Latest and greatest timing and deck height?

[Kurt Bozarth]

Bump. I get tired of trying to search for this thread when I need it.

[airplanescotty]

Could not agree more,,, it's ALL about the thumbs!!!!

Since my return to Pylon and exposure to all the new Tech, Serious motors , Programmable transmitters, Receiver Auto Pilots, digital servos, carbon props,, and airframe advancements, ton more strength & speed than F1,,, Oh My,,,,,

But then,,,, I've watched our World Champions consistent flying capabilities, in conjunction with my searching for the pylons, At Tavares Team Trials I was Number 2 Pylon judge and I could not believe how consistent Randy and Gino were at that turn,,,, I'm saying NOT just a couple heats,,, but ALL Weekend!!!!! Holy S&%T!!!!!

So,, Get your equipment into the competitive capable consistent 10 Lap range, then worry about smooth consistent Lap's,,, and then,,, and then,,,,

Enjoy the Podium

Scotty

[Kurt Bozarth]

Go suck an egg Scotty.

Kurt

[airplanescotty]

Got 18 chickens,,, I’ll bring ya one !

[rocket]

Thought I would contribute to this thread with the motor in the Cmad Sweet V this weekend at tangerine. First let me start by apologizing to the people who asked what the setup was for giving what I now know to be a incorrect answer. In my defense sometimes my dyslexia has a positive out come. Any how, what I thought I was running was 192/20 when it really was 190/18. I measured the exhaust timing to be .198*. The cool part was I built this motor with a used piston from a motor that ate the rod. At the champ race in Wichita I was elected to do motor tear down to make sure they were all on the up and up. They were. I did notice one motor was way older than the rest and the piston seemed to be, if anything, needed to be replaced. This got me to thinking. I have pistons in similar state of disrepair. What the heck let’s build it. The pic below shows the “pinch ring” of the SweetV motor from last weekend. When I wasn’t messing up as a pilot it was as fast as anything there. 190/18 with a 5 prop. The plug said raise the head after every flight, I opted to straighten out the coils with a needle valve needle. Forgot, the piston bite was 277 when measured after running it.

[Von Der Hey]

Sometimes the ugliest dog can hunt.

[GaryS]

Sometimes the ugliest dog can hunt.

Agreed!
I won the Nats in 428 with an engine that felt absolutely worn out. It had almost zero fit or seal to it, and didn’t tach well (I actually used a tach regularly back then), but it unloaded like crazy.

[rocket]

Let’s talk about “ramps” pros and cons. Earlier in this discussion we skimmed over weather or not their needed. Me personally, I don’t believe they add or adversely effect the performance. Watching lots of heats and stop watching just as many I really don’t see a huge benefit. I’ve been asking some fast guys weather they run them or opt for no ramp. I’ve heard a few reasons for not running them I.e they come loose, the restrict air flow. At the same time some believe they clean up dead spots, add velocity, make the motor act better. So my question is.. have you recorded performance numbers with and with out the ramp. Why do you think they help or hinder performance. Me personally, I don’t run them. I’ll do my best to pick it out if I get a crank that has one. If I order a new motor I ask to not have it glued in. What say you?

[vonderhey]

The ramp was created to help make the needling of the Nelson engine more docile. This was done at a time when many of the airframes were not as rigid as they are today, the front of the engine mount was rarely tied down and the use of the remote needle valve was not common. We have evolved to the point where almost all of the airframes produced are more rigid that they used to be, all of the engine mounts are tied down in the front and I’m guessing that seventy percent of the airplanes have a remote needle valve. So the question is does the ramp improve performance? So after numerous test stand runs there doesn’t appear to be any difference in rpm at the full unload range with or without the ramp. It looks like Ray came to the same conclusion with all of the testing that he has done. So the next question is, Do you want to keep the ramp in the engine? The answer to that question is probably not for the following reason. The ramps are installed with a high grade epoxy adhesive. However after a period of time the adhesive will start to deteriorate and the ramp could come loose and kill an engine. This failure never happens on the bench, it rarely happens on a test flight, it always seems to happen when you are in the heat of battle at a big contest. Eliminating the ramp could mean eliminating a zero and a damaged engine which is a big part of doing well at these contests. Von Der Hey

[rocket]

Removing metal on the crank to reduce reciprocating weight and replacing that with a lighter material is the only benefit I can see. There’s only so much air a motor can ingest. Once you reach the optimal opening size going bigger doesn’t mean going faster. It does however mean less reciprocating weight. The crank window in these motors is already optimized for weight/balance. It would take a ton of testing with multiple configurations of ramps to see which design and size would add any performance. You would be better off putting the crank on a flow bench and measuring that way.

