HDgyro wrote:(1) Is there a good rule of thumb for CFM needed per horsepower? I envision getting 25 - 30 HP per cylinder after modification. Would a single vacuum motor capable of 90 CFM at 44 inches (such as the Ametek 119347-01) be enough to flow heads, manifolds, carbs and throttle bodies in this class?
To add to what Tony said Pipemax is good software, some other software you may consider is Rick Jones' Controlled Induction and/or CamGen
Advances in technology and knowledge mean rules of thumb are outdated soon after they are thought up. Having said that with regards to airflow in an intake tract naturally aspirated 1.5 cfm per HP is about it for a performance engine.
Every job is a self portrait of the person who does it.
Autograph your work with excellence.
Wow sounds like a great and exiting project, and welcome to the forum.
Just as the foundation is needed in building a house there are many aspects of engine development that are important in having a safe dependable power plant. For me mostly a motorcycle guy i find working on a motorcycle should be more meticulous than an aircraft, Why? because the time window between failure and disaster is much shorter. When your ass is 27" off the pavement at 70 MPH if something major fails there is little time to develop a recovery plan. Where am i going with this well back in the OCC Chopper guy motorcycle boom of the late 90's to early 2000's a little company called Ridley came out with a bike that used a snow mobile torque converter as the primary drive (an Automatic) this was kind of pointed at the Biker guy's girlfriends motorcycle. It did well would go up the road at 70 mph and i never heard of much issue with the motors. They primarily used in there 750cc model a Kohler knock off motor some say private branded, i use this as an example as in the air reliability is paramount and on the ground these things have logged thousands of hours on Zero turn mowers day in and day out.
This I am sure you already know, but i think your foundation for research will be well worth it in the rewards, so buy rebuilding one of these and putting an aircraft type attention to detail the serviceability could be awesome. Please remember that what ever formula you use it is only good for a Potential Goal Result, i often use the formula for Potential HP as .27*CFM + HP/cyl so if an intake port could flow 100CFM it has the ability at some point to support up to 27HP but as you well know there are many other factors that play a roll in this game of chasing power.
With respect to flow benches don't be afraid to ask Bruce in a PM about bench top designs as we have been fooling with that for years and maybe you could be the prototype. For power consumption and bench efficiency i think you will need two motors which means it will need to run on 20 amp US residential circuit at 120VAC which is standard in any current built garage or outdoor circuit. as Tony said the DM does not see bench size and it is very salable.
As for porting i think you will find when you do, that in a good solid blueprinting of one of these engines that combustion chamber shape and port work (valves, valve shape, vale job and blending) will bring you the biggest results in efficiency and power.
I look forward to you posting progress on both your bench and you engine work as we have a great members project area here also.
Rick, thanks for the warm welcome! I was unaware of the source of the engine in the Ridley, but it makes sense in the application. The regulations regarding claimed horsepower have all the mower-motor manufacturers tuning for max torque at 2500 RPM, and max HP at 3600 RPM, because that's what they're allowed to advertise. Some use cams which don't hit .050 intake lift till after TDC and have no overlap, and jet the two cylinders differently in anticipation of charge loss through crude intake and exhaust systems.
These things all have heavy flywheels to protect against mower blade strikes or the abuses of wood chipping, and to reduce the risk of destructive torsional resonance in re-power applications the engine manufacturer can't foresee. They have lots of forced-air over the fins and through the oil coolers to protect against intakes clogged by grass clippings, restrictive multi-stage air cleaners to protect from the dust kicked up by mowing, and very compact mufflers, usually fed through very short primaries.
Driving a propeller requires almost no low-end torque, and runner length packaging is wide open on a gyro, so this application will take things in a very different direction. A prop loads the engine at the cube of RPM increase, and there's only one gear ratio, so torque demand drops off rapidly just a few hundred RPM below full power. I envision a belt reduction drive, a centrifugal clutch at about 2200 engine RPM, and continuous operation above 5,000 RPM. Needing only a very narrow power band really frees things up when considering modifications.
