Has anyone had any experience in cutting a beveled edge onto a rotor near the side seal? Does this make any more power by allowing flow into the chambers earlier and lasting longer or is it mainly just to keep the clearances good if the eccentric shaft flexes?

My -thought- on the idea that it allows more power by influencing the effective port open/close time is that it wouldn't help that much because even if the port gets open a little earlier, the amount of volume that can pass through the narrow hole is not worth the trouble if you're trying to do this to gain power....

Brian

 

i think pinapple does it
and yes it does give a few more degrees of intake

 

Guys have been doing it for some time in road racing.
Look closely at pictures of the new Ren. rotors or am I
imagining things?

 

The RX-8 rotors have them on the closing side of the rotor. Normaly it's done for both earlier opening and later closing of the port.

 

On the Renesis it only closes them later. It changes the port timing by 15 degrees on that engine.

 

I'd worry about blow-by on the side seals?


-Ted

 

nah
not much is taken off

 

How would you go about maintaining the balance of the rotors after beveling their edges?

 

Heres some info on thisclick here

 

What's the difference with this versus just porting the intake ports more?


-Ted

 

I'd assume it just adds more, on-top of port timing

 

think of a roadracing class where you cant port the engine....

 

You'll eventually hit a limit on the opening side that you can't go past as well as the closing side before you get to the water jacket. Some people don't like to backfill them. The bevel depending on which side of the rotor it is done on may allow you to open or close it a few degrees earlier or later. The Renesis does not have the bevel running the full length of the rotor but rather at only one end of each side to only affect port closing.

 

SDJ Motorsports has been doing this for a while, It does involve rebalancing the rotating assembly.

 

Oh, you mean CHEATING!

Seriously, if you bevel the opening end, the intake charge is going to be hitting a perpendicular wall, and that can't be good for flow...


-Ted

 

the rules say nothing about porting the rotor!

 

In theory it might not be all that good for flow but in actuality it kicks ***. You can only go so far on a NA aplication because you got to balance increased flow over lost in compression but on a boosted application you can go very wild!
You must re-balance the rotors once it's done though.
I've seen a street ported 12A make 217 rwhp with that done to it. On turbo aplications I'll just say it makes a huge difference. It gives you all the benefits of a small secondary BP without any of the drawbacks. I've also noticed that the motors become a lot more fuel efficent, less fuel for the same power.
The 1st time I heard a motor running with it done I swore it was bridge ported.

 

God damn, another thing I have to try when I "eventualy" need to pull the engine apart

How does it work on PP's LOL (Thats a JOKE boys !!!)

 

Ya good joke. Any ways, thats some pretty impressive power out of the street ported 12a > 215 RWHP. That must have been a pretty serious street port probably formed mostly out of epoxy and a serious exhaust port. Very good to hear though.

CJG

 

Would it not work with a pp or a partial pp?

 

no part of timing is determined by the side of the rotor housing on a PP, it's all apex seal.

 

Hmmm...the FC 13B NA 6-port end housings can go super huge street porting, compared to the turbo end irons.  I haven't messed around with the huge porting, but if it's intake duration is what you're after, you can't beat that.

Loss in compression?  Do you get that crazy on the bevel?  I'd think the side seals would be compromised or increase in blow-by is significant?


-Ted

 

I'll let you know how the beveling works out on the NA 6 port

 

Now I'm tempted to try this out for my 1/2 bridge turbo project.

 

Do you guys think that most machine shops with up-to-date equipment would be able to balance the assembly properly?