RotaryResurrection

iTrader: (3)

I do not feel that the additional center injector in the 09 will be sufficient protection either.

See above where the apex seal is NOT worn? IT's only on the extreme edges...about 5% on each side. So basically the oil is ONLY getting spread right where it is injected, and is not being spread anywhere further inward.

So, even if you add another injector in the exact center. What about the area of the seal in between the center and sides? The oil only spreads in a 2-4mm wide area away from the injector port, as has been shown with wear patterns on rotaries since the beginning.

I feel you'd need 5 or 6 injectors across the entire width of the apex seal to provide enough oil to lubricate the entire width of the seal without significant gaps.

BUT...more injectors won't mean much without more oil flowing through them. IF we currently inject X amount of oil per injector and we add 2 more injectors per rotor, you are spreading X out further and thus injecting X/2 oil at each injector now. And we know that mazda cant inject the proper amount of oil to lube the seal for long life and good compression, while still meeting emissions and cat life requirements. Thus we have what is one of THE 2 MAIN issues holding the rotary engine development back. Since emissions requirements will never relax to the point that we are allowed to burn as much oil as we need to for the longevity of the seals, we must conclude that better materials must be used for the seals and surfaces.

We are engaged in a battle between reducing oil consumption for emissions requirements and a better reputation for the engine, and providing enough lubrication for long life and a better reputation for the engine. Moving in one direction negates the other. I feel that mazda crossed the line away from reliability and towards emissions in 1989 with the e-OMP. Those engines, although the housing coating was superior to the older style engines, actually do not last as many miles on average as the older ones. And with each successive generation, mazda has removed more oil via the e-OMP, and each generation the engine life has gotten shorter.

That is of course how I see it...the armchair engineers likely have alternate theories that may blow mine out of the water.

Razz1

Proof that the rotary can last a long time with out premix.

RotaryResurrection

iTrader: (3)

...and probably much longer with it.

Had this engine been in warranty it would have been replaced by mazda due to the compression test numbers, although it still ran fine. Most people would call this an "engine failure" and so technically, this engine did not "last" without premix, per mazda's own definition (minimum compression of 96psi).

MazdaManiac

iTrader: (3)

Razz doesn't always read the text.

RotaryResurrection

iTrader: (3)

lol..

olddragger

iTrader: (3)

RR great summary and write up.
Some of us do have issues with dirty filters and fuel starvation/cut/low pressure on the track---mostly. i am working on a fix for this--i
part of my fix is an external filter--that way --it will not be a concern.
OD

nycgps

iTrader: (1)

Great write up !

I did a compression test on my motor about 2 months ago.

numbers were

Rotor #1 @ 288 RPM - Warm engine

Face I - 7.1 x 100 KPa (102.98 psi)
Face II - 7.3 x 100 KPa (105.88 psi)
Face III - 7.1 x 100 KPa (102.98 psi)

Rotor #2 @ 286 RPM - Warm engine

Face I - 7.5 x 100 KPa (108.78 psi)
Face II - 7.6 x 100 KPa (110.23 psi)
Face III - 7.8 x 100 KPa (113.13 psi)

I know Rotor #2 looks ok. Rotor #1 to me it looks so-so. What ya think RR ?

and notice, I've been using Premix on this motor for maybe 20K+ miles, but I "stop" my premixing for 2-3 tanks of gas before I do this test.

I have temp gauge installed. and for some reason, when my water gauge reads something like 100 Celsius or over and I stop my car, restart it maybe a minute later. and in some rare cases right after the motor started it just dies right off. and I need to crank it again. somewhere not working right ?

LambertRX8

I wonder what a 166,878 mile engine would like inside.

I often wonder that....hmmmm?????

ZoomZoomH

iTrader: (1)

come back when you become the first member of the 200,000 mile Renesis club :D

alz0rz

iTrader: (41)

Wealth of info, thanks RR.

LionZoo

Only 17,000 miles in 8 and a half months? You're slowing down.

robrecht

First, thanks for the EXCELLENT thread, RR! Great illustration and rationale for premix.

But I'm very curious why you don't recommend the 'water injection treatment'.

Potentiated

1. Dannobre said TC-3 may not be optimal for the rotary. What is the likely negative consequence?

2. If premix is as effective as RR (and others) suggest, then high mileage engines on premix from day one should show a very even apex seal edge. Are there any cases out there that have been observed? If not, this should be a priority for the RX8club.

3. When Mazmart tore apart expo's engine at 111,000 miles, the engine had a lot of carbon deposits on the rotors. Expo's response was that he would cut down on the premix with his replacement rebuild. In contrast, RR said a 2-stroke should burn very cleanly and not cause carbon buildup. Can someone explain please. Did expo not use 2-stroke?

