fallafalla

It would be easier just to swap in a REW, and a Renesis with P ports is missing the whole point of having them on the irons, its been asked and answered before in previous threads in greater detail.

kustus

iTrader: (1)

I understand the REW swap would be easier, but having both the port in the side iron and on the housing gives more port area in general and should be able to expel more heat because of that. Less heat=less problems (or so i believe) that's more of what I was getting at. Alas I will continue research. Thank you.

Carbon Fibr

Id say oil cooling is a must for stock OMP. But when you have OMP injection & not use the original engine oil that injection should be fairly cooler.
But also cooling of components the oil is actually touching the moving parts so an upgraded oil cooling system makes sense.
As to oil cooling kits; is there any decent kits you or someone has seen or herd of that reduce oil temps a lot?

TeamRX8

iTrader: (25)

FazdaRX_8

iTrader: (1)

the cast iron likes to hold its heat, brettus, is that just wearing down, or can you feel anykind of deformation in that area?

someone needs to make renisis side housings out of aluminum, with steel exhaust ports or something to handle the heat, then we might have something. according the mazda's 16x web page there working on just that.

j9fd3s

you do know the OMP only injects like 2cc/minute right? its like a couple of drops.

the rotors are cooled by an oil spray from the eccentric shaft.

Brettus

iTrader: (2)

No deformation . It's interesting that one of the ports has no sign of wear in that spot at all . Perhaps that port was not getting as hot as the others or was getting more lube . Would be good to know which .........

FazdaRX_8

iTrader: (1)

well the front iron exhaust area, would be the last spot the coolant gets to before it goes to the waterpump to the radiator. so really its the hottest or least effective. the middle exhaust ports flow less so less heat there too.

assuming the center iron port on the rear rotor was least affected?
you could also pull out the oil squirters and see if that side squirter was the cleanest.

olddragger

iTrader: (3)

actually the center port doesnt flow less overall. Think about it.
Brett-- I know you had youre coolant temps under control and didnt do prolonged high load, high rpm running---so you think your omp started it?
I do wish a breakthrough would occur and ceramic side/corner seals were available.
I also think more of use could use ceramic apex seals---for reasons other than strength.
Heck --while I am wishing--i wish we had aluminum rotors too

skc

The problem with ceramic seals is that they are not flexible and will shatter with detonation so your tuner cannot afford to make a mistake while tuning. It has many great properties such as light weight, does not harm housing, etc.

I wonder if they can do ceramic exhaust port sleeves

TeamRX8

iTrader: (25)

With a few exceptions, I never saw such a collectively poor series of not well thought out posts than the last dozen or so. Some of you people either have zero fundamental understanding of basic engineering principles or are severely lacking in practical experience. OD actually made one of his most lucid posts ever when he discussed the heat issue earlier, but it's like this thread derailed off a cliff shortly thereafter.

Pull your exhaust manifold off and run a Renesis without it. You don't need to measure exhaust flow because you can see with your own two eyes that the center port flow is less than the outer ports. Why would you even think it would flow the same when not only is the center port smaller than the outer ports it has a flat baffle plate in the center directly blocking flow as it exits the rotor housing?


Jeebus ...

Brettus

iTrader: (2)

Do you have any thoughts on the exhaust port wear issue seen here ? I would value your input.

dannobre

iTrader: (3)

I wonder why you suddenly seem to be injecting a lot more of your personal opinions in things...I always admired your ability to keep your nose out of things on here.

olddragger

iTrader: (3)

The centerport handles twice the number of exhaust pulses as the primary ports. The higher number of pulses also means the exhaust flow is smoother through this port. This also means the exhaust flow out the centerport has more velocity.
Yes the centerport doesnt flow as much as the primary port for each rotor face combustion event--thats true, but overall--I am thinking it it is flowing more than some believe.
IDK maybe I am full of gas--but it seems logical to me.

Brett here is an engine autopsy of mine some years back--maybe of some insight? IDK?

https://www.rx8club.com/tech-garage-...ight=od+engine

rotaryPilot

what was your vacuum reading at idle ?

Brettus

iTrader: (2)

It normally ran at around 16 - after this started happening it was around 14.5 when running ok and dropped to all over the place when it was playing up .

Brettus

iTrader: (2)

Cheers OD . Same bearing wear as mine i see .

