Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Engine timing..

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Old 09-10-2007, 02:04 PM
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Destiny-RCU
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Default Engine timing..

I'm looking for some timing specs on other engines (performance and sport engines). I have a fresh rebuilt TT .40 that i'm breaking in and I would like to do some small mods to it soon.

I've done a lot of reading on understanding how all they work, pipe timing and such. But I don't have any real numbers to go by?

I know some people say it's not worth tweaking an engine and I totally understand. But for a sport plane (viper) i'd like to do some testing for fun. Anyone have some numbers or a range I should stay in. I know raising the enhaust timing will help with the pipe but how much?....Thank you any info/ pointers would help.

Russ
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Old 09-10-2007, 02:17 PM
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NikolayTT
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Default RE: Engine timing..

Not only rising the windows, the gas-diagram is very different as far as I know for resonance tube and plain tube
in many parameters and mostly in the time segment the intake is open when the ehxaust is open too - to get
the resonance tube participate in the Fuel mixture "travelling". Do you see that on your TT and is that one good
for resonance tube or you do not want to use such one ?

Here are couple links you might enjoy:

1. Engine tuning:

http://www.bimotion.se/

and also

2. Resonance tube design:

www.mh-aerotools.de/airfoils/javapipe_en.htm

What have you been reading would be interesting to me at least;
please post some links and titles with some comments on them.

Regards,
Nick
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Old 09-10-2007, 09:11 PM
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Default RE: Engine timing..

Crankcase volume displacement ratio and proper port shapes might even be more important than timing.
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Old 09-11-2007, 12:39 AM
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Default RE: Engine timing..

some heli guys grind out the corners in the intake passage. Hard to change the crankcase volume tho would like to see that done too. Maybe CF to fill up the void under piston?

Clement
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Old 09-11-2007, 03:37 PM
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Default RE: Engine timing..

Well I already have plans to do some back to back testing after each change. i'll start out with cleaning up the ports and radius the bottom edges. I am thinking of playing with head shims, Nitro, and plug ranges too see the difference with that. Also have the Jett Stream muffler to add into the mix. Maybe clean up the carb/ crank entry, and raise the exhaust timing is about as far as I know to do.

Filling the crankcase could be an option. Not sure what to use and or where to put it.
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Old 09-11-2007, 08:42 PM
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Default RE: Engine timing..

Clementang, The Cyclon .15 has a backplate that the skirt of the piston actually dives into! There is a semi-circular slit [in the backplate] that the piston skirt passes into. The backplate practically touches the back side of the rod.The transfer port side of the piston skirt in some engines is ground away to unshroud the transfer port, it makes the route for the intake charge less of a sharp angle. This mod alone has done me more good than any other type of porting. Increasing stroke in a same size case increases the crankcase volume change, which really boosts pumping action. You have to maintain good rod length to stroke ratios, though.
I have only applied this idea to stuffing a .061 crank into a .049 case.......I'm not quite ready to cut my own stroker crank for a .40 yet. I guess Nelson already has?
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Old 09-12-2007, 12:22 AM
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Default RE: Engine timing..

talk about extreeeme...
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