Anyone know what a stock IO-360 Lyc AFR is at WOT?
I should be around 210-215 HP and my compression ratio is 10:1, if you look at that same chart for a HIO-360, which is a 10:1 200 HP helicopter engine, it show a rich and lean range between 19.5 gph and 16.5. At 17 gph my AFR is reading 10-1, which is pretty rich but seems to run just fine. I had it set at 15.5 gph, which gave me a AFR of 11-1. CHT's were ok, approaching 400 climbing to 3K from sea level. 17 gph is 50 degrees cooler, which is great.
Yeah I get all that. At 2500 RPM I am running at 12.5:1. Just running fatter at takeoff rpm. I am not concerned with my CHT's, it's my oil temp I am battling. I have a 13 row cooler mounted on the firewall and I am usually seeing 215-220 at TOC. I have a SJ cowl with a plenum and a 4" duct off the left rear cylinder baffle feeding the cooler. In climb there is not a lot of airflow unfortunately. As soon as you level off and speed up the oil temp comes right down. When I had takeoff set to 11:1 My CHT's were acceptable but the oil temp would hit 220-225 and I would level off to allow it to cool down. 10:1 gives me nice cool CHT's and about 10 degrees cooler oil so that's where I left it now.
Just wandered how rich a factory engine is for cooling at takeoff.
I guess I will have to order another Ballenger unit and slap it on a C172 or something. After filing all the appropriate paperwork and receiving proper approval from the FAA......
Yeah I get all that. At 2500 RPM I am running at 12.5:1. Just running fatter at takeoff rpm. I am not concerned with my CHT's, it's my oil temp I am battling. I have a 13 row cooler mounted on the firewall and I am usually seeing 215-220 at TOC. .
Using .5 BSFC 17 GPH puts me right about the HP I should be making.
I need to check the wideband calibration, 17 should not be that rich. I guess I can cross check it against the EGT next flight too.
I came across this chart from kitplane magazine suggesting that takeoff AFR is/should be/might be/? 10:1.
Yeah I get all that. At 2500 RPM I am running at 12.5:1. Just running fatter at takeoff rpm. I am not concerned with my CHT's, it's my oil temp I am battling. I have a 13 row cooler mounted on the firewall and I am usually seeing 215-220 at TOC. I have a SJ cowl with a plenum and a 4" duct off the left rear cylinder baffle feeding the cooler. In climb there is not a lot of airflow unfortunately. As soon as you level off and speed up the oil temp comes right down. When I had takeoff set to 11:1 My CHT's were acceptable but the oil temp would hit 220-225 and I would level off to allow it to cool down. 10:1 gives me nice cool CHT's and about 10 degrees cooler oil so that's where I left it now. Just wandered how rich a factory engine is for cooling at takeoff. I guess I will have to order another Ballenger unit and slap it on a C172 or something. After filing all the appropriate paperwork and receiving proper approval from the FAA......
Kitplanes editor says the AFR diagram was from George Braly (GAMI), so it is from the right people.