Author Topic: YS + low nitro fuel  (Read 1503 times)

Offline Yoda

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YS + low nitro fuel
« on: 29, February 2016, 06:40:39 PM »
Well I flew some F3A during the good spell of weather at the weekend. In fact I've now flown almost three times as many F3A flights this year (ten!) as I did in the whole of 2015 and I really enjoyed it :) I've also been experimenting with low nitro fuel which has been interesting. Will no doubt post a bit more once I have more data.

Offline steveplummer

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Re: YS + low nitro fuel
« Reply #1 on: 12, March 2016, 06:22:06 AM »
How little nitro are you using and which engine,did you go for the 185 zero ?

Offline Yoda

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Re: YS + low nitro fuel
« Reply #2 on: 02, December 2016, 11:01:33 AM »
Hi Steve,


I'll be getting a 185 Zero in the new year.


I was experimenting with low/zero nitro fuels earlier this year (only saw your question now). With my 175 CDi it had to be ran very lean on 0% nitro in order for it to throttle properly. The window between too rich (poor throttling) and too lean (sagging) was minute. Also power was not that great. 5% nitro was a big improvement but I think I settled on 6% or 7.5% nitro and 12% ULV Klotz. I was mixing it myself using my own blend from Optifuel and pure methanol. Basically the 175 CDi doesn't have the compression to run on 0% nitro. The 185 Zero is a higher compression engine so should run on 0% extremely well. Cheap as chips to run, plenty power and all the advantages of a big four stroke. Its a no brainer really in my book if using IC.

Offline Yoda

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Re: YS + low nitro fuel
« Reply #3 on: 25, September 2017, 09:27:25 AM »
An update.


Well I never bought the 185 Zero as a I discovered a virtually new 170 CDi back at the parents place. This is an early 170CDi without the cut out in the head to accommodate the spark plug cap unit. Anyway, I was running it on CDi for a short while back until March but the spark plug cap never located that well on the plug so predictably it wore out pretty quickly. I have a 120 degree spark plug cap unit but I've not used it yet. I went back to glow and it ran superbly so I just left it like that at the end of March. Fast forward to last Saturday and I flew it again on 17% nitro (not sure how I ended up with that percentage, but I did). Ran great. Went to a comp the next day but unfortunately I had no more 17% left only 12% nitro which I'd been running when on CDi. Anyway, I had an engine cut on the first flight at the end of the first manouevre. The next three rounds I upped it to 30% and it was superb. With that in mind and after tinkering with various 170 and 175 CDi engines on glow and spark I've reached the following conclusions:


On glow you basically need 15% unless running high compression (Zero spec). Running higher nitro makes a massive difference to the power and I do mean massive.


On CDi you can run them on 0% nitro but the main jet settling becomes extremely critical. For ease of use and slightly more power you are really looking at using 7.5% nitro and above. As with glow, running higher nitro does make a massive difference to the power.


At some point I will step up to the 185 Zero but I still have a new 170 here and Adrian's 170 CDi which has also seen little use so it probably wont be for some time.