Years ago , before Saito relocated the vent fitting we had seen quite a bit of rust and wear in the front . As a measure to combat that rust , we moved the fitting on our engines forward . This made quite a difference immediately . It was a bit later that Saito moved the vents on most of their production engines . The benefits are two fold . The oil is now encouraged to migrate forward to the important cam , gears and bearings . It also allows for an excellent point to introduce the after run oil . The ARO can then displace any remaing sludge and protect the surfaces from corrosion .It seems possible drawbacks to using a check valve would be losing the ability to ARO at that point as well as allowing higher pressure to build up in the bottom end . Higher pressure downstairs would mean less oil from the cylnder top end .

Originally Posted by Gary Cee

Years ago , before Saito relocated the vent fitting we had seen quite a bit of rust and wear in the front . As a measure to combat that rust , we moved the fitting on our engines forward . This made quite a difference immediately . It was a bit later that Saito moved the vents on most of their production engines . The benefits are two fold . The oil is now encouraged to migrate forward to the important cam , gears and bearings . It also allows for an excellent point to introduce the after run oil . The ARO can then displace any remaing sludge and protect the surfaces from corrosion .It seems possible drawbacks to using a check valve would be losing the ability to ARO at that point as well as allowing higher pressure to build up in the bottom end . Higher pressure downstairs would mean less oil from the cylnder top end .

The checks come standard in the FA300TTDP & mine gets plenty of oil to the top end.



There is no pressure increase in the crankcase. Instead of going in/out through the same route, it comes in @ the rear & out in front of the bearing.

More oil @ the cam case would probably mean more oil going up the pushrod tubes, not less.

I'm looking for spare rocker covers to D&T for nipples to run the pressure out through the rocker covers to a Y" fitting then an outlet check valve. Passages in the lifter bores will allow crankcase pressure to go up the pushrod tubes.

My FA180HC ran more stable & WOT W/the check valves W/no loss in maximum RPM.

I totally agree with the front mounted vent . As noted , we were doing that quite a while before Saito made the move and had good results .

Looks like the check valves work OK for you , results are what counts . So that concern is probaly moot . The cracking pressure on the intake check is probably actually helping to create a little more blowby during compression stroke , making a bit more oil available .

I would still prefer pumping the ARO right up front in order to displace the case sludge however .

The vent location on the timing cover should be especially effective with inverted engines .

We have been packing the rocker covers with synthetic grease . Probably overkill as the top end seems to do just fine with minimal lubrication .

Originally Posted by Gary Cee

I totally agree with the front mounted vent . As noted , we were doing that quite a while before Saito made the move and had good results .

Looks like the check valves work OK for you , results are what counts . So that concern is probaly moot . The cracking pressure on the intake check is probably actually helping to create a little more blowby during compression stroke , making a bit more oil available .

I would still prefer pumping the ARO right up front in order to displace the case sludge however .

The vent location on the timing cover should be especially effective with inverted engines.

We have been packing the rocker covers with synthetic grease . Probably overkill as the top end seems to do just fine with minimal lubrication .

The engine I have vented will be mounted horizontally. It might have been better to have the outlet on top of the cam housing (when horizontal) to promote oiling of the rockers.

Even W/the engine vertical I seem to be getting oil up the tubes as when I removed the covers, I had green synthetic oil in the rocker boxes.

In my 300TTDP the location of the inlet check has a bit of a funnel W/a screen.

I fill the funnel W/ARO & trun the engine over. It sucks the ARO in I do that several times.

If you wanted to spin the engine over W/an electric starter as ARO was dribbled into the inlet check funnel, you could get a lot of ARO into the engine, including the rear/middle bearing.

The inlet check located in the back cover of a single is not so handy. One could use the standard nipple W/an inline check to allow ARO application.

There is a pretty steady (fine) stream of oil coming from of the outlet tube. I have it routed to a spot out of the prop wash so I can observe it.

If you put a outward flowing check valve on the crankcase there will certainly be a steady flow out. To me the question is, does it reduce the amount of oil in the crankcase at any given time? Also it seems to me the additional inlet check valve also is very effective at evacuating the crankcase, and oil, so is it better than just a vent in the front? Only time will tell.

Greg

A lot depends on the actual cracking pressure of the check valves and the changes created between the upper and lower cylinder area .
Geez , The YS is looking quite elegant at this point

( A pulsed flow out )

Originally Posted by SrTelemaster

I got the FA180HC fired up & running last night & made a few test runs before it got too dark to use the optical tach.

