four stroke fuel

four stroke fuel (Full Version)

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Low Wing -> four stroke fuel (5/28/2002 8:24:50 AM)
ok, I'm passing through the depressing world of what % 15 -30 wild cat, cooool power, etc and how many clicks does it take to get to the center of maxium performance...right now I'm using 25% cool power mixed with 4 oz cool power oil...I have a 91 satio on a Cipmonk super 90...when I started out on this combo(91 and chipmonk) I used 15% cool power straight up...great performance> except you had to keep an eye on the motor over-heating...one click this way and you were in trouble, I was allways bugging someone to dial me in...OK, a tac and a half gallon of 25% wild cat later I'm slowing down on my speed and climb, not to mention orange gooo all over the model...then I switch to the present mix(that also sucks) tacing at 9 thousand rpm 13/8 prop where is my power...I know this ain't no pilon set up...but it seems I had more power in the front of this ride...What's up, have you been there and how did you get out...thanks

mglavin -> four stroke fuel (5/28/2002 8:32:07 AM)
I have several Saito engines, I run all of them on 15% nitro/16% oil by volume fuel. I prefer the Wildcat Fuel. I have tried other's and they work well also. The extra oil is not required... IMO Saito Engines seems to run best a little on the fat side for cool running and a long life. Sure the 30% helo-mixes will make more power, they cost more, have excessive oil content and help shorten the engines life.

Low Wing -> Thanks but? (5/28/2002 7:39:09 PM)
Right on...I'll try it...but let me clarify... the problem I spoke of in my prevous post was that I'm "not" getting the speed or power out of the 30% heli cool power/4oz cool power oil or the25% wild cat fuel...Are you saying that the 15%nitro to 16%oil wild cat gives you all the speed and power you want. I'm mean what kind of speed are you getting out of a 91 satio on a 60 size model 5 to 7 pounds...It's like my model is pissing around the sky...something is missing here, compared to my first flight's...Thanks

mglavin -> four stroke fuel (5/28/2002 8:11:49 PM)
The orange goo is most likely a byproduct of the oil, the addition of 4 ozs. to your fuel is not needed. The excessive oil is also going to rob power. Overheating is generally caused by low Nitro, prop loading and the needle setting. Fatten the engine up a little loose the fuel mixed with 4 oz. added oil. Which or whose 13/8 prop? 9000 rpm with a 13/8 prop sounds about right to me. What were the numbers you achieved previously? Same prop? If the engines is laying down in the air as you suggest it maybe LEAN... Fatten her up slightly... An engine that is tuned on the ground for maximum rpm does and will go lean in the air, the prop/engine will unload and you will see an increase in rpm as the prop screws through the air. A lack of fuel will create a lean fuel mix in the air. Again fatten her up. I like to run my engines up to maximum rpm on the ground as measured with a tachometer, I needle for the highest obtainable rpm, I then back the needle up to achieve 300-500 rpm less than realized at the highest recorded rpm. Lastly if your looking for speed try a higher pitch prop and use a performance engine like a YS. I had a 90 size Chipmunk with a YS 120 on it, it was fast...

ultrastik40 -> four stroke fuel (5/29/2002 8:00:10 AM)
After hearing your complaint that your engine seems to be down on power after running it for maybe a gallon of fuel or so, brings to mind a problem I had with a Magnum .52 4 stroke. I had exactly the same complaint. In my case the problem turned out to be a badly carboned exhaust valve due to running fuel with too much castor oil (even though Magnum recommends castor). The exhaust valve was carboned to the point that it no longer seated & compression was way down. I cleaned the carbon, relapped the valve, & reset the lash on both valves & now the engine is back to normal (like it was in the beginning). I now use 15% fuel with 20% total oil (16% Klotz synthetic - 4% Castor). You should probably start by checking the valve lash & noting how the compression seems. Hope this helps. Ray

Fuelman -> four stroke fuel (5/29/2002 8:15:51 AM)
Low wing, The instructions in the Saito's recommend 20% oil content. These engines run real well with 10% nitro up to about 25%, all with 20% oil. Less nitro will not necessarily make your engine run hotter, low oil and improper needle settings do. If you added 4oz of oil to a gallon of CP30% Heli, you have way too much oil in the fuel. These engines run best with 20% oil. Too much oil (a lot more than 20%) means less burnable mixture in the fuel, it can also make your engine have symptoms of too much compression which can cause detonation and damage. Start from scratch; Are you sure your engine is broken in yet? Get the McCoy 4-stroke plug (Saito origonal equipment), insure you have enough cooling air inlet and exit area (exit area should be more than twice inlet area), insure you have no leaks in the fuel lines and that the tank is set to the correct height relative to the spray bar in the carb. Insure you are not running it too lean, a keen ear and a tach helps. Insure your valve lash is correctly set. I can tell you from experience, when properly set up, Saitos running a fuel containing 25% nitro and 20% oil will run better and outperform Cool Power 30% heli hands down. You got a good engine there, don't give up on it. Fuelman

