Seems like the ST .51 (modern version) is becoming quite popular as a C/L engine.

Can somebody give me some information on it?

Bore, stroke, useable RPM range and WEIGHT.

Thanks for any help,

     Bob Z.

Hi Bob,
Here's the info on the Tigre 51:

Bore : 23 mm (.905")
Stroke: 20 mm (.787")
RPM Range : 2,000 - 12,000
Power output: .95 BHP @ 12,000 rpm
Weight without muffler: 313 grams ( 10.98 oz)
weight with muffler : 459 grams (16.2 oz) - "Chuck the muffler and use an
                                                               aftermarket muffler."
width of crankcase : 34 mm
length from backplate to thrust washer: 80 mm
height : 87 mm
prop nut size: 1/4-28

Features:
Dual ball bearings on crankshaft.
Schnuerle porting
Ringed piston

Supplier of stock engines :  Tower Hobbies $ 79.99   stock number LXFV87
                                         ( for the control line version)

Suppliers of modified 51's : Tom Lay is the most mentioned supplier but
                                        several of the engine guys offer "tuned 51's".

( I didn't see any mention of of piston /sleeve materials )

Bob, I hope this gives you the information you need.

                                                                 Pat Robinson

Bob,

I have several ST 51 engines, both Italian and Chinese.  There are very small visable differences in the versions; local wisdom is that the rings on the China versions either are not round or that they wear quickly.  Sometimes the ring lasts a long while---sometimes not. 

I am presently flying a Tom Dixon Italian ST 51 on a 64 oz. Score.  Powermaster 10/22 (50/50), APC 12x6 (heavy prop for CG location), take off at 8000 rpm.  Good, but not great 2-4 break, about 6.5 minutes on 5 oz. fuel. Using a Big Art tube muffler--I like it better than the tongue muffs; just because the tongue muffs spray exhaust all over.

Also, I have a stock Chinese 51 on a heavy, thrice rebuilt Cardinal.  Zinger Pro 12x6, take off at 7800 7900, same fuel, same muff, the ST doesn't even know the Cardinal is back there.  Seemd to run about the same as the Dixon 51.  The Dixon 51 uses somewhat less fuel than the stock 51.  The stock ST 51 needs 5.5 oz. for the pattern.

I have a T&L 51 waiting for the Magnum kit that Greg Barhman (spelling) gave me, also I think there are three other G51's hidden away in the engine cabinet.

A lot of bang for the buck, based on my limited experience.

Jim