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Speed,Combat,Scale,Racing => Combat => Topic started by: Dennis Toth on April 02, 2013, 01:27:34 PM
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Guys,
What is the recommended engine venturi size for a 35 size engine when using crankcase pressure into a hard tank? I seem to remember you couldn't get them to run right with the same venturi you use for conventional suction.
Best, DennisT
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Dennis ,what 35 are u talking about , the small venturi should work fine .if you are having trouble with settings it is probly the needle valve we used to run K&B 35's in pressure with the standard K&B ratchet needle valve with as big a hole as we could get in the pressure fitting and had no trouble with settings, we didnt know any better .now they run a .010 hole which to me seems to be harder to set Bob
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There's no set answer for your question, but let me suggest this:
Assuming your engine ran OK on suction with a .275 venturi, I would say that going up to about .320 would give you the power boost that pressure allows. Lots of people have gone bigger. Beyond a point the engine is sucking all the air it can get and a bigger hole doesn't bring in any more.
In F2D they reduced the venturi from "wide open all you can get" to 4 mm and the speed didn't come down all that much.