Mazda 13b w/ Tracy Redrive

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narfi

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email response from Marcotte,

Guy Marcotte said:
For the Mazda Rotary I manufacture the model 300 with a ratio 2.4:1.
The gearbox is supplied with a cast bell housing adapter,the flywheel and the elastomeric coupling.
The weight is 48 pounds and the price USD $ 4,500.00
 

rv7charlie

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I've never tried to do a poll, but I'd suspect that a 'significant minority' of a/c installations use the metering pump *with 2stroke oil adapter*. More than half just remove it & do premix. I don't know of anyone who's using it in 'stock' configuration, using crankcase oil for apex seal lube. What's driven the total move to 2stroke apex seal lube is the near-universal stuck seals symptom (major carbon & other gunk) in salvage yard engines. d's mention of his engines looking new when he opened them up after a season of racing did catch my eye. I've long wondered if the stuck seals issue in street cars was due more to the way the cars are operated (and failure to change the oil) than to the use of crankcase oil. Street cars are almost never run at anything like significant power levels; d's experience suggests that we could safely run the MOP in stock configuration with the higher power levels of a/c use. I have the adapter on my Renesis project because it was in the pile of parts that came with my project. Biggest issue, short term, that I see with letting it pump engine oil is that the lowest flows (or mixes) that are in use today is abaout 1/2 ounce per gallon of gas. With a few of 2 hour flights, that can be a noticeable drop in crankcase oil level. With separate MOP feed or with premix, all the guys I know have to *drain* oil from the crankcase periodically, because the 2stroke oil gets wiped into the crankcase by the seals.

d, when you were running the car, was there a reason for adding premix, instead of just increasing flow of the MOP? Guys flying a modified pump lock the adjuster arm and manually adjust flow downward until they crankcase level increases get minimized, or (more commonly) they get to the limit of their comfort zone on reducing flow. :) I think most Renesis fliers are running about 1/2 ounce/gallon.

narfi, that looks pretty reasonable, in 'today's money'. A little heavier than Tracy's drive, but tolerable, and if he's using an actual flywheel instead of a flexplate, that *should* minimize any TV issues. the 2.4 should still let you get ~180 sea level HP @ 2700 prop rpm.
 

narfi

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This is one reason I am posting here asking questions... I don't know much yet even though I have been reading for years now.
Isn't 2.4:1 a little low for getting good takeoff power for a big prop?
 

dwalker

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I've never tried to do a poll, but I'd suspect that a 'significant minority' of a/c installations use the metering pump *with 2stroke oil adapter*. More than half just remove it & do premix. I don't know of anyone who's using it in 'stock' configuration, using crankcase oil for apex seal lube. What's driven the total move to 2stroke apex seal lube is the near-universal stuck seals symptom (major carbon & other gunk) in salvage yard engines.
The reason "junkyard engines" are all carboned up is because most drivers do all the things the rotary hates- use the wrong oil- the factory specified 0-20wt oil, which was fine in testing but in the "real world" of massive amounts of idling and the cars never seeing redline the result was increased bearing wear and of course, carbon fouling.
The move to two-stroke oil being injected instead of engine oil was a reasonable idea that turned into a religion that has no basis in reality. The entire tenet was based around the idea that "engine oil does not burn, and was not meant to burn" which no one should have ever bought into.


d's mention of his engines looking new when he opened them up after a season of racing did catch my eye. I've long wondered if the stuck seals issue in street cars was due more to the way the cars are operated (and failure to change the oil) than to the use of crankcase oil. Street cars are almost never run at anything like significant power levels; d's experience suggests that we could safely run the MOP in stock configuration with the higher power levels of a/c use.
YES.
Mazda has publicly posted that the rotary engines should see redline each and every time they are driven, and the Renny is not an exception. The harder it is run the longer it will live. Without exception.

