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T O P I C    R E V I E W
urquiola Posted - May 20 2010 : 11:26:20 AM
Hi!: as you all know, when Toyota presented the concept of air injection in exhaust port to improve Wankel performance, specially fuel economy, they added also a Reed Valve (RV) close to the trochoid surface in the peripheral intake port; peripheral intake with variable geometry intake manifold made Mazda win Le Mans endurance and fuel use race (-SAE Paper 920309 , Ritsuharu Shimizu et al.). Yanmar Diesel showed also that reed valves improved the partial load and low r.p.m. performance of their small charge-cooled rotaries (SAE Paper 720466 Kojiro Yamaoka & H. Tado), but I got a letter from David W. Garside, that developed the Norton series of Rotary engines, telling that reed valves do impair the high r.p.m. performance, an untoward fact for their engines. As street car engines don't work long times at high r.p.m., anything improving low rpm and partial load performance would be very good for the average driver. RVs do generate opening and closing extra-flows, like an hydraulic ram, that improve volumetric efficiency; also, by tilting the RV angle, you can induce any desired amount and direction of swirl inside the combustion chamber, thus regulating flame speed and engine emissions. I had the concept of installing an Husqvarna 500 cc 2-Stroke engine prismatic reed valve in a rotary with peripheral intake, to improve low speed torque, fuel economy and emissions. I send this note to see if there is anybody with the expertise and will to receive the torch of this concept, implement it and let us know the results. Regards, salud +
15   L A T E S T    R E P L I E S    (Newest First)
RussellAhmed Posted - Nov 24 2013 : 10:51:34 AM
Toyota is a tested and super brand you know........In Automotive Engineering section serve us greatly for its saving cost....In simply i may said "awesome"
RussellAhmed Posted - Nov 24 2013 : 10:38:03 AM

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urquiola Posted - Nov 20 2013 : 7:27:01 PM
SAE paper 720357 'Combustion Characteristics of Rotary Engines', by K Yamamoto et al., describes the important issues of combustion chamber recess shape, among it the S/V ratio and the quenching it induces, plug placement, and the steps taken for improving it, almost the same info is in SAE 'Automotive Engineering', July 1972, Vol 80, n 7, pp 26-29, at a reduced cost. The Toyota research about air injection on exhaust and use of glow-plug of SAE paper 790345 'Analysis of light-load performance in Rotary Engines', by T Kohno et al.,is in Automotive Engineering, August 1979, Vol 87, n 8; pp 33-38. Hope you enjoy it!
urquiola Posted - Nov 15 2013 : 09:22:04 AM
Ford not even tested, along with Toyota, the Reed-Valve control for Intake Ports in their Wankel RCEs, but has two patents about it, Espacenet publication numbers are:
CA1032477 and CA1045553
An article in SAE Journal, (Automotive Engineering) Vol 86, n 2, Feb 1978; pp 31-42, describes in detail the advances in REs worldwide, and another one in Automotive Engineering, Vol 87, n 8, August 1979; pp 33-38, summarizes the Toyota results (of SAE paper 790435) on ways to improve light load combustion of REs, basically air injection in exhaust port, and a glow-plug in the leading site plug hole.
Full SAE journal back issues available for download at sae.org at U$15 each. Enjoy it!
Aaron Cake Posted - Oct 14 2013 : 10:37:30 AM
A 13B with stock ports at 8000 RPM moves about 300 CFM when the inlet is at atmospheric pressure. Air pump, no idea but it is much, much less.
urquiola Posted - Oct 13 2013 : 11:11:47 AM
A question: is there somebody willing to provide us with data about the flow of air (liters/min) and pressure (psi, or another unit: lb.ft, kg/m2, kg/cm2, gr/cm2, and so on...) at which the air pump injects air in the thermal reactor or in the emission reduction systems in the RX-7 and other RCE Mazda cars' exhaust, and also the same in connection to the displacement and power of the Wankel Rotary engine?
Thanks. Best regards. Salut
urquiola Posted - Sep 07 2013 : 05:40:32 AM
There's some room for improving Volumetric Efficiency of RCEs at low rpm, as pointed in the Curtiss-Wright's figures from SAE paper S236, by R T Hurley, also published in SAE Journal, June 1960, and the K Yamamoto 1981 book'Rotary Engine'. Let's see what happens if proposed changes are implemented. Salut

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urquiola Posted - Aug 22 2013 : 08:19:03 AM
Thermal Efficiency of an Engine can be expressed by: 100(1-Te/Tp) -in %, Te= Exhaust Temperature, Tp=Peak Combustion Temperature; as pointed in the 'Wankel Engine Breakthrough' YouTube Video, Wankel RCEs have high Exhaust Gas Temperatures, that from the early days of Internal Combustion Engines are known being linked to low Effective Compression Ratio, these first times because of poor quality of available gasoline. If changing the plug hole to an slot as Ernie Brink proposes, reduces greatly the Exhaust Gas Temperatures, this would mean a much higher Effective Compression Ratio, improving the overall efficiency of Wankel Engine; this looks as a change worth testing, but some welding and trochoid surface coating expertise is needed. Rounding the plug hole-trochoid surface intersection corner, and also port-trochoid surface intersection would improve engine's life, as it would minimize chances of seals hitting hardly the hole borders. We wait for more experimental data about these modifications, please! Salut
Boquilla=nozzle, port, tube, duct, hole.

