ST G-51

I have seen a few posts here with mention of the older version Italian made ST 51. Tower has the new version listed now for $89.99 and I have been told that it is the version produced in China. I own two ST 60'S, both of which have been tuned for stunt, and a SSW ASP 53 that Len tuned. All three of the above mentioned engines are fantastic stunt motors but I wonder if I have been passing up a chance to own yet another great stunt motor for as little as $89.00. Does anyone have experience with the G-51 made in China? What are your thoughts in reference to quality, power and stunt run ability out of the box?

Thanks

I hope the experts weigh in soon, but until then I can tell you that mine runs fine. If someone hadn't told me it was assembled in China, I would have never known. It broke in easily, like a ringed engine should and flys just fine (10 percent, all synthetic, T-bolt plug, Rev Up 12-5 prop) in a 58 ounce Time Machine.

I have been flying Super Tigre engines since 1965 and have always loved their quality, if not their weight. I don't have enough time on my .51 to know how it will hold up (rings, etc.), but I liked it so much I decided to spend the extra 90 bucks and get a spare.

Ron King

I, too, am interested in how your ST .51 is doing. I bought mine about 1-1/2 weeks ago and have yet to put it on the test stand.

Does it really need to be reworked for stunt use, or is it suitable right out of the box?

I was told when I purchase my first G-51, that it would fly stunt right out of the box, Well it didn't. I used the original muffler that was supplied with this engine, boy was that a mistake.

I saw a advertisment in Stunt News, back when the magizine was black & white, for Tom Lay and his ST conversions. Well I sent him my ST for conversion. After the conversion was finished I installed her back in the nose of my Sig Magnum, boy what a difference. The 4-2-4 break was more pronounced, the needle valve was not as sensitive and the engine did not try to runaway at the end of the run.
I have since upgraded two more of my G-51 engines. It was well worth the money. Tom Lay is an expert when it comes to ST's

LAST EDITED ON Mar-07-04 AT 09:17 PM (CDT)
 
I'm getting ready to put the finish on a Time Machine. I don't paint but use a combination of Monokote and Ultracote which seems to work well for me. I have also enjoyed success with Super Tigre engines. The airplane I have been flying for going on four years has a ST 60 in the nose and even though it is a little low on compression it just keeps powering through the pattern time after time. I did luck into a new, never flown, Big Jim reworked ST 60 last fall so I built the Time Machine around that motor. I have a couple other projects in mind and intend to use a SSW 53 in one and possibly a ST G-51 in the other if the G-51 gets favorible comments here on the forum.

Thanks

LAST EDITED ON Mar-07-04 AT 09:45 PM (CDT)
 
The ONE issue with G.51's is how the ring is fitted, and how round it is. Even Italian made ones had the same issues. If you don't know how, or want to, mess with rings, the safe bet is to "Let Tom Do It". I got one from Tower in January for $99.99 price, sent it to Tom Lay, got it back in a couple of weeks, and ordered another for the $89.99 price. Why? Well, now I have an engine that should be a good benchmark (Tom's!), and I can get some more Bowman rings and try it myself. I plan to plug the boost port on this one, but so far, I haven't even looked inside it (it came yesterday AM, and the wife was home). Steve

PS: Tom was very insistant on using 25% all castor oil fuel.

LAST EDITED ON Mar-07-04 AT 10:19 PM (CDT)
 
I own 3 of the G/51's and have had no issues with any of them. Why? Because their still NIB. I don't know why it is but I have a very hard time ever taking a new engine out of the box. It must be the collector in me. Anybody know how to overcome this affliction? I must have at least 50+ engines new in box that would love to do what they were intended to do.

Bill

Someone correct me if I'm wrong, but I dont believe that Tom blocks the boost port when reworks the ST 51. I had Tom rework my ST 51 and he told me that he refits a standard venturii, hardens the sleave, fits a new ring and laps the bearings- no mention of boost port blocking. These engines run a great stunt run as is, I dont know why you would want to block the boost port?
I have heard of many using the ST 51 right out of the box and they run great- Yes DO NOT use the supplied muffler- its a boat anchor, get a tongue or tube muffler from Len.
I just bought a new Chinese ST 51 and plan on having Tom rework it also. The main thing I dint like about the stock ST 51 is the venturii setup- the needle sets far too high for normal mounting.