4. Why can't a set of oil jets be used on the apex seals much like the jets on an inkjet printer, which can have hundreds or thousands? Is this technology not ready yet for some reason? Seems like it would be the goal for the future for perfectly even oil injection and distribution while minimizing the amount of oil used.

olddragger

iTrader: (3)

the oil is not injected--it is a weeping type of lubrication--it does have a very slight pressure to it from what I understand--but not enough to "spray" like a true injector.
its more of a drop and the seals spread it ---supposedly. i think i have that right.
OD

Razz1

If you have a nozzle that sprays... it will clog.

Remember we are using oil here, so we need a good technology that will not cause clogging nozzles.

05rx8mazda

iTrader: (4)

I never really gave it much thought about premixing.... even if you have the cobb MM tuned to inject more oil would this still be a issue?
Wouldt premixing clog the fuel pump?

GREAT THREAD!!

i am currently at 51K miles

compression test was

1st rotor: 110 PSI
2nd rotor: 105 PSI

they said it was still a good motor.

I will now begint to read up on premixing as im still a novice! so 2 stroke cycle oil... for gallon????

olddragger

iTrader: (3)

I have always liked the idea of premixing---but at the concentration needed-- to amount to anything. With Georgia's dirty gas and with us that track a good bit, there are certain things we have to address in order to do this.
Our fuel filter and pump assembly/delivery system is not made for the track. people will probably never have a problem on the street with it--but the track+r compound tires+mods and you start having fuel delivery issues. We believe pre mix compounds the problem by (over time) increasing fuel filter resistance through sediment/oil accumulation. There are other factors involved also. This is the best theory we have to date. We know for a fact that a symptomatic pump is down by capacity by approx 30%, we know that replacing the fuel pump assembly temorarily fixes the prob.
I am implementing a system that utilizes the oem pump/wiring and regulator/keeping it a returnless system but with an external fuel filter, a fuel can window and increased venturi action(shhhh---secret).
The reason I mention this on this thread is i too believe in pre mix---but due to these side effects i have been unable to do so with consistency. I still think that anything under 1/2 oz per gallon does nothing.
proper temp control will be just as important--if you get the sparkplug cracks you can pre mix all you want and you still will not get a long life engine. I believe it is going to end up being both.
Keep it cool (under 225F-230F) and keep it lubricated and you will continue to twirl the magic spinning triangles.
thoughts ????
Olddragger
Again good job man

04RX8man

man i wish i had a rotary motor just laying around to tear down.....would b someting fun to do while drinking some beers hahah

robrecht

OD, I know heavier weight oil is popular here, but I have not yet gone above 5w-30 because thinner oil is also said to be better at cooling. Not sure if this is merely a theoretical difference or something that makes an actual difference in practice, but do you think going to 10w-40 or heavier makes an appreciable difference in engine temperature? Others?

nycgps

iTrader: (1)

the most important Thing about heavier oil is that it protects better, cuz it it has greater film strength. cooling is just a "side-effect"

if u want to cool better, then you might wanna improve your coolant cooling system's efficiency, like better Water Pump(Mazmart), Better Water hose, and Radiator(Like BHR, Mazmart, and some others)

speaking of Radiator ... now I think Im done testing Mazmart's radiator. Next one would be ... *hehehehe* ... but kinda too cold to change any new rad now. so hehehe ....

robrecht

Better cooling is not a side effect of heavier oil but of lighter oil. I'm not currently trying to improve my cooling system (maybe if I used havier oil I would be). I'm just wondering how much increased heat might be produced by heavier weight oil, wether it would be noticable in the long term, eg, with reference to sparkplug hole cracks, or perhaps in the short term in looking for better water pumps or radiators.

olddragger

iTrader: (3)

heavier wgt oil has not increased my oil temps in any noticeable way. 20w/50 and 10w/40 here. true that oil does help cool this engine but the cooling of the engine comes primarily from the coolant not the oil. If you get the coolant temps under control--the oil falls right in line(as long as you have 2 coolers.
my on track temps on a cool day --mid 70's never got over 185 street temps with a/c on on a 95 f day(i do have forced induction) never over 195 even while sitting still.
RR dont mean to get off topic here--i guess this is discussing what it takes to get long life out of our engine.
OD

nycgps

iTrader: (1)

Sorry I didnt explain my post clearly

What I mean was the primary cooling comes from Coolant, not Engine oil. The oil will carry heat away thats for sure, but its just one of the oil's "side" effect. the main point of the oil is to "lube parts"

nycgps

iTrader: (1)

off topic for a bit -

Now Im wondering is there any small leaks inside my engine or something.

Cuz during summer days ~ after car fully warm up my coolant temp is always around 200-225 f ~~ (something like 95-105 Celsius)

Im running about 50/50.

and when going thru Tunnel (like Holland or Lincoln), my water temp might "shoot up" to around 230~f ~ (I've seen 110 Celsius), might have something to do with the higher pressure inside tunnel ? dunno

I got the temp reading from water gauge, I installed the sensor after the thermostat. maybe thats why? I dunno

robrecht

OK, now I understand what you meant. I presume your cooling issues did not develop as you started using heavier oil? Sounds a little more perplexing.