Speed,Combat,Scale,Racing > Carrier
Typical RPM's for Class I & PC Nelson Engines
Paul Smith:
--- Quote from: bdt-m on May 07, 2023, 06:44:31 PM ---Looking for what a high performing engine puts out on the bench with an APC 9x6 prop or whatever prop is best for Class I & PC. I understand the Nelson .40 & .36 engines are the current top choice of the winning entries.
Just trying to see what the target RPM is for each class on 10% Fuel, with the tuned muffler.
--- End quote ---
I've added throttles to combat engines for use in carrier.
Top RPM is not the issue, it's LOW RPM that matters.
The high RPM is whatever you want it to be as determined by the prop load.
Remember, it's an acceleration timing and less that 20 seconds at top speed, also, no need to stunt. This takes away some of the issues of combat engines.
I always do bench testing before I commit to a building project.
bdt-m:
--- Quote from: Paul Smith on May 11, 2023, 06:41:56 AM ---I've added throttles to combat engines for use in carrier.
Top RPM is not the issue, it's LOW RPM that matters.
The high RPM is whatever you want it to be as determined by the prop load.
Remember, it's an acceleration timing and less that 20 seconds at top speed, also, no need to stunt. This takes away some of the issues of comabat engines.
I always do bench testing before I commit to a building project.
--- End quote ---
Static RPM numbers on the bench are just a mark to strive for, as long as the testing is done properly the results will give you an indication of engine 'performance' in the air... yes bench testing is a significant part of the "building project". Just looking for 'bench' mark numbers.
Idle, "LOW RPM" resulting in spot-on throttle response is critical for a good LS hang, without it; you are just not going to be in the top spot(s).
I wonder how some of the other .35-36's & .40's compare to the very top engines...?
Kris Millard:
I have two LH .36 Nelsons that turn 19500 with a O.S. 4C carb and stock pipe. I had a much larger Perry carb on that turnd more RPM's but I couldn't get it to draw fuel properly when I slowed down so I went to the smaller O.S. carb at the advice of my mentor. This allowed me to learn the hang without the engine quitting in the transition. Now I'm looking to go back to the bigger Perry. What a party when it comes onto the pipe! I would ask Burt Brokaw what he runs as I have seen him do 100+ pretty consistently with his setup. (I think he runs a Perry, but I'm not positive) I suspect with the bigger carb you can hit 21K at speed.
Motorman:
My Fox Combat Special MK4 with Giffy mods hit 21K on the ground with suction insert, 10% nitro and apc 9-5 if that helps. It was a tiny bit slower than the Nelsons in the air.
MM
bdt-m:
--- Quote from: Motorman on July 14, 2023, 01:56:44 PM ---My Fox Combat Special MK4 with Giffy mods hit 21K on the ground with suction insert, 10% nitro and apc 9-5 if that helps. It was a tiny bit slower than the Nelsons in the air.
MM
--- End quote ---
--- Quote from: Kris Millard on July 13, 2023, 08:50:34 AM ---I have two LH .36 Nelsons that turn 19500 with a O.S. 4C carb and stock pipe. I had a much larger Perry carb on that turnd more RPM's but I couldn't get it to draw fuel properly when I slowed down so I went to the smaller O.S. carb at the advice of my mentor. This allowed me to learn the hang without the engine quitting in the transition. Now I'm looking to go back to the bigger Perry. What a party when it comes onto the pipe! I would ask Burt Brokaw what he runs as I have seen him do 100+ pretty consistently with his setup. (I think he runs a Perry, but I'm not positive) I suspect with the bigger carb you can hit 21K at speed.
--- End quote ---
Good information, benchmarks are just that, however useful. Now it's time to decide an engine direction... y1
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