T-von

Hey guys, I finally read this past months issue of Sport Compact Car mag. While reading about how effective the side exhaust will be, I could'nt help but wonder how the side exhaust will have a effect on the side seals. With the exhaust being in the rotor housing on previous engines, the apex seals took a little more abuse do to sliding over the exhaust port(extreme heat). NA versions never really had problems with the apex seals(less chance of detenation and less heat) as opposed to turbo charged models. I know the renesis is NA but, the side seals now have 2 ports to slide over. As thin as they are, do you guys think maybe we will start to blow side seals instead of apex seals(especially in future turbo charged models)?

wakeech

no way.... nothing to worry about

most of the side oil seals slide AROUND the ports (that's why they're shaped so funny) anyways, not to mention that the side seals don't have as much force acting on them, and have more support from the rotor and housings... good question.

T-von

Sooooo wakeech, what do you think now?

wakeech

is say there is an issue, but i can't say what. seals have always had to run themselves over a port, be they apex or side, and i'm not convinced that this is where the problem lies, as the componentry for the rotors (as well as the rotors themselves) is all new.

T-von

Well since I started this thread, I have no problem speculating about the problem. I understand your point that the seals(apex & side) have always had to travel over a port. However, the question here is the seals ability to handle the excessive heat while traveling over the hot port. In the older design, the "thicker"apex seals would have to travel over the extremely hot peripheral exhaust port. Now things are a little differant, the "thinner"side seals get the job of traveling over "two ports" and one of them is extremely hot. With that, I don't think Mazda did anything to improved the strength of the side seals. Why? They have never had a problem with them. My original quote: "As thin as they are, do you guys think maybe we will start to blow side seals instead of apex seals(especially in future turbo charged models)?" speaks for itself.

Now about the newer rotors, the overall design of the newer rotors are no differant than any other rotor out their(the exception being lighter weight, the compression seal above the oil seals, and the less shallow apex seal grooves). I believe the problem lies in the thinner design of the side seal that now has been put into a position of "more abuse" and the seals not being properly upgraded to handle it.

rotarygod

I'll dig this back up since it has popped back up elsewhere on the forum. Regardless of the level of heat, the apex seals still take all of the stress. Remember that each apex seal is always exposed to 2 combustion chambers at all times. The side seals are not. The apex seals see more extreme temperatures and pressures than any other seal in the engine. The apex seal location being at the tip of the rotors gives them easy access to hot gasses all the time. The side seals are shielded very heavily from the heat, even on the Renesis. They are down around the sides in between the very small space between the rotors and the side housings. while the Renesis side seals do in fact get much more heat due to the side exhaust ports, this should serve as no problem. The seals are much stronger than their older counterparts in the 13B. The side seals are immediately exposed to the cooler intake air from the intake ports as they pass over them almost immediately after they pass over the exhaust ports. There isn't much time to keep their temperature high. The peripheral exhaust engines apex seals never passed over the intake port directly except in peripheral intkae port engines and even then remember that they always have twice the pressure and almost always have a hot side and a cold side at the same time. The apex seals receive tons more stress thermally. The fact that the exhaust now goes past the side seals really doesn't do much to hurt them. The issues with not having a side exhaust port until recently have nothing to do with the heat stress on the side seals. The side exhaust port was actually tried by Mazda very early on back in the early '70s. The issues were carbon deposits from inefficient oil metering of the day combined with a far less formulated oil leaving carbon deposits in the engine. These buildups would get scraped by the side seals and then stick them in their grooves locking them in place. At other times the seals would just break but not due to heat. The new seals are wedge shaped and are always self cleaning themselves of any carbon buildups. The new seals will not stick or break from this. If the old side seals didn't have issues with the carbon, they too would have worked just fine. Even though the hot gasses are flowing past the sides, they aren't really touching the side seals all that much. Remember that the side seals are hidden "under" the rotor in relation to the direction of gas travel. Most of the energy never even touches them like it does in a peripheral exhaust port. They really aren't stressed any harder than the older side seals.

wakeech

...and to append onto that, even though the phasing of the exhaust cycles is such that the rotor from one chamber is blocking its own exhaust port (exposing the side seals) the other port is open (potentially blasting the other side with hot gasses), Mazda has included a baffle in the middle of the siamesed intermediate port to reduce this effect.

i'm still confident in the motor.