Phil.Griffin
70cc twin V2
I've printed it off too Terry. Thank you for doing that.
Basic engine tuning.
- Thread starter Terryscustom
- Start date
3Dchief
70cc twin V2
@Terryscustom , awesome job again as usual.
The two problems I see over and over is people moving up to GS from glow engines that think you should run gassers rich during break-in, and the myth of "factory settings". What runs well in the factory at sea level will not be the right setting and potentially even dangerous to the engine at 3,000 feet. The rich setting in glow engines is accomplished by a higher oil ratio in the fuel during break-in for gassers (32:1 or even 20:1 compared to 40:1 or more for a broken-in engine), so running it rich is not necessary.
A gas engine should be tuned for good performance before the first flight, as the performance changes during break-in, and then it will pretty much stay tuned after it is broken in.
The two problems I see over and over is people moving up to GS from glow engines that think you should run gassers rich during break-in, and the myth of "factory settings". What runs well in the factory at sea level will not be the right setting and potentially even dangerous to the engine at 3,000 feet. The rich setting in glow engines is accomplished by a higher oil ratio in the fuel during break-in for gassers (32:1 or even 20:1 compared to 40:1 or more for a broken-in engine), so running it rich is not necessary.
A gas engine should be tuned for good performance before the first flight, as the performance changes during break-in, and then it will pretty much stay tuned after it is broken in.
Terryscustom
640cc Uber Pimp
Yea good to note, I have always heard of people tuning to "peak RPM" and then backing off a smidge. I don't normally pay attention to RPM's on any engine (prop for performance not RPM), I just happen to be checking this one out for someone else.
The only problem I see with this is it is very very hard to get accurately and the 1-300 RPM more that you get with a super tuned high end is not worth the risk generally. Especially for guy's that are just learning to tune. Where I live the atmosphere can be dry and 60 degree temps one day and darn near 90 and humid the next. We also travel around to at least 6 or more different areas for events during the year ranging from 1000' elevation to just over 3000' elevation. I find that tuning with this process the engines are happy no matter where I go.
I also will add that I've never seen an engine tune as I described dead in the air from lean condition, and never seen one with scored or damaged internals.
Terryscustom
640cc Uber Pimp
Maybe someone can chime in that has more experience than me........when using canisters or tuned pipes I know the needles are effected in some ways. How are they effected and is the tuning process any different than normal??
3Dchief
70cc twin V2
I know that tuned pipes do make a diffence and will cause an engine that is tuned on regular mufflers to run lean. More air out means more air in, so the fuel in needs to increase as well. Not sure about cannisters, they do not have near as drastic an effect on stoichiometry as tuned pipes do.
Jetpainter
640cc Uber Pimp
I'm certainly no expert on Cans and Pipes, but they are all I've ever run. I've never run a stock muffler. As far as tuning the needles I do it much like you, and have had great results. I would say though that with a pipe you need to have the hi needle pretty close if you want the best performance. It's not hard, it's just not quite as forgiving as it is with a can. The big thing with a pipe is header length. I run DA's and have used their recommendations on header length and have never had a problem. Could I get better results with testing, probably, but the results I've had are good enough for me. Planebender can steer you in the right direction there.
Bipeguy03
150cc
@Terryscustom Thank you for posting this!!! There are a couple of guys in my club that are new to gas and are always asking me about tuning engines, and I'm never that great at explaining how to go about it lol. So I'm printing this off to give them a copy, great step by step instructions, and describing the symptoms of a too rich or too lean setting.
Excellent job!!!!!
Excellent job!!!!!
49dimes
Damn I'm hungry
Just my .02
I run canisters (pro flow) on every thing I fly. Don't laugh at this......Just a way of explaining.......
Canister over stock muffler or "in cowls" is like what a capacitor does to the voltage on a power supply. Smooth's it out.
Think of the fuel air mix heading in a specific direction but momentarily stopping and then starting again. With "in cowls" this can be more erratic. The canister (or tune pipe) makes the "starting and stopping" flow smooth. Hence Dave's term....Smooth Pipe .
The canister has not so much an effect on tune other than your tune will transition the engine more smoothly as well. The tuned pipe is going to affect the high side tune and will make a lean setting over what the "in cowls" do.
By smoothing out the pulse (starting and stopping) the engine develops maximum torque through out it's rpm band.
So.....A canister is less likely to cause a tune (with in cowls) to be excessively off where as a tune pipe will affect the high needle going lean.
Now header length is way more critical for a pipe over a can. Both however will have a header length determined mostly to the size prop you are running. Canister header length is typically longer than tune pipe header length but again the load (Prop) determines this.
No special trick with a pipe. "cut and measure" with the prop. I have headers stored with the specific prop I want to run for the appropriate engine.
I run canisters (pro flow) on every thing I fly. Don't laugh at this......Just a way of explaining.......
Canister over stock muffler or "in cowls" is like what a capacitor does to the voltage on a power supply. Smooth's it out.
Think of the fuel air mix heading in a specific direction but momentarily stopping and then starting again. With "in cowls" this can be more erratic. The canister (or tune pipe) makes the "starting and stopping" flow smooth. Hence Dave's term....Smooth Pipe .
The canister has not so much an effect on tune other than your tune will transition the engine more smoothly as well. The tuned pipe is going to affect the high side tune and will make a lean setting over what the "in cowls" do.
By smoothing out the pulse (starting and stopping) the engine develops maximum torque through out it's rpm band.
So.....A canister is less likely to cause a tune (with in cowls) to be excessively off where as a tune pipe will affect the high needle going lean.
Now header length is way more critical for a pipe over a can. Both however will have a header length determined mostly to the size prop you are running. Canister header length is typically longer than tune pipe header length but again the load (Prop) determines this.
No special trick with a pipe. "cut and measure" with the prop. I have headers stored with the specific prop I want to run for the appropriate engine.
