hsukaria

I can see where you wouldn't want to ride in an overpowered real plane. It would be scary. Most of the time I fly my models at around half throttle unless I get a hankering to go vertical.

By the way, you should have seen all the club-mates lecturing me about running my Saito at 5% nitro instead of 15+%. It was like I was commiting sacrilege. I suspect they are having insecurity problems.

Hobbsy

My Feedback: (102)

I know what you mean, I got bounced a few times here for mentioning that I even tried it. But it really works and works well.

Linkan2

Jafo 150 hi

http://www.youtube.com/watch?v=rnT8-jSKI4Y
her is a Midwest  Stearman and Saito 100TI
Lars Lindström

jafo150

thanks everyone. I will go up to the 120.

hsukaria

I don't know if it's because it is a Saito, or the 5% nitro, but it is incredibly easy to start. One turn over the compression stroke and it starts instantly. Explosive throttle response also.

One question I still have: Should I use a 4-cycle fuel blend instead of the 2-cycle fuel I am using now? Does 4-cycle blend mean less oil? I have also seen fuel blends for 2 and 4 cycles. Is that basically oil content less than 2-cycle but more than 4-cycle? Or is that some super secret formula?

JariV

Are you talking now about 2-t heli fuel or 2-t car fuel?

Car fuel has substantially lesser amount of oil in it, usually around 10%, 4-t heli fuels usually have around 20% of oil. I don't know about the 2-t heli fuel. Google the differences.

w8ye

My Feedback: (16)

I don't run the reduced oil 4 cycle fuel

I run Wildcat Premium Extra 2 stroke fuel in my four strokes.

Rudolph Hart

Hsuk just nominate what mix you want when you buy it premixed or you can mix your own fuel.I only run saitos so my experience is limited to fourstrokes,mine and others.I mix synthetic and castor with various ratios of nitro and lately have settled on 10% as an average for nitro.

hsukaria

Ok, thanks. I have been running 2-cycle fuel in my 4-cycle engines (same fuel as my other 2-cycle engines). So, I will stay with that (includes 5% castor oil).

earlwb

I never bothered to try special 4 cycle engine glow fuels in my 4 stroke engines. I just use the 2 stroke engine fuels. Yeah it has more oil in it, but the 4 stroke engine's bottom end, camshaft area and top end rocker arms only get oil from the blow by past the piston and ring and maybe a little blow by past the valve guides. In the earlier days of 4 stroke engines, i remember them stating to use 100% synthetic oil and using something like 14% to 17% oil in the fuel. But with my past bad experiences with 100% synthetic oils, I didn't believe them.
I think using a blend of synthetic and castor oil works the best, sort of the best of both oils then.

Hobbsy

My Feedback: (102)

Jim and I mostly run the same fuel although a few years ago I bought 4 gallons of Fox 5% with 20% blend of 50/50 syn/castor, that ran great in every engine I have except my ST 3000 and 4500. For a while I had some WildCat 10% Premium with 16% 80/20 syn/castorr blend for my RCVs. I no longer have any RCVs and no longer any of that fuel. I've come to the conclusion that the % of lube only changes the flow rate through the engine, talking only four strokes here. When pulling a backplate right after a run and being very careful to not tilt the engine there is always the same amount of residual oil in the crankcase regardless of the % of oil in the fuel. I am going to run my Saito .62 today to re-set the needles and am going to run WildCat 15% 2/4 which has 18% full synthetic. One thing I already picked on concerning this fuel is that the flat surfaces inside the engine stay wet, (with lube) where other all syn fuels I've tried run off the surfaces and end up dry. Is there such a thing in the lube world as a wetting agent?

PS, I'll take picture of the residual oil in the .62 after a full 16oz run.

blw

My Feedback: (3)

All we get here is pretty much Morgan fuel. I've been running Omega 15% 4 stroke fuel for a few years. I add about 4 oz of Morgan's castor to a jug. A friend of mine adds several oz of castor from the drug store without any problems so far. Of course, we get a lot of Cool Power users around here too.

Morgan Fuels is a 2 hour drive from here in Enterprise. I've heard they recently relaxed their policies on drive up buying, and they will sell to clubs without nearby hobbyshops.

hsukaria

I've been buying most of my fuel in the Toledo Show held in April every year. Mostly I buy Rich's Brew. But the LHS sells Morgan and Wildcat. I buy Morgan's fuel for special engines like the Fox and Saito.

One reason I ask these questions is that the Horizon Hobby website states 10-30% nitro all synthetic oil for the Saitos. But I read the owner's manual (older 1.8) and it states 5-15% nitro and I thought it said castor recommended. I will have to go back and re-read the manual again. Maybe I have an older Saito 1.8?

Hobbsy

My Feedback: (102)

As promised, here are a couple of pictures, one of the lube in the crankcase of the .62 and the other of the fuel used. While I was at it I tached the engine with a Graupner 12x7.
RPM===10,350, reduced to 10,150 and ran 12 oz of fuel through the engine
Fuel===WildCat 15% 2/4
Plug===Taipan 4c plug
Muffler=Davis In Cowl muffler, neighbor lady sleeping, she works at Mary Washington College at night. This muffler is super quiet and yet not restrictive. It's laying beside the fuel jug. The one with no paint. The missing paint is another story.

