ORIGINAL: Lazer
I've enjoyed the conversations and it's cantor. Keep it up.
I have just one question that relates to the older Perry Pump I have before the ones offered now that is diaphragm operated
will or
will not work on my OS .91 FS Surpass and what would be the least expensive, but dependable. I'm thinking that I will be using a newer engine if I can trade for one. I've found an OS 1.20 FS II Pumped that should pull a 8.5 lb plane very well on a prototype OS pipe I came across. What ever ideas come out of this will be great.
TMc
Lazer, You start a thread, everybody receive a lot of posts and you still have not all the answers!!
I did write, we only use (pump assisted) pressure controller(s) but I did ask my Physicisticated Hanna about your question, the pump on the four stroke glow engine and this is what she writes, read!
Hallo Lazer,
Taurus Flyer did show you how the pump works (your post 4) but now another question and my advice.
I am theoretical not enthusiastic about a pump on a four stroke, it does not make me happy.
First reason
A glow engine does suck the fuel only ¼ cycle time
But the other ¾ cycle time, while the engine is compressing, burning and exhausting the mixture, what is that pump doing on that moment? Waiting? No want the spray bar isn’t closed and the piston is pulsating a second time the crankcase pressure.
I think that the standard pump, as we know now, with it's constant (about) 0,25 PSI pressure, is pumping a second moment a little bit fuel in the engine near the closed inlet valve.
And that fuel maybe is waiting to blow out that little tiny candle in the cylinder, we all call the glow plug, the first moment the valve opens.
That little bit extra fuel wasn’t "spray barred" too, because with that closed inlet valve there was no air that second moment!!
So liquid fuel, wasted money? I am afraid so and so not Typical Dutch.
Second reason
The second problem still can be the mid and low range fuel adjustment when using a standard carburetor, because of that higher than normal inlet fuel pressure.
In mid and low range this pressure is relative some more when compare with the sucking pressure than in full power situation. So try to “second needle” to keep the money in the wallet seems to be a lot of experimenting.
Conclusion
These are the two main reasons I do not recommend to use a pump like Perry on the four stroke.
Let it be clear, I am a simple cat so maybe I am wrong.
Regards Hanna