Ah ... I kinda missed your mention of the Sohn adapter. (I want to do that to my car too but probably when it's out of warranty.) I don't really know, but I suppose you're right that Mazda's only objection to whatever additive comes from it being burned inside the the combustion chamber.

I Used More Than 1 Qt In 1000 Miles!

What type of driving did you do, lots of short trips, hard with lots of RPM's?

About 25 Miles Each Way To And From Work 18 Miles Highway Driving At About 75-80.

So because you used a "!" I take it you are using more oil now and thats what the "TSB" says. Are you using 5W20 or 5W30 and premix too?

Just 5-20 Got Into An Arguement With The Dealership Yesterday They Said My Car Required Motocraft 5-20 Synthetic Blended Oil. I Told Them No! They Fought Me Then They Said Well 5-20 Isn't Made In Conventional Oil. I Said You Better Call Castrol And Letr Them Know Because I Just Bought Some Gtx Yesterday! Then They Looked In Their Service Manual And Saw That The Motocraft Was Completely Different Api Standard Than What The 8 Calls For They Just Looked Shocked. They Have Been Puttig The Wrong Oil In The 8's They Have Been Servicing. Whats Even More Scary Is They Are The Only Certified Mazdaspeed Dealer In Maine. So They Say!

^^^^Scary!:Kill2:

Disappointing and Scary too....

just to share--it has been decided by independent study that the renasis needs 300cc of oil per 1 hr of driving for proper lubrication of the seals. Thats a lot more than we are using!
OD

That's a lot (assuming we went 70 miles in that hour). Assuming a more realistic speed averaging 35mph...that's a ton. At 35 mph for an hour we'd use 1.5 gallons of gasoline and 1/3 a litre of oil. That's close to 20 parts gasoline to 1 part oil. Crazy.

i have one good guess where that info came from.. ;)

beers :beer:

Please give us all you know about this study.....

The housing surface is not a hard chrome finish---the more shiny chrome you see the more wear. It is a micro channeled pinpoint pourous chrome. All designed to increase lubrication properties. Think about it--how hard is it to keep lubrication on a hard chrome surface?
This engine is a good engine with betterment capability.
Pre mix, a 3nd injector or sohn adaptors are a step in the right direction--but they are not the complete answewr. IMHO it is seal design, housing coating problems, engine hot spots, exhaust port problems and under addressed carbon build up that is "the problem".
This is not doom and gloom however--we are only evolving just like the earier models did.
rotor on
olddragger

tell sealbonekanobi we said hi!

beers :beer:

Who is sealbone? Wish I had that name!
olddragger

The chrome plated inner surfaces bothers me a bit. Why would chrome be used instead of a cast iron lining similar to the cylinder sleeves uses in the aluminum block of a conventional engine? I'm no materials expert but I do recall that cast iron has some major advantages to other materials when it's used in a lubricated, high heat/friction application. In fact, I think cast iron actually absorbs, for lack of a better term, the liquid lubricants applied to them.

Piston rings can be made compatible with cast iron cylinders, why can't apex seals? Or is it perhaps the fact the trochoidial the rotor moves in a bit too difficult to apply the equivalent of a cast iron cylinder wall sleeve?

cast iron ---to heavy and doesnt dispense heat as well. Each rotary engine (i think) has had a slightly different housing coating. Seals are not ran at the same tolerances as piston rings---much looser . The coating is actually placed on top of another bonded plate of metal--not aluminum.
olddragger

not sure about the weight, we're talking about a sleeve, not an entire housing. Seems the heat could be managed as it is in piston engines made from the stuff.

I'd be willing to bet they looked into it, we can only specuaate why they didn't use it. Could be weight but I'm thinking the difference might be just a few pounds.

piston engines do not have to deal with a 270 degress flame front. I thought you were speaking of the entire housing--my bad there:)
i am sure Mazda looked at a lot of different configs. Seems to me they need more field testing. Looks to me as if they designed a 75K engine---at the best.
olddragger

270, I assume that's 270C (518F). Honestly, that doesn't sound that hot. A internal combustion chamber using gasoline as the combustible has temperature averages about 1300C ( 2370F). Cast iron pistons and cylinder would get pretty hot I'd imagine in that environment. Cools by water jackets and by squirting cool (relatively) under the piston keep it down from that fur sure. But I'd bet these cast iron surfaces get to 500F or higher.

Housing is straight aluminium, the liner bonded to it is steel (composition unknown) with a micro-porous chromium coating (Mazdas patent).

The micro holes are designed to hold lubricant......

S

the 270 degrees refers to the amount of time the combustion surface is exposed to the combustion heat---recips have 90 degrees. so the rotory engine combustion surface is exposed to the c. heat 3 x's the lenght of time a recip is. result ---much hotter surfaces and therefore much more difficult to cool.
OD

ahh...now that makes sense. Sorry for my confusion.

So essentially, the thermal conductivity of the porouse chrome plated steel are greater than the the thermal conductivities of a cast iron lining.
But....the following may be of interest to you...

Thermal conductivity pretty much follows electrical conductivity (not perfectly, but similar). In other words a good conductor of electricity generally is a good conductor of heat. Both conductivities are affected by temperature (generally less conductive with increased heat).

Since Stealth indicates the steel is an unknown variety, the following table may not indicate much, but notice the thermal conductivity of pure iron is 42 at 68F, 1/2 that at 1832F, and of carbon steel it's 21-31 depending on carbon content at 68F, and stainless is 7-26 at 68F.

Yes, probably more than you wanted to know about these metal properties, and the engine has what it has...but the question does remain...why no iron lining in the rotor combustion chamber. Maybe marketing doesn't want their "high tech" engines to have any iron in them, LOL.


Metal Temperature - t - (oF) | Thermal Conductivity - k - (Btu/(hr oF ft2/ft))

Admiralty Brass 68 64
Aluminum, pure 68 118
200 124
400 144
Aluminum Bronze 68 44
Antimony - 120
Beryllium Copper 68 38
Carbon Steel, max 0.5% C 68 31
Carbon Steel, max 1.5% C 68 21
752 19
2192 17
Cast Iron, gray 70 27 - 46
Copper, pure 68 223
572 213
1112 204
Copper bronze (75% Cu, 25% Zi) 68 15
Copper brass (70% Cu, 30% Zi) 68 64
Cupronickel 68 17
Hastelloy C 5 70
Inconel 70 - 212 9
Incoloy 32 - 212 7
Iron, nodular pearlitic 212 18
Iron, pure 68 42
572 32
1832 20
Iron, wrought 68 34
Gold - 183
Lead 68 20
Lead 572 17.2
Manganese Bronze 68 61
Monel 32 - 212 15
Nickel Wrought 32 - 212 35 - 52
Platinum - 41
Red Brass 68 92
Silver, pure 68 235
Stainless Steel 68 7-26
Tantalium 68 31
Tin 32 36 - 39
Titanium 68 11 - 13
Tungsten 68 94 - 100
Wrought Carbon Steel 32 34
Yellow Brass 68 67
Zink - 67
Zirconium - 145