Mazmart

iTrader: (12)

I have been learning a fair amount about both oil systems and will share everything when Olddragger installs his RE-medy oil pressure kit.

Stay tuned .

Paul.

dannobre

iTrader: (3)

Can someone remind me why we are looking for more than 90 psi oil pressure ?

madcows

So that we can comfortably use 5W-20?

Mazmart

iTrader: (12)

HA HA! This is the funny thing I've been saying the whole time. There are some advantages to some increase in pressure but it is far from essential. Some have speculated all sorts of things in this thread about what is and what should be. We are offering the increase for those who know they can use it and for those who believe they need it .

Paul.

dannobre

iTrader: (3)

We were having high oil pressure problems on the FC racecar...and went to an external oil pressure regulator setup so we could adjust it better

The only problem I've had were some oil supply problems in corners that a bigger and better baffled oil pan seems to have fixed

olddragger

iTrader: (3)

not pressure we seek--better flow we seek, we do--with out tearing the engine down and redoing galleys etc.
maybe we can have better dynamically balanced rotors also?
OD

Brettus

iTrader: (2)

cuz someone on the interwebz said so

Flashwing

The problem is 90% of the stuff people think they need they don't. The illusion that you drive your car harder than it was designed for seems to be quite common.

GeorgeH

iTrader: (2)

+1.

ayrton012

Actually we have only 72-75 PSI max pressure on the engines with factory OC's, and regulators.

1. There is a reciprorating engine oil pressure rule, which tells that the technically minimum oil pressure is 10PSi at 1000 rpm, and 10 PSI more at every higher 1000 rpm, like 1000rpm-10PSI, 2000-20 PSI, 9000rpm-90 PSI. This rule is for the much cooler temps crankshaft bearing. ..and the 90 PSI is just the minimum!!!
We have much higher temperatured e-shaft (thinner oil), and we have only about 73 PSI max pressure at 9000 rpm. So what??

2. Bearing wear problem on almost every engine.

olddragger

iTrader: (3)

Has anyone seen any front e shaft flex in this engine?

I have heard through the grapevine that there is another reason that Mazda increased the oil flow in the 09's. It has to do with high rpm rotor balance. Rotor's are dynamically balanced so the oil flow within them will have a substancial affect?
OD

ASH8

Oh really, and that 90% also applies to the rubbish bought from after market auto suppliers too..

madcows

Of course, pressure can only indirectly indicate flow for any given engine. So theoretically, and engine with large oil galleys could flow more oil at only 10psi measured pressure vs. and engine with much smaller galleys and 100psi.

I think all the reputable engine builders that posted in this thread have suggested that they don't think there is a pressure/flow deficiency (at least on the top end) in the S1. But of course, higher flow minimizes the time oil is exposed to hot engine components, which should help prevent oil degradation, and potentially help cooling.

While I don't really understand how the dynamically balanced system works (it's open loop?), I wonder if increased flow would be a problem?


I'm still sticking with the thought the bearing wear occurs in the lower rev band with poor quality/broken down oil.

ASH8

Then why has this not been a issue with RX-7's, same bearings..(different Oil recommendation though).

I am thinking an "Inconsistence Oil Pressure, and Oil Starvation due to absent Sump-Oil Pan Baffles when doing around corners."

I also 'caution' the 09 Oil Pressure comparison, IMO all Mazda have done is stabilise the OP to where it should be and because of the external twin EMOP oil set up.

I still believe the S1 needs an increase in OP and attention to the sump oil pan.

Mazmart

iTrader: (12)

Shaft flex can occur in all rotaries especially in the front. The rpms that a problem exists are very high and more common with heavier rotors (Which have corresponding counterweights). We have seen where the shaft will bend a bit over 11000 rpm.

Paul.

Mazmart

iTrader: (12)

The reason that I don't think it's an rpm specific issue is that we've seen enough autos with this front bearing wear including some we know were not driven hard.
Now I'm the one sounding like the stuck record : 5W20 is the culprit with the bearings.

