FP or LA

What is the difference between the FP engine and the LA engine? I have 2 OS Max 25 FP and 4 OS Max 25 LA and I can't tell the difference on my F2D combat airplanes. Lots of people seem to like the FP engines I see used FP engines sell on ebay for more that the price of a new LA engine. www.osengines.com has no information on the FP engines. OS product review says the 40 LA is hard to start and falls in the low power range of 40 size engines. Produce page also says .40 FP Parts Listing - Discontinued. I have not tried the OS 40 FP engine yet maybe I should.

The LA series replaced the FP series of which they were a cosmetically different detuned version of.

Paradoxically the detuning (blockin the bypass port) made the LA's better stunt engines.

Tony

>The LA series replaced the FP series of which they were a
>cosmetically different detuned version of.
>
>Paradoxically the detuning (blockin the bypass port) made
>the LA's better stunt engines.
>

There's an interesting thread where are argue the contrary on Flitelines now. The 25LA's don't seem to have the poop at flying revs (11500 or so) that the 20/25FPs have.

Bore and stroke remain the same, but there are definite quality differences, with the LA being the lowest quality and the older the FP, the better the quality. You can still get parts for the 40 FP by using the (better quality and less expensive) parts for the Tower 40. Parts are interchangeable. And the shaft and rod can be used in the LA series as well.

I believe some of the earlier "ABC" FP's had true chrome on the liner which was more durable than the early ABN plating. That, and popular demand are the reason for the higher prices on of FP's. If you think you just gotta have an FP you will bid up the price. The LA's deliver plenty of cheap power and last a long time if you keep them clean. OS seems to have overcome the ABN problems with the LA engines.

The LA 25 makes such an excellent stunt engine. Right out of the box, stock .260 venturi and OS needle valve, 9/4 prop and mild, oily fuel. It will run a nice, steady fast 4 cycle, with a bit of a break if you want it. Very little adjustment is needed to get decent runs. Once you get some experience under your belt you can play with venturi size, fuel, and running larger props and bigger planes.

>I believe some of the earlier "ABC" FP's had true chrome on
>the liner which was more durable than the early ABN plating.(snip)

The first ones were iron piston, iron cylinder models and, to me, these are still the best. Ironically they were lighter (iron cylinder lighter than brass cylinder and lighter case, too, plus fully machined shaft (like the Tower shaft). Then came the ABN and I think it was a response to the cheaper RC fuel. The iron piston models need castor oil and at least 20% to keep their longivity. don't run them with cheap fuel. And if you buy one on e-bay that is used, be very careful to ask what they ran it with.

>OS seems
>to have overcome the ABN problems with the LA engines.

This they did. They seemed to have learned a few lessons in how cheap you can make them. There was a period where the plating was so thin you could see through it.

LAST EDITED ON Feb-22-04 AT 09:55 AM (CDT)
 
What is ABN?

What is ABC?

In another post they talked about pipe what is pipe?

The 40FP looks bigger and heaver than the 40LA. How much does it weigh?

40LA = 273 grams = 9.555 oz.
46LA = 266 grams = 9.310 oz.
Muffler = 87 grams = 3.045 oz.

Do you guys fly with the muffler?

Do you use muffler pressure on the fuel tank?

Gary,
A= aluminum piston
B= brass sleeve
N= nickle plating on sleeve

ABC= same but Chrome plating on sleeve

Bill <><

Pipe = tuned pipe exhaust system. It muffles and actually adds power if used properly. Usually found on rear exhaust engines.

Dump the stock muffler. Get a tongue or lighter tube muffler from Leonard (or others).

I cannot remember the exact weight of the 40FP, but think it was heavier than my current LA40.

Ron King

LAST EDITED ON Feb-22-04 AT 11:26 AM (CDT)
 
I have read a lot about the quality differences between the FP & LA engines. Let me say this, the LA engines are great and require no special mods to run great. I have 4 15 LA's, 5 25 LA's and 2 46 LA's and have never done a thing to them except replace the remote needle valve. I have some FP engines also with no issues, but I have to play around with them to get them to run how I want them. After I read Brett's recommendations on prop selections, I have really gotten the LA/FP to run perfectly...thanks Brett!

I ran one of the 15 LA's on a Flying Clown all summer with a ton of flights, engine was set for max power. I took it a part yesterday and it looked brand new inside with no wear.