>The ONE issue with G.51's is how the ring is fitted, and how
>round it is. Even Italian made ones had the same issues. If
>you don't know how, or want to, mess with rings, the safe
>bet is to "Let Tom Do It". I got one from Tower in January
>for $99.99 price, sent it to Tom Lay, got it back in a
>couple of weeks, and ordered another for the $89.99 price.
>Why? Well, now I have an engine that should be a good
>benchmark (Tom's!), and I can get some more Bowman rings and
>try it myself. I plan to plug the boost port on this one,
>but so far, I haven't even looked inside it (it came
>yesterday AM, and the wife was home). Steve
>
>PS: Tom was very insistant on using 25% all castor oil fuel.
>
>http://www.nwskyraiders.com/index.html

WHY PLUG THE BOOST PORT? The engine runs just fine.

Scott(if it's not broke give it to Steve)Riese}>

I didn't say or suggest that Tom Lay blocks the boost port. As for why block the boost port, you might ask Leonard about that, but if it can increase torque and prop size, that's interesting to me. I'll carve a soft balsa plug and not glue it in; easy to reverse the process. Steve

I didn't imply anything about TOM LAY. WHY would YOU block to boost port? Do you know something we don’t? And as for asking Leonard I'm not. I'm asking you. MISTER.

Scott(double talking free flight guy, I'm not)Riese}>

>I didn't imply anything about TOM LAY. WHY would YOU block
>to boost port? Do you know something we don’t? And as for
>asking Leonard I'm not. I'm asking you. MISTER.
>
>Scott(double talking free flight guy, I'm not)Riese}>

Scott: Brian Hadley seemed to think that I implied Tom Lay blocked the boost port. I have no reason to think he does, but haven't looked inside my T&L G.51, either. Not my job! You need to actually read the posts.

As for blocking the boost port, the OS .40LA gained bottom end and midrange torque when they deleted the boost port, much as Leonard does with the FP's and other engines. Why would you want to try a stupid looking Mac's Muffler? 1) Because you're curious. 2) Nobody has to give their approval; this IS America.

I didn't realize I needed your permission. It must not be in my copy of the rules. Excuse me! Steve

>>I didn't imply anything about TOM LAY. WHY would YOU block
>>to boost port? Do you know something we don’t? And as for
>>asking Leonard I'm not. I'm asking you. MISTER.
>>
>>Scott(double talking free flight guy, I'm not)Riese}>
>
> Scott: Brian
>Hadley seemed to think that I implied Tom Lay blocked the
>boost port. I have no reason to think he does, but haven't
>looked inside my T&L G.51, either. Not my job! You need to
>actually read the posts.
>
>As for blocking the boost port, the OS .40LA gained bottom
>end and midrange torque when they deleted the boost
>port, much as Leonard does with the FP's and other engines.
>Why would you want to try a stupid looking Mac's
>Muffler? 1) Because you're curious. 2) Nobody has to
>give their approval; this IS America.
I didn't realize I needed your permission. It must not be in
>my copy of the rules. Excuse me! Steve
>
>http://www.nwskyraiders.com/index.html

Time out OREGON!
I DID READ THE POSTS YOU DON'T NEED MY PREMISSION. As far as the MAC'S muffler I knew what I was doing.
My Statement is...If you read my post. Do you know something we don't know. Do you think it will work because WHY? What's the plus of blocking the boost. LOW end? Bigger prop? less fuel? user friendly?
OR is this something your just talking about doing later down the road? ANYWAY, how's the fishing, You comming down to the Stunt Clinic?

