Quantcast

Aero injector

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Mcmark

Well-Known Member
Joined
Sep 24, 2013
Messages
402
Location
Owings, MD
Guys and Gals,
Are any of you running an Aero injector on an A65-75 Continental?
Pros-Cons?
I won't have a fuel pump, so is it necessary to have a regulator?
What adapters will I need from Aeroconversions?
Thanks
Mark
 

radfordc

Well-Known Member
Joined
Feb 5, 2008
Messages
1,414
You definitely don't need or want a fuel pump or regulator with the Aero Injector. It is designed for simple gravity flow operation only. You need enough fuel flow to satisfy the engine....2 x the max hourly fuel burn.
 

MikePousson

Well-Known Member
Joined
Jan 12, 2016
Messages
465
Location
Ontario on the bay
You need enough fuel flow to satisfy the engine....2 x the max hourly fuel burn.
Could you please explain? I'll have an 11 gallon tank on the Starlet with a VW engine. The hourly fuel burn is approx 4gph. If it flies for 1 hour, then would only have 7 gallons left in the tank which is less than 2x burn rate. There is a fuel pump installed and also a gravity fed bypass. On this particular application, the bypass is there in case of pump failure, but it can be used in the opposite manner.
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
I have run an Aerocarb/aeroinjector for years on a variety of aircraft. For the most part, they really like gravity feed, with about 10" or more of head pressure. (minimum distance of tank above the carb) On our low wing Saberwing we have two wing tanks transfer fuel (via Facet pumps) to the 12 gallon header tank. We check nose high (climb/stall) fuel flow to a minimum of 10 gallons per hour when at minimum fuel ... one gallon in header tank. THis is 1.5X full throttle climb fuel (6.5 gal/hr). At one hour reserve (5 gallons) we see more than 12 gal/hr fuel flow. Check fuel flow at the carb itself by disconnecting your fuel line there, then turn on the fuel valve at the tank, and start the stopwatch. Use a 1 quart container and fill to full then stop the watch and shut off the fuel flow. Now do the math to calculate your fuel flow. (1800/seconds of flow/4=gal/hr)
Be sure to use firesleeve on you flexible line in the cowl area to reduce vapor locking. We use a K&N filter on the carb - no carb heat (not as recommended by Sonex). We typically use cowl air but have made a small opening into the cowling near the filter for cool air to enter the filter (not under pressure). Don't try to pressurize the carb - it will lean out as speed builds. The Aerocarb does not have a venture so does not draw out fuel like a standard carb. It uses flow over the needle to draw fuel from the needle opening. If you pressurize the carb you reduce the flow and it leans out. Keep it simple.
If you use an electric or engine driven pump use a pressure regulator (Holley has one through Summit Racing) and set to 1-2 psi.
If you have more questions about these let me know...Get to know how your carb works - no matter whos it is.

Bill
 

Pops

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 1, 2013
Messages
8,519
Location
USA.
Could you please explain? I'll have an 11 gallon tank on the Starlet with a VW engine. The hourly fuel burn is approx 4gph. If it flies for 1 hour, then would only have 7 gallons left in the tank which is less than 2x burn rate. There is a fuel pump installed and also a gravity fed bypass. On this particular application, the bypass is there in case of pump failure, but it can be used in the opposite manner.
150% fuel flow of engine at WOT at max climb angle + 5 degrees, not at cruise throttle. My 1835 cc , VW @ 60 HP. .55 lbs of fuel per hour per HP. = 33 lbs. 33 lbs of fuel = 5.5 gal per hour. 150% of 5.5 gal per hr = 8.25 gal flow at the carb. So I needed at least 8.25 GPH fuel flow at the carb. On the test of the SSSC I got 15 GPH.
Watch someone do their Bearhawk.
Fuel Flow Testing
 

Mcmark

Well-Known Member
Joined
Sep 24, 2013
Messages
402
Location
Owings, MD
Dan, I really appreciate your input and despite your dislike of the slide carb, you still provided some really good info.
Bill, Thanks for your positive endorsement and details. Would you be willing to share the K&N part number?
I didn't really give enough information, I am contemplating installing it on a Clipt Cubby. Would like to occasionally turn it upside down. My concern about needing a regulator was in regards to the engine going rich with positive G.
Am picking up the bird this weekend and need to look over a whole list of items that will be impacted.
Sonex is having a holiday sale and don't want to let it get away if it's adequate for this need.
Mark
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,526
Could you please explain? I'll have an 11 gallon tank on the Starlet with a VW engine. The hourly fuel burn is approx 4gph. If it flies for 1 hour, then would only have 7 gallons left in the tank which is less than 2x burn rate. There is a fuel pump installed and also a gravity fed bypass. On this particular application, the bypass is there in case of pump failure, but it can be used in the opposite manner.
Rad-C (you don't mind the moniker, do you, radfordc?) was talking about flow rate vs. fuel burn, not fuel burn vs. fuel capacity. In other words, how much fuel dribbles through the system in a given period of time compared to how much the engine burns in the same period of time. You could have a million gallons in the tank, but if you're flowing 5gph and burning 5gph you're on thin ice.

Would like to occasionally turn it upside down. My concern about needing a regulator was in regards to the engine going rich with positive G.
Good point. Of course, you don't have to be upside down to get extra head pressure (just a normal turn would do the same thing). Lots of planes with a gravity system and slide carb are OK with the temporary increase in head pressure. The thing to remember is that you're not pulling extra Gs for too long and the slide carb is tolerant of the temporary minor extra pressure. The needle is a flow restriction and I believe that just because you have 2x the head pressure for a moment or two, it doesn't mean that you get a mixture that's twice as rich. Maybe somebody could correct me if I'm mistaken.
 

radfordc

Well-Known Member
Joined
Feb 5, 2008
Messages
1,414
Rad-C (you don't mind the moniker, do you, radfordc?) was talking about flow rate vs. fuel burn, not fuel burn vs. fuel capacity. In other words, how much fuel dribbles through the system in a given period of time compared to how much the engine burns in the same period of time. You could have a million gallons in the tank, but if you're flowing 5gph and burning 5gph you're on thin ice.



Good point. Of course, you don't have to be upside down to get extra head pressure (just a normal turn would do the same thing). Lots of planes with a gravity system and slide carb are OK with the temporary increase in head pressure. The thing to remember is that you're not pulling extra Gs for too long and the slide carb is tolerant of the temporary minor extra pressure. The needle is a flow restriction and I believe that just because you have 2x the head pressure for a moment or two, it doesn't mean that you get a mixture that's twice as rich. Maybe somebody could correct me if I'm mistaken.
Correct. Many of us have done aerobatics using the Aero Injector carb. There isn't any noticeable change in engine performance as you can see here for yourself: https://youtu.be/zb-vfMPjKzY
 

gammaxy

Member
Joined
Nov 4, 2015
Messages
22
Location
Huntsville, Alabama
The needle is a flow restriction and I believe that just because you have 2x the head pressure for a moment or two, it doesn't mean that you get a mixture that's twice as rich. Maybe somebody could correct me if I'm mistaken.
I think the main thing that helps is that steady state flow rate (using Bernoulli's equation) is proportional to the square root of acceleration. For example, a 3G loop entry would only yield a 73% higher flow rate, not 200% higher like you might guess.

I agree that the actual increase is likely to be even less than this due to the reason you gave or maybe that the pressure drop behind the needle provides for part of the flow rate and is not strongly affected by acceleration.

The effect is also masked because the pilot expects the engine to bog down a little anyway while pulling 3G's.
 
Last edited:
Top