited the crankcase just pre Xmas so new engine is required. At this stage, case, crank, rods, oil pump all destroyed. Heads hopefully ok.

Plans:

Carillo or pauter rods
Should I use a stock crank or are there aftermarket options worth considering
Ditto pistons
Ditto oil pump
Anything else I should consider while we're at it?

Not chasing more power, just want a durable engine with current hp as I intend to keep the car. It's mostly a weekend road car with the occasional track day (club event, for fun, driven sensibly).

Funny, I thought mezger was bulletproof but now having experienced failure and searching on line, plenty of cases of turbos and GT2 suffering conrod failure with catastrophic results. I can't not rebuild it so I'll have to suck it up and move on.

Rough costs quoted A$30-40k......ugly but I assume there's no low cost way to build a proper engine that will last? Firm quote will be prepared next week once workshop(s) selected and spec confirmed.

jumper5836

480 rwhp would require internals to be upgraded specially the con rods, it's no wonder the con rods let go. These engines are bullets proof as stock and can safely push a bit more out of them but I suspect that comes with decreased durability but 480 rwhp is much past the safe limit.

powdrhound

It's all about the programming. 480whp is very mild and I seriously doubt you'll be bending rods at that level with good programming. I suspect some detonation lead up to the bent rods and ensuing destruction. Many guys run stock internals up to 650-700whp. I have over 100 hard track hours on my engine which is in the low 500 rwhp range running 1.2-1.3 and no issues with rods whatsoever...

jumper5836

so at the crank your pushing 580 hp? I'd say 480 at the crank is mild but not at the wheel?

993GT

+1,
OP sorry for your luck! Scan DME for over-rev's, something funny happened...perhaps a nasty overboost spike low-down in RPM's

powdrhound

480 at the wheels is mild. My old RUF 550 Rturbo set up was about 490whp and that was a very conservative set up. I'm now running UMW ZC turbos with UMW injectors and a RUF intake/exhaust. Track data shows the car to be a bit stronger. I'm guessing 520whp. Others have dynoed similar set ups in that range. Kevin might chime in. He probably knows what this set up does on the rollers. There is so much variation in dynos that comparisons are useless unless you are using the same dyno. Running on a long straight, my car is slightly stronger than a late model ZR1 or a Mclarren M4P. I think both those are listed as a little over 600 crank from the factory.

993GT

OP, as far as your rebuild goes, I'd rebuild to stock with upgraded rods for added safety margins(probably go Carrillo since the engine is apart anyway)

Macster

The Mezger engine is a real robust engine but 480RWHP is beyond the stock engine's design limits.

I read somewhere that at 500hp (crank HP) and over the factory uses titanium rods and bolts.

Furthermore, my info is titanium rods stretch and should be replaced every so often. I do not know the replacement schedule.

jumper5836

powdrhound, man you got a beast there.

AudiOn19s

This conversation scares me a little. Were there any revisions to the rods in the 997 Mezger motors?

Our 997 TT is right around 455hp to all 4 wheels as it currently sits which is where I thought it was making good power but still in a very safe place.

993GT

997 rods were slightly upgraded, but some of the greater power 'ceiling' comes from a better DME/tuning capability...
assuming basic maintenance and care and a quality tune, there is no need to be concerned at these power level 996 or 997...

Spyerx

Seems like a tuning or some other issue... I've seen my shop's turbo cars running way more power reliably with stock internals and bolt on turbos, intercoolers, and programming.

Anyway, their engine builder will not use after market cranks. Spend the $ and use the porsche part.

powdrhound

My engine is coming out next week for a rebuild. We're using a 997GT3 crank... Oiling is every 180º vs. 360º on the TT/GT2 crank...

993GT

^since your heavy tracking, planning on doing the 959/'GT3' IMS as well?

powdrhound

No. I don't think it's a straight forward swap. I'm really not aware if any issues with those. I'm keeping it pretty basic. RSR Crank/oil pump, Rods, 3.8 Mahle pistons/liners, and 997GT2 1-3 mainshaft in the gearbox..