Thanks for posting pictures and details on your hybrid engine! It's interesting to see experimentation of this type. I had a few questions:

How are you measuring the power figures you posted? Do you have some type of dyno, or are you using a formula to calculate the power from the propeller figures?

What altitude are you at? I know people at higher altitude can get away with higher compression without problems. What do you think is an upper limit on compression ratio with glow ignition?

With regard to the case venting, have you experimented with connecting the vent to the intake? Do you think a check valve would still be useful if the vent were connected to the intake between the carb and head (where there would be low pressure)?

Thanks!

Well i have found a plane that i like, the big Black Horse Chipmunk at 2.17 meters but it is sold for a 30cc to 45cc which seems a bit 'overkill' as there is a video on youboob where it flies balistically with a 30? has anyoune got a Saito FG 20 or there abouts powerwise moteur Iistalled in one ?.
http://www.rcmodelcentre.co.uk/Black...prod_2713.html

thanks Paul.

Originally Posted by flyrod

Thanks for posting pictures and details on your hybrid engine! It's interesting to see experimentation of this type. I had a few questions:

How are you measuring the power figures you posted? Do you have some type of dyno, or are you using a formula to calculate the power from the propeller figures?

What altitude are you at? I know people at higher altitude can get away with higher compression without problems. What do you think is an upper limit on compression ratio with glow ignition?

With regard to the case venting, have you experimented with connecting the vent to the intake? Do you think a check valve would still be useful if the vent were connected to the intake between the carb and head (where there would be low pressure)?

Thanks!

My altitude here is abot 258' above sea level.

The high compression ratio does not seem to work well W/glow plug ignition. Unless a colder glow plug could be employed, this seems to be a CDI application only.

The check valve pressure output will eventually be routed to a bleed-off valve to regulate pressure to the fuel tank. This will be used to allow a remote fuel tank location over the CG.

The power figures are being calculated with this static thrust calculator.
http://personal.osi.hu/fuzesisz/strc_eng/index.htm

The power calculations compare closely (within .1 HP) to Saito's ratings on stock engines so it is fairly accurate.

Regardless, of that, it does make for accurate comparisons in power gains.

Originally Posted by gkamysz

If you put a outward flowing check valve on the crankcase there will certainly be a steady flow out. To me the question is, does it reduce the amount of oil in the crankcase at any given time? Also it seems to me the additional inlet check valve also is very effective at evacuating the crankcase, and oil, so is it better than just a vent in the front? Only time will tell.

Greg

Since Saito uses the same sytem on their most expensive twin cylinder engine & I have never head of any issues W/the 300TTDP (unlike the non-positive crankase vented FG57 version) there would seem to be no drawbacks to the check valves keeping the crankcase evacuated of excess oil/sludge.

As long as there is enough oil it all works great. Maybe that's why these engine need so much oil in the fuel.

Greg

Originally Posted by gkamysz

As long as there is enough oil it all works great. Maybe that's why these engine need so much oil in the fuel.

Greg

But, what I can't understand is why the FG gas engines, that for the most part have the same rods (the FG57 as an example) as the FA counterparts yet they only require a 20:1 oil mix ratio.

Both the FA300T & FG57 use rod part # SAI300T10C

The 5% oil mix of the gas is even less oil delivered than a 5% mix W/methanol as the fuel delivery volume is about 40% more for methanol.

While gasoline might have more lubricity than alcohol to help lube the piston, rings & valves, the blow-by oil is all that lubricates the bottom end & cam/lifters.

The YS system looks better and better ...

YS uses 20% oil minimum. They are like a two stroke in regard to moving oil away from the crankcase. What were the issues with oil content when the YS CDI came out? Did leaner needle settings cause lubrication failures? IIRC, there was a low oil content update to the CDI.

Greg

Yes, The more I see , the better the YS system looks ..for Alcohol fueled GLOW engines .

The YS system WORKS great , lubricates very well , evacuates the combustion products , cools better , makes more horsepower , has excellent transtion ,provides for an excellent pressurized fuel system right out of the box .
20% is the MAXIMUM oil I use , the very same oil I use in my other glow four strokes including the Saitos . The CDI YS is likely the exception not the rule . My comment was in regard to a YS style system, not a particular , singled out YS engine .
The YS system looks great because it works very well indeed .