motionmachine

Its going in a H-2 custom project of mine, Heres what I got.
rc weight RTR- 15 pounds
wheels/tires- 18.5" roll out
f/r axle ratio- 3.25/1
tranny ratio's- 6.25/1 first, 4.25/1 second, 2.89/1 third


I want ballistic bottom end power, thus the 6.25/1 first gear. Im certain the 2 stroke will like it but the 4 stroke may be a bit undergeared and tach out quickly.
I can adjust the shift points to suit either engine.
The 4 stroke will like the gear changes but the 2 stroke may lack the power to pull overdrive (3rd gear) and fall on its face, anyone care to speculate here?


I calculated top end but the 2 stroke numbers scare me, would someone
please check my math, I must have missed something.
Under a load, 2 stroke rpms should peak at 30,000+ rpms and the
4 stroke might pull 9000 rpm's.

I also have another custom tranny in my 2 stroke (0-1) Pro Street Nova with 3.25/1 first and 1/1 2nd, would this gear ratio work with a 4 stroke in the
above H-2?

I dont need to go 100 mph, but 0-40 is important for this H-2 project, anything above that is just icing on the cake.

scale only 4 me

My Feedback: (158)

4-strokes for cars turn more than 9000 RPM
what engine were you planing on using?

motionmachine

my own 4 stroke eventually but right now Im planning on using a 2 stroke (0-1)for pushing the chassis to extremes.

scale only 4 me

My Feedback: (158)

I guess my question wasn't specific enough
What 4 stroke engine had you considered?

motionmachine

An OS FS.26S engine started it all, but its not a candidate for this project, not enough cubes IMO. I'd need a 40+ for this I think.

fhm101

Is this a transmission you are building, or are you looking for one?

motionmachine

Its a custom built enclosed tranny (details later) for my H-2o. I intended to run a dual 4 stroke but now Im thinking an insane 2 stroke would likely push it to "unheard of" top end speeds if the extreme rpm "slam" during the trans shift didn'y wreck the tranny or transfer shaft . Im just second guessing myself.

fhm101

I don't know how your setup works, but if it's constant mesh one thing that will help keep it together is to put all the rotating parts on bearings. A honda-matic 2 speed auto transmission is nothing more than a 2 speed constant mesh gearbox with everything riding on needle bearings. The bearings are the trick to slamming it into high without blowing it up.

motionmachine

Everything is on bearings. Im concerned with the 30,000+/- rpm extreme gear ratio/change shreading the plastic gears.