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15% vs 20% nitro fuel

Old 07-16-2018, 12:59 PM
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dbeeler
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Default 15% vs 20% nitro fuel

I have searched the forum for information on this question with no luck. I own a Saito 90 and a Saito 100. I have been using Powermaster 20/20 glow fuel in both with great results. If i remember correctly it is recommended for those engines. I am now finding it difficult to purchase that fuel but find 15% Powermaster more readily available and a bit cheaper too. has anyone "switched" to a lower nitro content in their Saitos? Does the power change much? Do the engines need to be retuned? Is 18% oil sufficient? I appreciate any help. BTW my flying field is approx 2700 feet above sea level. Thank you in advance.
Old 07-16-2018, 06:24 PM
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Hobbsy
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I use nothing but 10%, Saito's can benefit from higher nitromethane content, but they certainly don't need it. They run really well on 5% also. I personally have never tried 0%. Many folks in other countries use 0% with no issues.
Old 07-17-2018, 09:58 AM
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1QwkSport2.5r
 
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Almost all engines will run without Nitro in the fuel at all. The compression ratio can be raised to get the most benefit and in some cases, get very similar power levels as using a modest amount of Nitro in the fuel. I think the magic number for no nitro fuel is 13.5:1.
Old 07-19-2018, 06:20 AM
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r ward
 
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the power developed between 15 and 20 percent may be measureable with mechanical means, but I doubt you would notice it in real terms while flying .
Old 07-19-2018, 08:22 AM
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1QwkSport2.5r
 
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Originally Posted by r ward View Post
the power developed between 15 and 20 percent may be measureable with mechanical means, but I doubt you would notice it in real terms while flying .
Right. Ive noted on average a 200rpm difference for every 5% Nitro added to the fuel.
Old 07-22-2018, 06:04 PM
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JPMacG
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I run my Saito 72 and Saito 100 on 10% nitro with 18% oil. They run great. I have not noticed a difference between 10% and 15% nitro, but I do think I get a better idle on 18% oil than I do on 20% oil.

Last edited by JPMacG; 07-22-2018 at 06:08 PM.
Old 09-25-2018, 10:30 AM
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Hi I doubt that you will notice much change. Maybe a little less prop and you will have to lean it a small amount maybe quarter turn on the needle.
Old 09-26-2018, 04:57 AM
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I run home brew 14% synthetic oil, 2% castor, 14% nitro. In the past I have run Saito engines on zero to 30% nitromethane. Finally settled on the 14% as a good all around fuel for engines from the 30 single to the 170 R3 radial and the 182TD twin.. They all idle well, transition well and make excellent power. Needle settings are easy too.
The nitro affects the entire range of engine operation, not top speed alone. It can improve idle as well as transition. The 10% to 15% range usually provides the best results for the money at the idle and transition while top end improvements show up with the 20% to 30% cans. BTW, Make no mistake, a Saito can really sing with that 305 dose of nitromethane .

You will do just fine with 15%.
Old 09-26-2018, 05:25 PM
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the Wasp
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more Nitro more power, that's the concept LOL, I have been flying Helis for almost 20 years now, and 1 thing that I like about using higher percentage Nitro is, that the higher the Nitro percentage is the tighter/shorter the tuning envelope becomes, it's more noticeable so tuning is easier to feel and hear when tuning, but you will find that is more noticeable with 2 Strokes than is with 4 Strokes,, the best way to test this is to first use a given percentage of nitro such as 5%, then test by going up in Nitro by 10% or 15%.. never the less, 15% is a good choice for planes,

you will have to lean your needle more when going down in Nitro..

Jim

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