| Driving the Twin21 |
| MAR '02 This is what it is all about. Today I let this car loose on both engines (still both running pretty rich). What a blast. There is none of that initial 'lag' requiring a bit more throttle that you usually get. The car (in buggy mode at the moment) leaps off the line and is up to full scream in so little time it is amazing - each engine spooling the other one up super-quick. I will write a lot more as I get in more drive time, but at the moment, the engines are not quite singing perfectly, due to the richness of the mixtures. Each pipe is belching out enough smoke to drain a tank in about 3 mins I would say. Result: Car is a total success! I love it! SEP '03 After the initial report above, which was just with 2 engines and the still air box, I started having problems. By the time the monster wheels were fitted, the front disc calipers machined and attached, the Maxx shell mounted and a few other additional tweaks, I just couldn't get the truck to run right. This marked the start of my most frustrating time in all my years of R/C. For about 8 months the problem persisted, either one or the other engine would not run more than 10 seconds, would die on throttling up, or some other problem. With the complexity of this truck, meaning that certain tuning adjustments can only be made by removing the engines, it took a long time to solve the problem. 3 rebuilds of engine no.2 later and a carb strip, and I was back in business. I never did find a definitive cause of the problems, but it was most likely a bit of dirt in the carb which I did not notice when I cleaned it out. I was so glad when I fired the truck up for the first time and it idled fine on both engines! Now I had only got a little Blue Thunder 20% fuel left, and I could not face the �25-�30 bill for another gallon (note U.S. gallon smaller than UK gallon too), I switched to Model Technics Dynaglo 10 fuel, which I have used a lot before. Well, I should have stuck with this from the start, because the performance went up several notches, heat down and reliability was now fixed on 100%. This is when I really started having proper fun with this truck. With all my additions fitted and a serious amount of instant horsepower on tap, I took the truck out for half a gallon of turf shredding. Problems I encountered: 1) AIRBOX. Made of ABS plastic, this material proved too brittle and the box shattered when I hit a manhole cover. Luckily the engines both stopped on impact so they didn't suck in any dirt. I replaced the box with 2 standard doughnut type foam filters for ease. Much of the problem was caused by the super-heavy sub-c 5 cell receiver pack hitting the box, so I replaced it with a 5-pack of Sanyo 600ae cells. I had now dropped a lot of weight and acceleration was up even more. 2) Brakes too powerful. The twin front wheel discs with the Hitec HS645MG super torque servo can stop the wheels dead from any speed on any surface. During some high speed runs on grass, I was testing the brakes pulling rolling stoppies. I noticed the rear wheels were locked by their transmission brake while in the air, while the fronts where rolling on the turf, doing all the braking work. Now because of my diff spool in the centre, this is not possible unless there is gear slip somewhere. Sure enough, the rear diff ring gear was stripped - remember this is a machined, hardened steel 1/8 buggy diff so it is not really upgradeable. There is no stress on the front diff because the wheels are braked at the hub, not through the transmission. The solution is to machine some at-wheel disc brakes for the rears too - this I will do in due course. Until then I just tuned down the brakes a touch using the transmitter ATV function - and bought a new ring gear and pinion of course. 3) Melted T-Maxx wheel hex. Not a lot I can do about this except be more careful or make up some alloy wheels. The aluminium hex adapter I machined was an accurate fit so the wheel was rounded out by pure torque. This happened when I was blasting the truck round my local on-road R/C track so there was quite a bit of grip on the asphalt. 4) Lost my glow starter. This annoyed me because I have done it so many times. I now have 3 or 4 glow starter chargers but no starter. I decided to junk it once and for all and install a cool on-board glow system with a single AA NiMh cell for power. Now you just flick a switch and pull the handle and the engines fire up. |