View Full Version : twin engine HPI RS3 ... throttle linkage
bobfish
01-05-2011, 05:53 PM
Hello there fellow RC'ers
I'm part way through my twin engine HPI RS4 build, and I've hit a snag...
How does one go about hooking up the trottle linkage on such a small car? Having two servos adds weight but having split throttle linkages zig zagging across the car gets complicated :thumbdown: WHAT DOOOOO?! lol
tl;dr: has anybody got pictures of twin engine cars with detailed throttle linkage so I could steal their ideas?
Also its going to have a savage fuel tank!!! EXCITED.JPG!
dodgydiy
01-05-2011, 10:11 PM
rotary or slide carbs??? the twin engine dragster i made used rotary carbs, twin engines side by side running front to back. i used two 90 degree idler arms so there were straight linkages running across the car with one link straight back to each carb, room wasnt a problem so it was easy on mine to do this. dont have any pictures i am afraid.
bobfish
02-05-2011, 10:54 AM
rotary or slide carbs??? the twin engine dragster i made used rotary carbs, twin engines side by side running front to back. i used two 90 degree idler arms so there were straight linkages running across the car with one link straight back to each carb, room wasnt a problem so it was easy on mine to do this. dont have any pictures i am afraid.
thanks
um well i havn't exactly got the engines yet. i have enough engines but i understand that they both need to be practically identical? you cant use one older engine and a newer one. so im going to buy the engines myself once ive worked out how im going to go about the throttle.
however the engine i use at the moment is a hpi pro 12 xs which has a slide carb :/ which makes the throttle harder to set up. especially as the break connection is right between the two carbs.
i was thinking of using two rotary carbs with opposite rotations so just have a servo in the centre that pushes one and pulls the other at exactly the same amount. although the problem with that is the servo has to be mounted exactly in the centre ... where the driveshaft is :/
what engines did you use?
bobfish
02-05-2011, 10:55 AM
... * brake
not break ... :blush:
dodgydiy
03-05-2011, 11:46 AM
the engines i used were both os 12 czz's. i dont think engines being identical is that important, same make and model yes but you will never tune them to be the same. if you want it to take off well without losing too much traction set one of your clutches softer than the other although with 4wd you might not need to do that. the softer clutch doesnt let the engine spool up quite so quickly, two coming in the same just sent my creation sidewards. you know it could be fun rebuilding it.......
westie
03-05-2011, 05:47 PM
Two servo's using a Y splitter?
bobfish
03-05-2011, 09:18 PM
the engines i used were both os 12 czz's. i dont think engines being identical is that important, same make and model yes but you will never tune them to be the same. if you want it to take off well without losing too much traction set one of your clutches softer than the other although with 4wd you might not need to do that. the softer clutch doesnt let the engine spool up quite so quickly, two coming in the same just sent my creation sidewards. you know it could be fun rebuilding it.......
my understanding was that if you dont have them tuned perfectly together one engine takes all the work and the other over revs and can throw a piston because there is no load on it?
although your idea with the clutch is a good one...
also person below me the problem i have with using two servos is that it is a 1:10 car and space is extremely limited.
http://www.sciuridae.co.uk/big_boys_toys/images/clean1.jpg
thats a pic of the model of car that ill be using. as u can see there is no room at all.
to the left of the current engine there is a battery compartment which i have cut off and ill just stick the batteries to the front or something. lol
and where the current fuel tank is ill bodge in a savage tank :woot: and split the fuel and exhaust tubes
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