avanstory2000

My Feedback: (-1)

lets make one faster please help for pylon racein

bzpond

Assuming you've removed the baffle from the muffler, a few years ago, Stu Richmond from RCREPORT magazine had a suggestion to drill out the stinger with a 0.25" drill bit. I did it with mine, it does improve the power, but this engine is pretty wimpy no matter what. Maybe someone else here remembers more about what Stu said about it.

proptop

My Feedback: (8)

Yeah, you can improve the exhaust...even put a pipe on it, but you still have the small carb. with the (relatively ) tiny .220" venturi opening.

Maybe one of the Profile Brothers can tell ya about a "Mousse can muffler"...I seem to recall others having success with those.

You might try a different carb. but the neck's opening in the case is still small.

Jezmo

I am not quite sure why one would want to use an engine of this type unless the rules specifically require it. A ball bearing motor would be a much better starting place. In the case of rules requiring a bushing motor you could raise the exhaust port to help with running a pipe on it. Just know that messing with port timing is very critical and should only be attempted by those with the proper tools and skills necessary for this type of work. One small slip and a cylinder liner is ruined. You can also run a carb with a larger venturi size to get more mixture in and the transfer ports can be cleaned up to aid in the filling of the cylinder. Again, unless the rules require it I would choose a better piece to start work on.

This is in agreement with the above post. We posted at the same time.[8D]

loughbd

The manufacturers make modern engines to produce as much power as they can and still be reliable and user friendly

avanstory2000

My Feedback: (-1)

has anyone drill a carb would it help to drill the openin out

proptop

My Feedback: (8)

I've done that in the past, with different carbs that had a brass barrel, but the barrel is steel in the LA, and that would be more difficult.
There are certain aspects to doing that that can make it a PIA...
If you were really interested in modifying it just for the heck of it, you could get the control line versions venturi and drill that opening larger for more power, but you would have no throttle (obviously )...

Most pylon racers don't have a throttle anyway...

Rcpilot

My Feedback: (78)

The Macs black pipe muffler for the 46FX--TT Pro 46 works on the LA46 if you drill out the holes in the case a little bit. Makes a lot more power.

I wonder if the Macs muffler for the OS 40FX and the TT Pro 40 would also fit on the 40LA?

I just had to widen the hole spacing a little bit for the Macs pipe from the 46FX to fit on the 46LA. I posted some numbers on here a few months ago. Maybe do a search for 46LA Power Modifications Can't remember what I titled the thread.

It made a big difference.

Put a header on it and a cannister. Or a header and a full tuned pipe.

Take the head shims out and put some 25% nitro through it. Or put some 30% heli fuel in it--the kind the Saito guys use. It's got oil and nitro. Should give that engine a bit more snap. Just keep in mind that the tighter you wind it up--the more oil you need in that plain bearing crankcase. I don't know if a crank will seize under very high RPM or not, but if it was me, I'd be bumping the oil up to 25% or more if you really start making any kind of serious power with it.

Konrad

Drilling out an RC carb is generally a bad idea.
One must keep the relationship between the throttle barrel opening and the opening in the carb body so that the closing point of the cab throat is not at the lower edge. You must insure that the spray bar sees negative pressure at all times. This cannot be accomplished (guaranteed) with a drill bit.

The power limitation of the LA engines is that the crankshaft is too small for any high airflow. This is from the outside diameter not allowing any dwell (time that the crankshaft is fully opened under the carb), to the fact that the crankshaft bore inside the crankshaft is too small. A tuned pipe is probably the best option to gaining power. Time the power peak for low rpms (10 to 12K rpm).

But there is little point in making a silk purse out of a sow’s ear.

Have fun,
Konrad

loughbd

The LA's are entry level sport engines and never intended to be anything but that. They have airbleed carbs, plain bearings and very small venturis. They were designed for easy to use set up, reliability, and running on trainers and the like. Not racing.

rcdude7

My Feedback: (264)

One of the R/C mags did a .40 comparo several years ago and the la was at the bottom of course. It was not even close to the next engine up the ladder in terms of power. I don't even think that the la cyl sleeve has a boost port. This alone is a severe handicap to power and will gaurantee that this engine will always be a pedestrian in the .40 engine race.[:'(]

avanstory2000

My Feedback: (-1)

this is run what you bring racein but must have a la .40 on it so a found a super kraft F3D-30 put the la on it took the baffle out drill the spout out .venturis is small if i take the barrle out and rim the openin bigger would it help

DarZeelon

FYI, OS' predecessor to the .40LA, the .40FP, was also an entry level engine; a 'pedestrian', if you will.
But it had the whole kit, including a boost port, and did respond pretty well to MCP and a few other hop-ups.

