K

Kato's 8

Well Known Member
Hello all! I hate to stir a hornets nest or anything but this topic tends to get me flustered. Let me just say first that I had previously decided to NOT install a gascolator on my rv8 qb With Carburated engine. Yes, I said Carburated. I know Vans says it can be omitted on injected engines.
Primary question: if you we're a DAR and came across this set up with out the gascolator installed but had the airflow fuel filter installed for contaminate filtration, would that be something that would stop the inspection until the gascolator were installed? I'm not looking for what someone feels they want but more on reason or logic..
My reasons:
1) using a fuel filter
2) low wing tail drager makes tank lower than firewall
3) vans plans (-1 kit) seems to imply its not needed because the Carburated fuel line dwg has the line exiting pre punched hole in fire wall in same spot as the injected engine plans do and there is no room or indication of a gascolator there on either plan.

I could still cover the fuel hole and move it up higher for gascolator and then cover heat box pre punched hole and move it to other side but I'm comfortable with slumping my tanks for water rather than installing the gascolator. Unless it stops my airworthiness inspection.
Thanks for reading and be assured I can take constructive criticism here.
Thanks!
 
I have been kicking this around quite a bit on my 8. I finally decided on this, fuel filter per dwg's, fuel pickups in tank per dwgs. Gascolator installed on firewall. I thought about leaving it out and discussed it with some on here. I decided to install it because it was brought to my attention that it is more than a filter, it is also a water separator. I plan on sumping mains also but i think the gascolator would catch any water that may get through. I also thought about not installing the filter per dwg's, but the note in my aux fuel pump box says it needs a filter upstream. Like you I did not see the plans call for a gascolator, however it is included in their firewall forward kit for a carburated 0-360, on a rv8. So I am going to end up with a fuel delivery system just as Van's says to do it. They know more than I do about it. The more I thought about it the more I became concerned about changing something as important as my fuel system. Hope this helps you make a good decision for your system.

bird
 
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I have been kicking this around quite a bit on my 8. I finally decided on this, fuel filter per dwg's, fuel pickups in tank per dwgs. Gascolator installed on firewall. I thought about leaving it out and discussed it with some on here. I decided to install it because it was brought to my attention that it is more than a filter, it is also a water separator. I plan on sumping mains also but i think the gascolator would catch any water that may get through. I also thought about not installing the filter per dwg's, but the note in my aux fuel pump box says it needs a filter upstream. So I am going to end up with a fuel delivery system just as Van's says to do it. Like you I did not see the plans call for a gascolator, however it is included in their firewall forward kit for a carburated 0-360, on a rv8. They know more than I do about it. The more I thought about it the more I became concerned about changing something as important as my fuel system. Hope this helps you make a good decision for your system.
Sorry about the double post!
bird
 
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I do not have one on my O-360 RV-4. I have a summit racing billet filter and thats it. I think that they are worthless unless they are at the low point of the system. they also make a great heat sink sitting on the fire wall, just waiting to vapor lock.

bob burns
RV-4 n82RB
 
Mount it on the firewall at the lowest point. It will not vapor lock. What can an extra filter before your injectors hurt......nothing. I clean 3 a week, it's worth the investment.
 
My FAA inspector had no problem with using an inline fuel filter instead of a gaskolator on my RV8 with a carburetor. A gaskolator won't be at the low spot anyway. Sump your fuel tanks regularly and you should be fine. I had an Andair gaskolator in my wing root on my RV6 years ago and it filtered fuel OK, but I never got a drop of water out of it. The fuel filter is easy (in fact it's a FlowEasy) and it works well.
 
Resale Value.
All E-AB aircraft built or sold into Canada must have one and a lot of aircraft are exported to Canada these days. This includes fuel-injected engines.

It's not really that it needs to be at the absolute lowest point in the fuel system. That helps, but the design of a gascolator is that the water will find its way to the bottom of the gascolator bowl as the fuel+water flows through the system. This water is then drained out later.

