Davidnane Posted October 6, 2019 Share Posted October 6, 2019 I'm trying to diagnose the cause of problem that on my home build VK-30 with 914 F2 engine variable speed propeller. 1. Airbox temp goes up to 92 C to 95 C and all other parameters are NORMAL, like oil temp, CHT, EGT etc. RPM was 5000 ~ 5500 with no drop or any vibration issue gain height 12000 feet to 16000 feet. as per book, Airbox intervene at 88C as per book MANUAL. but here no such action was found. why? Link to comment Share on other sites More sharing options...
Yenn Posted October 11, 2019 Share Posted October 11, 2019 What do you mean by "Air box"? Is it the box directing air to the carbie, or is it where the cooling air comes before it goes around the heads? Link to comment Share on other sites More sharing options...
Davidnane Posted October 11, 2019 Author Share Posted October 11, 2019 airbox attached to turbochargers from one side and other is attached to carburetor. this is used for increased the boost pressure. Link to comment Share on other sites More sharing options...
facthunter Posted October 11, 2019 Share Posted October 11, 2019 Universal gas eguation . Increase pressure temp rises., Nev 1 Link to comment Share on other sites More sharing options...
Thruster88 Posted October 11, 2019 Share Posted October 11, 2019 airbox attached to turbochargers from one side and other is attached to carburetor. this is used for increased the boost pressure. [ATTACH]41697[/ATTACH] There would be an increase in temperature due to the turbo compressing the air, this is why most turbo engines have inter coolers. Check with rotax for spec. 1 Link to comment Share on other sites More sharing options...
Downunder Posted October 12, 2019 Share Posted October 12, 2019 At 12 to 16000 ft OAT is going to be pretty cold but the turbo is going to be working hard compressing air to sea level oxygen levels so I don't really know if this temp is normal or not. You will get the best answer from the "Rotax Owners" forum. There are a number of sensors on these engines to control boost limits. I imagine air inlet temp is one of them. 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 13, 2019 Share Posted October 13, 2019 What are you doing at those altitudes? . You can work out the boost required but at a guess... I'd think .5 Bar would be enough allowing for losses. You are also pressuring the Carbs with that set up and your coolant needs an actual positive pressure ( the cap is differential) to control boiling point. Legally you should have oxygen above 10,000 ft in this country. in some other places its 12,000'. Breathing pure oxygen has it's risks. and don't take a thermos with you. Nev Link to comment Share on other sites More sharing options...
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