Paul.

madcows

Out of all the rotaries placed in the RX-7s, doesn't the S1 RX-8 have the lowest OP @3k? This in conjunction with the recommended 5W-20 oil, and less than 60% of oil capacity being drained on typical oil changes probably contributes to the issue. Why would Mazda have substantially increased the pressure in this area? The only other reason is the MOP. And as far as the E-MOP is concerned, I don't exactly see where any substantial pressure is needed (as it's the solenoids that are pushing the oil through the check valves and into the injectors) other than possibly for self-cleaning duties. Again, OP measurements in an S2 throughout the rev range could confirm my thoughts.

ayrton012

There are not so much differences in oil galleys between car's engines. But there are of course.

Low flow means enough (longer) times for the oil to get too thin in the bearings. And too thin oil needs more pressure to make the same protecting against metal to metal contact. But actually the problem is that at such high temps, no matter if you use 20w or 60w oil, they are about the same thin. so only the higher pressure could help.

ayrton012

I think the same. Maybe S1 has the lowest oil pressure in the rotary history, and definitaly it has the highest number bearing wear problems in all of the world's combustion engines if you see the average.(except two strokes).

olddragger

iTrader: (3)

when i mentioned e shaft flex i was wondering if my supercharger pulley would be of concern. Belt tension is not high (bend it 90degres with 2 fingers at the longest part) which is how i also adjust the other 2 belts.
Auto's have the bearing wear too?---with only one oil cooler and lower rpms. Understand the 5W/20 is wrong--wrong--wrong.

Paul got the parts yesterday!! It is sweet that the initials of "RE" are on the bypass.
Thank you my friend! Install with Pics and results this w/e. Please inform Rick that I too insist on clean, clean, clean anytime an engine is opened. Stay tuned---oh and by the way I now have an oil pressure gauge that pegs at 110psi. Also trying to get the 09 filter on it before the install.
OD

GeorgeH

iTrader: (2)

Both of these statements are incorrect, if you go read the literature. Pressure does not affect film strength.

And, there is a difference between 5w20 and the higher viscosities under high temp, high shear conditions. It's called the HTHS spec - read up on it.

However, you are correct that a higher flow rate should keep the oil from heating up as much while in the bearing.

I believe the main reasons for the changes to the S2 are to make it more freindly for the typical consumer. An extra oil injecter to remove the need to premix, and higher flow rate to make 5w20 more viable.

I do agree the lower pressure at low rpm is a curiosity in the S1, but as long as there is enough flow to keep the bearing fed, there shouldn't be an issue. The rpms are low enough that there shouldn't be an issue with excessive heat, therefore the flow rate isn't critical.

9krpmrx8

iTrader: (46)

Lucky. DIY Video? kthxbi

longpath

iTrader: (1)

If it's a combination of the oil coolers being too low to drain properly in combination with the apparently borderline 5W20, then it seems that Mazda ought to have included some manner of drain plug or tap at the bottom of the coolers. Naturally, we can achieve a similar effect by either using a single high-mounted cooler in lieu of the OE coolers or by alternately lifting one side and then the other while draining during an oil change. Certainly, the 5W20 has little additional capacity; but having a system where a significant percentage of worn out oil is still trapped in the system has got to be asking for trouble. Indeed, if this (the positioning of the oil coolers and the trapping of old oil in them during an oil change) is the root cause, then it explains why even Auto transmission models are impacted, as, if anything, the Autos would be less likely to fully warm up the oil and vaporize volatile contaminants, whether from blow by or decomposition, allowing them to be inhaled from the "crankcase" breather and burned off.

jmc23200

^ Although I agree with you partially, you are forgetting that most Rx8 owners add 1-2 QT's of oil to the car in between oil changes, depending on how much oil the engine burns within the time frame. This would kind of balance things out a little bit.

longpath

iTrader: (1)

Now that's an interesting point. Do we know how much oil was typically added between oil changes on the cars with bearing damage or failures? Would it make a difference whether the car was hitting 3000 miles in 3 months or not (assuming the owner is going with the 3 months or 3000 miles rule)?