Engine Modification

FAA STC/PMA Approval Granted for Teledyne Continential E-225-8 & Modified E-228-8 Installation

We are pleased to announce that after five years of extensive research and testing we have received FAA STC/PMA approval for the modification of Teledyne Continental E-225-8 series engine and FAA STC/PMA for the installation of the modified E-225-8 engine in Beechcraft Bonanza model 35, A35, B35, C35, D35, E35, F35, G35.

Modification Upgrade

  • Enlarging case thru bolt holes from 7/16 to 1/2 inch to accommodate new thru bolts.
  • Modification of the intake system flanges from two studs to four studs.
  • Push rod and push rod housing.
  • Installation of new Continental or Superior Millennium IO470N cylinders.
  • Modification of some cylinder baffles.
  • Four stud exhaust collector system.
  • Installation of an air exhaust vent behind the oil tank on the left hand cowl door.


  1. Flight tests in high ambient temperatures revealed the following:
    • Shorter take-off runs
    • Increased rate of climb
    • Higher cruise speeds available at cruising altitudes
    • Dramatic decrease in cylinder head temperatures
    • Decreased oil temperatures
    • Minimum oil burn; one quart in twenty-five hours
  2. Static test results
    • Propeller and rotating mass vibration test meets FAA standards. The maximum stress level is well below the allowable for infinite life and stress actually declined at high RPM
    • Sea level performance graph indicated 260 HP at 2650 RPM and 30 inches of manifold pressure.
    • Detonation test revealed better than original specifications.
    • Fuel flow test date unchanged from original at given RPMs
  3. Final tear down for inspection by FAA
    • Bearings and rotating parts showed little or no wear
    • All rotating parts were within service limit.
    • Predictable longer cylinder life as result of lower temperatures


  • This modification does not require change of the carburetor or engine accessories;
  • Note: At this time, the electric propeller is not supported by our STC and must be upgraded to a hydraulic propeller;
  • Keep original nose bowl and engine mount fittings;
  • Use of 100 low lead fuel;
  • Shorter take-off runs;
  • A minimum increase of 30 HP, increasing the rate of climb;
  • Better cruise speeds;
  • A dramatic decrease in cylinder head temperatures and lower oil temperatures;
  • Less plug fouling occurs due to the higher compression ratio.

The TCM (E) series engine has a very reliable engine crankcase, crankshaft, and rotating parts. The E225-8 engine was built to last. However, one of the weak points of the E series engine is the cylinder which rarely reaches TBO due to heating and subsequent stress within the cylinder. The heat transfer was poor due to the lack of adequate fin area on the cylinder. The parallel valves are particularly sensitive to overheating and invite cracks between valve seats. The low compression and valve arrangement were less efficient than modern high compression cylinders with angle valves and more fin area which run cooler and more efficient. We have solved the problems and created a solution for a modern and efficient TCM E225-8 engine. Our solution…………..470N cylinders.

Looking to increase horsepower while decreasing cylinder head and oil temperatures? Would you like to gain power across the entire manifold pressure spectrum?

​E225-8 Engine Modification

​STC/PMA modification for Beech models 35 thru G35 allows you to keep your existing TCM engine while:

  • ​Increasing your horsepower without the huge expense of installing an IO-470 engine.
  • Shortening Take-Off Runs.
  • Increasing Rate of Climb.
  • Increasing Cruise Speed at Cruising Altitudes.
  • Dramatically Decreasing Cylinder Head Temperatures.
  • Decreasing Oil Temperature.
  • Minimizing Total Oil Burn.
  • Allows Use of 100LL Fuel.
  • Less Plug fouling occurs due to the higher compression ratio.

What an incredible time this is to increase the usefulness of your Beech Bonanza.

STC/PMA for Models 35, 35R, A-35, B-35, C-35, D-35, E-35, F-35, G-35; TCDS A-777

For pricing and purchasing information, message us using the form below! Please be sure to quote the part name/model in the comments section.

Engine Modification

  • This field is for validation purposes and should be left unchanged.
Scroll to Top