[MSALAZAR]

I don't use crank ramps for the reasons stated above.
I use front mounted spray bar needles in all of my engines and haven't had any issues.
When I started flying Q-40, I had a couple of engines with ramps on their crankshafts and they came off over time, at races (like VonDerHey stated above) rendering the engines useless...
There's a theory that engines with ramped crank shafts accelerate faster from take-off start to first turn... I haven't done extensive testing on this, but my personal believe is there's no difference.
When I order my new engines, they always get ordered with no-ramps, with front mounted needle valves, and with my secret settings!!!

Happy New Year everyone!

[rocket]

Slower air in Muncie.
Having spent near 3 weeks in Muncie, 2 for FAI then the Nats I got to experience numerous weather conditions. It's long been known the air in Muncie is consistently slower than the rest of the country.
FAI planes use no nitro so making horsepower goes hand in hand with weather conditions. Let's use a pilot who is know to be captain consistency when it comes to going fast as an example. How can this guy go out one round and fly 56s next round he Flys 59s. Ths is an example of how fast the air changes. It happened pretty much the whole contest. It wasn't just him but all the competitors who had the "setup" to fly 56s suddenly flew 58/59s. Fai being a race against time you would think the best in the world could read the air better. Having flown FAI and tuning MBs and playing with setups for years I've learned a little about making them run. Let's fast forward to AMA 422. I texted some elite pilots to get input for this thread. Most replies were what prop they ran and what rpm they saw, some even told what setup they were running which is helpful and some were old-fashioned none of your business. Here's the text..

"Morning, I'm doing some research on Muncie air and why it's slower. Don't need motor setups just what rpm you were seeing on the ground and was it lower than other venues. If so, how much. It's for the latest and greatest thread."

Altitude and oxygen, you thought you had it figured out...
I always went by barometric pressure. Lower the pressure i.e. 29" the heads went up the higher the pressure i.e. 30" the heads went down. This system has worked for me even though I'm not the fastest guy and i do most of my flying in S Florida.
We've covered setups in the beginning of this thread now let's cover the atmosphere.
Jason Duda sent this pic of "Muncie Air" thanks Jason. Here you can see the temp, humidity, pressure and the reason for this post DENSITY ALTITUDE.
to my understanding it's how high up you are from sea level but let's start with the 28.5" of pressure. Remember my thoughts on that? Pressure up head down, well, here's a complete opposite scenario.
Why? When you're at sea-level or closer to it your DA plays less into your setup and slight adjustments to your compression based on pressure will yield dividends. When you throw Altitude in the mix like muncie at 4351' your dealing with less oxygen in the burn chamber.
This means lowering the head, for some, just to get it to start.
The consensus on rpm being lower at Muncie was mostly unanimous as was the times being slower in the replys I received. Although I didn't ask for it in the text a couple replys i questioned further about adjusting their setups. none made any changes.
The motor in my Sweet V was set up at 193/18. Bullet fast in Miami but dog slow in Muncie. Well it seems I gorilla gripped the head bolts one too many times and it showed.
It took me a few rounds to find the problem "a loose head". I went with a lighter prop to find rpm. It spun the crap out of the 7.5 but went flat in the air. The motor changed and a trip to the test stand and were off. Get to the line everything seems fine but it's flat again. No smoke, plug said not lean so what gives.
Well that motor was 192/23. I flew it in Muncie a couple months before in practice but cought covid and didn't get to race it. I lowered the head a .001 every round as all I can do now is be a nut cracker. By the last round I was at 192/18. The lower head was the reason it ran harder in the Muncie air. My 11 lap time in the last round.

[airplanescotty]

Terry's consistencies are specific to Pylon #3 Destruction!!!!

[rocket]

Let me make a correction. Here's a couple replies.

"I had to go to my lightest prop and dropped .002 on the head. The motor would hit 25,000 on peak, but if I peaked too early it would overheat. So I began starting at 30sec and set the needle w 16sec to go, it ran well every time after that"
------------

Me.. How did you compensate with your motor with the density altitude being 4000'

Reply.. Higher AD, the lower the head.

------------

[Kurt Bozarth]

See you in Denver in August RR!