I'll pick this up again in the projects section when I really get underway. But in trying to figure out the most efficient way forward for both time and finances, I eventually realized I needed a simple dyno and flow bench early in the process, if only to feed programs like PipeMax with accurate data, and to baseline the original setup.
I had come to the same conclusion you did about the bench. It needs just a little more than what one blower motor could do. And the 27 HP per cylinder is 54 total corrected, which is what I project my next gyro will need to fly with safe margins for climb performance. The runway where I'm based is at 5,000' MSL, and summer temps can easily raise that to 8,000' equivalent before I even leave the runway, which will leave me with about 40 HP assuming the mixture is on the money.
I bought the plans and have been over them, and I now have to decide whether I want something cheap and simple to start with, or to bite the bullet and build a six-motor PTS bench which will accommodate future growth. Either way, I'll be getting a couple blowers from Lighthouse soon. And they won't have to be 120-volt motors - we just built a new house and I insisted on a 240 circuit in the garage.
"But honey! We may want to get an electric car someday. They're getting really popular!" (It was a much easier sell than wanting a flow bench!)
As for the flow bench the biggest cost is motors, and it you build it with the ability to add motors you can start with 2 and then add and to even hold the cost down further there are cheep motor controllers that work well on 2 to 4 motors. My bench uses something like this where i have 4 motors on a triac controller and 4 on add on switches. I do mostly Harley stuff and rarely use the add on motors. I can flow and honest 280 cfm at 28 on my first 4 motors using a 340 cfm internal plate thus giving me good range down low.
I had to laugh after reading your reply as your name made me think how perfect a Harley EVO motor would be for your aircraft if it were not for the massive flywheel and connecting rod weight. A bone stock 1340 (80") EVO motor made 56 rear wheal HP so about 62 crank HP and with minimal modifications 85 HP with stock heads.
Build the bench first if you are like most here you will have 3 to 6 months is woodwork before you get to really needing to invest further and if your handy with the tools and have access to machine tools you can make allot of the small part and save.
Well from now thank you very much for accepting me in the forum I want to manufacture my flowmeter and I need the plans as for 400 hp motors, thank you very much !!! Sorry I don't know how to write in English !!!!
Hello, Ive been Modifying and working on stuff for 40 years, I love old 2 valve Japanese bikes you can do alot with them. I acquired an SF110 and I realize the limitations, but alot of good work was done with these benches, my bikes are for the street so reality may be more lenient on me ...lol
My motor controller isnt working and I would like to get a wiring schematic or diagram to begin troubleshooting it, any help would be appreciated
bandit1216 wrote:Hello, Ive been Modifying and working on stuff for 40 years, I love old 2 valve Japanese bikes you can do alot with them. I acquired an SF110 and I realize the limitations, but alot of good work was done with these benches, my bikes are for the street so reality may be more lenient on me ...lol
My motor controller isnt working and I would like to get a wiring schematic or diagram to begin troubleshooting it, any help would be appreciated
Sent private message . . .
Bruce
Who . . . me? I stayed at a Holiday in Express . . .
Just found my approval for membership
Thanks
My initials are my screen name. I needed an easy fix that could be unique
My current plan is to have a bench flowing by 2022 for a single cylinder under 150cc. Small cube two and four cycle air cooled, for now. I've been hacking on stuff for decades and it's time to qualify or is that quantify the results while building clones of the better outcomes.
Not much else to add but this was where I started as a kid on engines and then progressed to big American muscle car V8's being surrounded by those, SBCs most of my life in one form or another, boats, trucks, cars and exhaust chamber piped two strokes or no pipe. My writing skills are still pretty weak so good luck
Hi Bruce and all. I’m not really a first time member, more a returning again member. If I recall I bought the bench plans and a router, then other stuff got in the way.
So my question is - where is everybody?
