Symtec (Installed 9-98) (612) 571-9193 http://www.symtec-inc.com Three 110-watt heaters, wired in parallel (draw less than three amps) Thermostat keeps unit between 170 and 200 degrees F. Thermal fuse set to 300 degrees F to protect against overheating (must be returned to factory to reset) Size: 5.5" x 4 5/16" Lightweight: 13 ounces

The Surestart - Preheater Co (Bought 3-97) (800) 247-4866 http://www.surestart-preheaters.com 150 CFM blower 18 x 8 x 9 toolbox case 18 lb. 5 feet of 4" heater air hose Solid State push button ignitor 20,000 to 60,000 BTUs Outlet temperature gauge

Other major players in preheat are: E-Z Heat Inc. (800) 468-4459 http://www.e-zheat.com Flame Engineering (800) 255-2468 http://www.flameeng.com Kennon Covers (307) 674-6498 http://kennoncovers.com McFarlane Aviation (800) 544-8594 http://www.mcfarlane-aviation.com Reiff Preheat Systems (414) 968-2342 http://www.reiffpreheat.com/ Tanis Aircraft (800) 443-2136 http://www.tanair.com

My test scenario consisted of:

• JPI EDM-700 4-EGT, 4-CHT, OAT and oil temperature type K hastaloy-x tip bayonet probes installed 4-97.
• The oil temperature probe was submerged down the dip stick hole.
• AGAC Tiger Lycoming O-360-A4K with 6.5 qts of oil.
• Logged data every 6 seconds with HP LX-100.
• Old blanket draped over the cowl.
• Averaged the four EGTs and CHTs into one line each.
• 5 point rolling average to smooth lines.
• Done inside a hanger.

SureFire Test Conditions

• 1-9-99 9pm to 11pm
• Full data available in http://www.logan.com/cht/data/surefire.csv
• It took a few minutes for me to notice the new propane bottle was out after 1.5 hrs. When I finaly changed the LP bottle I aired out the hanger to ease my headache.

Symtec Test Conditions

• 1-8-99 from midnight to 8am
• Power was removed about 7hrs after the test started.
• Full data available in http://www.logan.com/cht/data/symtec.cap

Conclusions

• EGTs displayed the air temperature around the engine while the CHTs probes in the top of the cylinders have more mass around them.
• Blankets and cowl covers will maximize the achievable temperature for a given day, but won't help much with the early rate of change.
• It takes a long time for hot oil to warm cylinders.
• The oil pan heater never reached its thermostat level.
• The SureFire should be aimed at the largest thermal mass, the oil pan, as cylinders will soak up excess heat relatively easily.
• 60,000 BTUs is a great deal of energy, but the oil pads transfer their energy more efficiently.
• It would be fun to graph an oil pan heater and Reiff's 50 Watt per cylinder hotbandd heater.
• Or one can use the rented car's battery to power the surefire's superior BTU rating for warming the cyls and a StatPower 250 inverter for superior heat transfer to the largest thermal mass.
• Also read this article.