[NSRCA-discussion] Fuel Regulation in 2C Engines
John Pavlick
jpavlick at idseng.com
Sun Mar 5 12:52:11 AKST 2006
Yeah, I tend to agree with Nat here. After some discussion about the Perry
loop idea, I know someone who actually tried it. It came down to the theory
vs. reality thing i.e. "only one way to find out..." It seemed like a good
idea, but it didn't seem to work on our big motors. I think that in order
for this to work properly, you would need a pump that is capable of way more
volume AND pressure than you need. In addition to this, the regulator should
be an external device, not inside the pump like the way it is with a VP-30,
or the internal regualtor needs to have an eaxternal "return" line. This is
how a fuel-injected automotive system works, so it is possible. The Perry
loop thing works for R/C cars and smaller motors but I think the pump needs
more volume to feed our big motors with that big gaping "hole" in the system
(the return loop). Maybe tuning the size of the return loop with a
restrictor would be worth a try. Is it worth the effort? Generally a VP-30
that is properly adjusted will give reliable performance with just a vent
line and no tank pressure / no return loop. Props have a big effect on what
happens when you return to idle too. If you want to help downline braking,
look at props before you spend a lot of time re-designing the fuel system.
Also, try setting the idle a little bit richer. The slow transition to idle
condition is sometimes aggravated by a lean idle mixture. Not trying to
discredit anyone's theories, just passing along some of my observations.
John Pavlick
http://www.idseng.com
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Nat Penton
Sent: Sunday, March 05, 2006 3:48 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Fuel Regulation in 2C Engines
Diaphram operated fuel pumps made by OS ( Hanno, 140 RX, 91 SH <Perry?>)
are self regulating in that output is proportional to RPM, proportional to
need. These pumps can be adapted to any 90 to 160 two stroke with JB Weld
and without maching skills. The tank is vented and there is no pressure in
the system.
I have had impeccable performance using these pumps on the OS91FX for the
last four years. I believe the logic in the circulating systems is flawed.
Nat
----- Original Message -----
From: vicenterc at comcast.net
To: NSRCA Mailing List ; NSRCA Mailing List
Sent: Sunday, March 05, 2006 12:22 PM
Subject: Re: [NSRCA-discussion] Fuel Regulation in 2C Engines
Hi Brian,
You got it right. In the OS 160 we would like to set up the pressure in
the header before the carb as close as possible to the original design
(muffler pressure with tank close to firewall). In this way, the carburetor
metering system will work as was originally designed. I will be doing some
test and see what will work better.
The expert at Perry recommended to send the overflow to the tank.
However, I agree that loop around the fuel pump could work since that is one
old method to control pressure in industrial pumps.
Vicente
-------------- Original message --------------
From: brian young <brian_w_young at yahoo.com>
So I guess the thinking behind doing this is that you deliver the fuel
to the carb and its there for the carb to take. But the fuel at the carb
nipple will only be under atmospheric pressure (since the tanks vented),
anything extra is free to go back to the tank. The venturi affect of the
carb will draw the fuel into the carb. I dont see why you would need to go
clear back to the tank, just loop around the pump.
This sounds like it could take the variability of pumps out of the
equation and at the same time let the pump deliver fuel to the carb, but not
push fuel into the carb.
Interesting.
Wayne Galligan <wgalligan at texasairnet.com> wrote:
Vincent,
!
I wonder if this "T" setup would work on an OS 1.40. I already use
the check valve in the vent so a couple of "T's" and maybe I would be in
business. Would you have to change the pump pressure?
Wayne Galligan
----- Original Message -----
From: vicenterc at comcast.net
To: nsrca-discussion at lists.nsrca.org
Sent! : Sunday, March 05, 2006 8:19 AM
Subject: [NSRCA-discussion] Fuel Regulation in 2C Engines
Good morning all,
I have been using the OS 160, OS 140 RX and Mintor 140 with good
results in the last 4-5 years. We have been comparing and discussing the
advantages of YS compared with 2C. One of the main advantages of YS is that
in transition when power down the engine goes instantly to 2000 RPM or less.
The 2C engines always takes too much time to get down to idle and I believe
that causes us (in pattern) some problems.
I have been thinking that the problem is that the carburetor and
or fuel system that can not regulate properly (pressure or flow). I think
in these engines, the pumps are set to deliver fuel at full flow (or
pressure) without any regulation system (like the YS). ! I had the
opportunity to discuss this issue with Perry Pump and they recommended to
install a by-pass line. The idea is to send the excess fuel (pressure) back
to the tank during transition. Perry Pump recommended to install the T as
close as possible to the carburetor needle valve. Also in their web site
they have an idea that he said is used for cars that is a by-pass line that
loop around the pump (http://www.perrypumps.com/instructions.htm, Click on
Pump and By-Pass Systems). I think the ideas deserve some checking since it
is natural to have this type of regulation to maintain constant pre! ss! ure
in the line before needle valve. I tried the other day the by-pass to the
carburetor but I installed the T too far from the carburetor and forgot to
open the vent in the tank. Of course the results were bad since I was
developing vacuum in the tank. I wi! ll try these options of by-pass lines
as soon as get warmer. However, I think someone out there already tried to
do this and know results so I am looking for feed back.
Thanks in advance,
Vicente Bortone
----------------------------------------------------------------------
_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
--------------------------------------------------------------------------
Relax. Yahoo! Mail virus scanning helps detect nasty viruses!
----------------------------------------------------------------------------
_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
----------------------------------------------------------------------------
Internal Virus Database is out-of-date.
Checked by AVG Free Edition.
Version: 7.1.375 / Virus Database: 267.15.6/257 - Release Date:
2/10/2006
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date: 3/3/06
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20060305/d0ec08c8/attachment-0001.html
More information about the NSRCA-discussion
mailing list