I have the adapter on my Renesis project because it was in the pile of parts that came with my project. Biggest issue, short term, that I see with letting it pump engine oil is that the lowest flows (or mixes) that are in use today is abaout 1/2 ounce per gallon of gas. With a few of 2 hour flights, that can be a noticeable drop in crankcase oil level. With separate MOP feed or with premix, all the guys I know have to *drain* oil from the crankcase periodically, because the 2stroke oil gets wiped into the crankcase by the seals.
So herein lies the issue, and why I no longer believe the SOHN adapter to be a good idea. The Renny, especially the S1 engine as used by pretty much everyone, really needs a lot of oil injected into it to be reliable. One of my two cars had the SOHN and the other did not. At the end of a 50 minute race with the engine seeing5-9400rpm and burning 11gal of gas, we would have to add about a half qt of engine oil to the non-sohn car. The Sohn equipped car would use less than an 1/4qt, closer to an 1/8th. This tells me that the engine is not getting enough oil. I base this on the fact that we have long known that Mazda was sparse with the MOP rate to meet emissions and this has lead to greater wear, especially in street cars that never see higher RPM. SoRB has the rate of MOP flow just about as high as it can stand it. The gravity fed seems to not deliver as much oil to the engine as the pressurized engine oil, and so I will never even dream of using it. Ever. Especially in a flight engine. We always ran a qt above the "full line" as there is no crankshaft to care about it being overfull. In a flight engine I would say you could safely run 6-8 hours of flight time before becoming concerned about oil level (and there IS a low oil level switch) based on 6000rpm at cruise power.

d, when you were running the car, was there a reason for adding premix, instead of just increasing flow of the MOP? Guys flying a modified pump lock the adjuster arm and manually adjust flow downward until they crankcase level increases get minimized, or (more commonly) they get to the limit of their comfort zone on reducing flow. :) I think most Renesis fliers are running about 1/2 ounce/gallon.
I ran between 8oz of Redline Racing Two Stroke oil to 5 gallons of fuel. The reason was because I was not 100% sure the MOP could flow enough oil at the RPM we were turning- and remember, we mostly did 50 minute sprint races but also did (and won) endurance races like the 9 hours at Road Atlanta etc.- and because RB had found that premix did in fact add power, which was mirrored on my dyno tests.

narfi, that looks pretty reasonable, in 'today's money'. A little heavier than Tracy's drive, but tolerable, and if he's using an actual flywheel instead of a flexplate, that *should* minimize any TV issues. the 2.4 should still let you get ~180 sea level HP @ 2700 prop rpm.

The only downside I see to the Marcotte is the weight and the slight offset of the prop, neither of which are real deal breakers.
 

rv7charlie

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I know it's unlikely, but did you ever leave the oil in the Sohn-equipped engine long enough to see a change in its color? As I mentioned earlier, every flying engine I'm familiar with (both Sohn & premix) actually sees their crankcase oil levels *increase* over time, and if their 2stroke oil is a distinctive color, it shows in the crankcase oil. Any chance that the difference you saw was because the non-Sohn was drawing from the crankcase, and the Sohn engine had a separate supply?

Of course, the a/c I know never attempt the kind of peak power levels (or rpm) that ground racers reach.
 

dwalker

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I know it's unlikely, but did you ever leave the oil in the Sohn-equipped engine long enough to see a change in its color? As I mentioned earlier, every flying engine I'm familiar with (both Sohn & premix) actually sees their crankcase oil levels *increase* over time, and if their 2stroke oil is a distinctive color, it shows in the crankcase oil. Any chance that the difference you saw was because the non-Sohn was drawing from the crankcase, and the Sohn engine had a separate supply?

Of course, the a/c I know never attempt the kind of peak power levels (or rpm) that ground racers reach.
I'm not sure how the two stroke oil from a sohn could teach the crankcase without there being a leak between adapter and the oil return for the original MOP that should be blocked off. The pressurized engine oil can escape the oil control rings into the combustion chambers but I would be amazed if the reverse could happen and excess oil from the Sohn could somehow not be burned but instead not be blown out of the exhaust and instead find its way post the oil control rings against high pressure oil and then into the oil pan.

