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7/12/2014 6:34 am  #1


upgrading power for no bar

I have a reasonable no-bar, 1.123 in 1/4 mi, Mura old school single gp20, 1 3/16x.300, 162 gms; Drag radial car. I wanted to ramp up the power so i put a boss 490 in it 10/60  gears; bottom line, it was hopping badly off the line & slower. Another 12 grams weight did not enough to stop the hopping, & it was still slow... Now I am thinking the boss is for bar cars & I will try a neo with a big pinion in this car.

Other alternative is to rebuild a quad with a MM20 arm. Thats a lot of work; will have to order a slug, don't know what size, also glue bb into eb, order new copper eb hardware, but may be the better option as opposed to the easy neo bolt-in with its explosive power... any thoughts, trying for 1090 with this one. BTW current weight with boss is 175 grams.  

Last edited by Macman (7/12/2014 6:36 am)


Formerly of SARN
 

7/12/2014 7:29 pm  #2


Re: upgrading power for no bar

Hmmmm....  I would think a single magnet 20 motor should be more than enough to push a 175 gram car into the 1.090 range.... 

Here's a question for you....  Is your no bar car solid or slip joint?  Ok, I lied, I have another question...  Why is it so heavy?  Where is the weight placed?  All on the nose?

 

7/12/2014 8:11 pm  #3


Re: upgrading power for no bar

A car that hops near the start is too flexible. I would go more in the direction of a S16 or grp15 motor, and take some of the weight out of it. All that power and weight is flexing the chassis too much to work early in the run. A 175gr car with .300 wide tires isn't going to stop very well either.

I would also use a .530-.535 airgap to soften up the launch on a ceramic motor.


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
 

7/13/2014 9:57 am  #4


Re: upgrading power for no bar

http://i1267.photobucket.com/albums/jj558/Ben_Kernan/no-barupgrade1.jpg
Here is top view of chassis #175 grams, prior to adding .032 plate ahead of guide to hold more weight. Main rails are 2 parallel .055 piano wire, WRP kit.
Could add a third rail on each side, with an additional "package tray" behind rear tires for additional weight. I didn't want to pile up more weight in center of chassis, so thought more up front would be more effective, at the end of the fulcrum... up to 193 now, & changed to VR20... Starting to come around; looking for low to mid 10s.


Formerly of SARN
     Thread Starter
 

7/13/2014 10:14 am  #5


Re: upgrading power for no bar

I would not recommend adding weight behind the rear tires of any slotcar, even if it had wheelie bars.


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
 

7/13/2014 10:45 am  #6


Re: upgrading power for no bar

I would go with a larger pinion gear and smaller crown, like 15/40-2 or 16/40-2, that's what I've used in my no-bar cars.. No launching problems and drove smooth down the track, and probably less weight too.

  DVan


"Where legends are made and records are broken".
 

7/14/2014 2:51 pm  #7


Re: upgrading power for no bar

take and cut  2 pieces of weight goop(glue) to side area between axle bushing an motor mount plate , take cut parts off that big center chunk to put on each side of the guide ,then a hunk in the body low as possible behind the grill, change gear ratio to what DVan said , lighten to 150 -160 ... 

 

7/20/2014 9:09 am  #8


Re: upgrading power for no bar

/goung to move weight to motor bracket, already added weight to nose. changed motoe to VR-X, got a fastest run of 1.007, un repeated, also 1.040, both below track record ,1.050 with a 212 gm car. Drag radial heating up! currently geared 13 /48, going to bump it to a 14 to soften launch.
http://i1267.photobucket.com/albums/jj558/Ben_Kernan/720no-bart-bird.jpg

 


Formerly of SARN
     Thread Starter
 

7/20/2014 10:32 am  #9


Re: upgrading power for no bar

http://i1267.photobucket.com/albums/jj558/Ben_Kernan/720nobartbirdnose.jpg

Thinking of adding strips of .062 brass to nose beside braid both to add weight, & to raise front body mounts. Chassis is $10 WRP with 2 rails of .055. may have to add splitter to this car later...


Formerly of SARN
     Thread Starter
 

7/23/2014 8:43 am  #10


Re: upgrading power for no bar

start thinking more aerodynamics ,getting fast enough to lift down track , weight is the enemy and  what you have to balance between front and rear

 

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