| Thanks Al I was only thinking peak torque.
Steve On 02/11/2010, at 12:10 AM, Al Gietzen wrote: Keep in mind that the graph is peak torque (T)); not peak HP. The peak HP (which is what you’re after would be at higher rpm. HP = T x RPM Al -----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of stevei@carey.asn.au
Sent: Monday, November 01, 2010 1:09 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EM2 Numbers Hi Mark I have attached the Leman intake dimensions from Paul L. Hope this is helpful. Can't remember whether this measurement was to the rotor face or manifold face. <image001.gif> On 01/11/2010, at 8:40 AM, Mark Steitle wrote:
I understand the sausage illustration. But if what you propose were true, then why did Mazda make such a major effort to design and implement the variable intake on their LeMans 26B p-port motor? That tells me that runner length does make a significant difference on the p-port motor. Also, if tuned runners didn't matter for peripheral ports, then why do they tune the exhaust runners on the 13B's? Somewhere I have a chart showing the effect of runner length, but I'm not sure that the data is from a p-port motor. Mark, I don’t think that will work with the PP. You never actually block the inlet. You just cut off the end of the flow of air as the apex flies by and it starts to fill the next chamber. Think of the flow as a long sausage that is going through a propeller made of a strand of wire 2 or 3 MM thick and being cut into sections. It is never blocked. I doubt that there are any reflections and if there are, they would be very small and of little benefit to enhance. I think that is why the PP is so much stronger than the side port. Bill B
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EM2 Numbers
Sorry for the delayed reply, but I had to go to the hangar and measure the runner length to be sure. It is 24" bellmouth to rotor face, 2" OD. Exhaust is 2" OD also, running the stock 20b exhaust splitters. So, my power seems to peak around 6000 rpm. What length intake runner length would it take to bring peak power up to around 6500 rpm? That's interesting; can you tell me what is your PP size, runner length and exhaust header ID size. Sent: Saturday, October 30, 2010 7:38 PM Subject: [FlyRotary] Re: EM2 Numbers Bill, With the current setup, it appears to be around 6000-6100, but I'm still tuning on the upper addresses of the EC-2. My old engine did best around 6500-6600 running the same prop. So, I feel there is something that isn't quite right on the new P-Port motor... maybe intake runners too short, intake or exhaust too restrictive, timing off a bit, etc. It definitely makes more hp than the old motor did in the 5000-6000 range, but I feel that it should be producing more hp than I'm seeing in the 6000-7000 range. So, things are still developing. Yesterday, I reinstalled the old air-filter box which has a ram-air feature incorporated into the design. I haven't flown it yet to see if there is any improvement, but I hope to see at least a little improvement. On a side note, I have determined that there is a 250 rpm discrepancy between the rpm readout of the EM-2 and that of the M/T prop controller. I have an optical tach that I will be using to determine which one is in error. Stay tuned (no pun intended), Mark, It would seem that if you flattened the pitch of the prop, the engine rpms would increase, but at some point, you would begin to lose airspeed and start to slow down because the prop was just not taking a big enough bite. Conversely, it seems that if you increased the prop pitch, the engine rpms would decrease, but the airspeed would increase up to some point and then after that, an increase in pitch would cause a decrease in airspeed because you are taking too big a bite and the engine just can not pull it. Somewhere in there is a “Sweet Spot” of propeller rpm that gives the highest airspeed. Lets say that this question assumes that you are at WOT and 8500 feet, which should give you roughly a 75% power output. Do you know where that sweet spot is with your propeller? Bill B
Sent: Thursday, October 28, 2010 10:00 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] EM2 Numbers
Rotarians, Things have been a bit quiet on the list lately, so I thought I would post this picture of my EM-2 taken on a trip from Galveston, TX (KGLS) to Lockhart, TX (50R) yesterday. I was level at 8500msl when taking the picture. A/C is a Lancair ES (4-place), engine is a n/a p-ported 20b. Please disregard the oil temp as the reading on the EM-2 is measured after the first cooler and before the second cooler. Oil temp readings out of the second cooler (measured at the oil filter pad) track water temps within a few degrees. Leaned to "Economy Cruise" and dial the prop down to 1800 rpm and the speed drops down about 15 mph and fuel burn drops to 9.1 gph. You pay dearly for that 15 mph but sometimes it is just too much fun to slow down. Mark S. ---------- Forwarded message ----------
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