How do you set your 360 for cruise? RPM/MP?

[moespeeds]

Just curious how guys cruise their 8.

I'm generally 4500-6500 MSL, 2350 RPM on my Whirlwind RV-300, MP +2 over square if possible, but no more. LOP, or 100* ROP.

[Carl Froehlich]

Typical is 8K'-10K', 2480 RPM, WOT, ~20 degrees LOP. This yields a repeatable 173 KTS TAS @ 8 to 8.2 GPH.

Higher cruise depending on winds. I do not like 6K' or lower as fuel burn goes up for the same speed.

2480 proved to be (very) slightly better speed vs fuel than 2450 or 2500. 74" Hartzell BA prop.

Carl

[bjdecker]

Cruise settings...

IO-360-A1B6 (Angle Valve, 200HP, 8.7:1 CR)

Altitude: 6500 (P.Alt)
Throttle: Wide open (~24")
Prop (Hartzell BA 7497-2) : 2500RPM
Mixture: 40°F LOP ~ 9.8GPH

Yields 175 KTAS. 4-way/GPS verified.

[Dan 57]

IO-360 on the -8, using the same settings as on my -6.9i, 19-24 @ 2’000 up to 12K’ then upping the RPM as necessary to continue a climb, or maintain altitude performance. Both ships with an MT 3bl prop.

[Walt]

I run at 2400 typically, if I need a lower RPM for rain penetration I go down to 2000 rpm <22".
The below is from WW but pretty typical recommendations.
2000 or 2100rpm is lugging a 4 cyl engine at full throttle/highMP IMO.

Recommended Continuous Operating Ranges
Whirl Wind follows historical industry standards and recommends that continuous operation between 2,050 - 2,300 RPM and 2,600 - 2,700 RPM be avoided when used on Lycoming and similar four cylinder aircraft engines. (Take off and climb out is not considered continuous operation.)

The full article from WW:
https://www.whirlwindaviation.com/faq.asp

[Mark33]

I typically cruse at 10-12k’, WOT, 2200 RPM’s, at 8-8.5 GPH which puts me right at peak and an AFR of about 14.7:1 At those altitudes the MP is below 65% power, so I don’t worry about hurting anything running at peak. I really just pay more attention to fuel flow than anything else. With the Hartzell BA prop, these settings at these altitudes typically yield around 167 knots TAS. The engine seems to be real happy there.

[rv8ch]

Originally Posted by Walt

I run at 2400 typically, if I need a lower RPM for rain penetration I go down to 2000 rpm <22".
The below is from WW but pretty typical recommendations.
2000 or 2100rpm is lugging a 4 cyl engine at full throttle/highMP IMO.

Recommended Continuous Operating Ranges
Whirl Wind follows historical industry standards and recommends that continuous operation between 2,050 - 2,300 RPM and 2,600 - 2,700 RPM be avoided when used on Lycoming and similar four cylinder aircraft engines. (Take off and climb out is not considered continuous operation.)

The full article from WW:
https://www.whirlwindaviation.com/faq.asp

Thanks Walt, this is very interesting. Do we know if this depends on MP? Is the curve the same no matter the power setting? Just curious if the stresses are ok at high altitude/low MP/low power settings.

Strangely, I find 2250-2350 RPM to be a very "smooth" setting for high altitude, full throttle, low MP cruising. Dropping below 2250 felt a bit too much like I'm lugging the engine, even at altitude.

I might need to see about checking my prop balance at 1950-2000 RPM, or just get used to the additional noise at 2450-2500.

[moespeeds]

Originally Posted by rv8ch

Thanks Walt, this is very interesting. Do we know if this depends on MP? Is the curve the same no matter the power setting? Just curious if the stresses are ok at high altitude/low MP/low power settings.

Strangely, I find 2250-2350 RPM to be a very "smooth" setting for high altitude, full throttle, low MP cruising. Dropping below 2250 felt a bit too much like I'm lugging the engine, even at altitude.

I might need to see about checking my prop balance at 1950-2000 RPM, or just get used to the additional noise at 2450-2500.

My WW 2 blade came with the RPM restrictions outlined here, but for the RV-300 3 blade they told me no restrictions. They didn't find resonance at any RPMs. The 3 blade runs very smooth and quiet at 2350.

[FL Flier]

O-360, Hartzell CS prop. I usually cruise at about 75% power. 2300 RPM, set MP based on a performance chart, pull mixture until it gets rough, then enrich just enough to smooth it out. If I want a bit more speed, then lean to rough, and enrich until airspeed increases.

With one electronic ignition, it’s burning about 8 GPH at best economy and 9 GPH best power, so roughly 1 GPH less than dual mags.

[Walt]

From the Diamond ops manual, DA40, 360 w/3 blade MT