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09-03-2014, 11:09 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by FasGlas
Humm, I've never seen a FI plane without a gascolator. It's imperative you keep any contaminants out of the injection system.
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The last 3 airplanes I've owned were fuel injected - and not a one had a gascolator. All had filters, however.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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09-03-2014, 11:16 AM
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Join Date: Mar 2014
Location: Prescott, AZ
Posts: 739
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Each to their own. It's not required in home built's, nor is any other parts we install for safety or convenience. But we do for safety and convenience.
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09-03-2014, 11:27 AM
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Join Date: Oct 2012
Location: Scottsdale, AZ
Posts: 150
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Quote:
Originally Posted by FasGlas
Each to their own. It's not required in home built's, nor is any other parts we install for safety or convenience. But we do for safely and convenience.
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In my case, the gascolator is making the plane less safe. By transferring heat to the fuel it's increasing the chance of vapor lock while not providing much of any real benefit beyond the fuel filter at the electric pump. There are several things I could do:
1. Nothing
2. Remove the gascolator
3. Add a cooling shroud to the gascolator and connect the blast tube to it
4. Remove the gascolator and add a second pre-firewall fuel filter
So, what kinds of failures would necessitate a 2nd fuel filter (3rd actually because there is on at the servo)?
Last edited by bjohnson1234 : 09-03-2014 at 11:32 AM.
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09-03-2014, 11:39 AM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,686
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Quote:
Originally Posted by FasGlas
Each to their own. It's not required in home built's, nor is any other parts we install for safety or convenience. But we do for safety and convenience.
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Gascolators IMO are a hazard on an RV due to the high under cowl temps creating an ideal environment for vapor lock, in addition, they are not rated for the pressure of a FI system.
Note the "Note" on ACS website:
http://www.aircraftspruce.com/catalo...gascolator.php
__________________
Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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09-03-2014, 11:44 AM
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Join Date: Oct 2012
Location: Scottsdale, AZ
Posts: 150
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Quote:
Originally Posted by Walt
Gascolators IMO are a hazard on an RV due to the high under cowl temps creating an ideal environment for vapor lock, in addition, they are not rated for the pressure of a FI system.
Note the "Note" on ACS website:
http://www.aircraftspruce.com/catalo...gascolator.php
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The Usher gascolator (which I have) can be used in FI engines up to 50 PSI, but I still agree with you on the rest
http://www.aircraftspruce.com/pdf/20...l/Cat15163.pdf
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09-03-2014, 01:27 PM
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Join Date: Mar 2014
Location: Prescott, AZ
Posts: 739
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Quote:
Originally Posted by Walt
Gascolators IMO are a hazard on an RV due to the high under cowl temps creating an ideal environment for vapor lock, in addition, they are not rated for the pressure of a FI system.
Note the "Note" on ACS website:
http://www.aircraftspruce.com/catalo...gascolator.php
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Unless you're mounting a gascolator after the fuel pump where is no pressure, it's flow. If anything it would be a vacuum, if the tank got plugged.
Has anyone here ever measured the cowl temps at the firewall? I have and do every flight. I live in SoCal, very hot, the temps never hit 150F at the top cowl, the hottest point. I have a much tighter cowl then an RV.
These discussion always remind me of an old auto radio show I was listening to maybe 25 years ago. They had a guy from GM on there taking questions. It was just a matter of time before the holy grail of engine topics was asked. " I want to remove my radiator thermostat because everyone tells me my engine will run better if I do ". After a few seconds the guy from GM said " I get this question asked of me more times than I can remember ", " the answer is, If the engine didn't need it no car maker would waste the money to install it ". I will never forget that answer.
All I can say about the use of gascolators is my own experience. Every experimental I've been involved with, from Reno racers to OSH grand champion winners, and everywhere in-between, has a gascolator. Not one has ever failed, leaked or burst. Not one has gotten vapor lock from a gascolator. It's far more likely a fuel line next to a 400F cylinder would get vapor lock then the fuel in a gascolator at the bottom of a firewall.. Heat rises. But again, each to their own.
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09-03-2014, 01:37 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by FasGlas
All I can say about the use of gascolators is my own experience. Every experimental I've been involved with, from Reno racers to OSH grand champion winners, and everywhere in-between, has a gascolator.
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I would hazard a guess that you have not been involved with too many F/I RV's in that case.
Add my plane to the long list of gascolator free F/I RVs.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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09-03-2014, 01:37 PM
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Join Date: Oct 2012
Location: Scottsdale, AZ
Posts: 150
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Quote:
Originally Posted by FasGlas
Unless you're mounting a gascolator after the fuel pump where is no pressure, it's flow. If anything it would be a vacuum, if the tank got plugged.