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Aaron Cake Posted - Jul 06 2013 : 10:34:06 AM
Mazda also has to follow very strict emissions guidlines, which is part of the reason the emissions system was always very complicated on the rotary. Unlike the pison engine the rotary emissions systems needed to deal with overlap, high EGTs and in general a far more "2 stroke" like exhaust output. They have always made judicious use of secondary air from the air pump, alternately injected into the exhaust ports, into the intake manifold, into the cat or vented depending on conditions. Or sometimes all 3. For example, during light decel air is directed into the intake manifold to lean the mixture and prevent backfires. During warmup it's pumped into the exhaust ports to combine with the rich mixture which lights off the cat.
urquiola Posted - Jun 29 2013 : 4:58:15 PM
Your comments are right. I just would like to remark that the people around the Corvair flat-six air cooled engines say that if you have the opportunity, it's better that you have the valve seats reinstalled and the whole think reviewed, as the engines that left the production line of GM were not very well finished, and it's better having the valve seats and other things in the engine having a remake by an expert. Mazda is a serious producer of engines and autos, but sometimes, the kind of changes that private owners can apply to their engines wouldn't be practical in a big output production line, this may be the reason why some changes described by private researchers or even other engine makers are no applied to the series.
Aaron Cake Posted - Jun 22 2013 : 10:40:09 AM
Lead for a long time was used as a lubricant in fuels. Of course it was banned due to the major health effects of every vehicle spitting lead from the tailpipe. Older piston vehicles especially need different valve seats now that we have lead free fuel. Without the lubricating properties of lead, old valves would fail in short order.

So it stands to reason that it would benefit a rotary as well. Perhaps nowadays there are better choices as you suggest. One would need to examine the emissions changes by burning any moly based grease, as well as the decreased longevity of spark plugs caused by fouling.

Mazda for years has worked to reduce apex seal lubricating oil consumption, mainly as a component of meeting more strict emissions standards. With a few hiccups along the way, the stock metering oil system has worked very well for all these years and there are many high mileage rotarys out there continuing to run just fine. Obviously when building much more power than the stock system was designed for we must move to a 2 stroke premix system.

Apex seal wear was solved long ago by Mazda. In 250,00 miles you're typically only wearing about 2MM off the apex seals. So aside from the stupid Mazda decision in the mid '80s to go with idiotic 3 piece seals (which they have since replaced with proper 2 piece seals), the issue of apex seal is basically solved. Now if we really want to move further, we need to build ceramic seals and housings.
urquiola Posted - Jun 18 2013 : 09:17:16 AM
Info from the 1974 book by E McGovern 'The Rotary Engine Handbook' about trochoid wear with leaded and unleaded fuel. As leaded fuel is not available, the solid lubricating agent action of Lead can be alternatively given by additives containing MoS2, as stated above. Salut +

Download Attachment: Unleaded vs leaded fuel trochoid wear in RCE.jpg
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urquiola Posted - Jun 18 2013 : 09:11:53 AM
This is another image from the same SAE 790435 paper

Download Attachment: PP with R-V Toyota data.jpg
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urquiola Posted - Jun 18 2013 : 09:08:09 AM
Here are some charts in the SAE paper 790435 by T Kohno et al, from Toyota: 'Analysis of Light-Load Performance in Rotary Engines', It contains info about EGR in a Reed-Valve ctd' Peripheral Intake Port Wamnkel RCE. I'm not sure if copyright allows this, so, it's easy to delete everything if necessary.

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Download Attachment: Toyota SCRE EGR data.jpg
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urquiola Posted - Jun 18 2013 : 08:37:57 AM
I've got a response from the Liqui-Moly people in Ulm, Germany:

For 4-Stroke engines, the amount of Liqui-Moly added is 4-5% (It seems that it's referred to the amount of Liqui-Moly in the total of lubricating oil in the engine)
For 2-Stroke engines with separate lubrication, the amount of Liqui-Moly added should be 4-5% of total of lubricating oil.
For 2-Stroke engines with lubrication by oil-fuel mix, the amount of Liqui-Moly added must be 1-2 ml per liter of fuel.

For 2-Stroke engines, the amount should be 2% if the clutch is in bath of oil.

For Wankel engines, it's essential differentiating if the oil is added to the fuel (This is the approach giving the best results in any condition and for any endpoint considered) or if the lubricating oil is separated; in the case of lubrication by oil-fuel mixture, the proportion of Liqui-Moly should be as for the 2-Stroke engines with lubrication by oil-fuel mix, and if the Wankel engine is one that has a separated lubrication, this would be the case of most automobile engines, that have a pump that adds a small amount of oil to the places where it's needed, the amount of Liqui-Moly added should be as in the 4-Strokes with separate lubrication.

Liqui-Moly comes in 300 ml cans (18.3 in3), I've found no information about the amount of MoS2 it contains.

The information that Wankel engines do better if the oil is added to the fuel, as in the old moped and other applications 2-Stroke engines is of importance, it comes from the www.rotaryeng.net website, adding oil directly to the fuel can add a lot to the engine life, the problem of choosing the right oil remains, users pointed that for air cooled engines with an oil-fuel mix lubrication, the oil that gave the best results was Shell Rotella 30, and for the liquid cooled engines, Citroen for example advised using a 20W-50 multigrade Total mineral oil, a multigrade oil is required for cold weather engine starts, and a mineral oil is necessary, as synthetic oils do produce a higher and noticeable amount of gums and ashes after being burnt, and this can foul the plug, and stuck the seals.

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