Originally Posted by m42racer

I too ask about the RPM. Is this really what you are going to rev the engine to? This along with the use of Ti Valves in a Turbo engine is contrary to proven conventional wisdom.

Originally Posted by Bigrigger

I wouldnt say so, the Toyota Supra 2JZ and Nissan Skyline RB26 motors when custom built can rev that high and both run high boost levels no problem.

Originally Posted by Bigrigger

No they are not, but this is

http://www.youtube.com/watch?v=aShLPpWs3Wo

Stock redline is 8000, he pushes it to 9200.

I totally understand what your concerns are with high RPM Boxer motors, but if one puts in the time, effort, and funds to ensure the build is done properlly, then the spoils of one efforts are his to enjoy and brag about all he wants.......until "something" happens and then you have to improve on what you have and the circle of performance tuning continues.

Originally Posted by m42racer

""In addition touching 10K for a moment doesn't prove a thing. People have done that in over revs. Sometimes they survive, other times they don't. Drive there or hold it there for awhile (like GT3's do at 8600 to 9100) and that is what we are talking about.""

I've been known to do this on several occasions. However, it was not in the design plan.

Your correct about holding the engine at 10K. A short burst on a dyno to show it ran at 10K is one thing, running it up there continuously is another.

I'm no expert on engine balance or the design criteria, but I do know that these engines have really good primary balance up to a certain engine speed. As they have opposing cylinders the balance is good until the speeds get above the point where the 2nd order of (un)balance takes over. The weight of the Pistons and the rest of the parts is far greater than Crankshaft can handle. These Cranks have very little counter weight to balance out the secondary forces. This allows them to rev up quicker at the lower speeds and because of the opposed engine configuration, do not require the counter weights.

Looking at the Crank in the photo, it looks pretty standard for a Porsche Crank. It is also streamlined for windage. This is only working against the high engine speed. I have seen Cranks made for these engines where the "counterweights" are loaded and offset to help with the secondary forces.

It also looks to have standard oiling. At 10K this may be an issue. Testing will tell. I hope not for their sake. I do not see the need to rev the engine anywhere close to that number. I would guess the engine will make its peak power well below this number. Friction and all of the other losses will no doubt take over, least of all the air flow should max out at a lower speed. There are other more serious issues that need to be addressed when running an engine at this speed. Not sure if they have been addressed. I would hope so. Most of the internal parts of these engines were not designed to be used at this speed. Some will show up sooner than later. I expect this engine to be a used at that speed very little, so hopefully all will be well. I hope so. Not to find fault, but when this sort of engine is built professionally, it is expected that all of these design issues are understood, considered and addressed.

I have seem many Porsche cranks in two pieces due to high engine revs.

Originally Posted by m42racer

""In addition touching 10K for a moment doesn't prove a thing. People have done that in over revs. Sometimes they survive, other times they don't. Drive there or hold it there for awhile (like GT3's do at 8600 to 9100) and that is what we are talking about.""

I've been known to do this on several occasions. However, it was not in the design plan.

Your correct about holding the engine at 10K. A short burst on a dyno to show it ran at 10K is one thing, running it up there continuously is another.

I'm no expert on engine balance or the design criteria, but I do know that these engines have really good primary balance up to a certain engine speed. As they have opposing cylinders the balance is good until the speeds get above the point where the 2nd order of (un)balance takes over. The weight of the Pistons and the rest of the parts is far greater than Crankshaft can handle. These Cranks have very little counter weight to balance out the secondary forces. This allows them to rev up quicker at the lower speeds and because of the opposed engine configuration, do not require the counter weights.

Looking at the Crank in the photo, it looks pretty standard for a Porsche Crank. It is also streamlined for windage. This is only working against the high engine speed. I have seen Cranks made for these engines where the "counterweights" are loaded and offset to help with the secondary forces.

It also looks to have standard oiling. At 10K this may be an issue. Testing will tell. I hope not for their sake. I do not see the need to rev the engine anywhere close to that number. I would guess the engine will make its peak power well below this number. Friction and all of the other losses will no doubt take over, least of all the air flow should max out at a lower speed. There are other more serious issues that need to be addressed when running an engine at this speed. Not sure if they have been addressed. I would hope so. Most of the internal parts of these engines were not designed to be used at this speed. Some will show up sooner than later. I expect this engine to be a used at that speed very little, so hopefully all will be well. I hope so. Not to find fault, but when this sort of engine is built professionally, it is expected that all of these design issues are understood, considered and addressed.

I have seem many Porsche cranks in two pieces due to high engine revs.

Originally Posted by Bigrigger

Bump for updates