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RV8 CHT's and EGT's, what's normal?

Gabe214

Member
Hey everyone, I'm new to Aviation, I'm a low time pilot of maybe 150-160 TT (all tailwheel minus 10 hours). Obviously my aircraft experience is very limited. I'm a mechanic by trade (although I'm not an A&P) but I try to use my mechanical common sense. That's the only way I've been able to afford flying so far. I own an RV8 with a Carb O360-A1A 180HP. My plane was completed in 2003. I have a few questions that have come up in the past 24 hours regarding not only my airplane but my friends newly acquired RV8 as well.

My RV8 when built was kept with warm weather climate in mind. The airplane was built in South Louisiana and now lives in South Mississippi. My RV has an oversized oil cooler with oil temps averaging 165-180* on hot summer days. My CHT's are usually around 275* on average but seeing anywhere from 250-300* at cruise is typical. I rarely see anything over 300* (take off only) I dial in my EGT's around 1300*. My average fuel burn is 8GPH. (I dont have a fuel flow meter yet)

My friend recently picked up an RV8 with an IO360, Fuel injected, 200HP with Port matched Cylinders from Lycon. His head temps on take off hit 415* and when leveled off for cruise came down to 368*. His oil temps were between 195*-215* (215* temps on takeoff and climb). He was leaning his engine to roughly 1300* egt's. His fuel burn ranged from 9.5-10.5 GPH with climb burn of 12+ gph.

Now here's the question, are my engine temps too cool/can I run my engine a little hotter? Are his temps a little high? What are the Normal temps of your average RV? Were both inexperienced with RV's and are curious to find an answer. Obviously no RV8 is identical but it's something we're both pondering. Any help or information is greatly appreciated.

Thanks! - Gabe
 
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Have you look at your engine manufacturer specs for your engine? That states what parameters, by design, you should be looking for. Your chts are on the cool side, you may have to put duct tape over some of your oversized oil cooler in cooler situations. Yes, your friend is on the warm side, but chts are not in any prohibited range for climbing/TO, and look good at Cruise. Push nose down, retard power if wanting to reduce the 415. Just one perspective…enjoy growing with you skill, knowledge of your RV!
 
Your temps are reading abnormally low. I suspect your CHT leads are reversed somewhere between probes and engine monitor. Check with probes in boiling water.
 
Gabe, your CHT and oil temperature, and your friend's, appear normal for well built RV-8's with stock cowls, given the respective configurations. Caveat; there are a few unknown details. I'm guessing you're running mags, while your buddy's is a hot-rodded parallel valve, and has advancing ignitions. I would recommend raising yours a bit.

While CHT and oil are absolute values, there is no "normal" EGT. The indicated temperature varies with probe location, a build variable. You're not interested in an absolute value anyway. You're interested in degrees from peak EGT. Peak EGT is roughly stoichiometric mixture, so mixture either richer or leaner than peak results in a lesser EGT.

You will see max turbine inlet temperature listed in the operating manuals, but that has no bearing on our NA applications.
 
250-300 in climb in the summer seems too low to be right. Suggest verifying probe accuracy. Also look for probe mismatch. Type k probes with type c configured, etc.
 
Gabe, your CHT and oil temperature, and your friend's, appear normal for well built RV-8's with stock cowls, given the respective configurations. Caveat; there are a few unknown details. I'm guessing you're running mags, while your buddy's is a hot-rodded parallel valve, and has advancing ignitions. I would recommend raising yours a bit.

While CHT and oil are absolute values, there is no "normal" EGT. The indicated temperature varies with probe location, a build variable. You're not interested in an absolute value anyway. You're interested in degrees from peak EGT. Peak EGT is roughly stoichiometric mixture, so mixture either richer or leaner than peak results in a lesser EGT.

You will see max turbine inlet temperature listed in the operating manuals, but that has no bearing on our NA applications.


Noted, thank you very much! It's been a learning curve but I'm loving every minute of it as I'm sure he is.

As far as temps, when I'm on climb out, my CHT's are typically 300-325*. I should've been more specific on that note, my apologies there. Typical cruise CHT's, I'm reading 275* average running EGT's 1300*, 100* ROP. I can check the sender or instrument for wires being backwards. The temp pickup is a metal ring around the base of a plug. It may behoove me to change sending units.
 
Noted, thank you very much! It's been a learning curve but I'm loving every minute of it as I'm sure he is.

As far as temps, when I'm on climb out, my CHT's are typically 300-325*. I should've been more specific on that note, my apologies there. Typical cruise CHT's, I'm reading 275* average running EGT's 1300*, 100* ROP. I can check the sender or instrument for wires being backwards. The temp pickup is a metal ring around the base of a plug. It may behoove me to change sending units.

300-325 is a bit more realistic. With no experience, I suspect that the sparkplug ring probes may read 20-30* lower than the traditional type and that would bring your temps closer to typical.

Larry
 
Mike Bush indicated that spark plug style CHT probes read 40* cooler than standard probes.
 

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