More performance from a OS FP .40 ??
 

Any tips on getting more performance from this engine? Would drilling out the exhaust hole in the muffler help? Glow plug change? I know this is no racing engine, but I need a little more out of it.

More performance from a OS FP .40 ??
 

Opening up the exhaust would probably help. Also you could run a higher nitro fuel like 20%.

But sport engines are not as responsive to tuning changes as are highly tuned engines.

More performance from a OS FP .40 ??
 

Intake, bypass, and exhaust timing are all very mild on this engine, and the carb is tiny. If you want more power, you'll need to modify these parameters, but you'll lose some low end torque and flexibility. Why not just spend the money and buy a .46FX, or a Thunder Tiger .46 Pro, an Irvine .46, a GMS .47, or some other more powerful engine? Keep the FP for doing what it does very well - hauling trainers around - and step up to a more capable engine.

More performance from a OS FP .40 ??
 

No better words were ever spoken.

For to change the FP, you will have as much money in it as buying a higher performance engine.

The FP is a very nice engine for what it was ment to be.

Jim

More performance from a OS FP .40 ??
 

The only substitute for cubic inches is more cubic inches! Best get a bigger & better engine> >>>>>>>>>big max 1935

More performance from a OS FP .40 ??
 

Thanks for the help. Problem is, we are limited to a bushing .40 on our club pylon planes, and these seem to be the best choice. Uh, actually I'm just doing research to see if any of the other guys may be cheating, being they are supposed to be stock, baffle removed in exhaust is the only thing we can do. (that will be my excuse if any of the guys see this!) So, aftermarket mufflers, are out, I don't know if they would allow bigger carbs or not.

More performance from a OS FP .40 ??
 

Pylon flying...OK...who needs low end torque for that...you're after RPM's! You're still in a small bag of tricks with this engine, but here's a few that are easy to do and will help the top end somewhat...

The Tower .40 has a larger throttle barrel bore than the OS FP .40...that part is interchangeable...no one will notice unless they get a set of calipers out. The spraybar doesn't have to be halfway across the throttle barrel bore either...1/4 way is more than enough, you could even go less since high RPM running will draw fuel fine...more space for air to get through. If you can bore the tail pipe out on the muffler, do it...stock it has a slight taper to the hole. If you choose to bore out the hole, do it a little at a time...otherwise you might split the pipe and ruin the muffler. I bore them out until the hole is about the same diameter as it is at the end of the tailpipe...but the same diameter all the way in...it is a little louder that way. I imagine that you are probably stuck with a set nitro % fuel. The higher the nitro the cooler plug you will need for optimal performance. I typically run 10% nitro and have found that the OS #8 works great on all of my 2 stroke engines. The glowplug is something you might need to do a lot of trial and error checking with to squeeze everything you can out of this engine.

Also...by chance if you can use another engine other than an OS FP .40...get your hands on a TT GP .40 or a Tower .40 and do these same modifications...they will net more top end than the OS FP .40.

A club that uses a bushed .40 for pylon competition has my vote...makes you think a bit and use your skills...I like that!;)

FP .40
 

Another possibility is, if the engine has a head shim, remove the head shim for a small increase in compression ratio.

Some guys heavy into pylon racing send their engines off to be cryogenically frozen. It changes the properties of the metals and reduces friction. If that is allowable, it is worth checking into.

This won't help on an engine you already have but just know that all FP .40s are not created equal. It helps if you can hand select one with the best fit of piston and sleeve. Additionally, you would look for one that not only has a nice fit but feels ever so slightly gritty as you move the piston in the sleeve. These seem to seat the piston better. Also, a clean engine, without any varnish or carbon from castor will, all else being equal, turn a few more rpms. The engine will stay much cleaner using all synthetic fuels.

Here is another trick that worked extremely well for me. We used to race Fourstar .40s with the Supertigre GS .40 engine. I set my needle where the engine was running on the ragged edge of being too rich. All of the other pilots are tweaking their needles for just about the maximum rpms. What happens is that for the first two or three laps is that they would have a slight speed advantage over me but as the race continued, their engines would begin to heat up and lap by lap they would be slowing down while I picked up speed and became faster and faster because my needle setting supplied adequate fuel to the engine as it "unwound" in the air.

Another item that helps is the Tettra fuel tank which has a bag inside it to prevent the muffler pressure air from having any possibility of mixing with the fuel and leaning out the engine. As you may already know, as fuel burns down in a tank, the tendency is for the engine to run a little leaner. With the Tettra tank, you have a consistent fuel flow to the last drop without this tendency to become lean.

