stunthanger.com
Engine basics => Engine set up tips => Topic started by: bob werle on January 26, 2011, 12:40:37 PM
-
I have a couple of older Super Tiger .15 yhat came from a combat flyer. I would like to try them on a smaller stunt trainer but not at combat speed. Can I run them at their normal rpm but use a low pitch prop to control lap times? These are great little motors and I would like to use them but my reflexs will not handle the speed.
Bob
-
I have a couple of older Super Tiger .15 yhat came from a combat flyer. I would like to try them on a smaller stunt trainer but not at combat speed. Can I run them at their normal rpm but use a low pitch prop to control lap times? These are great little motors and I would like to use them but my reflexs will not handle the speed.
Bob
Yes I would suggest using a larger diameter low pitch prop than you would normally, That along with low nitro fuels should do exactly what you wanting
You can also stay away from very short lines.
Randy
-
I built a Ringmaster-Light with a OS 25 engine. It was too fast. Instead of running the engine out of its intended fast 2-cycle, I just reversed the prop. The resulting inefficiency slowed the speed just right.
Sometimes the obvious solution is the best. (Ocam's Razor)
Floyd
-
Hello Bob,
I did just that a few years ago, I had to increase the diameter by about 1.5" and I think I used a 4" pitch prop, worked like a charm! As F ~> ~>loyd says Occam is usually right!
Regards,
Andrew.
-
Makes sense to me: if you have power but don't want to go fast, shift to a lower gear. Bigger diameter with lower pitch gives less speed and more grunt for going uphill.
-
I thought about the lower pitch but didn't think of the larger dia. Now I know why I comr to this forumn. The information is always there for us poor old retreads.
Thanks again
Bob
-
"Can I run them at their normal rpm but use a low pitch prop to control lap times?"
Well considering that these engines had their 'normal' peak power rpm of 22 000 when using a 7X4 prop, how low does the pitch have to go with the diameter increase to keep it in that rev range?
I mean is there any 8X2/3 prop or similar that would allow those kinds of engine speeds?
I think that much will have to be sacrificed in order to tame the beast down.
-
I have a couple of older Super Tiger .15 yhat came from a combat flyer. I would like to try them on a smaller stunt trainer but not at combat speed. Can I run them at their normal rpm but use a low pitch prop to control lap times? These are great little motors and I would like to use them but my reflexs will not handle the speed.
Sure, that's about what everyone else has been doing for the last 20 years. Most of the magic of piped engines is in the 3.5-4" of pitch you run. I don't know which engine you are talking about - a g20/15 will work OK doing this, I expect, if you put in a small enough venturi to draw fuel.
Brett
-
I used to use ST.G20/15's in combat and had venturi's made for them with larger intake hole, I also tried drilling them out and several I used like that because those combat engines were used with bladder pressure,they were originally fitted with suction size venturi's. have you tried to run them on suction it may not work too well. The same thing with the ST. G15 goodyear engine (rectangular venturi) that was run on crank pressure I believe. After a few years I changed to using Rossi15's and never looked back.
Reason for this post is you might find you need different venturi's to run on suction. Good luck those were really good engines and easy warm starters.
-
I used to use ST.G20/15's in combat and had venturi's made for them with larger intake hole, I also tried drilling them out and several I used like that because those combat engines were used with bladder pressure,they were originally fitted with suction size venturi's. have you tried to run them on suction it may not work too well. The same thing with the ST. G15 goodyear engine (rectangular venturi) that was run on crank pressure I believe. After a few years I changed to using Rossi15's and never looked back.
Reason for this post is you might find you need different venturi's to run on suction. Good luck those were really good engines and easy warm starters.
Hi Richard,
I think your tips are needed. The proper venturi will definitely be necessary to get the engine to run right, speed wise, regardless of props used. ;D
I don't have a clue as to what size would be good for those engines.
Big Bear