My Sohn equipped car never added to the oil pan, and did not use/inject what I've felt was a proper amount of oil.
 

rv7charlie

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In the a/c installs, the crankcase oil level increases happen in the engines running just premix, too. Only explanation anyone can think of is that the rotor side seals are literally wiping the 2stroke oil off the chamber walls, into the crankcase. Very common in a/c-converted rotaries.
 

FinnFlyer

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"We consistently made best power at 210-215deg as measured by the AIM dash reading a calibrated sensor. It will live a very long time at 215deg. It will live a much shorter time at 230deg. At 230deg we noted a consistent tapering off of power. Below 205 deg the engine makes less power throughout the curve. "

Walker, is that coolant temps? Renesis standard temp probe/sender location where coolant exits engine?

If so, it looks like I could safely increase my coolant temp alarm limit.

BTW, I can confirm oil level increase in 13B engines with 1 oz/gal premix and no OMP/MOP in the 800+ hours I've flown them. Really the main reason for oil change. Don't know that the Renesis will be different. Tracy recommends 5W-50, mainly because oil is also used in the PSRU (gear teeth shear forces). Another reason for removing the OMP/MOP was fragile plastic lines from OMP to rotor housings. Perhaps that was later solved by Mazda too?

Finn
 

dwalker

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"We consistently made best power at 210-215deg as measured by the AIM dash reading a calibrated sensor. It will live a very long time at 215deg. It will live a much shorter time at 230deg. At 230deg we noted a consistent tapering off of power. Below 205 deg the engine makes less power throughout the curve. "

Walker, is that coolant temps? Renesis standard temp probe/sender location where coolant exits engine?

If so, it looks like I could safely increase my coolant temp alarm limit.
Coolant temp, measured in the same area as the stock sensor (we had to maintain the stock sensor for the ECU) and both dash and OBD2 data from the ECU agreed as to coolant temp.

BTW, I can confirm oil level increase in 13B engines with 1 oz/gal premix and no OMP/MOP in the 800+ hours I've flown them. Really the main reason for oil change. Don't know that the Renesis will be different. Tracy recommends 5W-50, mainly because oil is also used in the PSRU (gear teeth shear forces). Another reason for removing the OMP/MOP was fragile plastic lines from OMP to rotor housings. Perhaps that was later solved by Mazda too?

Finn
I re-read what Charlie said and it made more sense the second time this morning . This phenomenon occurs in a few conditions- fuel dilution from a rich tune, excessive idle and short trip driving, porting done wrong, fuel injectors too big or with a bad spray pattern, fuel injector leaking down when engine is off, oil control scraper ring and/or iron faces worn unusually- none of which are show-stoppers in and of themselves, but could lead to issues.

One thing about the Renesis if using the stock injectors is they love to give issues. I replaced them with cleaned and balanced injectors at every rebuild and suggest that if you are flying on them to have a complete spare set ready to install on hand. If anything changes in the running of the engine or fuel usage, change them out and send the ones removed off to be cleaned and balanced.

The fragile plastic lines- which are not that fragile when new- we replaced with -2 AN teflon lined hose, with either a kevlar or steel braid outer. Been awhile since I made a set but I am pretty sure we simply re-used the existing banjo fittings with Oettiker clamps and moved on.
Hope that helps.
 

FinnFlyer

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I'll increase my coolant temp warning limit.

Wasn't aware of stock injector issues. Thanks for the heads-up!

Finn
 

Urquiola

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In the Le Mans long endurance race winning RCE, Mazda added MoS2 to oil, see SAE paper 920309; SAE paper 922375.
LiquiMoly of Germany suggests adding 1 cc of their Mo additive for each litre of oil in gasoline mix, expert Mazda RCE users (www.rotaryeng.net) indicate always adding at least 1% of lubricating oil directly to fuel, oil pumps sometimes fail, this a cheap and easy safety step. There was Molykote A MoS2 additive to be added to engine oil.
Don't know why, but I won't use MoS2 additive in oil radiator cooled engines, such as avionized versions of Citroën twin-flat engines.
Not all oils are same, not every RCE accepts same oil, while Citroën advised Total GTS 20 W 50, for their Comotor Birotor engine in GS, a Multigrade oil is good for Cold Starts, Norton, for their Liquid Cooled birotor, banned multigrade oils.
Sachs Air Cooled Housing, Charge Cooled Rotor engines indicated SAE 30 oil; for hot weather: SAE 40.