Water and carburetors don't mix. Fuel filters don't work in this application, only gascolators. Messing with the design of the fuel system is not a good idea, and used to be a significant cause of accidents in newly-built aircraft.
 
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It saved my bacon a few years back on my RV6 with an O-360. WATER! Drained the tanks and nothing, flew some trips ok but on the next fillup i decided to drain the gascolator and found water. Then raised the tail up and found water in tanks
 
I'd first find out if all certified piston engine aircraft have gascolators. If they do, I'd have my answer:)
 
My old Grumman Yankee never had a gascolator - and it was certified. (It also had a lawn mower choke cable repurposed as a carb heat cable, so you can judge for yourself....)
 
The AP Filter is a bit of a nightmare to "service" in the plans location for the RV-8.

We substituted it for the Andair GAS375 "Gascolator" fitted in a much more accessible location, and used that as a filter. Does not require pipe fittings undone to service.

Call it a "filter" or "gascolator" according to the religious beliefs (see above) of who is enquiring / inspecting your RV ;)
 
I'd have to differ on 'it won't vapor lock'. It sits in the hot exit air from the cowl; just about the worst possible place & practically begs for vapor lock. Personal experience in an RV-4: severe rough running shortly after departure, after sitting on a hot ramp on a 100*+ day for a couple of hours (plenty of time for the engine itself to cool down). This was a carburated engine. It almost quit 2 or 3 times before I could get it back on the ground. Never found anything to cause it; the plane is always hangared in my private hangar; no water in the fuel (hadn't even rained for weeks) and flew fine on the ~1/2 hour flight to the airport where I had the problem. A thorough check on a cooler day revealed no problems at all with engine operation.

On a 2 seat taildragger RV, it's really hard to imagine getting water from the gascolator & not finding it with the sump drain, unless the flow paths at the bottom skin/back baffle intersection are blocked by proseal or other foreign matter. I suppose it could happen if it's parked on the side of a (steep) slope & the tank sump is checked without getting the plane on level ground, or in a trike with the nose pointed down hill. This assumes, of course, that it's sumped *before* running the fuel pumps. :)

Charlie
 
Per Vans Plans

I built my RV8 'Borrowed Horse' per Vans Plans. With the Gas collator on the firewall. So far,,, every thing is working good. 550 hours
 
Andy,
Would that be in the wing root by any chance ??
__________________
Jan
Click to expand...
No - under the left "mid cabin cover". The drain port is plugged since it is in "cockpit", so not a true gascolator i.e only gets checked for water when serviced. None found.
 
vlittle said:
It's not really that it needs to be at the absolute lowest point in the fuel system. That helps, but the design of a gascolator is that the water will find its way to the bottom of the gascolator bowl as the fuel+water flows through the system. This water is then drained out later.
Click to expand...

+1. There are plenty of high wing airplanes with gravity feed systems in which the gascolator is not at the low point in the system, at least not when parked.

When water enters at a fuel pickup, it will collect in one of two places...the gascolator, if installed, or the carb float bowl.

BTW, you often read discussions about air heating the gascolator and causing vapor lock. We've measured some typical lower cowl air temperatures here in the last few years and most are not very hot (like 120F). Yes, there is always some transfer of heat energy from the air into the fuel, but perhaps it's not as much as many think. Instead, consider the proximity of the gascolator (and fuel lines, and engine driven pump) to the exhaust system, a very hot lower cowl component with huge surface area, radiating heat.

Consider a radical example. I've recorded cowl exit air temperatures as high as 238F. Sure, it's fuel injected, but per conventional wisdom I should be having vapor lock problems, hot pump problems, whatever. In reality, the nearest thing is some idle roughness during hot taxi. Remember that big aluminum cowl exit bell? It's a nice radiant heat shield between the collected pipes and the fuel pump, connecting hoses, etc.

Point is, if you think you might have a fuel system temperature problem, think about putting something reflective in the radiant sight line to the pipes.

Look at Tom's photos here:

http://www.vansairforce.com/community/showthread.php?t=109300

2rmmb9f.jpg
 
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