Low Cylinder Head Temps
It's been a while since this thread was looked at but someone on here was hoping to see their CHT's in the low 300F degree range. If you see this then send me an email and I'll help you with what I've done on my RV-6, it is far from stock firewall forward BTW. Here are some numbers / temps if anyone is interested.....
#1 CHT 280F / EGT 1390F
#2 CHT 278F / EGT 1374F
#3 CHT 289F / EGT 1392F
#4 CHT 278F / EGT 1394F
NOTE: These temps were colder than normal because I had the larger 4 1/4" round inlet diffuser rings and not the smaller ones installed on this flight.
Oil Temp is controlled VIA inlet door / NACA Duct / I keep Oil temps at all times 185-190F
YES these TEMPS are correct. I calibrated and tested the Mircovision Probes and guages with a $5,000+ Jofra calibrater that is certified.
The day I took these numbers were at an Ambient outside temp of 64F degrees. 5,500 Ft, 23" MAP, 2,450 RPM, indicating 186mph / true airspeed ???210 / 212 mph ????. Fuel mixture at 100F lean of peek. 4 1/4" ID diffuser inlet rings. The engine I built is an IO-360A1B6 with 10:50 comp pistons custom made, Slick mags with 22degree timing top, 20degree bottom timing / split timing, no electronic Yet.... I applied Thermal barrier coatings to many internal parts such as piston tops, cylinder combustion chambers, intake / exhaust valves, rod / main brgs, exhaust and intake ports, internal barrier coating inside the oil pan, valve covers, valve springs, external Heat dispersent coatings applied to dissipate heat on cyl / head cooling fins, insulated intake runners. Camshaft timing change, 'Techline' coating to 4into1 exhaust that I custom built. Heat is a killer!!!! What happens inside the combustion chambers needs to be kept there and spent / swept out the exhaust system. If the combustion chamber temps disperse outside through the cyl/heads then the cooling system / air flow over the cooling fins has to cool things more without the thermal barriers... That means you need more cooling air/mass etc.
Engine in my RV WAS stock then I tore it down to make changes.
I did a before and after test with the coatings and the temp changes were very impressive. Tests were done before cowling mods OK.. Later saw more temp reductions with modifying other cooling items...... Cowling is a Highly modified Barnard design, high pressure plenum is modified, cylinder tin mods, cowl outlet design change, coke bottle design / venturi and extended past firewall 6", reduction on diffuser ring inlets, lower plenum mod below cylinders. You can look at over 50+ pics on this site:
http://groups.yahoo.com/group/JamesAircraft/ Join the group as its free. The group is mostly about the "HOLY COWL" / Sam James cowling / plenums. Attention to detail is the key. I normally run my CHT's in the 300F range but others might disagree, If I want to go faster I reduce my diffuser inlets down very very small and get the CHT's up in the 375-380F range and yes I pick up speed. I'm a firm believer in CHT's on the minimum with the oil temp in the green and at times but I will run the oil temp up to 220F to boil off condensate via oil air inlet door on NACA duct. Leakdown tests are always 78,79/80. Oil samples are below normal PPM. If anyone has questions feel free to ask and I'll share anything with you.