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Old 09-18-2014, 03:43 PM   #1
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Default Tips on running 40% Nitro

Hey guys, can someone help me with an optimal set up for one of my spare Novarossi .21 engines I want to try 40% in for a few quarts or so just to try. What should I do. Its stock now, so should I add .2 of shims and go to a colder plug? Could I get away with running an OS P4 plug? I have to run OS plugs for now cuz thats what was run in it last.
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Old 09-18-2014, 04:51 PM   #2
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Try it as it is but richen the fuel blend.
Adding a 0.2 shim is not the best way to lower the compression and can actually make the engine detonate if the distance between the piston top and head at TDC is too big.
The squish band should be as small as possible to keep squish velocity up.

The squish band is outermost area of the head button (the 'ring' that looks almost flat, it's usually slightly angled towards the center of the head button).

Start with a colder plug and go up in heat. Run the hottest plug possible for best power.
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Old 09-18-2014, 04:57 PM   #3
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Quote:
Originally Posted by SManMTB View Post
Try it as it is but richen the fuel blend.
Adding a 0.2 shim is not the best way to lower the compression and can actually make the engine detonate if the distance between the piston top and head at TDC is too big.
The squish band should be as small as possible to keep squish velocity up.

The squish band is outermost area of the head button (the 'ring' that looks almost flat, it's usually slightly angled towards the center of the head button).

Start with a colder plug and go up in heat. Run the hottest plug possible for best power.
So what other way can he lower compression (which needs to be done) without changing the piston (which isnt going to happen)?
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Old 09-18-2014, 05:09 PM   #4
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The best way is to use a lathe to machine the button a bit but that's not the answer anyone really wants to hear... right

0.2mm is actually quite a lot to go up. Try a 0.1mm shim.
To squeeze as much power as possible and to get the engines to run the best the 'hard' way of doing it is the best. But, for a test.. OK try 0.1mm.
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Old 09-18-2014, 05:59 PM   #5
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Okay great replies guys thank you!!
So if I do everything properly and tune it well, will I still see good engine longevity with 40%?
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Old 09-18-2014, 06:17 PM   #6
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It's impossible to predict engine life but it surely won't go from 100% to 10% (unless something breaks). Running 40% means the engine can burn more fuel since nitro contains oxygen. More fuel burnt also means the engine will actually get more lubrication.

Rule of thumb :
More power generated --> less life
More rpm --> less life

An un-optimized engine running 40% could make the same amount of power as an optimized one running 30%. To take advantage of 40% and make the most power it takes a bit more than adding shims. Just saying it will not necessarily make more power because there is more nitro in the fuel.

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Old 09-18-2014, 06:29 PM   #7
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Yes, but it will run stronger through and through so hopefully its more reliable
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Old 09-18-2014, 07:07 PM   #8
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Can't say really

I think it's fun to try to get as much power as possible and test new things, but hey that's me. Just be cautious and use good judgment and have fun.
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Old 09-18-2014, 07:53 PM   #9
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Well, what do you think I'm trying to do? I just realized I still have 3/4 of a case of Werks 30% still. Looks like ill be using that up first LOL
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Old 09-18-2014, 08:48 PM   #10
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Oh, In that case........

Just pump it full of 40%, richen up and go.
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