The oil giving better results ever in Sachs engines was Shell Rotella, available in Vintage Tractors and other sites, other oils generated lots of ashes and gums, it can block seals, destroying engine.

In the early days of Wankel Engines, gas was leaded; lead additives acting as a solid lubricant, ceasing lead in gasoline requires an extra amount of oil, Aixro indicates Mobil 1 Racing 2T, 50:1; Spanish Aixro dealer indicates 4%; too much oil can foul plug, too little, increase wear. RCE is very good for Ethanol in gasoline mixes, SAE Paper 840237, M Gutman.

About cooling, the SAE paper 741091, by G A Paul, Dow chemical, shown better results with a coolant fluid based in propylen glycol, instead of the usual, and poisonous, ethylenglycol.
There is a Navarra based company, Pequinsa, producing such a coolant liquid for Solar energy installations, 'Solar 57', where 57 stands for the propylenglycol content. This company is now in the orbit of Soros or other transnational investors.
I purchased several cans of this Solar 57 cooling liquid for my 1987 NA Mazda 13B, but not installed it yet.
Blessings +
 
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dwalker

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I skipped over the engine oil remarks-

I used Redline Racing 30wt Race oil. As I noted earlier, On teardown no measurable wear was noted. Not a direct comparison but when I ran the MG Midget 1500cc engines, which I turned to 10,000 rpm while racing, I started out using Valvoline conventional oil- which back then had ZDDP.This was a 14.5-1 compression NA motor using carbs and an electronic ignition. At the beginning of the season I started with a fresh motor, and tore it down after 10-12 race weekends prior to the Runoffs. The engine would show slightly lower compression that after break-in, and tear down would show a ridge at the top of the bore, top and center ring wear, and bearing wear. After my second year it was suggested to me to switch to Redline oil as 7 out of 10 National Champions were using it, and not having to rebuild thier engine twice a year.
The first season I tore that engine down prior to Runoffs as normal, despite compression not having dropped off and actually showed higher than right after break in. There was no measurable wear, no ridge in the cylinders, and if fact you could still see the light crosshatch marks from honing. No valve wear was noted, and the bearings looked like we had just bedded them in. I put the engine back together, missed runoffs due to work stuff and ran a couple other races that season instead. After that I freshened the engine once a year out of habit, but went from changing the oil every race weekend to changing the oil when I changed the motor, only adding as needed. I also became a huge believer in Redline and have used it in every racing engine I have run since.

Using a "Straight" 30wt oil in an aircraft should not be an issue, as much like the race cars, planes really are not started and then flown without being "warmed up". I would also be careful of 50wt oil in a healthy/fresh Renesis. The oil pump in the Renesis and the stock pressure relief valve will easily hit over 100psi on 30wt oil, and more on 50wt. That is how oil filters explode and other issues arise. Having split an oil cooler open on cold startup, I am a bit more aware of these things than I used to be. Of course, it is YOUR airplane so test and evaluate and make good decisions.
 

FinnFlyer

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... I would also be careful of 50wt oil in a healthy/fresh Renesis. The oil pump in the Renesis and the stock pressure relief valve will easily hit over 100psi on 30wt oil, and more on 50wt. That is how oil filters explode and other issues arise. Having split an oil cooler open on cold startup, I am a bit more aware of these things than I used to be. Of course, it is YOUR airplane so test and evaluate and make good decisions.
Actually 5W-50 Mobil 1 synthetic is hard to come by now. In any case, Tracy recommends at least 120 deg F oil temp before applying full power.

