Return-Path: Received: from fed1rmmtao09.cox.net ([68.230.241.30] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 3221772 for flyrotary@lancaironline.net; Sat, 08 May 2004 12:40:27 -0400 Received: from smtp.west.cox.net ([172.18.180.57]) by fed1rmmtao09.cox.net (InterMail vM.6.01.03.02 201-2131-111-104-20040324) with SMTP id <20040508164015.FOWW19329.fed1rmmtao09.cox.net@smtp.west.cox.net> for ; Sat, 8 May 2004 12:40:15 -0400 From: To: "Rotary motors in aircraft" Subject: Surging Fixed Date: Sat, 8 May 2004 12:40:15 -0400 MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=____1084034415690_k6p75QWFaA" Message-Id: <20040508164015.FOWW19329.fed1rmmtao09.cox.net@smtp.west.cox.net> This is a multi-part message in MIME format. ------=____1084034415690_k6p75QWFaA Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Well, you guys did it, but I'm not sure how. I must have fallen prey to the old "changing too many things at once" senario. After listening to everyon'e input I just went back and put everything as "right" as possible but made no change that I haden't tried before. Vala, runs great! I can now get it to idle down to about 900 rpm (though it is just a little rough and smokes quite a bit). It runs beautifully everywhere above 14.5 MAP in the normal region (where MAP and RPM both increase together). I am still using my 550cc injectors (came with the engine) and same fuel pump and pressure regulator. I will probably try some 460cc injectors and see if there is any improvement. I think the most important thing that I changed was the injector staging. Because my injectors are different sizes (550cc stock turbo and 52lb/hr TWMs that rusty tested and said they don't even flow that well) I had move the injector staging point down below idle, thinking that I would just adjust Mode 3 and not have to worry about the staging point. Moving the staging point back up to 19" allows me to run on the primary injectors alone and open up the pulse duration. I had previously discounted this as the problem because when I tried running on either set of injectors alone the surging still occured. I must have had some other problem as well. The injector staging point was a little difficult to program into the MAP table as the difference in mixture is about a 150 deg turn of the mixture knob. It required several tries (at each 1/2 in of MAP) to advance the throttle and mixture together so that it would even run on the other side of the transition long enough to push the button. But now the transition is no big deal. Thanks for everyone's help. Dave Leonard ------=____1084034415690_k6p75QWFaA Content-Type: text/html; name="reply" Content-Disposition: inline; filename="reply"
 
 
 

 

Judging from the predominance of big injectors and high fuel pressure among this group, it sounds as if you guys have all been indoctrinated by Paul Lamar (Bigger & More is Better!)  It just ain't so!  Remember, we are not pushing the limits of what the engine is capable of, and that's just the way it should be.

 

Tracy

 

Some folks say bigger is better; others say size doesn’t matter – but the reason we use the 550 cc/min injectors is because they come with the engine, and replacements are very spendy.

 

Al

 

True, you and John are using what you got (right thing to do) but a lot of builders are going out and buying larger injectors, higher pressure fuel regulators, etc.  Got one request today for opinion on using 70(!) PSI due to the recommendation of one racing equipment manufacturer.

 

Can't say this enough -  When it comes to rotaries on aircraft installations, racing practices are almost always the wrong (or unnecessary) thing to do.  A mild street port (on 4 port engines) is one of the very few exceptions.

 

Tracy

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