Has anyone here ever measured the cowl temps at the firewall? I have and do every flight. I live in SoCal, very hot, the temps never hit 150F at the top cowl, the hottest point. I have a much tighter cowl then an RV.
These discussion always remind me of an old auto radio show I was listening to maybe 25 years ago. They had a guy from GM on there taking questions. It was just a matter of time before the holy grail of engine topics was asked. " I want to remove my radiator thermostat because everyone tells me my engine will run better if I do ". After a few seconds the guy from GM said " I get this question asked of me more times than I can remember ", " the answer is, If the engine didn't need it no car maker would waste the money to install it ". I will never forget that answer.
All I can say about the use of gascolators is my own experience. Every experimental I've been involved with, from Reno racers to OSH grand champion winners, and everywhere in-between, has a gascolator. Not one has ever failed, leaked or burst. Not one has gotten vapor lock from a gascolator. It's far more likely a fuel line next to a 400F cylinder would get vapor lock then the fuel in a gascolator at the bottom of a firewall.. Heat rises. But again, each to their own.
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If you are blindfolded standing in a wind tunnel, you can't tell the difference between a fan in front of you "pulling" and one behind you "pushing". There is still "pressure" going through the gascolator even though mechanical fuel pump is pulling the fuel through instead of pushing it. Also, the electric fuel pump is pushing it through.
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09-03-2014, 01:51 PM
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Join Date: Oct 2012
Location: Scottsdale, AZ
Posts: 150
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Quote:
Originally Posted by FasGlas
Unless you're mounting a gascolator after the fuel pump where is no pressure, it's flow. If anything it would be a vacuum, if the tank got plugged.
Has anyone here ever measured the cowl temps at the firewall? I have and do every flight. I live in SoCal, very hot, the temps never hit 150F at the top cowl, the hottest point. I have a much tighter cowl then an RV.
These discussion always remind me of an old auto radio show I was listening to maybe 25 years ago. They had a guy from GM on there taking questions. It was just a matter of time before the holy grail of engine topics was asked. " I want to remove my radiator thermostat because everyone tells me my engine will run better if I do ". After a few seconds the guy from GM said " I get this question asked of me more times than I can remember ", " the answer is, If the engine didn't need it no car maker would waste the money to install it ". I will never forget that answer.
All I can say about the use of gascolators is my own experience. Every experimental I've been involved with, from Reno racers to OSH grand champion winners, and everywhere in-between, has a gascolator. Not one has ever failed, leaked or burst. Not one has gotten vapor lock from a gascolator. It's far more likely a fuel line next to a 400F cylinder would get vapor lock then the fuel in a gascolator at the bottom of a firewall.. Heat rises. But again, each to their own.
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Here in Phoenix the ambient temps are 110. The difference between the gascolator and the fuel line is that the gascolator is a good conductor of heat and a firesleeve wrapped fuel line is not. Interestingly enough, the fuel line to my spider doesn't run between the cylinders, it comes up from behind the engine and goes through the baffle. Just because in your personal experience no one has gotten vapor lock doesn't mean that it doesn't happen. The original suggestion to remove the gascolator came from Don at Airflow Performance and I think you'd be hard pressed to find anyone here who doesn't think he's an expert on the topic. Since I bought my plane it's had an issue with fuel boiling in the lines causing small hiccups at low rpm when the plane is hot. Other people with the same problem have fixed it by removing the gascolator. There is little doubt it contributes to the problem and it's very likely that my non-standard fuel routing is causing a problem, the only question is the seriousness of it. Did my plane vapor lock on the runway or did it suck up water? Probably the later, but I don't know for sure.
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09-03-2014, 02:01 PM
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Join Date: Mar 2014
Location: Prescott, AZ
Posts: 739
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Mike, I do fly with some RV's, as you know, and we work on some as well. I can't recall any RV Reno racers.... We all use the same components for the most part and as I stated these are my experiences with many FI Lycoming powered aircraft. Maybe it's the build and not the parts. I can't say.
bjohnson, Pressure is not the same as flow! If you have your fuel tank wide open to you filter and the pump is pulling the fuel through it it is not pressure, it's flow. There is constant pressure and there is constant flow. A Harley Davidson engine runs on only a few PSI of oil pressure but flows a gallon a minute of oil over the bearings and cylinders, put a gauge on the pump port and read 5 PSI.
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