mglavin -> four stroke fuel (5/30/2002 11:02:31 AM)
Fuelman has made a valid statement regarding Saito recommending 20% oil content for there engines. It does make sense from a manufacturers perspective as well. Consider the wide range of uses and inexperienced modelers their product has to service... I have tried numerous mixtures of various fuels with dozens if not more Saitos and other four-stroke engines. My partners and I abuse our sport engines with hovering, torque-rolling and such. We do not baby our engines, at the least we beat them down... That said the Saito's hard-part engine components will last significantly longer than their bearings on 16% oil by volume. They run smoother, smoke less and maintain needle settings without issue... As a rule were not lugging our engines down with large disc area and high pitch props. I don't recall excessive heat ever being an issue either. These considerations maybe a factor with our results. I have recommended 15% nitro-16% oil for Saitos to many for years now and have always been advised of good results. who knows, it works for me, my partners and other's it may work for you too. I have also played around with the higher nitro/oil fuels with the Saitos. I deemed it a waste of money, nitro and oil for sport flying. I did find that you could make more power but at the richer settings that provided reliable power you were burning more fuel and loosing/transferring/wasting heat with the increased oil content. At the rich needle settings the higher Nitro fuel exhibited a sub-cooling effect and made a bigger mess on the model to boot. The cooling effect, realized from a rich needle setting is a byproduct of the higher Nitro.

Fuelman -> four stroke fuel (5/31/2002 8:27:21 AM)
You make some good points mglavin. The fact of cooling effect with higher nitro is a point that few can realize. When the conditions are right (rich needles and lots of nitro), super cooling could happen. Too much oil can be a problem as well, the 23% or 24% of light weight oil found in CP 30 can actually be testing the limits of the engines ability to properly compress the air/fuel mixture and when conditions are right could be over compressing the engine. This overcompressing can cause detonation and overheating when the needles are not in the "sweet spot". We've avtually blown holes through the tops of pistons in 2 and 4 strokes running high nitro and high oil (30 nitro / 22-24 oil) during testing. Back the oil down to 20% and the engine is happy again. This is when we found that 25nitro/20oil blend and even with the rignt tuning 20/20 would outperform CP 30 heli fuel. Since I manufacture glow fuels (and gas engine oils), I have to be carefull of what I post. Considering the varied users frequenting the boards, I always side with what the engine manufacturer recommends for oil contents, or greater (to a point). For the experienced, running less (or more) is a matter of personal prefrence based upon experience generally gained from years of setting needles. Excellent thread Fuelman

Low Wing -> Break Through (6/3/2002 8:07:39 AM)
Low Wing here...as of today better known as no-brain :stupid: went to the field today and after spending two hours installing new re-tracks I was gonna fly my Super 90 Chipmunk...I fueled up with 15% to 16% Byrons four stoke brew, the %'s suggested in the post's above... But there was still a problem on my power and speed side...well I heard the norm, it's a hot day what kind of prop ya swinging and what fuel are ya burning...well one of our top guy's jumped in and said let's fill it with my stuff, Wild Cat 20/20...well I had tried the Cat pee before and felt like it sucked too, but I tried it again anyway...we started her up and the the muffler came loose, Randy noticed the threads weren't all the way up in the block...well the battery needed a charge anyway so I told him I'd pull the cowl off and hook up later after I'd adjusted the muffler pipe...Sooooo all that crapp to admit this to you...I asked myself(scratching my head)what was different on this that wasn't here before(when she was running good)are you ready :confused: ...it was a muffler pipe extension that I had put on with a new muffler after miss placing the old one...I pulled that piece of S#@*! off and would you beleive :D that model took off like a stuck pig...I was chocking the motor with that thing...I couldn't believe it... were talkin' day and night crawling to hauling ass just like that...I went from 70% power to 100%...Those rubber directors don't work for crapp anyway...pass it on...but please don't mention my name...Thanks

mglavin -> four stroke fuel (6/3/2002 8:59:33 AM)
[SIZE=4][COLOR=red]DUDE[/COLOR][/SIZE] You forgot to mention an extremely [COLOR=blue]BIG[/COLOR] change.... So how did the fuel mix I suggested work with the constipated exhaust system??? You are also a [COLOR=blue]BIG[/COLOR] man......... :D LOL

Low Wing -> four stroke fuel (6/3/2002 6:08:47 PM)
:D wellllllllllll...I haven't exactly run the 15%to16% if that be the fuel yer referring to...that is since the muffler change...I did run Byrons(15%to16%) after picking some up per your post(not that you suggested Byrons)I think you said wILD cAT...that was last week and I it made a differince, I liked it alot better than my Cool Power mix...I hope to run the15%to16% tonight after work, with the muffler change...and I have no doubt it will be great...THANKS :)

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