gas builds up behind the seals at high rpm.. springs are for startup and to keep it all tight... right... "please correct if wrong"

 

I can't see how gas or pressure penetrate under the seals, especially in a running engine with carbon buildup adjacent to the seals and in the grooves.

 

Ok well my scanner still doesent work so please excuse the roughness of my diagram



The black would be the rotor near the side seal grove, red would be the side seal, pink is the spring, and the blue dot's represent combustion pressure


the spring keeps a light load pushing the side seal against the iron, pressure from the combustion and exhaust stroke will first push the seal inwards and then the only area left to push pressure would be the top, which increases sealing pressure against the iron

-Jacob

 

Sorry, I can't buy into that. IF the blue dots represent combustion pressure, they also represent carbon particles. Thus, the seals would carbon lock almost immediately after the engine ran, if said pressure/components were penetrating under the seal to the degree being stated here. There'd be just as much carbon under the seals as there is on the rotor faces, which is never the case on the hundreds of engines I've torn down.

 

Wanna buy a vowel?
Blue dot specials this week!

 

CrackHeadMel,

thanks for that illustration. call me gullible, but it makes sense and answers my question as to how the combustion gases get under the seal and how clearances can make a difference.

for the record, i'm not looking to argue, but why would you think there would be just as much carbon buildup in the seal grooves? i find carbon in the seal grooves and like you, it's nowhere near the amount on the rotor faces, but i don't expect it to be. just curious.

 

exactly as I thought.. and yes carbon is our 1# enemy.. hence carbon lock or stuck seals etc.. these are princaples that I learned in the piston world...

 

You picture "IMG_5555" shows marking of a corner seal on the rotor side, as if it was stuck between rotor and side iron.
Did it happen same time?

JD

 

Yes, this is exactly the way it works and exactly why NASCAR engine shops used to gas port their pistons for qualifying engines. They would run piston rings that had virtually no spring force in them to reduce drag. They would then drill real tiny holes all the way around the top of the piston into the top ring groove to help pressure during the compression and power stroke seal the rings. This reduced the amount of friction on the intake and exhaust strokes. Today instead of drilling through the top of the piston which was found to make the top ring land pop off, they come in through the side of the top ring land and with the tight tollerances they run now they have to do it. And yes carbon build up is an issue any way you go about it.

I was working on trying something similar with my rotary while I had access to all the machinery, I was going to get 3 mm apex seals and lap them down to a tighter than stock clearance and then gas port the groove. I was hoping this would lessen chatter. With the shitty season we where having though I got layed off though

 

I believe CrackHeadMel was referring to the second paragraph on page 73:



RotaryResurrection: I've been meaning to ask you...

How did you like the signed Jeri Ryan Photo?

 

arrggg... ok I tried to edit my post and I guess I spent too long writing because I lost it when I tried to save it.

Anyways I'm pretty sure you don't have as much carbon build up in the seal grooves as on the rotor faces for two reasons. The first is you don't really have much, if anything burning in there. The second is unlike the faces of the rotors you don't have much gas movement. When pressure is low you may have a little moving through the apex seal groove but after pressure builds and a seal is made gas flow stops and so would the movement of additional carbon into the apex seal grooves. Kind of like a water faucet, once you shut it off and it seals you still have water behind it but it's not moving anywhere.

 

That would be it.