bzpond

I got a ST 45 in trade, and am pretty disappointed in it. Running Cool Power 10% Nitro, only turning an 11x6 APC prop at 10,500. It was 90 deg and pretty humid that afternoon. My 46 AX is good for 2k rpm more with same prop and fuel. Is this typical for this motor? It is an older Italian ST. It has very good compression. Am I running the wrong prop?

djlyon

Sounds like something is wrong with it. It should be turning that prop at over 12K. You say it is and old engine, maybe it needs to be taken apart and completely cleaned and degummed.

Denis

bzpond

Oh yeah, I'm running a macs muffler on it. I ran it once w/o a muffler, and an 11x3 prop and it ran at 13500. So I bought the macs muffler, and put an 11x6 on. Would the muffler downgrade the performance that much?

djlyon

I've only run mine with a pitts style brisson muffler. It's not very restictive. the Macs could be causing some slowing but I'm not familiar with them. I've only run mine on 11/5 power props and 12/4 apc props. The 11/5 will run over 13k, that's why I think the 11/6 should get to 12k but certainly over 10.5k. I can't remember what the 12/4 turns. The 1/6 could be breaking it's back though. Try a 10/6 apc and if you go over 14k you are in real good shape and don't have an engine problem. Even if you only get to 13.5k I wouldn't worry

Denis

Cyclic Hardover

My Feedback: (3)

At one time I had all three, the ST 45, 46fx and 46pro and I wuld give them all equal in performance, so something is up. Thing is I used them for speed and was running 10/6 or 10/7 apc. What would help is what kind of plane and flying do you want out of it.

bzpond

I have it on my Magic, if it works out, I may take the 46AX off my 4* and put the ST 45 on the 4*. I'm not wanting 3D performance, just a little better than what I got.

therotund1

My ST GS45 (Chinese) is turning a MAS 10-6 prop at 15K with a Mac's black muffler. A friends is turning 14.2K with an APC 11-7 also with the Mac's muffler.

I love mine!

Flyboy Dave

My Feedback: (21)

The 11-6 APC is too much prop for it....use the 10-6.

FBD.

rafaxmen

I recommend you the 10x6 or even 10x7 nylon prop...

Jezmo

Mine turns a 10X7 14,600. That's with the stock ST muff.

Duane-RCU

My Feedback: (5)

Does it have 6 head bolts or 4? Might try something like an 11x4 too.

DarZeelon

A friend's ST .45 ABC engine... 14,100 RPM on a Generation II MA black prop.

This number is quite respectable.

downunder

I picked up a second hand ST GS45 and got 14,600 with an APC 10x6. Fuel was my running in fuel, no nitro and 25% castor. Why do so many seem to have trouble with the ST carb?

rcdude7

My Feedback: (264)

Good question. They maybe less foolproof than a OS carb, but they certainly are not hard to figure out either.

Flyboy Dave

My Feedback: (21)

I've had the old 45 ABC, an old .61 ringed, and a new .40 ringed....

....they are very simple to adjust the carb, and once adjusted they stay that way.

FBD.

djlyon

The problem is with the "so many" not the ST carb.

Jezmo

Yep, I've never had a problem adjusting one either. I do have to confess my biggest has been a 90 but I've had everything up to and including that. Started using them around '77 or '78 and I've kinda been partial to the ring motors but the ABC's have treated me good as well.