“Subsequent versions from Mazda were successful certainly, but its latest Renesis as fitted to RX8s is an unmitigated disaster with them all requiring rebuilds early in their life.”
Take a look at https://www.rx8club.com/australia-new-z ... ld-113724/
; the discussion starts with:
“To the wise ones.
I'm just at 190,000km's on the RX8 with the lease just about up.
Looking at purchasing the car for future project and wondering what sort of K's the 8 would cover (freeway driving) before major rebuild??”
Provided the post and the discussion are not fake,
it appears that Mazda did a great job with the rotary engine.
Worth to mention: a Wankel Rotary is so good and smooth at higher revs that it operates regularly near red (which is bad for the long term reliability), becoming an “addiction” for the driver.
Nevertheless, the operational principle of the Wankel rotary is so wrong for emissions and fuel consumption that it was phased out by Mazda some years ago.
You also write:
“So, the 2T is still undeveloped and suffers but one problem (thus far unsurmounted) namely high levels of UBHC in the exhaust stream. A typical value for a simple 2T appears to be in the region of 4-5000 ppm and, is due to fuel loss more than the one-pass oiling utilised.”
Here are the old, the current and next “euro” emission regulations:
With their TPI (Transfer Port Injection) the 2-stroke KTM EXC250/300 of 2018 complies with the euro4 emission regulations.
the high-tech 4-stroke Ducati Panigale 1299 (desmodromic) is phased out because it is not euro-4 compliant
(while the expensive (US80,000$) Panigale 1299SL (SuperLeggera), is euro-4 compliant).
The lubrication of the abovementioned KTM EXC of 2018 is of the “total loss” type.
Quote from http://thedirtbikerider.com/ktm-exc-tpi ... injection/
The amount of 2t of oil constantly adjusts the computer’s ECU, depending on the engine rev , and the scale itself is constantly changing.
But the average fuel usage is ,oil is 80: 1
Capacity of the tank for 2 Stroke oil: 700ml, enough for approximately 5 fuel tanks.
End of quote.
I.e. today, you can go and buy and drive a euro-4 compliant 2-stroke motorcycle which is cleaner / greener than many 4-strokes.
Now compare the total-loss lubrication of the euro-4 compliant KTM250/300EXC of 2018, with the “4-stroke-like” lubrication of the PatBam PatAT HCCI of the animation at the top of this page.
The space underside the piston crown is sealed from the crankcase.
The oil scraper ring (at the middle of the piston) never passes over ports.
The oil scraper ring keeps the lubricant into the crankcase (as in the 4-stroke engines), allowing plain bearings to be used and splash lubrication of the cylinder liner (whereon the thrust loads are taken).
At the BDC the lower compression ring abuts on an area of the cylinder liner whereon, 180 crankshaft degrees earlier, was abutting the oil scraper ring.
I.e. when the piston passes from its BDC, the lower compression ring abuts onto an oiled area of the cylinder liner, making unnecessary the conventional "total loss" lubrication of the ported 2-strokes.
In case the crankcase is to be used as the scavenging pump, the design can be modified as the following PatATeco 2-stroke:
More at http://www.pattakon.com/pattakonPatATeco.htm