so in my quest for streetable 600WHP i have had a few ideas and drawbacks. but i been tossing around the idea of having the rotors beveled. i have only known of one motor a friend built that did it. it put out some nice power at low boost on a street ported turbo II.



im looking at doing this to my half bridged 13b-REW. for the stock port it will be enlarged using the pineapple racing medium street port template. i want to make the turbo work harder than the motor. thus, giving my motor more streetability and hopefully a longer life.



what are the drawbacks of beveling the rotors? and tips, or experienced opinions on this would be nice. not someone putting it down just because they have never done it, and know nothing about it...



(and yes i know i will have to get the entire rotating assembly balanced)

I don't believe it is necessary for power (as I believe porting is where it's at when it comes to increasing engine VE) and I also believe it is a bad idea:



- possible imbalancing of the crank assy

- possible weakening of the rotors



There's much more proven ways to yield power, IMO. Don't touch the rotors.



B

The rotors are reduced along side the corner seal area to allow the rotor to tip slightly between the irons without touching the irons. When you increase bearing clearance, you allow for slightly more movement, and invite contact. At high power output the rotor tries to move away from the combution chamber,and tends to

bend the crank into an "S" shape. So, the rotor tips a bit between the irons.



So the clearance between the small of the rotor housing is called out as a minimum, and rotors in violation of the minimum require the area along side the combustion chamber in the rotor face to be reduced to arrive at the minimum clearance. Otherwise they drag on the housing opposite the plugs. Check all three faces. That part is as cast and in error on occasion.



When you cut off .040" or more in places, to lighten rotors, they hold up pretty well, and are still pretty thick

after lightening. So machinig off only .010" is not going to kill them or make them weak.



This has nothing at all to do with making power. It has to do with still having an engine to play with after one missed shift at full power.



Practice on a junk rotor. Use a lathe or milling machine, that you know how to run.



Balance the whole rotating assembly after you finish.



Run a rev limiter.



Buy a Racing Beat catalog (and read it).



Read everything on Paul Yaws web site. www.yawpower.com



Lynn E. Hanover



The picture is page one of a simple flow bench you were supposed to have built already but didn't.

The rotors are reduced along side the corner seal area to allow the rotor to tip slightly between the irons without touching the irons. When you increase bearing clearance, you allow for slightly more movement, and invite contact. At high power output the rotor tries to move away from the combution chamber,and tends to

bend the crank into an "S" shape. So, the rotor tips a bit between the irons.



So the clearance between the small of the rotor housing is called out as a minimum, and rotors in violation of the minimum require the area along side the combustion chamber in the rotor face to be reduced to arrive at the minimum clearance. Otherwise they drag on the housing opposite the plugs. Check all three faces. That part is as cast and in error on occasion.



When you cut off .040" or more in places, to lighten rotors, they hold up pretty well, and are still pretty thick

after lightening. So machinig off only .010" is not going to kill them or make them weak.



This has nothing at all to do with making power. It has to do with still having an engine to play with after one missed shift at full power.



Practice on a junk rotor. Use a lathe or milling machine, that you know how to run.



Balance the whole rotating assembly after you finish.



Run a rev limiter.



Buy a Racing Beat catalog (and read it).



Read everything on Paul Yaws web site. www.yawpower.com



Lynn E. Hanover



The picture is page one of a simple flow bench you were supposed to have built already but didn't.

The picture was too big. Here is yet another attempt.



Lynn E. Hanover

The rotor machining in this case would be a bevel or radius on the opening edge of the rotor for an earlier port opening timing like the RX-8 has and earlier "street port only" race engines had.



I believe it would be a bad idea to do this to a rotor with a bridge port as bridges already open earlier than is ideal; bridge port was a compromise port used in racing when peripheral ports were banned.



On a 1/2 bridge it may add power if it was done only on the rotor face with the unbridged port.



Besides having to balance the rotating assembly the only other downside I have heard of from beveling the rotors on a street port is that there is a much higher chance of foreign objects (apex seal bits, etc) getting wedged between the rotor and side housings and gouging the side housings. A real bummer when you have so much work in porting and oil system modifications.

beveled rotors can open earlyer and later if top and bottom are done.. the draw back is that it lets more heat get to the side seals witch can cause a side seal to fell... other then that rock out and make more power https://www.nopistons.com/forums/pub...#>/biggrin.gif

Never had one failed from heat due to bevelling even in 700hp dialy drivers. https://www.nopistons.com/forums/pub...IR#>/smile.gif

What can happen though is if you were to break an apex seal and it gets wedge between the bevel and the rotor housing the rotor will end up jamming the side seal in place. By reducing the area above the side seal results in weaker rotors. I've seen rotors taken to the extreme in beveling where they cracked from normal running.

Sounds like a good reason to me to avoid doing it as there's ways that are much safer to yield power, IMO.



B