Note that lube oil fills the notch in counterweight and flows over into rod big end channel. This may be completely useless info but there it is.

hsukaria

So the picture on the left shows that the oil remains sticking to the surfaces, despite being all synthetic. And based on your earlier post, some/all other synthetics do not remain sticking to the smooth surfaces?

This reminds me of the automotive synthetic oils in the past. The synthetic oils would completly drain to the sump, leaving the valvetrain dry. The mineral oils would remain sticking to the engine parts after shutdown and would keep the parts lubed for next startup. But the automotive synthetic oils have gotten better recently and do remain sticking to the valvetrain.

earlwb

The issues I had with synthetic oils in glow fuel, was that the oil breaks down at a lower temperature, stops lubricating than Castor oil does and no protective varnish layer is there either. Then the synthetics seem to do nothing to stop the engine from rusting on the inside. Where castor oil sticks tenaciously to the metal surfaces and protect against corrosion the synthetics seem to let the metal corrode anyway thus not protecting the engine.

With castor oil if you had a lean condition in the air, you have time to go oops, and cut throttle and land before any damage is done. With synthetics as soon as you go oops, it is too late. So synthetics offer no forgiveness in these lean run situations.

Hobbsy

My Feedback: (102)

I'm not advocating the use of Synthetic lube but wanted to try it and so far my experience has been fine but I use after run oil religiously. Afew years ago I bought an MDS 1.48 from a gent in Ariz. who bragged that it had never had any fuel through it except fuels with synthetic lube. When I received the engine it was stuck. I dismantled it and found the ring rusted to the cylinder and the entire inside of the engine dry as a bone except for the bottom rod bearing. This fuel seems to do better than that.

H-man I started to run this Saito I traded an Enya .90 for but hit a snag. It wouldn't accelerate beyond about 3,500 rpm not matter where I set the HS needle. I had an obvious Swiss cheese brain moment and took the carb apart only to find it was just fine. What wasn't fine was that the LS needle was way too far in. The small end of the LS needle was more than halfway into the spraybear. Picture #1 shows where it should be.

hsukaria

Luckily, I am having a great idle and transition with my Saito. But I have another 4-stroke that has given me fits since I bought it 2-years ago. The maximum rpm I can get with the break-in prop is 8500 and the idle is quite high. As I continue to adjust the LS needle to get the idle to go lower reliably, I end up with the LS needle almost all the way closed. When I end up with a good idle, the top end is gone down to 8000 rpm or lower. I might end up donating that engine to my son to use it as a learning tool.

AmishWarlord

My Feedback: (5)

Can't believe this thing sold for $118

http://www.ebay.com/itm/180722086876...84.m1423.l2649

earlwb

I had that same thought, but then if you had a 1.50 engine and you needed a carb or something, it might be worth the cost. The cylinder/head unit is $100 and the carb itself costs $80.

Rudolph Hart

There's a thread next to this one talking about how hard two and fourstroke engines suck fuel and the merits/demerits of exhaust pressure for a positive fuel feed.I believe atmospheric pressure is a much greater factor but have yet to try it,any thoughts all?

hsukaria

Atmospheric pressure might be higher at the bottom of the world, where you are!

But seriously, atmospheric pressure is at the exhaust, intake, and open fuel tank. When you close the fuel tank and pressurize it with the exhaust, the absolute pressure at the tank and fuel inlet to the carb is higher than atmospheric pressure. That pressure increase is called the "gage" pressure.

absolute pressure = gage pressure + atmospheric pressure.

Gage pressure will vary with engine running condition, like throttle. Low throttle, low gage pressure. High (WOT) throttle, high gage pressure. I don't have numbers, but I imagine that gage presssure based on carb throttle varies a lot more than atmospheric pressure.

Ideally, if gage pressure is considerably higher than atmospheric pressure, then the total absolute pressure in the fuel system will be less affected by atmospheric pressure variations. That is one benefit of pumper carbs, they are less affected by atmospheric pressure variations.

earlwb

The intake vacuum or low pressure pulses that occur in the intake on our single cylinder engines varies wildly with RPMs and load (bigger smaller props for example). At idle a manifold pressure gauge will show the individual low pressure suction pulses very well. As the RPMs increase the pulses get more weakly visible as the pulses blend together. Under a high load the manifold pressure tends to go up towards atmospheric pressure resulting in little to no fuel draw. Full throttle or WOT has a similar effect in that the low pressure zone or point moves towards the front of the throttle (barrel or plate).

I made a few videos a while back when I was explaining how the pulse pumps work on a 4 stroke engine and how they don't work under load at high speed. But you can see the effect in the videos below and how it would affect the fuel draw at the carb.

For example, here is the vacuum gauge on my scooter (when I was testing it out, with no bleed valve to smooth out the pulses) at idle:
http://s27.photobucket.com/albums/c1...gineIdling.mp4

here is the same engine in the scooter travelling up a hill at 50mph:
http://s27.photobucket.com/albums/c1...uumAt35mph.mp4

earlwb

Some pics showing the effects on the carb.  Basically the low pressure area inside the manifold moves out from behind the carb to the air filter at WOT.  granted we don't have air filters on our engines so it moves to the entry point to the carb.








ref http://www.swaircraftappraisals.com/MeyersForum/Engine%20Info/Engine%20Operation/Manifold%20Pressure%20Sucks!.htm

hsukaria

Yeah!! That vacuum sucks.