RAM 160 HP upgrade
- Thread starter Mike McMurtrey
- Start date
. But if you can get most of the improvement for a fraction of the price, that's great and you can postpone the upgrade to the day your engine needs to be replaced anyway.brucesheri
Practicing Landings
Spreading out upgrades piecemeal was more affordable. I'm finally satisfied.
brucesheri
Practicing Landings
Update.
Just replaced all the cylinders and pistons from RAM, and in the process discovered serious air leaks past the carburetor heat flapper valve.
Had a low compression on one cylinder (had the RAM piston upgrade only) and ended up replacing all the cylinders and pistons. Big difference in power.
Repairing the carburetor flapper was also a big deal in terms of power. Suggest you all check your carb heat flapper in the air intake box when you replace or clean the air filter.
Just replaced all the cylinders and pistons from RAM, and in the process discovered serious air leaks past the carburetor heat flapper valve.
Had a low compression on one cylinder (had the RAM piston upgrade only) and ended up replacing all the cylinders and pistons. Big difference in power.
Repairing the carburetor flapper was also a big deal in terms of power. Suggest you all check your carb heat flapper in the air intake box when you replace or clean the air filter.
brucesheri
Practicing Landings
With the two combined mods of the PowerFlow and the RAM STC to 160hp, the issue of the prop pitch beleaguered me.
More power does not equate to more airspeed with a fixed pitch prop. Will mean better climb. However, it will exceed the maximum TCDS static RPM.
After trying pitch changes on the McCauley, I finally bought a new Sensenich STC cruise prop for the 172N, with the maximum rated cruise pitch of 62".
The issue is the TCDS below:
Static rpm at maximum permissible throttle setting:
Not over 2370, not under 2270
So while the Sensenich 62" was listed by Sensenich as a cruise prop for the 172N, I'm at the highest static RPM end of the TCDS or 2370rpm, meaning that the "cruise prop" pitch (Sensenich description) for the prop I bought is actually a "climb prop" with the PowerFlow exhaust and the RAM STC because I can't go beyond 2370 rpm (which would be the case with a lesser pitch).
In other words, I can't get more climb with less prop pitch because my combined mods RPM are at the top end of the TCDS allowance and the top end of the STC cruise prop pitch from Sensenich for a 172N. Loose translation is that I'm getting more than 160hp from the two mods combined.
AIRCRAFT ENGINE.....................................................................................................STANDARD....................CLIMB............................... CRUISE
Cessna 172N, 172P/ 160 (STC Sensenich) Lycoming O-320 /160.........74DM7S14-0-58.......74DM7S14-0-56.......74DM7S14-0-62
Whatever, it's great.
Flying solo, I get 800+fpm at 2000' density altitude and 110mph indicated.
Cruise at 135mph TAS (it's a 1969 172K).
During the approach to 4R at Honolulu, betwixt incoming jets, I can easily do 130+ kts (150mph) indicated, somewhat keeping up with the jet traffic.
More power does not equate to more airspeed with a fixed pitch prop. Will mean better climb. However, it will exceed the maximum TCDS static RPM.
After trying pitch changes on the McCauley, I finally bought a new Sensenich STC cruise prop for the 172N, with the maximum rated cruise pitch of 62".
The issue is the TCDS below:
Static rpm at maximum permissible throttle setting:
Not over 2370, not under 2270
So while the Sensenich 62" was listed by Sensenich as a cruise prop for the 172N, I'm at the highest static RPM end of the TCDS or 2370rpm, meaning that the "cruise prop" pitch (Sensenich description) for the prop I bought is actually a "climb prop" with the PowerFlow exhaust and the RAM STC because I can't go beyond 2370 rpm (which would be the case with a lesser pitch).
In other words, I can't get more climb with less prop pitch because my combined mods RPM are at the top end of the TCDS allowance and the top end of the STC cruise prop pitch from Sensenich for a 172N. Loose translation is that I'm getting more than 160hp from the two mods combined.
AIRCRAFT ENGINE.....................................................................................................STANDARD....................CLIMB............................... CRUISE
Cessna 172N, 172P/ 160 (STC Sensenich) Lycoming O-320 /160.........74DM7S14-0-58.......74DM7S14-0-56.......74DM7S14-0-62
Whatever, it's great.
Flying solo, I get 800+fpm at 2000' density altitude and 110mph indicated.
Cruise at 135mph TAS (it's a 1969 172K).
During the approach to 4R at Honolulu, betwixt incoming jets, I can easily do 130+ kts (150mph) indicated, somewhat keeping up with the jet traffic.
MRC01
In the Clouds
- Joined
- Oct 9, 2019
- Messages
- 4,044
You're right, that's effectively a climb prop for your configuration. 135 mph is 117 kts which my 172 would do before the 180 HP upgrade. You must be bumping into redline before getting full power.
For comparison, my 172 with the standard 180 HP engine (O-360-A4M) and fixed pitch prop cruises at 130 KTAS / 150 mph at high power at about 2100#. At max GW (2550#) that drops to 125 KTAS / 144 mph. By that I mean full power, pull back just enough to disengage the carburetor enrichment circuit, lean to peak RPM/power.
A big factor in cruise speed & efficiency is how well the airplane is rigged. Just a little drag takes a lot of power to overcome.