How many of you did the break-in on a bench?
11-25-2004, 09:53 AM
#26
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RE: How many of you did the break-in on a bench?
Does anyone run an air filter?
Once a no air cleaner decision is made break-in has zero meaning. Two tanks of fuel without a cleaner will undo the most careful break-in.
Bench running to understand the engine characteristics and check the needles does make sense. If the engine is cowled running again in the airplane also makes sense. The cowl changes the air delivery to the carburetor.
Once a no air cleaner decision is made break-in has zero meaning. Two tanks of fuel without a cleaner will undo the most careful break-in.
Bench running to understand the engine characteristics and check the needles does make sense. If the engine is cowled running again in the airplane also makes sense. The cowl changes the air delivery to the carburetor.
11-25-2004, 10:51 AM
#27
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RE: How many of you did the break-in on a bench?
Bill,
You have a valid point, however, I'll bet that most people do not run an air filter. Personally, I would worry about air flow to the carb, and many others might worry about how the filter looked on the plane.
I understand your point regarding cowls, but keep in mind that each case is different. For example on my H-9 Cub, running a G-26, the carb sticks way out of the cowl. In the case of my Byron P-47, the velocity stack protrudes out of the cowl slightly, and finally the Y/A P-40 that I am currently building will utilize a rear induction engine. The carb is buried in the engine box, so I'll need to provide an alternate means of supplying fresh air. In each case, the cowl is a non-issue. I can't imagine trying to service the P-40 air filter!
Regards
Craig
You have a valid point, however, I'll bet that most people do not run an air filter. Personally, I would worry about air flow to the carb, and many others might worry about how the filter looked on the plane.
I understand your point regarding cowls, but keep in mind that each case is different. For example on my H-9 Cub, running a G-26, the carb sticks way out of the cowl. In the case of my Byron P-47, the velocity stack protrudes out of the cowl slightly, and finally the Y/A P-40 that I am currently building will utilize a rear induction engine. The carb is buried in the engine box, so I'll need to provide an alternate means of supplying fresh air. In each case, the cowl is a non-issue. I can't imagine trying to service the P-40 air filter!
Regards
Craig
11-25-2004, 01:35 PM
#28
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RE: How many of you did the break-in on a bench?
ORIGINAL: Futurase
We do not pet and baby a new chainsaw when we get it and no one will ever convince me a airplane enviroment is a harder load and yet they do not over heat in hard, long use in the hot summer time and all everyone talks about is how much you need to baby our engines. I have a DA and Zenoah and I am doing the break-in like DA says to. I think we baby the things way to much as most all engines are from a chainsaw or etc except for the DA's, 3W's and etc. If the general populus had to baby every chainsaw and weedeater like we are told to then Stihl and everyone else would go bankrupt!!!
We do not pet and baby a new chainsaw when we get it and no one will ever convince me a airplane enviroment is a harder load and yet they do not over heat in hard, long use in the hot summer time and all everyone talks about is how much you need to baby our engines. I have a DA and Zenoah and I am doing the break-in like DA says to. I think we baby the things way to much as most all engines are from a chainsaw or etc except for the DA's, 3W's and etc. If the general populus had to baby every chainsaw and weedeater like we are told to then Stihl and everyone else would go bankrupt!!!
11-25-2004, 03:48 PM
#29
Senior Member
RE: How many of you did the break-in on a bench?
Craig,
Yes you are correct. No one runs a filter. Maybe they should also not worry about break-in since no filter ruins all previous caution. A filter does looks bad when the carb is side mounted. The thin flat filter used in some Stihl saws might represent an alternative that doesn’t look so bad.
Experience indicates that the cowl is removed for other purposes more often than the filter needs servicing.
The plenum chamber (air box) is very important to the operation of any engine. When time permits, crank an engine at night and shine the car lights on it. You will see fuel pulsating in and out of the carb especially without a velocity stack. Much of the mixture is lost to the air stream. More horsepower might be available if all the fuel mix could be utilized.
You may find that the cowl acts as a more efficient plenum chamber than simply leaving the velocity stack open to the air stream.
It is not suggested that anything different could or should be done. But it is surprising that we are able to get the engines run at all. Understanding how badly we violate sound design principles might help when trouble shooting in the future. If one were searching for maximum HP or broad power band the air filter and plenum chamber begin to be much more important. Fortunately we always have ample HP. I am using filters and plenum chambers for the rear induction engines in process but don’t have a good method to measure the end result.
Fifteen years ago a 80cc Yamaha motor cross engine would produce 25 + HP. Seems inconstant with the meager HP from airplane engines in the same size range. And yes they had a pipe and a gearbox but …
Bill
Yes you are correct. No one runs a filter. Maybe they should also not worry about break-in since no filter ruins all previous caution. A filter does looks bad when the carb is side mounted. The thin flat filter used in some Stihl saws might represent an alternative that doesn’t look so bad.
I can't imagine trying to service the P-40 air filter!
The plenum chamber (air box) is very important to the operation of any engine. When time permits, crank an engine at night and shine the car lights on it. You will see fuel pulsating in and out of the carb especially without a velocity stack. Much of the mixture is lost to the air stream. More horsepower might be available if all the fuel mix could be utilized.
The carb is buried in the engine box, so I'll need to provide an alternate means of supplying fresh air. In each case, the cowl is a non-issue.
It is not suggested that anything different could or should be done. But it is surprising that we are able to get the engines run at all. Understanding how badly we violate sound design principles might help when trouble shooting in the future. If one were searching for maximum HP or broad power band the air filter and plenum chamber begin to be much more important. Fortunately we always have ample HP. I am using filters and plenum chambers for the rear induction engines in process but don’t have a good method to measure the end result.
Fifteen years ago a 80cc Yamaha motor cross engine would produce 25 + HP. Seems inconstant with the meager HP from airplane engines in the same size range. And yes they had a pipe and a gearbox but …
Bill
