flyenforfun

flyenforfun

Well Known Member
Hey everyone, as you my know I just started flying my RV-8 and I have endless questions. So I wanted to start a thread where I could post these questions for you experts out there and hopefully it will help someone in the future as well.

I am going to start with some simple ones.

RPM... If I fly at level flight and go full power, my engine will creep above red line (2720 to 2750). I have an O-360 and the vans recommended prop (72FM8S9-1 (85)). 75% power I am seeing RPMs above 2500

Fuel pressure.. 14-15 psi? Too high?

CHT.. Cyl 1 and 2 around 380, Cyl 3 and 4 around 345 degrees. Normal?

I could go on all day..
 
flyenforfun said:
Fuel pressure.. 14-15 psi? Too high?
Click to expand...

I don't believe so.

flyenforfun said:
CHT.. Cyl 1 and 2 around 380, Cyl 3 and 4 around 345 degrees. Normal?
Click to expand...

Let me guess, you followed the Van's instructions for the baffles and riveted on the air dams for the 1 & 2 cylinders onto the angle . Yeah, me too. My 1 & 2 are also the hottest cylinders and cutting the air dams down a bit is one of the items on the Phase One To Do List.
 
Congrats...

flyenforfun said:
Hey everyone, as you my know I just started flying my RV-8 and I have endless questions. So I wanted to start a thread where I could post these questions for you experts out there and hopefully it will help someone in the future as well.

I am going to start with some simple ones.

RPM... If I fly at level flight and go full power, my engine will creep above red line (2720 to 2750). I have an O-360 and the vans recommended prop (72FM8S9-1 (85)). 75% power I am seeing RPMs above 2500

CHT.. Cyl 1 and 2 around 380, Cyl 3 and 4 around 345 degrees. Normal?

I could go on all day..
Click to expand...

I can't speak to the fuel pressure issue as I have a carb but the other issues are real familiar. As Bob said, you will probably end up cutting down the baffle dams or completely removing them like I did (Florida based though so temps are probably higher)

Second, I have the same engine/prop (on a -6) and have the same symptoms. I easily get above 2700 red line so I figure my choices are to re-pitch the prop or live with it and pull the throttle back a little. Speeds are Van's numbers so I think I'm good. I would rather have the better climb rate so I will live with it.

Hope this helps.... stay safe
 
RV's have a very wide speed performance range compared to typical certificated airplanes that most people are familiar with flying.
Consequently, the resulting compromise that a fixed pitch prop causes is a bit more pronounced (don't expect it to be the same as the 172 or cherokee you are used to flying).
So, without info regarding what altitude you are at when full throttle puts you over red line, no one can help.

In general, to obtain well rounded performance in an RV, using a fixed pitch prop., you should have to climb to at least 9000 DA before you can run WOT and not go over red line (all altitudes below this, the pilot is the prop governor). If you are more interested in high altitude performance, then you would want that number to be higher (10,000 +).
If you are only interested low altitude speed, you could use more more pitch but higher alt. take-off and cruise performance will suffer.
 
Talked to Lycoming yesterday, they said our fuel pressure readings are high, should be more like 8 PSI max. He said to bleed the fuel pressure sensor line.
 
fuel pressure

I have an 0-360 Lycoming carb with Vans fuel pressure transducer and standard analog Vans fuel pressure gauge. Similarly, at idle I'm showing 8 psi and it increases to 12 psi at 2000 rpm. I just ordered a new transducer (I also have issues with the oil press trans) and hope that makes a difference. I'm also headed to the store to purchase a fuel pressure test gauge. Other suggestions on this site recommended a good ground between the transducer and the firewall. I tried that--it didn't help.

Jim Diehl RV-7A
Ready to begin Phase 1
 
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