Received-SPF: pass
 receiver=logan.com; client-ip=64.12.137.9; envelope-from=WRJJRS@aol.com
References: <list-2193618@logan.com>
To: flyrotary@lancaironline.net
Content-Transfer-Encoding: quoted-printable
Subject: Re: [FlyRotary] last time, i promise - carb vs EFI
Date: Mon, 23 Jul 2007 11:56:21 -0400
In-Reply-To: <list-2193618@logan.com>
MIME-Version: 1.0
From: wrjjrs@aol.com
Content-Type: text/plain; charset="iso-8859-1"; format=flowed
Message-Id: <8C99B59264723C2-338-272D@webmail-de17.sysops.aol.com>


-----Original Message-----
From: kevin lane <n3773@comcast.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, 22 Jul 2007 11:01 pm
Subject: [FlyRotary] last time, i promise - carb vs EFI


I still never got an answer to my original question;=A0 how much more=20
power comes from EFI vs. carb?=A0 or is it=A0a case=A0that efi is just bette=
r=20
tuned at all rpms since it has so many easily controllable parameters?=A0=20
does efi produce an optimum mixture and finer fuel droplets that can't=20
be matched by the carb?=A0 if it does produce more complete burning and=20
efficiency, how much?=A0 I hear these type stmts, but never numbers.=A0 are=20
we talking 5%, 10%, 20%?=A0=A0=A0 kevin (renesis in my future :-)

Kevin,
  To properly answer your question, It depends on lots of other factors.=20
If you use the same engine and manifold set up and have the exact same=20
level of restriction, (slide throttle vs. slide throttle) the=20
difference will be minimal at WOT. When they were testing on the big=20
dyno at Kawasaki the difference at WOT,(unning 4 cycles) was about 3%=20
in favor of TIMED PORT EFI. They tested some of the 2 cycles that=20
actually did better with carbs. The thought was there was dampening of=20
the reversed pulse at the time. Also PORT EFI was hard to get to work=20
on 2 cycles due to the flow reversals. Most of the 2 strokes went to=20
direct injection which was better, albiet somwhat more complicated. On=20
the 4 cycles EFI had a advantage almost everywhere else. Sometimes a=20
drastic advantage in mid-range operation. The dyno guys also liked the=20
remote tuneability of the EFI which made it much easier to tune new=20
engine combinations. Interestingly the worst thing for EFI on bikes was=20
trying to get it to be smooth at low throttle openings. The earliest=20
ones were so sudden off the like I thought they would pull your arms=20
out of their sockets! Later versions were de-tuned at idle speed to=20
improve this area.

Bill Jepson
________________________________________________________________________
AOL now offers free email to everyone.  Find out more about what's free=20
from AOL at AOL.com.
=3D0