Using the engine oil for the PSRU is a compromise. Ideally you'd have separate oil for the PSRU but that adds complexity with separate PSRU oil cooler and pump.

After reading several posts I was expecting high oil pressures and used a 150 psi sensor. However on my factory-new but old Renesis I'm only seeing 70-80 psi. Perhaps in later versions of the Renesis the oil pressure was increased?

Finn
 

dwalker

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Actually 5W-50 Mobil 1 synthetic is hard to come by now. In any case, Tracy recommends at least 120 deg F oil temp before applying full power.

Using the engine oil for the PSRU is a compromise. Ideally you'd have separate oil for the PSRU but that adds complexity with separate PSRU oil cooler and pump.

After reading several posts I was expecting high oil pressures and used a 150 psi sensor. However on my factory-new but old Renesis I'm only seeing 70-80 psi. Perhaps in later versions of the Renesis the oil pressure was increased?

Finn
I would not even want to guess, there are so many variables, I can only relate my experiences and understanding. If its working for you and not breaking anything I say go with it! I do agree with the oil temp before runup though.
 

thjakits

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thjakits, That's apples & pomegranates. I'd love to do an LS motor in something if I live long enough, but I'd never rape a 2 seat RV airframe with that much anchorage. The powerplant needs to fit the airframe (actually, the airframe needs to fit the powerplant, but the airframe is harder to change). And it's a lot easier to make a belt survive at 3000 rpm input than 7500 rpm input.
Well, I was answering to Narfi's interest in a rotary for his 750HD build. Your RV7 certainly would be a bit upset if you throw anything LS on it (not so the RV8 or even the RV10 though)....
Even for a 750HD one would have to be VERY careful to not build too heavy.

I remember the article about the Long-Ez with a direct-drive V8 in the back.... - also all the crazy stuff Ray Ward did to and with his BD-4.... - obviously more experience is out there now and I think it should be possible to build a optimized engine (V6/8) for the task...
As mentioned in this thread - to keep the Wankel happy you need to be quite aware of it's needs - operation, oil, fuel, etc... - I wonder if the outback/bush is the right place to stay on top of this. On the other hand a properly built LS (or Lexus or BMW or "your preferred lump"!) should be able to feast on any gasoline provided, from Avgas to whatever you can get at your local pump....
One would have to do the homework and virtually (....as in on your PC) build a few different versions (direct vs. sru - turbo vs. na) and see which would be the lightest... E.g. - It would be interesting to see if you can build a Lexus V8 to produce enough power at 2800rpm.... - on the other hand a alu big block should have no problems to give you 200+hp at 2800, obviously you select the "low rpm heavy haul truck torque"-cocktail ingredients for that...

As you mentioned - a belt drive at 6k+ rpm may not be the best sru solution, but I doubt you would want to run your V6/8 at more than 4800 cruise and maybe 5k at take off....
Here some interesting details to belt-drives:


https://www.mitsuboshi.com/english/product/catalog/pdf/V836-E_jis.pdf (...that's their design manual for that belt range)


Now - where is the NXT owner with the urge to put a turbo 4-rotor into his missile...


thjakits
 
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rv7charlie

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The RV8 uses the same series of engines as the -7, and both apparently use the same series of engines as the 750SD. An RV10 could handle an LS motor's weight with only a slight penalty, especially if a light weight fixed pitch prop was used.

My belt comment applied to the rotary; 3k-4K rpm in a rotary just won't make enough HP to justify using it. The Robinson helicopter drivetrain begins with a ~3000 rpm aircraft engine, right?

No readily available current tech engine likely to be used in a 2+ seat normal size/weight aircraft will run on as low an octane rating as a NA rotary, so I fail to see any bush flying penalty on the subject of fuel. The other issues with the rotary are the same as any other water cooled conversion engine. The only things that are slightly harder to deal with on the rotary are EGTs running a couple of hundred degrees hotter, and noise (with the older 13B). Now, if you need to find a mechanic to work on one....
 
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