My Saito 100 was working ok but when high Gs involved, the engine was struggling a bit. A pump would solve the problem but instead I tried this :

I connected the breather line directly to the tank vent line. The result generated too much pressure that I can not regulate by leaning the needle. Then I put a small brass tube between the breather and vent connection I made ( see attachment ), and made a tiny hole in this tube in order to relieve excess pressure.

I have to say that it worked like a charm. Now whatever I do, engine works like a clock, and there is no richening in the midrange. The pressure generated by this setup is more than muffler generated pressure. High speed needle needs to be leaned a bit, low speed mixture is not affected by this setup.

I used a 1/8" brass tube with a hole diameter of about 1 milimeter. You can enlarge the hole if there is still excess pressure.

The advantage of this over a pump is it is cheaper, simpler and it is easy to operate.

I think anyone who has fule draw problem in an engine may use it.

I would like o hear about our comments.

Thanks.

finally i been thinkin of doin the same thing but i didnt want to risk any cam or follower lube problems but i went for it. only instead of using your brass tube idea i used a "T" and put in one of my old OS needle valve's i had laying around that way i could adjust the "relief orfice". I ran it tonight and every thing seemed to work great ill try flyin it tomorrow to put it to the real test

Interesting, every time I have restricted the crankcase pressure performance fell off after a short flight time. My restriction was caused by having a hose too long on the breather.

How long is the hose before you get to the metal tubing with the hole in it?

Ed M.

Jakac_26, if there is an unused one around, I think it is a better idea to use a needle valve. I have to tell the engine is working so well that maybe someone from Saito has to have a look at this setup. This setup contributes to fuel savings also I believe.

Bentgear my tubing between the brass tube and the engine breather is about 3 inches, I think if it kinks during flight, it may cause some performance problems and maybe some serious engine failure, maybe it is better to fix it somewhere in the firewall, I will fix mine.

I made about 50 flights with this setup, lots of full power flat spins, lots of negative ( and positive ) G maneouvers, no problems at all, 0 dead sticks. I think I will do about 20 more flights this weekend, I will keep you posted.

Thanks for your thoughts.

I made another 30 flights with the setup and it still works ok. Seems like smaller the pressure hole better the system works. I leaned the low end a little bit. There is no problem in the midrange.

You are going to have trouble with your setup in the long run. You will eventually experience power degradation as bentgear did.

You need to instal a "Tee" in the line between your orifice and the engine and this tee branches to the atmosphere.
as jakac did.

Enjoy,

Jim

How about just "tee" and connect the third end to the muffler?
Frankly nothing new in this variant.

I think Saito Fuel Pump, Style # : SAI300TTDP102, works on the same principle. With one difference, it is $50, our solution is $1.

W8ye, I did not understand why I would eventually see power decrease by this setup, can you please tell me why ?

So far, it works like a charm.

Thanks...

This trick is outlined in the manual for Saito twin engines by way of an picture (I believe the engine in the picture is the Saito 300TTDP, but I may be wrong). The picture shows a pressure adjusting valve to the vent line (as with the needle valve mentioned earlier by Jakac_26). The manual is available at the Horizon Web site.

George

ORIGINAL: obolel



W8ye, I did not understand why I would eventually see power decrease by this setup, can you please tell me why ?


i think w8ye meant that if its not vented to atmosphere the bottom end of you engine will not get the amount of lubrication it needs . once the pressure equalizes there will be no more movement of oil to the crankcase, which is why the vent is on the crankcase to start with.