Saturday, August 06, 2011

Performance during the AVC race


If you are interested, I thought I would explain a few things about what is going on here. To see the photo better, click on it and hit Ctrl + a few times and the screen will enlarge.

First off, note the oil temp is 15 deg. That is due to the faulty sensor.

Altitude: 2,860' and a very slight climb. The density altitude is 4,940' with an OAT of 82F.

3,130 RPM WOT, with a fuel flow of 8.0 GPH.

IAS is 194 and TAS is 208 mph.

Look at the cylinder head temps:
#1 409
#2 395
#3 330
#4 366

Cylinder#3 is 79 degrees cooler than#1. Admittedly, #3 is right in the breeze and #1 is furthest back but I think there is something going on here.

One of the racers heard somewhere, from a Lycoming rep, that if your cylinder head temps were lower than 230 degrees, you were loosing speed due to excessive cooling. Kind of makes sense. Maybe I should look into some kind of a cowl flap arrangement to possibly pick up a few extra mph.

What do you think?


2 comments:

av8rdav said...

My friend owns a 182 and we put an STC io-520 in it. We did the baffling and all 6 cylinders run 350 to 375 in a climb during summer with a full load of jumpers. I'd say you need to do some baffle work. Not a plenum but aluminum and rubber baffles.

Sam Hoskins said...

Could you provide some specifics?