Bottom line is the LA/FP are both great engines that have very little vibration and are reliable. I don't disassemble each engine and measure tolerances, I bolt them on and fly and have never had a problem with any LA engine.

Are there better engines.......not for 70 bucks and under!!!!!

Hi Circle Burner
You say:
"Have never done a thing to them except replace the remote needle valve."
I have a .25 LA and a .46 LA
What needle valve do you use?
What about props?
What are the sizes and weight of the planes for yoyr .25's and '46's

My new F2D combat airplanes weigh 8.5 oz without the engine. The OLD F2d airplanes probably have a 1/2 ounce of fastcal on them. The OS 25 LA weighs 189 grams = 6.6 oz. I use 8x6 and 9x5 props. The 8x6 APC prop weighs 16 grams = .56 oz. The 8x6 is the fastest clocks 74.9 mph. The 9x5 times at 73 mph. I use the needle valve that comes with the OS 25LA I don't like it because it gets broken off easy. I always cut a slot about half way throught the plastic needle valve body with a hacksaw so when it brakes it will brake where I want it to brake. Once its broken off I drill a hole through the plastic needle valve body and bolt it on to a tiny aluminum bracket. If the needle valve ever needs to be replaced a bolt on type needle from an OS 40 LA works perfect on the 25LA. I have 1 russian made F2D combat airplane that is a size larger and need a larger engine to make the airplane balance so I put an OS Max 46LA on it. The prop on the OS 46LA is 9x10 it flies 105 mph. I don't like to fly it because its too fast for me. After about 15 crashes one of the combat airplanes didn't fly well with 2 lbs. of fastcal so I recovered the wing with white monokote and put a McCoy 35 on it just for fun. It flew sorta slow with that engine. Here is a pic of a couple of bad guys holding the airplanes.

>Pipe = tuned pipe exhaust system. It muffles and actually
>adds power if used properly. Usually found on rear exhaust
>engines.
>
>Dump the stock muffler. Get a tongue or lighter tube muffler
>from Leonard (or others).
>
>I cannot remember the exact weight of the 40FP, but think it
>was heavier than my current LA40.

The FP is an ounce to an ounce and a half lighter. It depends on which variant you get. Early iron piston versions were the lightest. Early ABN versions were a bit heavier and later versions got heavier because of the change in chrankshaft (two additional shafts with less machining, each of which got heavier). The LA uses the heaviest crank. Replace it with the early FP or Tower crank and you will take about a half ounce off th engine with better balance.

And then there is the case and head on the LA. Lots of aluminum. It does have a light liner, though. Thin.

OS .40FP weighs 8.32 oz (236 g) sans muffler

Bare

Barry Baxter

You have all missed the main difference between the two. The FP has a boost port and the LA doesnt. The LA comes out of the box ready for a nice 2-4 stunt run. The FP can be a run away nightmare unless properly propped and setup.

The LA 25 "bites it" in my book. I fought mine for months. 100 flight of weird runs and many different tanks and fuel choices later I took the motor off. The morning of our p 40 contest I bolted on an FP 25 new out of the box. Ran it once on the ground for 3 minutes to check for leaks and make sure all was well. First flight on a Tongue muffler and in a screaming 2s(missed the needle) Second flight, stock muffler with a slightly enlarged exit, first official for the day was better but still fast. Lots of power comparitively to the LA. Thrid flight second official yielded a killer run that would beep in and out a 4s in level flight and go to a nice strong full 2s in the maneuvers. All this was on an APC 9X4 with Sig 10% on a sullivan plastic tank. I eneded up in second place with a Mike Pratt P-Force. The FP 25 has it over the LA 25 in my book.

The LA 40/46 have it over the FP in my book. The non boost port makes the motor plug and play for stunt. It is no brainer all the way. You will never get the run away, unless you just over prop the heck out of it. The FP was notorious about running off on you. You would have send it out to get cut or do some mods. That is a thing of the past with the LA series 40/46. And the 46 will spin a 12 X 3.75 APC and 2-4 break with the best of them.

I know Len is all about the quality thing. But the motors around here are all working fine and there has been no complaining about quality issues with any of the LAs. No one has reason to remove the plastic backplate so that is not an issue. Heck Saitos come with plastic backplates and that is some of the finest quality on the planet. There is no reason for the backplate to be removed anyway.

