Return-Path: Received: from imf16aec.mail.bellsouth.net ([205.152.59.64] verified) by logan.com (CommuniGate Pro SMTP 4.2b4) with ESMTP id 130074 for flyrotary@lancaironline.net; Fri, 04 Jun 2004 13:32:06 -0400 Received: from [192.168.1.103] ([68.219.38.107]) by imf16aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040604173132.QQLH18879.imf16aec.mail.bellsouth.net@[192.168.1.103]> for ; Fri, 4 Jun 2004 13:31:32 -0400 Message-ID: <40C0B1E7.6080701@bellsouth.net> Date: Fri, 04 Jun 2004 13:31:19 -0400 From: Mike Robert User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Turbo boost limits in the EC2 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit sqpilot@earthlink wrote: >----- Original Message ----- >From: "Mike Robert" >To: "Rotary motors in aircraft" >Sent: Friday, June 04, 2004 6:38 AM >Subject: [FlyRotary] Re: Turbo boost limits in the EC2 > > > > >>John Slade wrote: >> >> >> >>>>Cutting fuel till the MAP comes down is the only workable solution I can >>>>see. >>>> >>>> >>>> >>>> >>>Yes, I tend to agree. Tracy - are you listening? Does this make sense to >>>you? >>>Anyone else care to comment? I'd really like to get something built into >>> >>> >the > > >>>EC2....soon. >>>Regards, >>>John >>> >>> >>> >>> >>> >>> >>>>> >>>>> >>Again, - I'm speaking auto use - you have to be very careful using fuel >>cut in a boosted rotary, all it takes is a couple of hard knocks >>instigated by a transient lean condition to break apex seals. There's >>plenty of fuel coating the inside of the manifold, etc., to do this even >>if you shut the injectors completely off. It's a very short phenemenon >>but it is there. Another thing - hard fuel cuts are scary in a car, I >>would imagine the soiled underwear factor is quite a bit higher while >>flying when you hit cut. I use hard fuel cut as a rev limiter in my NA >>and it STILL gets my attention. That said, I believe Tracy's ECU manages >>spark as well as fuel. Random spark cut and/or massive retard may be the >>way to cut your boost in those temporary situations. >> >> -Mike >> >> >> >Hi, Mike....my concern is that if you cut spark, and still have fuel going >into the engine, you may end up with a flooded engine, or worse yet, a >terrific backfire due to the excessive fuel build-up then reintroducing >spark. I used to take my 1960 Ford, coast down a large hill with the >ignition off (standard transmission in gear), then turn the key back on, and >scare everyone with the loud backfire. Did that until I blew my muffler >right down the seam one day. Got too expensive for a 16 year-old (expensive >firecrackers). Just another consideration. Paul Conner, MicroTech ECU with >fuel cut boost limiter. > > >>>> >>>> > Good point, Paul. I do know that some aftermarket ECUs do the random spark cut thing as a soft rev limit. I have no experience myself with that scheme other than getting grounded for a month after doing the key off/coast/key on/kablam thing with my father's 1972(?) Torino, blowing most of the exhaust system apart. :-) I'm wondering if a closed exhaust (cat, restrictive muffler, etc) is necessary for the exhaust backfire scenario? The hard fuel cut may be the least worst method of emergent excess boost management now that I think about it some more. I would think that the lean transients could be minimized if not eliminated by injector placement. In the irons, as stock, is a great place to address the lean transient thing. I have a 20" intake tract on my car with the injectors at the TB - there's enough wall wetting in that system to run the engine for a good 2-3 seconds after I kill the FI electronics. The stock / near port placement of injectors would not/ does not do this AFAIK. -Mike