Running Fast and Cool

Owners of older Continental IO-520- and -550-powered Beech Bonanzas should take note: Atlantic Aero — a longtime, well-known purveyor of Continental IO-550 mods — now offers an engine upgrade — dubbed the 550TI — that can give you 310 continuous horsepower, 180-knot true airspeeds, lower engine operating temperatures, and higher recommended times between overhauls (2,000-hour TBOs). For $49,248, Atlantic Aero will ship you a zero-timed, factory-rebuilt Continental IO-550-R (the normally aspirated version of the engine used in the early Continental-powered Piper Malibus) with a three-blade Hartzell "super-scimitar" propeller. It's this combination of tuned induction system, prop, aerodynamically cleaned-up cowling, and new nose bowl that's responsible for this modification's performance claims. Also included in this 550TI (the TI stands for tuned induction) package are a new starter, fuel pump, and alternator. If only new will do, then customers have the option of choosing a brand-new IO-550 for about $3,000 more. The mod is designed to fit three airplanes in the Bonanza series.

C-, E-, and F33A

This range of Bonanzas began production in 1966 with the C33A and ceased with the 1994 F33A model. These airplanes are powered by Continental IO-520-Bs of 285 hp, which have 1,700-hour TBOs. Under optimum conditions, stock 33-model Bonanzas have maximum cruise true airspeeds that hover around the 172-kt mark. With the 550TI installation, you'll have 25 more horsepower, and Atlantic Aero says that 190-kt airspeeds are possible.

S- through V35B

Similar performance improvements should accrue to the V-tail Bonanzas in this series, which were built between 1964 and 1982. These airplanes use the same engine as the 33-series Bonanzas, carry the same 1,700-hour TBO, and have similar cruise speeds. Atlantic Aero claims that 190-kt cruise speeds should also be achievable in 550TI-equipped airplanes.

36- and A36

Built from 1968 through the present, the 36-series Bonanzas started out using the same 285-hp engines as those just mentioned, but switched to the 300-hp Continental IO-550-B engine in 1969. These engines also carry 1,700-hour TBOs. With the stock engine, maximum cruise speeds run about 176 kt. Because of this Bonanza's larger size, wetted area, and flat-plate drag, the 550TI's cruise speed hike amounts to less — about 12 to 14 kt — than those realized in the 33- and 35-series airplanes.

Cooling techniques

A big part of the cooling strategy in the 550TI installation is bound up in the induction system, which meters the fuel-air mixture more efficiently and evenly among each of the engine's six cylinders. The metering is so precise, Atlantic Aero says, that optimized-flow fuel nozzles such as GAMIjectors are not necessary. In addition, a thermostatically controlled oil cooler keeps oil temperatures well under control. A valve begins routing oil through the cooler when it reaches 170 degrees Fahrenheit. When it reaches 180 degrees, all engine oil is routed through the cooler, which then maintains oil temperatures at 180 degrees. This helps to reduce engine wear because, as Bob Minnis (Atlantic Aero's director of engine installations) says, "at 200 degrees, oil has the consistency and viscosity of water."

Another cooling strategy involved reducing the size of the cowling's air inlets. The modified cowl has openings that are 70 square inches in area. Stock Bonanzas sport cowling inlets almost twice that area. Reducing the inlet area carries a double benefit: increasing airflow velocity through the cowl and reducing cooling drag.

To further reduce frontal drag and make the cowling more aerodynamic, the 550TI's propeller was extended 3.25 inches forward. This produced a sleeker cowling and nose bowl shape.

During early tests it was learned that the engine was running too cool. The solution was to eliminate the cooling louvers and chevrons found in the standard Bonanza cowlings. As a result, the cowling supplied with the kit has a cleaner, sleeker look than stock cowls — and the slight hump on the cowling upper surface (needed to accommodate the intake manifold plumbing on top of the engine) is sure to attract attention on any ramp.

A turnkey kit

The logistics of the 550TI involve first sending in your old engine as a core exchange. Atlantic Aero then ships out a very complete kit. This includes not just the engine and propeller, but also all the baffles, control cables, gauges, hoses, and exhaust components you'll need, as well as the carbon fiber hinged cowling and nose bowl. New magnetos are also thrown into the deal — but you'll have to supply your own propeller governor and vacuum pump(s).

At this writing, the first three 550TIs are being installed, and four more are on order.

Atlantic Aero says that any well-versed FBO will be able to perform the installation, but if you want the work done at the Atlantic Aero facility, the price will be $54,859. Atlantic Aero is located on the Greensboro, North Carolina, Piedmont Triad International Airport.

The promise of extra power, speed, and climb rate (1,200-fpm-plus total rate of climb is the claim for A36s; more for the -33s and -35s) without the penalty of high engine and oil temperatures makes the 550TI yet another big player in the Bonanza-upgrade market, and one certainly worth watching as it racks up more hours in service.

E-mail the author at [email protected].

For more information, contact Atlantic Aero LLC, 6423 Bryan Boulevard, Greensboro, North Carolina 27409; telephone 336/668-3324; fax 336/668-3987; or visit the Web site ( www.atlantic-aero.com).