POLINI THOR 250

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Mark Roberts

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Joined
Apr 19, 2021
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9
I am about to buy a Polini Thor 250 engine for a puller style ultralight. From everything I have seen it seems like the engine should work but does anyone know of any problems with that engine that I overlook. Thanks
 

Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
Armilite is 100% correct here; common sense tells us running ANY high performance engine at its maximum possible power level for any length of time is going to shorten its lifespan a lot.

It must be understood that the people writing the brochures for these engines are part of the sales department, not the engineering department. The Polini, Simonini, and probably other hi-po 2-stroke engines will probably make their 36HP as advertised, but the engines were designed for a "duty cycle" that is nowhere near 100%. I have no experience in paramotoring, but the videos I have seen SEEM to indicate that they are flying around at cruise power after takeoff, not "wide open throttle".

When we translate this from sales language into aviation language, what it means is that the engine is safely rated for 36HP for takeoff and maybe a minute or two, then the "maximum continuous power" from that point onwards has to be accepted as something less than 36HP.
 

billyvray

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Aug 17, 2005
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848
Location
Newnan, GA
They are good looking engines. Polini has a LOT of experience in the high performance scooter market (don't scoff, some of those things FLY!), but I agree, scooter duty vs airplane at WFO throttle alot of the time is not great.
 

Bille Floyd

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Joined
Sep 26, 2019
Messages
469
Polini Thor , has a Very good reputation ; for building dependable
ultralight aircraft engines. They even go so far as to tell ya, how
much time, each component in the engine ; should last, under
normal usage.

Bille
 

cgifly2

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Feb 27, 2005
Messages
30
Location
so cal
Good advice! Always try to use an engine thats rated for 1/4 more hp then you need. So at cruise it is at 3/4 of its maximum output. Especially 2 strokes. I am a definite proponent of 2 strokes and have successfully flown behind them on that principle for many trouble free hours. I use as an example my Hummelbird that I flew with a McCullogh engine rated at 72hp @4200rpm. The Hummelbird flies fine on a 36hp half VW but must run at or near full power. and there are plenty documented engine failures. Not that the Mac has a perfect record, but most 2 stroke failures are traced back to quitting under full power or right after being run full power and having the throttle shut off creating a lean condition. But I ran the Mac at 3800rpm cruise without taxing it and never had a problem. Point being never plan on needing a 2 strokes maximum output and you will good!
 

Flyguyeddy

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Mar 28, 2020
Messages
84
Good advice! Always try to use an engine thats rated for 1/4 more hp then you need. So at cruise it is at 3/4 of its maximum output. Especially 2 strokes. I am a definite proponent of 2 strokes and have successfully flown behind them on that principle for many trouble free hours. I use as an example my Hummelbird that I flew with a McCullogh engine rated at 72hp @4200rpm. The Hummelbird flies fine on a 36hp half VW but must run at or near full power. and there are plenty documented engine failures. Not that the Mac has a perfect record, but most 2 stroke failures are traced back to quitting under full power or right after being run full power and having the throttle shut off creating a lean condition. But I ran the Mac at 3800rpm cruise without taxing it and never had a problem. Point being never plan on needing a 2 strokes maximum output and you will good!
I bet that was a LOUD bird
 
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