3.4 Engine - Cylinder Walls

Hello, I've been researching the 996 3.4 engine. The following seems to be the issues related to the engine (not talking about the heads) when and if they fail: 1. RMS leak - easy fix with a Porsche upgrade/improvement for this (the seal and special tool). 2. Intermediate shaft - The sealed bearings seem to be able to break loose. Porsche and others seem to have an improved replacement part for this. 3. Cracked cylinder walls. My question relates to cracked cylinder walls. It seems there a few outfits rebuilding the 3.4's now. Does anyone know what they do to repair a cracked cylinder wall? Will this make it stronger than before (does it in anyway improve the cylinder wall from future failure)? I believe that remanufactured engines are going for around $12.7K now (not sure if anything has been done in these to improve the cylinder walls?) and that rebuilt 3.4's go for $7k (such as the one on Ebay now) installed. I know you get 2 year warranty with the remanuf. Porsche 3.4 and a lot of ancillaries are new also, but wondering if there is anything else that commands the $6K+ difference (with labor)? Thanks P.S. This is not a thread related to whether or not 3.4's are more susceptible to failure than any other type of failures. All engines have the above problems to lesser or higher degrees, IMHO. I am just trying to learn what is done to repair cylinder walls and if there are any improvements available now as compared to what existed with OEM. Separately, I know that you can have a 3.4 bored out to 3.6, 3.8 or 4.0 now. But I imagine that this does not improve the strength of the cylinder walls?? Any comments/corrections to help educate me are appreciated.

my head hurts already

Add cracked heds, broken rod bolts, broken crankshafts, expansion plugs dislodged in the camshafts, cylinder heads and crankcase, scavenge pump failure, timing chain failure, IMS tensioner paddle failure and of course oil starvation that creates main bearing failures. Of course those are failures that effect the entire engione and the heads, but all are noteworthy.. With an extensive program EVERY ENGINE, whether it has failed cylinders or not gets a full set of Nickies billet cylinders. Most repair only the broken cylinders, using a ductile iron sleeve and do not take preventive measures to ensure that cylinders that have not failed, won't fail in the future. Thanks Yes.. There are materials and processes that exist today that Porsche never employed due to the costs associated.. Some of these (Nikisil plating) was used as OE in the aircooled 911 and Porsches in general for the better part of 4 decades. With stronger cylinder liners come stronger cylinders, even if they are thinner as I have learned through 12 years of Nickies implementation in my aircooled engines, making up to 116HP/ liter N/A with excellent longevity using the exact same billet extrusion as the watercooled "Nickies" cylinders are using. This is in both 4 and 6 cylinder Porsche engines.. The thermal conductivity of advanced materials helps the cylinders to run cooler, and the Nikisil plating helps to combat friction, resulting in lower cylinder temps. That said, the development we have done proves the safest size the 3.4 can be (**safely**) effectively bored to (today) is 99mm, for 3.6 liters, we take the 3.6 up to 3.8 and I am building a 4.0 now as another R&D mule.. The 4.0 is generally built from the 3.8 engine, but to put the technology to the test this 4.0 is being built from my core 3.4 for my 911. I am using a billet stroker crank to achieve the added displacement along with a larger than **safe** bore size. Total details of a lot of these developments are not published as we are still learning every day and constantly breaking our own rules while searching for the limitations of the materials and processes. Unlike the development of my aircooled program, where we slowly increased performance until parts began to break, we have instantly gone very big and pushed the limits right out of the gate. We had 5 years of development in the program before we sold the first engine to a paying customer, for 4 of those years no one even knew I was working with the M96 platform :-).. There are lots of ways to address the shortcomings of the engine, but all too often they are approached with economic constraints as a compromise.....

Wow, very informative. Just what I was looking for. Thanks! Which company are you with?

Here's an article by Jim Pasha which may help http://www.renntech.org/forums/index...e=post&id=3223 Just before he passed away, Jim Pasha wrote another article, published in the Dec 2008 issue of Excellence, "M96: Past, Present, and Future" which basically goes into great detail about issues with the 996 engines. Jake Raby and other experts are quoted extensively in that article. If you can find it, it's worth a read. Look here for more info http://www.flat6innovations.com/ http://www.lnengineering.com/