X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from access.aic-fl.com ([207.30.253.2] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2272039 for flyrotary@lancaironline.net; Sun, 19 Aug 2007 08:38:45 -0400 Received-SPF: softfail receiver=logan.com; client-ip=207.30.253.2; envelope-from=unicorn@gdsys.net Received: from main (gdsi-46.gdsys.net [207.30.255.46]) by access.aic-fl.com (Rockliffe SMTPRA 4.5.6) with SMTP id for ; Sun, 19 Aug 2007 07:34:24 -0500 Message-ID: <002601c7e25d$d021a410$2dff1ecf@main> From: "Richard Sohn" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Power! More Power, Scotty! was [FlyRotary] Re: Air/fuel... Date: Sun, 19 Aug 2007 07:37:11 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0023_01C7E233.C0DAE950" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0023_01C7E233.C0DAE950 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn, as always, your inputs are real world. I think I am at the point where I = have to confirm or refute the float level issue. I am running at this = time at up to 6gph and the goal is closer to 10gph. Even if I do not = have that problem now, it may still come and bite me later. Thanks a lot for your inputs!=20 Richard Sohn N2071U ----- Original Message -----=20 From: Lehanover@aol.com=20 To: Rotary motors in aircraft=20 Sent: Saturday, August 18, 2007 10:15 PM Subject: [FlyRotary] Re: Power! More Power, Scotty! was [FlyRotary] = Re: Air/fuel... In a message dated 8/18/2007 10:28:31 A.M. Eastern Daylight Time, = unicorn@gdsys.net writes: Nevertheless, Lynn,s comments safed my day. I was trying to tune the single rotor over the past few weeks. Using = a 38mm Mikuni round slide, I got it to idle clean up from 1600rpm. = Transition into midrange and up to WOT is no problem. Trying to get the = mixture richer at WOT, I did not get the response to enlarging the main = jet I expected. The mixture stayed lean, indicated by high EGT and white = plug insulators, to some extend supported by the O2 reading. The air = flow rate at 6000 rpm is almost double of what Mikuni says is max. I = started wondering. Now Lynn said " carbs get leaner to the top of their RPM ranges" . = There may be the answer to my problem: bigger carb! Richard Sohn N2071U Years ago, we took our new race car (RX-7) to Sebring Florida to race = it for the second time ever. It ran hot, and had poor power up high, = then it would miss after a few laps. By the end of the race Sunday we = had added an additional oil cooler, bigger main jets, small air = correctors, bumped up the fuel pressure, retarded the timing a bit and = dumped in aviation gas. The driver dropped out a lap before the end, = saying the car was too hot inside to drive, and it was getting real = loud. The muffler had melted inside and was blowing up like a big steel = balloon.=20 The next week end at West Palm Beach with no improvement, a local = fellow stopped by and wanted to know if we wanted to use his stand pipe = because it sounds to lean. So he gets his stand pipe, and its a standard = piece of Weber tuning equipment. It screws a banjo bolt into the side of = the float bowl and replicates the fuel level in the bowl outside where = you can see it. He revved my engine to 9,000 RPM in a long blip and the = engine shut off then dropped back to idle. He did it again and after = returning to idle it stopped. The bowl couldn't fill fast enough to = support an idle. By the time it got to 9,000 RPM, the bowl was empty.=20 The biggest needle seat is too small, so you use a Gross jet. Two = balls instead of a needle. Then you find the hole into the needle and = seat well is limiting the flow, so you drill that out. Then the bug = screen in line with the needle flows only half of what you need, so you = throw that out. Then it runs OK but still goes lean at the top. So, you = raise the float level until the boosters drip, then lower it just a bit. = Then increase the fuel pressure until the needle and seat cannot control = it. Then lower it just a bit.=20 Then you drill into the void that would have been the accelerator pump = well for the other handed version of the same carb, to increase bowl = volume.=20 Then for short tracks all is well, and for long straights you can rig = a backup pump to come on when 5th is selected.=20 Then you can use a Weber carb at twice its rated flow. Piece of cake. Lynn E. Hanover -------------------------------------------------------------------------= ----- Get a sneak peek of the all-new AOL.com. -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.476 / Virus Database: 269.11.19/953 - Release Date: = 8/14/2007 5:19 PM ------=_NextPart_000_0023_01C7E233.C0DAE950 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Lynn,
 