Just as all FP .40s are not created equal, the same goes for props. You can take say, 10 props, all the same make, diameter, and pitch, and one of them will give you more rpms than the rest. In pylon racing, every rpm makes a difference.

All of these things help out a small amount but collectively they can make a big difference.

Re: FP .40
 

This is a good idea for low nitro fuels...10% and less. If you are using more than 20% nitro you might want to add a head shim to lower compression and prevent detonation...which will slow the engine down.

GREAT tip on the slightly rich needle setting! The hotter an ABC engine gets while running the looser the piston/sleeve fit gets...and the less power it is able to produce. I usually point a plane straight up on the ground and tweek the needle just slightly richer than full lean...end of tank runs are excellent!

More performance from a OS FP .40 ??
 

I am using a moocan muffler on my 40FP I went from 11,600RPM on 10x4APc with stock muffler w/ baffle removed, to 13,600 with a moosecan.

More performance from a OS FP .40 ??
 

Hideho all,

Nice to see Gene back and dispensing with his vast knowledge of engines.
Gene knows his stuff for sure, I've taken his advice many a time with spot on results.

I too have a couple of FP's laying around I may try to "soup up" a wee bit.

Just for the snot of it.

More performance from a OS FP .40 ??
 

I found this a couple years ago in a forum. Don't know who wrote it, but it might be of interest to someone trying to soup up an FP40.

"Racing the Magnum GP40 (clone of the FP) for club-level racing, it had to be "stock", but there are a few things you can do. 1) Back out the spray bar so that it does not project into the carb throat. Just loosen the jam nut, back it out until it is flush with the side of the barrel, and retighten the jam nut. 2) Try removing the head gasket; this helped with most engines, but not all, so experiment. On the OS25, the plain-bearing engines have .016 head gasket, while the BB engines have a .008 head gasket, so if removing the head gasket does not help, you might try a .40FX head gasket - it might split the difference. It might not meet the strict interpretation of the rules - not sure on that. 3) If you remove the head gasket, you might start blowing plugs. We found the McCoy plugs to hold up much better than others, and use a non-idle-bar plug. 4) Some guys disassembled the engine and lapped the crank / main bearing in an attempt to minimize bearing drag - not sure if that really helped or not - sounds good in theory, but I never tried it 5) Believe it or not, one of the guys discovered that if you run a long plug WITHOUT the plug gasket, he picked up several hundred rpm. I tried it on my engine and son of a gun he was right! Must have had something to do with the placement of the coil in the combustion chamber. 5) Disassemble the muffler and make sure there is no casting flash or machining chips in the exhaust stack or tailpipe openings. Typical rpm on these engines with a 9x6 prop was mid to high 14k range, some guys had stronger engines up in the low 15k range. You might try a 9x7 prop; our event mandated a 9x6, but I tried a 9x7 when test flying and it seemed to give better speed. Purely non-scientific."

You might wanna make sure you don't make contact with the piston before cranking the engine if you follow the tip about removing the glow plug gasket.

GoMike

More performance from a OS FP .40 ??
 

I had lots of hop-up tips, but your going to run a stock class, so none of them will work for you. I'd try some of the other thing these fellows are telling you.
Suptter

More performance from a OS FP .40 ??
 

Great stuff! Now I know some stuff to try, I mean look for out at the field! They don't seem to worried about cheating, it is just racing for fun. But I think there have been a few guys inside the motors! Limited to a stock MA 10x6 prop, any fuel, can only remove internal muffler baffles. Motors are supposed to be stock otherwise. I think these mods would not be breaking any rules, just "bending" them a little. I think I will buy a TT GP 42 next, since it really still seems to displace as a .40, and is an accepted motor with the club.
Oh forgot to add, I already have a Tettra tank :D

More performance from a OS FP .40 ??
 

I don't want to take any credit where it is due to another person...

Most, if not all, of what I am conveying comes from the late George Aldrich. That man FORGOT more about model airplane engines than most of us will EVER know.

And there we have it.

More performance from a OS FP .40 ??
 

All right! Something seemed to help, first I drilled the exhaust opening to 9/32" was less than 1/4" before, plane seemed to fly faster, then I moved the spray bar back, seemed a little faster. I did all that before borrowing a tach to verfy rpm increases. Removing glow plug gasket seemed to lower rpm a little but that was with an idle bar one, removing head gasket got highest reading 12,700, but I could see it leaking, so I put it back. I still need to try OS#8,and a McCoy mc-59, I wonder how much that will be worth? So far, looks like about 12,500 on the ground is best, any comments? I don't know how much more to drill exhaust outlet, spray bar is about 1/4 in, and that is also with 10 percent fuel, need some 15 or so too. Oh, and we have to use a stock MA 10x6 prop.