Tweet
I had a engine cooling breakthrough on my Bearhawk with a O-540 running 10-1 pistons.
During Airventure 2018, while walking by the Lycoming tent, there was an immaculate F-1 racer in front without the cowling with an engine similar to mine. The owner was talking to someone about cooling and how the beautiful fiberglass induction plenum did nothing to improve the cooling but the curved sheet metal transition to the firewall and tunnel did and made all the difference in the world. I did not take pictures, should have but didn’t.
That idea incorporated to my installation significantly improved my CHT by 20 degrees. No louvres in the cowling.
For example, two minutes after takeoff with 90 degrees F, max power, the CHT on cylinders 5 & 6 would be 422. Same conditions with the modification temperatures are 402.
Those are worst conditions: slow speed, high power with fuel enrichment valve open. In all other regimes of flight, temperatures are nominal.
Additionally, the exhaust was moved as far to the sides as possible and all pipes, ducting, cables were re-routed to clear the area under the cylinder cooling exhaust air.
The transition from the firewall to the tunnel needs softening so the cooling air smoothly enters the tunnel. Anything impeding the air creates turbulence and correspondingly forms a wall stifling airflow.
Hope this helps. I have a friend with a BH and cooling issues yet to adapt the mod. Let’s see how he does. Did not ask permission to use his name (rhymes with Smokey). 509 still for sale.
Scott Williamson N509RF & N924PL
During Airventure 2018, while walking by the Lycoming tent, there was an immaculate F-1 racer in front without the cowling with an engine similar to mine. The owner was talking to someone about cooling and how the beautiful fiberglass induction plenum did nothing to improve the cooling but the curved sheet metal transition to the firewall and tunnel did and made all the difference in the world. I did not take pictures, should have but didn’t.
That idea incorporated to my installation significantly improved my CHT by 20 degrees. No louvres in the cowling.
For example, two minutes after takeoff with 90 degrees F, max power, the CHT on cylinders 5 & 6 would be 422. Same conditions with the modification temperatures are 402.
Those are worst conditions: slow speed, high power with fuel enrichment valve open. In all other regimes of flight, temperatures are nominal.
Additionally, the exhaust was moved as far to the sides as possible and all pipes, ducting, cables were re-routed to clear the area under the cylinder cooling exhaust air.
The transition from the firewall to the tunnel needs softening so the cooling air smoothly enters the tunnel. Anything impeding the air creates turbulence and correspondingly forms a wall stifling airflow.
Hope this helps. I have a friend with a BH and cooling issues yet to adapt the mod. Let’s see how he does. Did not ask permission to use his name (rhymes with Smokey). 509 still for sale.
Scott Williamson N509RF & N924PL
Comment