Robotech

That's the company that made the 21 conversion kits that both Steve Pond at RCCA and I used on our .21 Supers. It wasn't that one, that's their newer one that actually address chassis weight and layout issues that come with bolting in a .21 to a Super Nitro. At that point though it's no longer a nitro sedan...It's an 1/8th scale nitro car like a Serpent or Proceed...just not as good.

In addition, that conversion kit still doesn't address the issues of gearing. When I did the 85 mph car I was trying to replicate what RCCA had done but with all off the shelf parts. I was running a RS4 Nitro 3 2-speed clutchbell because the pinion gears could be screwed on and off. I would run the two speed clutch but had the clutch locked down so I could use the much smaller 2nd gear spurs. Then on the two speed clutchbell I'd use the largest 2nd gear pinion I could find. I think we were running something like a 37/22 combo (the 23 tooth gear wasn't out yet and later we went to a completely different clutchbell but I never got a chance to run it with that setup). The belt pulleys were stock size but the HPI steel pullies.

While the rubber tires caused their own issues, their size and their tendancy to balloon probably helped since it increased their diameter and shrunk the contact patch thus producing less friction. No evidence of this and obviously the rubber tires wouldn't have carried us to 100 but I wonder if our gearing setup would have let us get to 85 had we been running foams.

Lastly is a matter of where do you run it. RCCA used an airstrip...I had a very long, very flat, very unused section of asphault. a 70+ MPH needs a lot of room to get to that speed and even more room to shut down.