Currently my flying partner and I have been flying some Craigslist Specials.  A Sig Twister with a LA46 and a Banshee with a OS 35 FP. We have been running Magnum fuel that is 10% Nitro and 20% lube that is a Synthetic/Caster mix.

I would like to ask for the experience and opinions on these modern engines for fuel. We are at around 6000 feet here in Colorado and considered playing around with some 15% Nitro fuel. We want to take good care of these engines so I thought I would ask if this is too much Nitro? 

While I dont have specifics in the lube ratio at the moment I am writing this, is there any concern over the current fuels that are a much higher percentage of Syn to Caster in these particular engines.

Thanks!  Mark

15% is not too much nitro.  At high altitudes 15% nitro is the preferred amount for most stunt fliers. I would suggest adding 2.6 ounces of castor oil to your Magnum fuel. That would make it approx. 22% lube total.  

I've run many FP's and LA's especially the 46.  I pretty much agree with what Dennis M. said about fuel.  However I would simply add that I've used up to 25% nitro here in Tucson (2500 ft 100+ temps with no real problems).  I've also tried low oil content and found that theLA46 runs best on 10-15% nitro and 18% oil (half and half, with Klotz)...notice I said "best".  The plain case bearings wear out with a resultant loss of power and greater fuel usage in about 200 or so flights with the low oil content.  One of my buddies here in Tucson swears by 24% oil content and gets good runs.  Personally I think the 22% half and half using Klotz is probably the best compromise.  I have a couple of LA46's that have always been run with this mix and have over 1000 flights with no real deterioration in run quality.  The Klotz keeps everything nice and clean inside the engine also, which I've found not to be completely true with all synthetics.

Randy Cuberly.

Thanks everyone for the responses so far.  Great stuff. That Randy Smith article is a wealth of information. I will have to check the fuel jug today to verify exactly what it says on the lube.

Mark

I checked the fuel jug this morning.  All it says is Syn/Caster Blend.  It looks like I'll need to call the manufacturer up to get the ratio.   Mark

I am using brodak's 10% Nitro 11.5% synthetic 11.5%castor in my os max .25 &.15. These are earlier engines so they may like the castor more than the newer ones. I am also using os 8 plugs. Both engines run extremely well. As I remember the .25 turns 14,500 or so with a 9X4 and the .14 does about the same with a 8X4.

Howdy,

I just spoke to Buzz at Magnum Fuels. He was very willing to help me out and answered all of my questions. All his fuels are blended with the ingredients measured by Volume.

The Magnum “10% Sport” that we are running and the “15% Sport” that we are going to try out are a 18% oil pack. The ratio on the oil pack is 13%-Syn and  5%-Caster.

Per the Randy Smith article:  For motors with larger bushings and bushed rods like the OS FP , Magnum GP series, Tower, and  Brodak’s  a 22-25% half-and-half oil mixture works the best.
(We are currently running OS-FPs and OS LAs)

Per Buzz I can add 7 ounces of Caster to the new 5 Quart jug of “15 Sport” and  get an oil percentage of 22% +.  There is a jug of Sig Caster at the hobby shop they are holding for me that I will be picking up to do this.
In the future I can request specific custom blends through my  local hobby shop that Buzz said could be easily mixed with no lead time and sent along with his regular order.  We try to support our hobby store (Pikes Peak RC Hobbies) whenever we can and this will help us do so as he now only stocks Magnum Fuels due to the requests of his larger customer base.

Plans are to get a mix like the one we are doctoring up now as a custom blend from Magnum and a “Fox, McCoy, S MAX” blend made up.  (Fox Mix = 10% Nitro, 50/50 Syn-Castor 26% total)

Thoughts on the mixes before I order them up?

Thank you!

Mark