Scott(your excused)Riese

LAST EDITED ON Mar-09-04 AT 09:09 PM (CDT)
 
>>>I didn't imply anything about TOM LAY. WHY would YOU block
>>>to boost port? Do you know something we don’t? And as for
>>>asking Leonard I'm not. I'm asking you. MISTER.
>>>
>>>Scott(double talking free flight guy, I'm not)Riese}>
>>
>> Scott: Brian
>>Hadley seemed to think that I implied Tom Lay blocked the
>>boost port. I have no reason to think he does, but haven't
>>looked inside my T&L G.51, either. Not my job! You need to
>>actually read the posts.
>>
>>As for blocking the boost port, the OS .40LA gained bottom
>>end and midrange torque when they deleted the boost
>>port, much as Leonard does with the FP's and other engines.
>>Why would you want to try a stupid looking Mac's
>>Muffler? 1) Because you're curious. 2) Nobody has to
>>give their approval; this IS America.
>I didn't realize I needed your permission. It must not be in
>>my copy of the rules. Excuse me! Steve
>>
>>http://www.nwskyraiders.com/index.html
>
>Time out OREGON!
>I DID READ THE POSTS YOU DON'T NEED MY PREMISSION. As far as
>the MAC'S muffler I knew what I was doing.
>My Statement is...If you read my post. Do you know something
>we don't know. Do you think it will work because WHY? What's
>the plus of blocking the boost. LOW end? Bigger prop? less
>fuel? user friendly?
>OR is this something your just talking about doing later
>down the road? ANYWAY, how's the fishing, You comming down
>to the Stunt Clinic?
>
>Scott(your excused)Riese

Scott: I'm not dissatisfied with the ex-D.Dirt psuedo GMA reworked G.51 in the 62 oz. Mutant Magnum (Tom Dixon's Magnum Plus), but would like more torque. I like the airplane (would recommend it highly), but I always wish I could stick my 2Star .60bb in it. Maybe I could, maybe I should. But the Tom Lay G.51 will make a difference, I hope, and give me a stronger running "benchmark" G.51.

As I said, the .40LA's reportedly got better low/mid torque without the boostport, so I thought it might be worthwile trying a temporary block (a soft balsa plug should work, maybe with some silicon gasket stuff). I want to get a couple more Bowman rings, and fit one to the latest G.51. That partly just for the experience (haven't ever messed with ringed engines much, except Volvos). Also to give this engine the best possible chance. From what I've read about ST's ring fits, roundness, etc., it didn't sound like the Italians did a great job at this, and I doubt the Chinese will improve on that. Just a guess.

I'm not taking my T&L G.51 apart to see what Tom did, I'm not taking my SSW ASP .53 apart to see what Leonard did, nor either of the GMA engines I have. But I worked on model engines a lot in the '60's, and notice I didn't say "reworked". Fitting & setup counts for a lot, even if the engine is really stock or just slightly tweeked. I'm not serious about flying contests, but I am still curious about engines. I'm not convinced that the CL version of the G.51 is the right G.51 to try this with, or try with a Mac's Muffler, for that matter, but I'm not buying an R~C version to find out. OK? Steve

PS: Fishing should be getting good real soon. When the water temp gets up to the upper 50's, I be goin'. C'mon up. I probably won't be going to the Fireball's Stunt Clinic. Probably will be all tuckered from fishin'. Wish the Clinic was on the Saturday.

