" With all the discussion going on about port shapes and timings, has anyone looked at how the square edge of the rotor affects flow on opening and closing? I am convinced that some sort of bevelling on the rotor itself is benefical to both the flow, and to maximising the open time of the port.

If you look at the renesis specs the inlet opens at 3° ATDC. I've not looked closely at the positioning of the corner seals compared to earlier 13Bs but I would suspect that they haven't moved it. Therefore you are gaining nearly 30° on inlet opening from the bevel on the rotor. Again not looked closely at one, but would also suspect that the bevel has not been flow optimised, so there are some gains to be had from looking at this on a flowbench.

Yes you need to rebalance the rotors and yes a BP will give you even more timing, but for a reliable and streetable package i can't help wondering if this is the solution to getting a really wild street port without any reliability issues.
"

The above is a quote from the other forum , this mod seems simple enough with a good promis of good gains , I would like to know if this mod could be used with a semi pp motor , would the overlap be too much ??.

 

More info here : http://www.nopistons.com/forums/inde...howtopic=51719

 

No one is doing this?

 

Rob at pineapple has been doing this for years, infact i'm pretty sure mazda took this idea from him.

 

I have this done to my latest engine

 

Rice any pictures of your rotors? I'm wondering how much to bevel etc...

 

Stan at SDJ does it also

 

When they come back from your country after balancing I will take photos

 

Rice , you think I can do this to my semi pp motor , would the overlap be too much ??.

 

I asked Rob about the rotor beveling combined w/ cutting into the cornerseal track as opposed to a bridge and he indicated the beveling does put more thermal stress on the sideseals.

Would one have to run more sideseal clearance as the RX-8 does?

 

Great.

 

So I guess I'll have to find out myself then ??

 

Maybe I'm confused but, why is this since the side seals aren't exposed to the excessive heat from an exhaust port like in the Renesis?

Also does anyone know if the rotors are beveled, could the rotor face still be ceramic coated?

 

The sideseals are more exposed to combustion/exhaust heat once you bevel the edge of the rotor. When you bevel you have just made a trench to guide the hot gasses right at the sideseal.

How much effect- dunno?

 

The gases are not that hot at all due to boundry layer effects, you know this when you tear down an engine as see just how much carbon is built up on these surfaces. all these edges stay relatively cool due to this effect and the oil cooling of the rotor, the effects *bad* are not worth worrying about as they will be very minor indeed.

The side seal constantly gets cooled with fresh intake charge and its always transfering any excess heat to the side housing walls and or rotor slot walls, the amount of it that is exposed is so small that no ill effects can happen to it basically.

 

Good explanations guys!

 

I guess the amount of overlap introduced by the bevelling depends on how much of an indentation is made . With my semi pp's I guess I'll just have to run less of a bevel than normal ?? .