Engine Teardown & Inspection

This is the engine for my 427 that just came off the dyno. The logical question is "why tear it down?" The answer is quite simple. This is a very high performance engine that has many one-of-a-kind features and parts. I am going to be installing it in a car that will take years to build. I do not want to have any problems a year or even 20 years after I put it in. The only way to ensure all of the components I installed were chosen correctly is I have to look at how they all worked together. I inspected the main and rod bearings for abnormal wear. The thrust bearing did show some wear, but the amount of torque and horsepower this thing is making that can be expected. The cam and lifters were in excellent condition. The pistons we good except for one that had some skirt scuffs, probably from when the piston stopped firing for a few minutes. The rings were perfect with no blow-by or oil leaks from the bottom up. Absolutely zero problems with the heads and the port/polish worked as designed. The intake manifold was not sealing properly. A small leak at one position was allowing oil to get sucked back up into the intake. I will fix that when I put it back together. One thing I did was have an additional "0.010 shaved off the heads. This removed 1.5 cc's from the overall size increasing the compression to 9.85 from 9.72. This will help a bit with dynamic pressure in the cylinder and maximize potential horsepower. Overall the parts look like they worked together as planned and I can put it back together with a high level of confidence it will last a very long time.

Porting and Polishing

I posted a video on YouTube awhile back about porting and polishing cylinder heads. I had many comments, mostly positive, but there were a couple that claimed polishing the head that much was not good and roughness was needed to create turbulent flow. While that may be true for a naturally aspirated engine, the engine for my Cobra is fuel injected. The only thing going through the intake will be air that will mix with fuel vapor right at the injector and dump right into the cylinder. The picture above is of a freshly machined cylinder head for a 2012 engine. As you can see the runners are very smooth because most engine parts are precision sand cast. Old sand casting for cast iron left very porous surfaces that allowed carbon and other contaminants to build up. New castings are very fine. Precision sand casting and lost foam technologies produce an intake runner that is very close to a final port and polish job. Laminar air flow is more efficient and is being used more and more on newer engine designs. Combined with direct injection, these new manufacturing processes are what give smaller engines more horsepower and better economy.