>>>>I didn't imply anything about TOM LAY. WHY would YOU block
>>>>to boost port? Do you know something we don’t? And as for
>>>>asking Leonard I'm not. I'm asking you. MISTER.
>>>>
>>>>Scott(double talking free flight guy, I'm not)Riese}>
>>>
>>> Scott: Brian
>>>Hadley seemed to think that I implied Tom Lay blocked the
>>>boost port. I have no reason to think he does, but haven't
>>>looked inside my T&L G.51, either. Not my job! You need to
>>>actually read the posts.
>>>
>>>As for blocking the boost port, the OS .40LA gained bottom
>>>end and midrange torque when they deleted the boost
>>>port, much as Leonard does with the FP's and other engines.
>>>Why would you want to try a stupid looking Mac's
>>>Muffler? 1) Because you're curious. 2) Nobody has to
>>>give their approval; this IS America.
>>I didn't realize I needed your permission. It must not be in
>>>my copy of the rules. Excuse me! Steve
>>>
>>>http://www.nwskyraiders.com/index.html
>>
>>Time out OREGON!
>>I DID READ THE POSTS YOU DON'T NEED MY PREMISSION. As far as
>>the MAC'S muffler I knew what I was doing.
>>My Statement is...If you read my post. Do you know something
>>we don't know. Do you think it will work because WHY? What's
>>the plus of blocking the boost. LOW end? Bigger prop? less
>>fuel? user friendly?
>>OR is this something your just talking about doing later
>>down the road? ANYWAY, how's the fishing, You comming down
>>to the Stunt Clinic?
>>
>>Scott(your excused)Riese
>
> Scott: I'm
>not dissatisfied with the ex-D.Dirt psuedo GMA reworked G.51
>in the 62 oz. Mutant Magnum (Tom Dixon's Magnum Plus), but
>would like more torque. I like the airplane (would recommend
>it highly), but I always wish I could stick my 2Star .60bb
>in it. Maybe I could, maybe I should. But the Tom Lay G.51
>will make a difference, I hope, and give me a stronger
>running "benchmark" G.51.
>
>As I said, the .40LA's reportedly got better low/mid torque
>without the boostport, so I thought it might be worthwile
>trying a temporary block (a soft balsa plug should work,
>maybe with some silicon gasket stuff). I want to get a
>couple more Bowman rings, and fit one to the latest G.51.
>That partly just for the experience (haven't ever messed
>with ringed engines much, except Volvos). Also to give this
>engine the best possible chance. From what I've read about
>ST's ring fits, roundness, etc., it didn't sound like the
>Italians did a great job at this, and I doubt the Chinese
>will improve on that. Just a guess.
>
>I'm not taking my T&L G.51 apart to see what Tom did, I'm
>not taking my SSW ASP .53 apart to see what Leonard did, nor
>either of the GMA engines I have. But I worked on model
>engines a lot in the '60's, and notice I didn't say
>"reworked". Fitting & setup counts for a lot, even if the
>engine is really stock or just slightly tweeked. I'm not
>serious about flying contests, but I am still curious about
>engines. I'm not convinced that the CL version of the G.51
>is the right G.51 to try this with, or try with a Mac's
>Muffler, for that matter, but I'm not buying an R~C version
>to find out.
>OK? Steve
>
>PS: Fishing should be getting good real soon. When the water
>temp gets up to the upper 50's, I be goin'. C'mon up. I
>probably won't be going to the Fireball's Stunt Clinic.
>Probably will be all tuckered from fishin'. Wish the Clinic
>was on the Saturday.
>
>http://www.nwskyraiders.com/index.html

OK

LAST EDITED ON Mar-08-04 AT 08:20 AM (CDT)
 
My understanding is that the Chinese ST 51 is a good runner right out of the box. I have a NIB but have not run it. I will send it to Tom Lay before I use it for contest work simply because that's what I will do. I had my first one redone by The Layster in '93, and it was still running great when I sold it this year!
Make sure you have the C/L version since the sleeves are different.
Bill <><

>My understanding is that the Chinese ST 51 is a good runner
>right out of the box. I have a NIB but have not run it. I
>will send it to Tom Lay before I use it for contest work
>simply because that's what I will do. I had my first one
>redone by The Layster in '93, and it was still running great
>when I sold it this year!
>Make sure you have the C/L version since the sleeves are
>different.
>Bill <><
>
>
>Just an Old Advanced flyer.
Bill is correct about the difference in the sleeves for the C/L and the R/C versions.
I just changed a new ST51 RC to a C/L version and the ports are sizably smaller on the C/L version. No I didn't measure them.I'm sure that others have already done that. My Chinese version looks just as nice as the Italian version. Dennis

I remember from some months/years back (here on SSW) that one of the gents from down under (another Brian?) related G-51 stories about fuel used. It worked best on 25% all castor fuel as I remember him saying. This being a near to box stock motor. With less lube in the fuel performance was markedly less satisfactory. The fuel alone made all the difference. FWIW.

LAST EDITED ON Mar-09-04 AT 07:04 AM (CDT)
 
What a memory
With my usual 20% all castor (zero nitro) nothing would stop it from going from a great 4 stroke into a screaming 2 stroke and settling down about 3 laps later. After a month of playing with venturis, plugs, needle valves and compressions I took it back to box stock to start all over again. By sheer good luck (meaning I ran out of my normal fuel) I tried a tank of 25% all castor just to have another flight and never looked back after that. Not a sign of any 2 stroking, just a lovely growl through the entire tank. Powerwise I can't really pick between it and my Stalker 61.