Just my 2 cents worth.

>>>ready for a nice 2-4 stunt run<<<

It is ready also for pipe without any modification.

LA .46 with CF pipe plus BE UCT 2 blade prop 12x3.5 works well.

Doug I agree with the exception of the 25LA. I think the 25FP has more power, but I have never had any issues with the 25LA once I removed the remote needle.

The 46LA is a great engine, it's high quality and runs the same everytime!

Several people have mentioned the needle problem with the 25LA. What is the needle problem no one has said what it is?

The only thing I don't like about the needle is it is plastic and cast as part of the crank case cover. When it brakes off it usually brakes out part of the crank case cover which means you have to buy a new cover. I always cut about half way through the plastic with a hacksaw blade so when it does brake off it brakes at the weak spot that I created. Once it is broken off I drill a hole in the needle valve body and mount it with a screw to a tiny aluminum bracket to the engine. I make a venturi on the lathe and replace the RC carburator. The 25LA engines run great for me on combat and stunt.

Gary, the problem I had with the remote needle is consistency through-out the run. Once I switched to a regular needle valve the issues went away. The 25LA and FP run great for me, it doesn't matter if I'm running a standard vent, uniflow, or pressure they run the same for me.

The plastic back plate is not a problem and they don't leak. I just cut the remote needle mount off and let it eat!

I have two models with LA .46 and pipe. One has remote needle another regular NVA. I never got any inconsistency in run BESIDE the way how it leans at end of flight. The remote NVA makes 4C sound like rich, but in reality it stops lean in few seconds. It is thanx of bubles in tubing between NVA and spraybar. Once you understand it, there are no other problems.

I have been flying the 25LA and 25FP for about 4 years and never suspected the needle valve to be a problem. I have always suspected it was the left over fuel in the needle valve dried out leaving an oil deposit that later got sticky or gummy and sorta clogged it up. The longer the airplane sets before the next run the harder it is to get the needle adjusted the next time we fly.

I have noticed on the first flight of the day I can adjust the needle and about half way into the flight the engine will start to run rich. I have learned to set the needle a little on the lean side to start out so about half way into the flight it starts to run like its suppost to run. Then at the end of the flight it starts to run rich.

The second flight I turn the needle in slightly lean but not as much as I did on the 1st flight. After a few laps the engine is running perfect it might start to run slightly rich at the end of the flight.

The 3rd flight I turn the needle in to get a 2 cycle run then turn it back just to the point where it starts to run 4 cycle. Back and forth a few times to make sure I have the correct needle adjustment. I want the needle set at the spot where it is at the very beginng of the 2 cycle. Once the airplane is in the air ram air in the venturi makes the engine run leaner 2 cycle for combat screaming wide open full speed ahead. Once the needle is set I can do 20 flights and never touch the needle.

In the spring when we get to fly ever day I never have to touch the needle from one day to the next day. Every day we fly with the same needle setting. BUT, if we don't fly for 2 weeks then I have to turn the needle out because the needle acts like its stopped up with something. I think its stopped up with dried fuel. As fuel flows through the needle on each flight it seems to me like the fuel is cleaning out the needle. If the engine does not get started for a few weeks I have to turn the needle out 1/2 turn to get the engine started but after the 3rd run the needle is screwed back in 1/2 turn where it was before and the engine is running great.

I have run the 25LA and 25FP on my Flite Streak and Ringmaster and I have the same problem. It takes about 3 flights to get the needle set but once it is set we can fly 10 or 20 flights and never change the needle.

Is this the needle problem you are talking about?

I think you discovered another little maintainence trick we all should be doing after flying. Squirt some alcohol through the fuel line to flush out the oil in the needle valve so it doesn't gum up. Maybe the all synthetic guys can get away without this. Never had this trouble on a Fast combat ship:)

The other way around it is to flush the NVA with fuel prior to the first start. I turn the prop backwards against compression(to close the shaft valve and prevent flooding) and put a finger over the tank vent when the tank fills to push a quarter ounce or so of fuel through the needle valve. Doesn't hurt to open it one full turn first and then put it back after the tank is full. The engine usually needs a prime anyway for the first start so this kills two birds with one stone.