I believe it is still being raced in some current club categories, even though it is no longer in production.


Mine did peel its nickel at the time, maybe in part from being fed 'Cruel Power' fuel...

w8ye

My Feedback: (16)

This "poor man's racing" class is set up with device restrictions to keep costs down. The LA 40 is not very costly and it doesn't do much good to put any money into it.

This keeps everyone about even.

rcdude7

My Feedback: (264)

The FP was a very nice inexpensive sport engine. The LA on the other hand is just inexpensive,....... I don't know what OS hoped to gain by replacing the FP with the LA engine line. Oh well...........


Hey avanstory2000, It's going to be tough to open up the venturi in that steel barrel. A .46la or .40fp carb may be a better choice if you can get one. Experimenting with several apc props may give you the best gains in your quest for speed with this engine.

Good luck

proptop

My Feedback: (8)

Do you need to (by the rules ) have a working throttle?
The difficult part of opening the steel barrel is getting it to rotate smoothly and seal adequitely after the "operation"...

If you don't need to show that you have a working throttle, why not just open that sucker up...
You could easily go up to .250 (1/4" ) which would help quite a bit with the "flowed" muffler.
In the past, I have used a "flame" or Christmas tree shaped grind stone to make the straight through barrel opening into more of a true venturi shape. Then de-burr it so it rotates smoothly in the carb body. Just don't get carried away.

Speaking of which, you can radius the inside of the muffler's tailpipe opening to allow the exh. to flow more smoothly out of it.
Pull the rear cone off the muffler and get out the Dremel and put a nice radius around the opening of the drilled out "tailpipe".

loughbd

The 40LA HAS a boost port as do all the LA series and it is rated at the same HP by OS as the FP. 1 HP@15,000 rpm. The big difference in the two series was the heads. One has a four bolt head and the other a 6. Oh, and the LA is blue (well some are) but I don't think that affects the power output. Cost effectiveness is why they changed. Power and reliability remained about the same.

It's the same reason OS went to the SF series from the FSR. It was less costly to manufacture a one piece Crankcase than the two piece case the FSR's used. One less casting to make and several machining steps less. That was one reason the 50FSR and the 108FSR lasted as long as they did. They had one piece cases.

MyWay

The LA engines I have worked on do not have a boost port .

w8ye

My Feedback: (16)

It would not be productive to use the LA 46 carb on the LA 40 because they are one and the same #40D

It has been my understanding that originally, the 40 LA had a boost port but in later versions there is no channel for it in the block. The Tower pictures depict a boost port. I do not have one of these engines on hand to verify this.

Hobbsy

My Feedback: (102)

Here is an LA sleeve, which one is the boost port? The LA .65 is the same only much larger.

proptop

My Feedback: (8)

My LA .40 doesn't have a boost port, but it looks like the case could be machined for one, so they didn't change the casting, just the machining process.

I've also got a .46LA but haven't had that one apart. IIRC, looking thru the exh. port, I don't remember seeing a boost port?

Motorboy

When i converted the 25 LA to dieselengine for my friend, there was not boost port in the liner.

Jens Eirik

Konrad

What is a boost port?

The original Schuerle patent showed only two ports flanking the exhaust port. It was thought that the velocity of the incoming fuel charge had to be kept high to scavenge to upper part of the cylinder. Someone realized that these two ports were in fact restrictive so a third "boost" port was added just opposite the exhaust port. Many of the early 3 intake port Schuerle engines had the two side ports open 4 degrees earlier than the boost port. Now days most engines have all three ports open at the same time, though they may not all be pointed in the same direction. Please note that small high velocity ports make for nice mellow engines just what a beginner needs. The LA engine is built for the entry market. It is not expected to make power nor is it expected to last much past the learning stage. It is expected to generate lots of profit for OS. OS is not dumb why build a great motor that will spend most of its time digging holes in the ground for the begineer pilot. Now are there better engines out in the market for the same cost? That's another topic!!!
Konrad

P.S.w8ye, I assumed that all intake ports cut into the sleeve flowed from the crankcase cavity. Dead end ports are something I hadn't fathomed.[X(]

MyWay

Interesting, Even the OS CVA 15 is made without a boost port, however, it still puts out good power.

Hobbsy

My Feedback: (102)

Hey Prop, that sleeve is out of a Dieselized .46, I checked the .65 and no third intake port either.