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What types of things from a mechanical standpoint limit the max RPM on these cars?

See my setup in my sig. I feel I have more room on the turbo (still pulls hard as anything to redline), and fueling should be fine. My limiter is currently set to 7,000prm. I'd like to be able to rev this thing to 7,500rpm-8,000rpm because the power still feels like it's there at 6,500rpm.

This winter I'd like to take the head off and do some home-brew head porting and wanted to start doing research on the limiting factor here. On the Chevy 350's I used to work on, in our application it was valve float and valve train that would limit RPM to an extent and by running a good set of double valve springs, hardened pushrods, roller rockers, roller lifters, etc, we were able to safely run a higher RPM, which often times contained usable HP.

Thoughts?
 

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Your going to get a lot of mixed feelings on this probably. I asked a very similar question some time back as I am used to driving vehicles that rev higher and make power at higher rpms then we are used to with the st. In my opinion the 2.0 ecoboost shortblock itself is definitely designed to handle high rpm operation, however it is build with a cast crankshaft that I have heard isnt balanced very well from the factory ( read about that in an engine build thread on here.) Now to top it off the cylinder head flows well at low rpm, but with how small the ports and valves are it would be a limiting factor for sure. Just my 2 cents. Personally I had my bone stock st's rev limit set at 7700 with my stratified tune and i drove it that way for quite sometime. The engine handled it quite well aside from running out of power at about 6500rpm.
 

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When you pull the head, are you going to get the bottom end ballanced?

If you want to go that extra mile, while the piston speed will be high, i suspect a properly ballanced stock bottom end will take 8k sub 350hp. But you are asking alot of the crank.
 

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I believe there is a way to determine your optimal shift points based on your dynograph and your gearing. Some cars would benefit from going to redline and beyond, and others well short of redline. This might help you determine if it even makes sense to raise your redline.

For example: Optimal Shift Point

Plugging in my gear ratios and based on a typical stage 1 dyno for a Focus ST, *my* shift points for optimum acceleration are:
1st to 2nd at 37 mph, or 6450 rpm
2nd to 3rd at 58 mph, or 6050 rpm
3rd to 4th at 80 mph, or 5650 rpm
4th to 5th at 101 mph, or 5500 rpm (however, if you are going to cross the 1/4 mile just after a shift into 5th, it would likely be beneficial to ride out 4th gear instead of having the dead time of an extra shift right before the finish)
 
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