flyrotary@lancaironline.net Mailing List Archive

Zero manifold pressure? You could only have that if you were in outer space. Obviously there is a misunderstanding here but I don't know on which end it is.

Let me try this: The two items associated with each address are these - Address is associated with a particular manifold pressure (or rpm if less than 2500 AND less than the threshold pressure which is adjustable, not fixed at 13"). The other item is the DATA in that address which is the correction factor applied at the manifold pressure (or rpm) associated with that address. Neither of these 2 items will look remotely like the numerical value of the actual manifold pressure. For instance, the bottom of the mid-range rpm table (address 32) represents a manifold pressure of about 8" Hg which is about the minimum that any engine will run at under normal conditions.

Tracy

On Wed, Oct 28, 2009 at 11:39 PM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

Tracy,

I think I didn’t explain what I am seeing properly.

The addresses 0-63 should have associated with them two items. (I think)

The manifold pressure that is associated with each address and the mixture correction that is associated with that address and manifold pressure.

My table for addresses 0-63 ALL have a manifold pressure of ZERO associated with them. The mixture correction for each address varies, mostly zero, but not all.

It is the manifold pressures that are all zero! Shouldn’t they have either manifold pressures or perhaps RPMs listed??

On the addresses 64-127, the manifold pressures start at 10.0 and increase by .5 with each additional address. Not so with the earlier addresses. I think this is not correct, but I don’t think there is any way that I can affect the manifold pressure indications.

Since the EC-2 can flip back and forth between the high and low addresses at the same manifold pressures but different rpms, several folks have reported having to ensure that the corrections were similar at the two locations. I intended to verify that they were similar, but since I don’t have the manifold pressures in the table at the low addresses, I don’t know how I would compare them. But more than that, I don’t understand how the EC-2 could know what manifold pressure the lower address corresponds to and therefore which correction it should apply.

Perhaps it only looks for +/- 13 inches to go to addresses above or below 31? But then, wouldn’t it need an RPM in each address to determine the correction???

Bill B

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy Crook
Sent: Wednesday, October 28, 2009 11:09 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: MCT values in the 0-63 area of the EC-2

The default values in the table are supposed to be all zeros. There is a conceptual misunderstanding about these values in your question. It is not the Data that corresponds to the manifold pressure, it is the address. The data is a correction value for the corresponding manifold pressure. The values can be from -127 to + 127 with negative values causing the mixture to be adjusted leaner and positive values richer.

Does that help?

Tracy

On Wed, Oct 28, 2009 at 6:35 PM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

Tracy is back! What about this question, Tracy?

The below from a previous email…

Now I have more questions. I went over and copied down the information in my MAP table today. I was surprised to learn that the manifold pressures for all addresses from 0 to 63 were set to Zero. I expected to find actual manifold pressures in there. Starting with addresses 64 through 127 the manifold pressures increase from 10.0 at address 64 in 0.5 inch increments all the way to 41.8 inches at address 127. My engine is naturally aspirated, so the manifold pressures above about 30 or 31 will never be used. I understand that the 0 to 31 addresses are used when the RPM is below 2500 and the manifold pressure is below 13 inches, and that the addresses from 32 to 63 are used when the RPM is between 2500 and 3800 and the manifold pressure is above 13 inches. But I still don’t understand how the controller would know which address to use with no manifold pressures entered in the table. Tracy is this is OK? Will these pressures be added when the engine is ran??

Bill B