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Engine basics => Engine set up tips => Topic started by: big ron on July 28, 2015, 07:42:43 PM
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What is the size of the bore on a 20fp venturi
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What is the size of the bore on a 20fp venturi
6.5 mm/0.257"
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Thanks
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Also is the thrust washer on a 25la the same as the 20fp
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You might try a 6mm venturi. I used a 6mm on a 25FP last weekend. Mounted on a Ringmaster on 59' lines, I was getting 5.3 second laps with a perfect 2-2-2 run.
http://stunthanger.com/smf/index.php/topic,40075.0.html
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You might try a 6mm venturi. I used a 6mm on a 25FP last weekend. Mounted on a Ringmaster on 59' lines, I was getting 5.3 second laps with a perfect 2-2-2 run.
http://stunthanger.com/smf/index.php/topic,40075.0.html
It might well be a good idea because even a 20FP is too much power, stock, for a Ringmaster. 6 mm might be a bit small for the 20, however. You need a smaller venturi on the 25 than the 20, since you can get more air/power through it with 25% more displacement, and you can't possibly use the full power of the 20 or 25 on a Ringmaster. We tried the 20, and running correctly with all the stock parts and an APC 9-4, it goes about 3.8 sec/lap on 60 foot lines.
Brett
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We tried the 20, and running correctly with all the stock parts and an APC 9-4, it goes about 3.8 sec/lap on 60 foot lines.
I'm going to have to try mine again now. It didn't seem that fast to me, but when I built it I was in the habit of going pretty quick.
Brett probably knows better than me, but on the bigger engines you can get the same effect of a smaller venturi by piling layers of nylon mesh onto the venturi intake. This allows you to tune the "venturi size" fairly easily at the field when you're getting a new plane dialed in.
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Also is the thrust washer on a 25la the same as the 20fp
If you mean the drive washer, not the thrust washer, the answer is NO.
FP drive washer outer dia is slightly larger than LAs. This is the reason why APC 10 inch prop does not fit well on LA25.
Aki