Brian H. (not Brian E. or Brian G. )

The Layster does advocate all castor fuel in his ST 51s. He sets up the Bowman rings to run on 25% all castor will no ill effects.
I tried it this year with 1/2 and 1/2 20% oil, the engine runs were erratic (albeit very minor) but it returned to itself when the all castor was used.
Tom doesn't "change" any of the timing AFAIK, just fits and blueprints them. I haven't found another engine in this cost/size/weight class that runs as good, or as strong.
If the engine is not going to be for serious stunt competition, I would go with the stock set up. But, if you can afford it, send it to The Layster!
Bill <><

Well guys I finally broke down and ordered one from Tower along with a couple extra gasket sets. I have heard so many good things about the engine I knew if I missed the chance to get one at Towers price, and then they stopped making them (again), I would hate myself later.

Bill, Brian, and others.
Finally the post I wanted to hear. Thank you all.
I run my ST-51 from Tom Dixon & MY stock ST-51 with 25% all castor and I never had a bad run. Their GREAT ENGINES. Looks like I’ll have to pick up another.

Scott (KISS) Riese

Bill,

I have 1/2 and 1/2 20% Sig fuel and to get my ST .51 to run well I need to add about 12 ounces of castor to the mix, then the engine smooths right out into a nice 4 stroke. If I don't add the castor the engine runs erratically.

Just asking? Why is the much heavier newer ST G-.51 a better choice stunt engine than the OS LA series CL in .40 or .46? Both OS .40 & .46 have more hp and more rpm range. Does the ST behave "more" like a true stunt 4-2-4 in runs? I'm used to the older 'V' .51 and have found absolutely no problem with it. At the last two shows in Tucson, the OS LAs seemed to be the rage.

>Just asking? Why is the much heavier newer ST G-.51 a
>better choice stunt engine than the OS LA series CL in .40
>or .46? Both OS .40 & .46 have more hp and more rpm range.
>Does the ST behave "more" like a true stunt 4-2-4 in runs?
>I'm used to the older 'V' .51 and have found absolutely no
>problem with it. At the last two shows in Tucson, the OS
>LAs seemed to be the rage.

1) The ST 51s, while heavier are also fitted with ball bearings in the lower end.

2) And as they are typically used in models designed around ST 60s, the weight is not of concern.

3) They generally sound pretty cool.

4) Tom Lay will work on 'em, knows his stuff.

5) They aren't blue.

As to lots of castor oil in the fuel, I didn't find that to be the case with either of my ST 51s, one of which Steve is still flying. Hmmm, that is misleading, as I never actually tested either motor with a butt load of castor in the fuel. In fact, during early testing I went from 10/11/11/68 to straight SIG 10% "Champion" fuel which is 10/10/10/70 and a lot less hassle.

Steve, have you done any testing. More to the point, has my reputation been sullied by your test results?

Oh, and I understood your posts perfectly. As always.

I remember the first ST .51s in the Northwest..... Gary Nelson had one reworked by Tom Lay & Tom recomended all castor lube. Gary's .51 ran perfectly with all castor. Mine was reworked by George Aldrich I tried running it with all castor one flight it flooded out at the bottom of the inside square & I never tried it again.I always ued a 50% castor-Syn. lube blend. Red Max,Taffs,Sig. The things run fine. I think Gary's had a bit more spice but with that much power who's keeping track?
I still say Jerry Eitchen's done by Tom Dixon sound the best again they mostly all run good.

The only fuel options I really have are Powermaster GMA 29% or 22% oil mixes. I've always used the 22% in the G.51, with no complaints, but maybe I'm just not critical enough. It really honks for the last two laps or so, but I like a pretty strong warning of impending glide. It did "runaway" last July at Arlington, when I put a full 12-5 APC on it instead of the usual one, clipped to 11.5". But it was REALLY HOT. The 11-6EW seems to be more load than it likes. Maybe more castor would fix that? This strong running during the last two laps made me wonder if a 12-4 would work. Not.

