marcus219

I'm kinda of confusing myself on this one...but when oil control rings leak...oil will seep into the combustion chamber..my question is how does this happen when the side seals and corner seals are in its way..I take it, its b/c oil can find it way through about anything and the seal between the side seal and corner seal is not perfect. Ive torn down my blown 13B before and I pretty familiar with all the internal peices... Please can I get intellegent people to respond.....you know who you are!

thanks.

SonicRaT

iTrader: (6)

You are correct, basically rubber blocks oil better than metal, so it seeps through the creases and burns away, depressingly enough if it's really bad the car will act like a oil pump and it'll look like your exhaust is a oil mine in texas!

CrackHeadMel

iTrader: (2)

im guessing it finds it way by going between side seals and corner seals. Im no expert though

marcus219

thanks man..another question..carbon build up..in a boinker motor..carbon build up on a piston will raise the Comp. Ratio and can cause detonation. Now when I tore down my s4 13B with 140k on it, that rarely saw over 4k RPM being driven by a grandma with the stock oil injection. My rotors were just completely caked with carbon...how come rotaries dont run into detonation problems with all that carbon? Not enough of it..or does it have to do with the design..

marcus219

yup..i just wanted to clarify..

SonicRaT

iTrader: (6)

I'm pretty sure it's got to do with the design, but I'm not positive, that and we naturally burn oil intentionally, so we have even more buildup.

marcus219

I agree....and the oil that we burn stock is motor oil which leaves alot of carbon when it burns...unlike a 2 stroke oil...

White_FC

Carbon buildup inside engines (any internal combustion engine) can cause detonation, not because it raises the compression though, but because it creates a rough edge and can also act as a glow plug and ignite the fuel/air mix.

CrackHeadMel

iTrader: (2)

That makes sence, damn ive learned so much today

marcus219

I agree...but how does it not raise the C/R? Anytime the the space between BDC and TDC is decreased the compression ratio goes up. If you have alot of carbon build up on top of a piston it will make that relationship smaller. Although maybe not enough to cause detonatoin..just thinking...

j9fd3s

iTrader: (3)

the na's are pretty detonation resistant, its would take a lot of carbon, and maybe a plugged fuel filter

mike

rotary>piston

it does raise the C/R. Our C/R is 9.4 or 9.7 (s4/s5), but the actual psi ratings are much lower. My Volkswagen Rabbit, with a C/R of 8.2:1, got over 180 psi when brand new. My RX-7, with a C/R of 9.7:1, would only get about 120 psi brand new.
Generally, in any N/A car (except maybe a ferrari), it takes a lot of carbon to cause detonation.
You should be more worried about carbon lock than detonation. Just redline occasionally, and maybe steam the engine (put water in intake).
And, about the oil ring Q: the oil rings were designed to hold the oil in. The side/apex seals weren't. Plus, there are spaces between the seals in some areas. The oil rings are circles, so there are no edges for the oil to seep through.

White_FC

I would be _VERY_ suprised to see a noticable difference in compression ratio caused just by carbon build-up, it would chip off and carbon lock your motor long before it got this far...

rotary>piston, your analagy is flawed, pistion engines and rotary engines make their compression quite differently, dare I say it, piston engines seal better than rotors at really low RPM's (ie, cranking) generally speaking..

SonicRaT

iTrader: (6)

White_FC is right, thus the rich idles, and why they smooth out so nicely in the higher RPM's. I also agree that by the time carbon changes your C/r, you're going to have at least 3 apex seals sitting in your exhaust manifold.

marcus219

I agree

marcus219

I agree 100% on that as well....my rear rotor ate up to apex seals due to carbon lock.....the rotor and housing got thier ***'s kicked!

SureShot

What then prevents pinging is the knock sensor.
Next time you have a timing light handy, hook it up & watch the timing retard as you tap the engine with a small mallet.

White_FC

eh?
Of course the knock sensor retards timing, thats it's sole purpose in life.
Still does not change the fact that it should not be pinging in the first place and that it has nothing to do with the compression ratio 'change' due to carbon build up.

rotary>piston

well I guess I'm wrong about that compression thing.
And I don't think N/A's have knock sensors

White_FC

No your right, they don't. At least im 100% sure S4's don't and i'm and fairly certain S5's wouldn't either..