Rossi 91 A Run

Another of the engines my friend Chris has loaned to me to run on the channel. APC 14x6, Cool Power 10%, OS A3 and OS #8 plugs.
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[@frisk151]

Wow! You just brought back some serious memories... I had a Tiger Tail 4 with either a Rossi 61(?) or a 91, rear exhaust and tuned pipe from back in the mid 80's when I was a kid.. It never ran well, probably because I was really young at the time and on a limited budget... It came from the Nats in Louisiana in 86', by Ron Chidgey (sp?) (designer of the Tiger Tails) himself.. Regardless.. When it was on the pipe, the power of the Rossi was incredible.. I had a Byrons originals ducted fan F-16 I eventually tip stalled.. That hair drying ducted fan Rossi .91 gave up the ghost at least 1/2 the time, and I tried to nurse it back to the runway too many times.. I'm no Dubb Jett (though I own a number of his engines still), but I think the carb was a problem.. Theory on my part.. I was about 12 years old.. And, I don't think we had #8's available back then.. I always flew my nitro helis with OS #8's.. I almost certainly couldn't afford a strip or sheet of OS 8's back then.. Thanks for sharing!!!

[@frisk151]

P.S. Do you or anyone know exactly the range in props and pitch for this engine? I realize there is no tuned pipe, where mine always shined in Q500 pylon racing and even the ducted fan jet... I could be completely wrong, but I thought it was actually peaking closer to 13k.. This one also sounds pretty rich, and based upon comments about unburned fuel (legit sign) splattering arms / hands / whatever behind the muffler.. I am going to go back and be direct now that I finished watching and your comments / conclusions.. The Rossi truly was a beast.. However, I NEVER found a comfortable median trying to tune them.. It is like they were built for wide open throttle.. You lean it for it, with a bit of richness for when it really starts to unwind, but my experience with Pattern airplanes where you actually need the smooth and good throttle management across the range.. Yeah, Rossi sucked.. They were not cheap either, even back in the late 70's thru mid 80's... I don't have one any longer, but if I did, I might try to see how I could make it perform today.. IN ROUTE to me burning it up and throwing it away...

[@user-pd4bo1ts7n]

Thank you David for running lots different engines. This is the best medicin for me since i can’t run my engines due to hand surgery. So your efforts help me a lot. Br from Sweden.

[@mikewilliams9715]

I do like the way a Rossi sounds so happy to be running. Have a couple 45's one has the original tuned muffler, the other I did some work on the ports. She's a screamer with a tuned pipe and a 9x7 prop.

[@weofnjieofing]

I think that muffler is less than ideal. The original Rossis come with a black tuned muffler and would respond well to a smaller prop within the mufflers tuned range. At least you gave it a go David and agree it’s nothing I’d want to spend any time or money with

[@Irvine7214x6apc]

My Irvine 72 peaked @ 10,250 completely stock with the very same APC 14x6 prop... without the head gasket (for increased compression) and the exhaust baffle, it now peaks over 10,800 rpm... and it's a 72. Somewhat disappointed from the Rossi 90 - nice running for sure, but.. not that powerful?

[@chrisross7936]

I feel the same way you do about it David. The 14x6 might be better with an appropriate tuned pipe set up?? I may try an 11x8 or a tuned pipe in the future to see if it livens it up at all. It weighs as much or more than some 1.20 size engines so my expectations were definitely not met , at least with the 14x6 anyway. Nice run nonetheless!

[@Caninaracingatodovapor]

I agree, I think with that prop the engine don´t reach the best of the powerband. A smaller one maybe can allow it to jump up 2k rpm

[@donrichter3523]

Yup, a pedestrian ST 90 could spin at least that fast. In fact, I think a 75AX could as well.

[@luisgarza2036]

Maybe this engine is a long stroke compared to other engine designs, for a 91 2 stroke it's HUGE and possibly heavy for today's standards.

[@johnsonwayne9279]

Can you put a muffler on it?

[@dmrcflyr2]

It has a bisson muffler on it