Lynn, Tracy, David and Jeff;

Thanks for your perspectives. Lynn, based on your note, I may have experienced Detonation, plug wire cross fire, high intake temp due to no intercooler, and I may have had the leading & trailing plug wires switched on the rear rotor (tip seal damaged rotor). I noticed that one when removing the engine)

I originally misstated that the rear side housing cracked (it was the front side housing, which is near the fire wall. my bad) But the rear rotor (near the flywheel) broke all the tip seals and may have had switched lead/trail plug wires.

Confused?

I have a TO4E P trim cartridge with .81 AR on-center exhaust housing.    It has a 60-1 compressor. I have been warned that the AR is too tight, so I just ordered a 1.30 AR exhaust housing. I plan to go back together with stock port '87 side housings to get a slightly slower idle (previously street ported). I have 8.5:1 '87 turbo rotors.

I did not set the timing by strobe timing light. 4000 RPM with the tail tethered is too scary for me. That's wailing with no one I can trust sitting in the seat. I set it via the EM2 for best RPM @ about 3500 RPM.

Questions: Tracy,

1)  Does the EM2 fire both L & T plugs at the same time, or is there a difference?

2)  What is the static timing, or some lower RPM timing value I can check without scaring myself to inaction? I would like to check it while cranking over with the fuel injectors and pumps shut off.

 

 

-----Original Message-----
From: Lehanover <Lehanover@aol.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Sent: Mon, Jun 24, 2013 3:32 pm
Subject: [FlyRotary] Re: Blown engine

A detonation event at wide open throttle will usually break out the dowel hole in the rear iron. This was a big problem in the FC models and Mazda added material around the dowel hole in the FD twin turbo engines. Detonation will continue until some parameter changes, like a seal shears off and compression is lost. Throttle setting is reduced, or, the knock sensor causes the timing to be pulled out smartly.

 

A crossfire where a rear housing plug wire excites a front plug wire or front ignition primary or trigger wire will break out the front iron dowel hole. That is a 180 degree too soon ignition advance. A lump of FOD can do in either dowel hole.

 

Detonation is charge temperature dependant. It is uncommon in NA engines. It is common in boosted engines. Notice that Racing Beat recommends testing boosted engines at not more than 10 degrees of total advance, and racing on not more than 12 degrees. As boost pressure goes up so does effective compression ratio. So, the burn rate (Flame front velocity) goes up and the amount of advance required to maximum cylinder pressure at 50 degrees ATDC goes down.

 

Intercoolers are used to reduce charge temperatures. Over cooling the oil to reduce rotor face temperatures is a help. Coolant temps not over 180 degrees helps. Water spray on the intercoolers, water and oil coolers helps. Run over rich during high throttle settings to fuel cool the mixture helps. Over rich premix includes extra top oil as well. Using high octane fuel.

Using ICE COLD heat range plugs helps.

 

Piston engines can survive a FOD event (you find a 10-24 nut pressed into a piston top 2 years later) a rotary will not survive a FOD event of any but microscopic size.

Run an air filter for all powered operations.  

 

On another note:

 

I saw the Dayton airshow crash along with my daughter and her male friend. I am jaded to this type of disaster, but my daughter and her friend were not. It seems as though several thousands of

guests were not ready to suffer this calamity. I called out to my daughter when I saw the problem hoping she would turn to me and not see the outcome. But I was too late.

 

In my opinion: The turn into the show line was from too low an altitude. It was very hot about 86 degrees. The turn was to down wind. The roll to inverted was crisp and slowed the plane further.

The pilot pushed forward stick (late) to raise the nose, then I suspect he attempted to roll upright when he felt a stall start, after only a second of inverted and I saw him pull up elevator while partially inverted. The down wing struck the ground. Another 25 feet and he might have pulled it off. There was very little fuel on board, but enough to make a large fire ball. The engine sounded

like it was making full power all the way to the ground. Last night was the first time I did not dream of it. The show went on again Sunday but attendance was even worse than Saturday. No military stuff at all. Thank you Obama.

 

Lynn E. Hanover

 

In a message dated 6/24/2013 3:00:36 P.M. Eastern Daylight Time, jwhaley@datacast.com writes:

I broke an iron once …  the engine slipped during hoisting and broke the casting of one outside tension bolt carrier … not thermal shock.

Jeff

 

From: Tracy <rwstracy@gmail.com> Subject: Re: [FlyRotary] Re: Blown engine Date: Mon, 24 Jun 2013 11:00:53 -0600 To: Rotary motors in aircraft <flyrotary@lancaironline.net>

FWIW,  the thermal shock story is totally bogus.    Tracy  Sent from my iPad On Jun 24, 2013, at 9:44, David Leonard <wdleonard@gmail.com> wrote: Scott, I have never heard of an iron breaking from thermal shock.  I routinely mistreat mine in that manner.   Don't forget to take everything Dave Atkins says with a grain of salt.  He has not always been the most straight forward of salesmen.   On Fri, Jun 21, 2013 at 4:27 PM, Scott Emery <shipchief@aol.com> wrote: I showed the damaged rotor, rotor housing and front side iron to Dave Atkins, the local expert. He thinks my engine suffered FOD but the entry point is a mystery. The broken side iron is My fault: thermal shock. The aluminum rotor housing experienced thermal expansion faster and greater than the side iron because I went to high power before the engine was sufficiently warm. The alignment dowel was moved outward by the growing aluminum housing and cracked out the side iron around the dowel, which is also the oil gallery Sent from my iPhone

 

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