Smokin240sx

IN AN RC DRIVER MAGAZINE I JUST WENT ON THE RC DRIVER WEBSITE BUT THEY DIDN'T HAVE THE JAN ISSUE SORRY[]

peggerbuilt

HI. I'm relatively new to the nitro sceene, but I have exstensive knowledge in the automotive and aviation engine departments. Reading through this thread someone stated that you could raise the compression by removing one or two washers from the head. That would indeed raise it. Someone else brought up the detonation issue. My experience with gasoline engines is that when you raise compression you must also raise the octane rating of the fuel to prevent detonation. So the question I have is if you do remove one or two of the washers from the head why would you not want to run the 30% nitro. Seems to me that if you didn't, you would run the risk of detonation.
[quote]ORIGINAL: smallblock

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Frost_

My Feedback: (1)

You have it backwards.

The nitro-methane is very volatile. The addition of more nitro actually has the effect of 'advancing' combustion (relate it to spark-timing). You know what happens to an engine when the advance curve is too steep, or especially when it tops out at too many degrees of advance. The nitro-methane is somewhat oxygen-bearing. When thinking of comparable items in real engines think of the timing retard neccessary to control the combustion of a forced induction engine (turbo, nitrous, supercharging) which forces a more stout and volatile mixture. Raising nitro % has the opposite effect (to a degree) of raising octane content. Raising octane helps control over-timed and/or high compression/forced induction combustion because it's flashover is later than lower octane fuel, but raising nitro increases the rate of combustion and flashes sooner.

Frost_

My Feedback: (1)

To relate to you a bit further... when I switched from 20% to 30% a very curious thing happened; I realized what it was and why it happened immeadiately, but was suprised by it nevertheless...

After a few beers or something (who can say) I refueled the Savage almost immeadiately after a run. For no reason that I can now cite, I reached down and snapped the pullstart (engine still at 200 or so degrees) and the engine FIRED RIGHT UP WITH NO GLOW PLUG HEATER/IGNITOR... I have never seen this happen with 20% or lower... Perhaps I should video it. Amsterdamn witnessed it as well, he could attest the same...

AJ DRAGON

Hi

Myself I'm running the Tower Power 15% Premium, and my engine runs like a raped ape. As soon as I can get the money saved up I'm going to get the Tower Power 25% Premium.

Richie-EB4

I run Tornado 20% because its all my LHS has in stock..........or MT 16% []

peggerbuilt

Thank you for clarifying. That makes sense. So im guessing I should stay with the 20%. I recently put together an SS and its not fully broken in yet(didn't have time before the snow hit I HATE SNOW). The manual says the needles are preset from the factory for break in. It also states that it is set very rich for this process and you should see "a heavy trail of blue smoke when accelerating". I'm using O'Donnel fuel which to my understanding is full synthetinc. The thing that concerns me is that for being set to run very rich I really don't see very much smoke coming from the pipe. Is this due to the fact that the synthetic blend requires less oil to maintain the same lubrication as petroleum based products or is it because of the colder more dense winter air is causing it to run some what leaner than a "normal break in condition" which would have warmer more humid and less dense air? If so I should probably richen it up a bit huh.

Frost_

My Feedback: (1)

It's the density of the air, given it's temperature... I ran my truck (from a tuned 68degF) on a 32 degF day recently and had to richen it up quite a bit.

Also to the best of my knowledge there is no petro. lubes used. Castor oil and synthetics are all I know of.