Theoretical top speed for 2 spd, 3 spd and 3 spd with high gearing

[lokky]

Assumed max engine rpm of 30,000.

Savage nitro 2 speed
29/9 (diff ratio) x 29/32 (gearbox) x 9/23 (gearbox) x 47/17 (spur/pinion) = 13.69 gear ratio
Nitro engine = 30,000
30,000/13.69 = 2,191.4 wheel rpm
Tyre diameter = 15cm
Tyre circumference = (15 x 3.14)/100 = 0.471m
Convert 1 km/h = 0.6213711922 mi/h

mph = ((2,191.4 x 0.471 x 60)/1000) x 0.6213711922 = 38.5

Savage nitro 3 speed
29/9 (diff ratio) x 30/31 (gearbox) x 38/24 (gearbox) x 47/17 (spur/pinion) = 13.65 gear ratio
Nitro engine rpm = 30,000
30,000/13.65 = 2,197.8 wheel rpm
Tyre diameter = 15cm
Tyre circumference = (15 x 3.14)/100 = 0.471m
Convert 1 km/h = 0.6213711922 mi/h

mph = ((2,197.8 x 0.471 x 60)/1000) x 0.6213711922 = 38.6

Savage nitro 3 speed high speed
29/9 (diff ratio) x 30/31 (gearbox) x 36/26 (gearbox) x 47/17 (spur/pinion) = 11.94 gear ratio
Nitro engine rpm = 30,000
30,000/11.94 = 2,512.6 wheel rpm
Tyre diameter = 15cm
Tyre circumference = (15 x 3.14)/100 = 0.471m
Convert 1 km/h = 0.6213711922 mi/h

mph = ((2,512.6 x 0.471 x 60)/1000) x 0.6213711922 = 44.1

 

[Torquematters]

Are you doing this to analyze the cost/benefit ratio of the 3 speed transmission and new gearing? Or is it just to put numbers to assumptions? We build street/strip cars and granted those aren't toys so it's not a fair comparison, but I won't spend time or money on anything unless I know its going to get me a 2/10th or more faster. For me, the trucks my son and I are messing around with are for tearing up and fixing when we need to while having fun. Now what I would like to do is see if we could take one and make it do a 100mph? I saw a video of a guy that says he did it, but I couldn't see the numbers and I am always skeptical of anything online, because 75mph can look like 100mph on a video until I see proof.

 

[MySavageWillBeatYours]

I have clocked my 3 speed sav F4.6 17/47 with dirt bonz at 41mph. There was a guy from savage-central that build a savage that went 75mph. His videos are still on youtube llkoolskillet was his name.

 

[Torquematters]

My son is working on right now. He just ported an engine and is trying to figure out the best taller gearing. He is going to make it two wheel drive and then is looking at lighter tires that wont balloon. After all of that, I think he is simply going to run out of power, so it just may not be possible unless he can cram more air/fuel into that little nitro engine. He is a whiz with tuning anything so if anyone can figure it out, he will.