OFNA Dual-Engine Titan Double Shot
Since its release, the OFNA Titan has had exactly one mission: to be the biggest and most powerful RC monster truck on the market. In its latest “deluxe” incarnation, the Titan rolls out with a whopping 16-inch wheelbase, and flattens the ground with massive 6×4.5-inch tires, and its Force .25 engine is the largest-displacement power-plant available as standard equipment in an RTR truck. Big, big, big. But OFNA has another trick in store for the Titan, one that will put this monster way over the top in power and give it a place in the RC history books under the “Firsts” column as the first production monster truck to include dual engines. We’re the first to drive a Dual-Engine Titan (“Titan DE,” for short) outside of OFNA’s R&D guys. A pair of glow starters are charging as I type!
Returning Titan Deluxe features
With the obvious exception of double Force .25s, the Dual-Engine Titan is pretty much an off-the-shelf Titan Deluxe. That means all this stuff is standard, along with a polished (instead of orange-anodized) chassis.
* Pivot-ball suspension
* Steel-gear center transmission
* Dual-disc brake system
* Aluminum threaded-body shocks
* 2.5mm double-deck chassis
* CV-type universal-joint front axles
* Sealed differentials
* Dual 125cc fuel tanks
* Enclosed radio box
* 6×5.4-inch split-chevron tires with foam inserts
* Chrome 17mm hex wheels
Dealing with dual engines
“Man, how do you tune that thing?” is question number one when you’re confronted with a pair of engines jammed into one truck. Actually, tuning the Titan DE is relatively easy. The key is to dial in the engines separately. There are two reasons:
* Although the Force .25 engines are identical, simply setting their carb needles identically doesn’t mean that both engines will operate equally. The settings will be close, but not spot-on. B With both engines running, it’s virtually impossible to determine how well they’re performing individually. The exhaust notes blend together, and the engine in the better state of tune masks the other engine’s out-of-tune performance.
So, we first ran the Titan on one engine until we had it tuned for best performance, then we shut it down to tune the opposite engine. We tried to do this with as little high-speed running as possible, since the clutch bearings in the non-running engine were getting a heck of a workout. (Remember, when a clutch is engaged, the clutch bell and crankshaft spin together; the clutch bell only spins on its bearings when the vehicle is coasting or braking).
Room for two
It’s no small challenge to put a pair of big-block engines on a chassis, but the Titan seems ready-made for its dual power-plants. The centered transmission is key, as it allows the engines to straddle the spur gears, and since the reduction system is below the upper deck where the engines live, there was no need to relocate transmission parts. Only the radio box had to be relocated, and it was moved from the right side of the chassis to the front half of the upper deck.
Copyright Air Age Publishing Sep 2003
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