Originally posted by alberto_mg
Check Ron K. Miller's "hot air out" mod thread. I think there were some figures in there.

"it is ironic that the rotary is considered by some to be unreliable. granted there were initial developmental issues with apex seals etc but that was a long time ago and those issues have been long ago successfully addressed. i believe that if properly clearanced and assembled the rotary engine is more reliable than the piston engine. i think most of the root of the rotary unreliablity issue comes directly from the fundamentally flawed fd oem turbo system. it was a great design on paper but it is thermally a disaster on many levels... 72 hoses baking in an oven, 22 pounds of cast iron manifolding heated to as much as 1700 degrees baking the block which is part aluminum. so we have 22 pounds of the most heat retaining material, cast iron, heated to 1500 degrees and transmitting it's heat to one of the most heat conducting materials, aluminum. bake bake bake. in addition, the design of the manifold would make anyone owning a flowbench cry. that's why there probably isn't one oem manifold on an fd today without major heat cracks. chapter 2 of this saga is inevitable. lose an engine from heat, then junk the stock turbo system if you don't want a repeat trip to engine replacemant-land. a step in the right direction but many correct decisions need to be made re fuel supply, boost etc. many opportunities to make the wrong decision. thankfully we have the internet and the incredible resources it conveys...
as i said initially it is ironic that the rotary may be considered as a dicey engine reliability-wise. road racing has been my game. 22 seasons National SCCA racing the last 6 in gt3 running a tube frame mazda rx3. i built around 30 of my piston engines. 4 cylinders, 2 valve head, overhead cam, big weber dcoe sidedrafts... w grafted exhaust ports we made 210 hp from 122 cu in/2 liters. in order to do that we had to run a huge cam (w trick roller followers) and the valve to piston clearance was almost zero... (in order to fill the cylinder). if a valve spring were to fail at 10,000 rpm, or any valve float at all, you just can imagine the carnage that would ensue. pistons rods pieces of valvetrain all over the place.
the rotary has none of that! it just needs fuel, timing and a good port job. in 6 years of racing i had only one rotary engine failure and it was sort of expected as we elected to shorten top gear a click for qualifying making the engine run 10,300 instead of 10,000 at the bottom of the hill at the end of the road atlanta backstright. we lost an apex seal but not the motor. another telling example of rotary durability is the 24 hours of daytona. at the end of the race the piston engine cars that are still running pull in the pits and are unable to idle under 3-4000 rpm as they are completely shot... valve guide are leaking etc etc. the rotaries come in and most mazda drivers make a point of getting out of their cars and letting the motors cool down by idling... and they idle just like they did before the 24 hour race. i really agree w Judge Ito that if properly fixtured and tuned the rotary is more reliable than a piston engine and everyone in SCCA that races against the rotary knows that to be a fact. this thread is about building them right and is valuable especially if it separates the good from the shoddy builders. my point is that if you build it right and put the right support pieces on the rotary should outlast lots of highly modded piston motors.
one other point re making power w the rotary. Crispeed made a huge point recently... he said that turbo'd engine builders don't spend the time they should optimizing airflow and harmonics that NA builders do. most hp gains in NA motors come from using (air)flow benches and dynoing on engine stands so as to ascertain runner length/harmonics. most turbo guys are just looking to turn up the boost, which is o k but missing a huge amount of the total hp picture. the same harmonics, charge air coming to a halt as the intake port closes etc etc apply to the rotary.
howard coleman"

Originally posted by adam c
Don't all of RonKMiller's threads have a lot of hot air??

Originally posted by alberto_mg
Check Ron K. Miller's "hot air out" mod thread. I think there were some figures in there.