The only grief has been at least one broken NV from vibration (the 2Star .60bb also did that, with Nelsoni NVA's), and the orignal D.Dirt glowplug didn't run well, probably due entirely to the "Old Glowplug Syndrome", recently explained in another thread. Nice engine. I like 'um. I think it'd be great on a Humongus, Shark 45, Buc 746, or Time Machine 50. Steve

Thanks John. Yup that Dixon .51 runs a great 2-4 break, although power seemed limited somewhat by a fairly small venturi. My favorite prop was a Bolly Clubman 11.5-6. I used SIG Champion 10% nitro, 10% castor with 10% klotz. If memory serves I put 4 extra ounces of castor in every gallon. Haven't ever tried it on all castor like Scott suggests. I'm afraid to fly that plane anymore cause the controls seem really worn out..

You bring up a valid point about the power output and weight of the G-51 as compared to the LA 46 and LA 40. I own both, an LA 40 and an LA 46 and in my oppinion the LA 46 is a great stunt motor. I favor the 46 over the 40 because my experience has been that my LA 46 seems to have quite a bit more power than my LA 40 and the 46 is a little lighter. My 46 also seems to run more consistant than my 40. I have also seen the stats Tower has listed with each of the engines that seem to indicate that the LA 40 and 46 produce more bhp than the ST G-51. I dont really know what to make of that. Even though I love my LA 46 and feel it is a fantastic motor, I will say that the ST 51's I have seen perform in other peoples stunters seem to have a great deal more power than any of the LA 46 engines I have seen including my own. Maybe I am wrong and I'm sure there are guys that will argue that statement but flyers I know that have both engines have told me the Tigre is much stronger.

Horsepower isnt the prime consideration for a good stunt motor. Take a look at the specs on the ST 51 RC motor and you will see it has a lot more HP than the CL version. Whats also important is torque, and the type of run, i.e. smooth breaks, no runaways, consistent performance. I havent seen specs on it but I would imagine that the ST 51 has a LOT more torque than the LA 46. I can run far larger (3 blade) props on the ST than I can on my LA 46. Not to say that the LA 46 isnt a great stunt motor, but for larger models (like a Magnum) I think the ST is a better fit, IMHO.
Brian;)

I took my #3 Tiger .51 out last week turning a Zinger 12-6 at 8,400 rpm NO SWEAT. Now it wont perform like a GOOD Tiger .60 but it will turn a 12-6 easy.

I got my ST G-51 in the mail today and I noticed something that I hope won't be a problem. I pulled the engine out of the box and oiled it with a little Hobbico after run oil and when I turned the crankshaft I noticed that the thrust washer looked a little funny. As I turned the crank the thrust washer appeared to be slightly warped but the crankshaft did not appear to be bent. I called Mike Condon because Mike owns more Super Tigre engines than anyone else I know. Mike said that there was a good possibility that the thrust washer wasn't competely seated and suggested that I put a prop of the engine and after tightening, take another look at the thrust washer. I put the prop on the motor and tightened it up good and snug and from what I can see the crank is not bent. The thrust washer still looks a little funny. The only way I can describe it is the distance between the rear of the thrust washer and the front of the crankcase seem to narrow and widen very slightly when you turn the prop one full revolution. Mike said it could be something as simple as a slight machining flaw in the thrust washer making the width non uniform around the washer. This is something that appears to be so minor I can't even believe that I noticed it at all but since I have it bugs me. What do you guys with ST experience think? Should I send it back for another engine or can anyone shed some light on the subject?

LAST EDITED ON Mar-11-04 AT 11:34 PM (CDT)
 
Rick,

If the rear flange of the drive washer rocks while turning then most likely the prop flange has the same problem. Bolt the engine in a test stand with a prop installed and measure one of the blade tips to a point on the stand, then turn the engine 180* and measure the other tip to the same point on the stand. Just a few thousandths at the drive washer will be easy to see at the tip. It could either be a bad drive washer or the tapered cone that slips on the crank under the washer. Either way I would send it back for another one.

Todd's got the right idea. I would pull the prop driver and check out the collet and prop driver as best I could. Maybe defective, but maybe something simple, like burrs on the collet. Steve

Rick, I have honest answers to all of your questions, but no time to respond until after VSC.
Tom Lay
T&L Specialties

A message for Tom Lay,

I was going to give you a call for some ST info but the number I have for you is not current. How can I reach you?

Thanks

Yes, Tom, how can people reach you. This inquiring mind would like to know...
Nick Vanmatre