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Old 07-12-2008, 08:56 PM   #1
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Default Percentage of Nitro

Looks like this summer is time to get a new .12 engine. I'm looking around. I'm thinking either Novarossi 353, Murnan modified Nova 353, or the JP Eagle. While I was on Novarossi's web site getting data I noticed that Novarossi says this regarding the 353:

Fuel recommendation: This engine has been developed to be used with a fuel with a maximum of 16% nitro content and with an oil percentage not lower than 7%. We therefore suggest not to use it with different percentages compared to the ones specified here above.

The track where I run everyone uses 25 percent and I've always used that. I wonder, if I dropped to 20 or 16 percent would I be at a disadvantage? I thought using more nitro gave you a cooler engine and more punch? Or, could I simply tune my engine and more or less get the same power (and lap times) with a lower nitro content? What would be the advantage of using 16 percent as Novarossi recommends??

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Old 07-12-2008, 10:01 PM   #2
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They are set up for 16 because that is the max legal limit in most of the world. It should run fine on 20. 25 you might want to add a head shim to be safe but I have run them on stock head clearance before without problems. 30 definitely add a shim.
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Old 07-12-2008, 10:10 PM   #3
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What would be the advantage of using 16 percent as Novarossi recommends??
Lower nitro content = longer engine life
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Old 07-12-2008, 10:14 PM   #4
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i did not have these engine (353 etc)so i can't comment but i down from 25% to 20% on my MAX C5 and OS Speed II, no big difference compare to others engine at track running 25% and i'm running both with stock shim.
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Old 07-12-2008, 10:15 PM   #5
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Originally Posted by rocket-mtrsprts View Post
Lower nitro content = longer engine life
Personally I don't find that to be true. The motors I run on 30 last just as long as the motors I run on 20. With proper care they do fine either way.
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Old 07-13-2008, 02:56 AM   #6
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Quote:
Originally Posted by rocket-mtrsprts View Post
Lower nitro content = longer engine life
If you run an engiine on 25% which is normally setup for 16% then what you are saying is true. If you do re-shim the head to the right nitrocontent then nothing will go wrong.
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Old 07-13-2008, 03:35 PM   #7
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In the States we use 25 and 30 percent all the time. I run the 353 Nova and use 25% with a shim amount of .5. It works great with this setting at sea level.

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Old 07-13-2008, 08:48 PM   #8
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Quote:
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In the States we use 25 and 30 percent all the time. I run the 353 Nova and use 25% with a shim amount of .5. It works great with this setting at sea level.

DJ Apolaro
DJ, when you say .5 do you mean a .5mm shim added to the standard shim that comes with an engine? On my JP FX-12 engine it came with a silver shim under the inner head. Do you add another .5mm shim to it? Or the total shim thickness is 0.5mm for all shims added together?
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Old 07-13-2008, 08:54 PM   #9
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I believe he means .5 total but since I don't have a 353 I would let him say for himself.
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Old 07-13-2008, 09:56 PM   #10
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Yes .5mm total.

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Old 07-14-2008, 06:20 AM   #11
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Default shim on 353..

Quote:
Originally Posted by dj apolaro View Post
In the States we use 25 and 30 percent all the time. I run the 353 Nova and use 25% with a shim amount of .5. It works great with this setting at sea level.

DJ Apolaro
hi, i run a 353 with the standard head shim of 0.3mm here in Asia with 25% nitro fuel..

was contemplating on whether to add another 0.1mm but did not in the end.. after 1 race, i open up my engine head, notice all ok and not pit marks on the head (no detonation also..).

guess it's ok then not to add shim ? ... what you guys think ? ...

thanks in advance..
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Old 07-15-2008, 04:56 PM   #12
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adding a .1 shim would give you a bit more top end / rpm with slight decrease in bottom end.
I have been running all my .12 motors between .35 - .45 total clearance.The larger clearance on larger flowing tracks and at altitude.
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Old 07-15-2008, 05:09 PM   #13
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any ways to tell if u added too many shims? what's the effects?

i'm been using 0.4-0.5mm of shims for my engines with 25% nitro; sea level.
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