as always, your inputs are real world. I think I am at the point = where I=20 have to confirm or refute the float level issue. I am running at this = time at up=20 to 6gph and the goal is closer to 10gph. Even if I do not have that = problem now,=20 it may still come and bite me later.
Thanks a lot for your inputs! 
 
Richard Sohn
N2071U
----- Original Message -----
From:=20 Lehanover@aol.com
Sent: Saturday, August 18, 2007 = 10:15=20 PM
Subject: [FlyRotary] Re: Power! = More=20 Power, Scotty! was [FlyRotary] Re: Air/fuel...

In a message dated 8/18/2007 10:28:31 A.M. Eastern Daylight Time, = unicorn@gdsys.net writes:
Nevertheless, Lynn,s comments safed my day.
 
I was trying to tune the single rotor over the past few weeks. = Using a=20 38mm Mikuni round slide, I got it to idle clean up from 1600rpm. = Transition=20 into midrange and up to WOT is no problem. Trying to get the = mixture=20 richer at WOT, I did not get the response to enlarging the = main=20 jet I expected. The mixture stayed lean, indicated by high EGT and = white=20 plug insulators, to some extend supported by the O2 reading. The air = flow=20 rate at 6000 rpm is almost double of what Mikuni says is max. I = started=20 wondering.
Now Lynn said " carbs get leaner to the top of their RPM = ranges" .=20 There may be the answer to my problem: bigger carb!
 
Richard Sohn
N2071U
Years ago, we took our new race car (RX-7) to Sebring Florida to = race it=20 for the second time ever. It ran hot, and had poor power up high, = then it=20 would miss after a few laps. By the end of the race Sunday we had = added an=20 additional oil cooler, bigger main jets, small air correctors, bumped = up the=20 fuel pressure, retarded the timing a bit and dumped in aviation gas. = The=20 driver dropped out a lap before the end, saying the car was too hot = inside to=20 drive, and it was getting real loud.  The muffler had melted = inside and=20 was blowing up like a big steel balloon.
 
The next week end at West Palm Beach with no improvement, a local = fellow=20 stopped by and wanted to know if we wanted to use his stand pipe = because it=20 sounds to lean. So he gets his stand pipe, and its a standard piece of = Weber=20 tuning equipment. It screws a banjo bolt into the side of the float = bowl and=20 replicates the fuel level in the bowl outside where you can see it. He = revved=20 my engine to 9,000 RPM in a long blip and the engine shut off then = dropped=20 back to idle. He did it again and after returning to idle it stopped. = The bowl=20 couldn't fill fast enough to support an idle. By the time it got to = 9,000 RPM,=20 the bowl was empty.
 
The biggest needle seat is too small, so you use a Gross jet. Two = balls=20 instead of a needle. Then you find the hole into the needle and seat = well is=20 limiting the flow, so you drill that out. Then the bug screen in line = with the=20 needle flows only half of what you need, so you throw that out. Then = it runs=20 OK but still goes lean at the top. So, you raise the float level until = the=20 boosters drip, then lower it just a bit. Then increase the fuel = pressure until=20 the needle and seat cannot control it. Then lower it just a bit. =
Then you drill into the void that would have been the accelerator = pump=20 well for the other handed version of the same carb, to increase bowl = volume.=20
Then for short tracks all is well, and for long straights you can = rig a=20 backup pump to come on when 5th is selected. 
 
Then you can use a Weber carb at twice its rated flow.
 
Piece of cake.
 
Lynn E. Hanover



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No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.476 / Virus Database: 269.11.19/953 - = Release Date:=20 8/14/2007 5:19 PM
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