FazdaRX_8

iTrader: (1)

Brettus is my hero

Brettus

iTrader: (2)

where's my apple ?

TeamRX8

iTrader: (25)

I could care less about Ray's continuing personal attacks against me - .

Energy will follow the path of least resistance to reach a state of equilibrium. The equilibrium in this particular case will be the common back pressure experienced by each port during the combustion event. In order for the back pressure to be in equilibrium between the center and outer port simultaneously the flow through the larger outer port must be inherently greater than the smaller center port. The larger outer port does not just sit idly by unused while the combustion event forces itself out the smaller center port at high velocity. There is also good high velocity and bad high velocity as it relates to flow smoothness/turbulence.

The general design of the center siamese port is very restrictive and turbulent i.e. bad high velocity. What velocity may be generated in the center port is countered by low flow. The net energy passing through the center port for each individual combustion event is then low. With a greater amount of flow passing through the larger outer port how can you make the claim that the velocity through it is lower than the center port? The net energy of the combustion event through the larger outer port is much greater than the center port.

Being that the center port is siamese and carrying a pulse from each rotor is not relative to the individual rotor combustion event perspective. It is relative to other topics, just not this particular one. You have to remember that what velocity may be generated per combustion event loses it's velocity in multiple steps. First it slams into a flat divider plate. Second it passes from the divider plate into the larger undivided port outlet area. Third it passes from the larger port exit area into the much larger still header/manifold tube that is the same flow size as the larger outer ports. The siamese part comes in when the combustion event from one rotor is followed by a combustion event from the other rotor.

So yes, there will be twice as many pulses in the center port exhaust tube. However, you can't simply approximate/guess/fantasize at what the magnitude of the combined pulses in the center port is. Overall the center port is smaller than the outer ports, it has a flat divider wall in the center that makes the port just that much smaller, and that divider also presents it as a flat wall that is very close to port entrance and directly impedes flow out of the combustion chamber space. This is what results in turbulent/chaotic bad high velocity flow though the center port.

Intuitively my assessment was that, despite the center port/tube having twice the pulses due to being common siamese flow path between the two rotors, the net magnitude of energy passing through it is lower overall than the outer ports. Having personally watched the combustion events passing through the ports on a header-less running engine this visually also appears to be the case. If you delve into the Renesis design literature it was stated that the small center port came about because with just large outer ports only, which Mazda initially tested, there was too much EGR effect being left in in the process. A port on one side could not effectively clear out the combustion gases on the far side of the rotor face away from it. So they threw the center port in to the mix to allow a partial combustion gas clearing path on the opposite side from the main large outer ports just for that purpose.


.

Harlan

iTrader: (3)

Thanks for the insight!

olddragger

iTrader: (3)

Now that makes a lot of sense Team and appreciate your thoughts. I was agreeing with your assessment when I said that per rotor face combustion event the centerport doesnt flow as much as the outer port however I think I may have confused the issue of how the centerport contributes to the evacuation of a single combustion event when i allowed my post to gravitate toward discussion of overall exhaust flow. My apologies for this unintentional misdirection.

I never knew that the centerport was added to address excessive internal egr. That makes sense and it fits in with some some other stuff I have learned concerning that system.

Just for the curious
Here is a site in which others are addressing siamese exhaust port issues.
small gains in high plains | Mini Engine Stuff

Brettus

iTrader: (2)

Couple of things to add :
*Hymee had a video of an Renesis being dynoed that clearly showed the center tube servicing the Siamese port was glowing red hot whereas the outer tubes were not . So - the overall combined flow from the Siamese ports was more than either outer port.
*The test I did should have considerably improved the flow path though the siamese port runner. The fact the I didn't see any gains may be because the improved flow path was counteracted by crossflow of gas into the other chamber, which possibly decreased the efficiency on that side .

X7rotor

iTrader: (2)

Sounds like the single port in a mechanical stand point is just a scavenge port...if its hotter then the other two ports would be done by oil leaving that port morw often then the others (in two strokes adding more oil in a premix leans it out and causes more heat can lead to seizure)
Its no different in a rotory. Add more oil your internals will run hotter. Oil is just lubrication.

A lot in common.

olddragger

iTrader: (3)

--our pre mix ratios are ridiculously low.