Author Topic: Review of the Brian Gardner ST 51 Piston Liner and Rod Set (Read 11287 times)

proparc · « **on:** March 06, 2016, 08:14:58 AM »

March 3rd 2016, I received my Brian Gardner piston, rod and liner set for the ST 51. I immediately installed it and I ran it the next day. First off, let me say that the quality of the parts is amazing. True workmanship.

Once installed, the change in run quality and the overall character of the motor is astounding! Once was once a paperweight on my desk, has turned into a true competition caliber stunt motor. The increase in compression is incredible.

As per the instructions, “if you get it too wet “it will bite you”. The compression is very strong and snappy. The motor started right up with a just a minimal prime. Right off the bat, the first thing I noticed is the big jump in power. The other noticeable thing is that, the motor is louder-a lot louder! It really growls.

The engine has a VERY rapid and consistent start pattern from hot or cold, (rare for an ABC motor). Hand starts were very fast and consistent-the way I like it. A seat of the pants assessment is that, I now feel the motor is on par with a K&B 61 stunt or, an Evo 61. The interesting thing is that, even after running the motor, the compression is still so strong, I cannot turn it over by hand. I have to fix a prop to it to play around with it.

Once was once an engine relegated to the scrap heap is now top on my list for a new stunt ship. Can’t wait to fly it!

tom brightbill · « **Reply #1 on:** March 06, 2016, 09:31:32 AM »

Brian's last name is Gardner.

proparc · « **Reply #2 on:** March 06, 2016, 09:33:26 AM »

Quote from: tom brightbill on March 06, 2016, 09:31:32 AM

Brian's last name is Gardner.

Duh!!! Thanks

Steve Helmick · « **Reply #3 on:** March 10, 2016, 02:05:17 PM »

Mine must be stuck in Customs! Meanwhile, I bought a 'lectric motor, two batteries and a charger...

Steve

Jim Kraft · « **Reply #4 on:** March 10, 2016, 02:46:22 PM »

"Lecric motors ony go Mmmmmmmm, while Anderson Spitfires go BRRRRRRRRRRRRRRRRRR.

Chris Wilson · « **Reply #5 on:** March 10, 2016, 03:35:20 PM »

Quote from: proparc on March 06, 2016, 08:14:58 AM

Once was once an engine relegated to the scrap heap is now top on my list for a new stunt ship. Can’t wait to fly it!

Brilliant use of a plastic bread board as your test stand mounting plate! (In the original post's attachments.)

You have just solved a problem for me.

Thanks

Andrew Tinsley · « **Reply #6 on:** March 10, 2016, 04:23:24 PM »

Thanks for the review, it sounds very much like my experience of Brian's ABC P/Ls. The ST 60 P/Ls were a revelation. More useable stunt power, smoother running and not the usual fistfuls of vibration. I am currently setting up one of his P/L s in an OS 35 and have used a Randy Smith rod and CNC tube muffler. I have only run it on the bench, but it is full of promise!
I am awaiting the ST 51 P/L, as I have what was, a new Italian made engine that was the biggest heap of rubbish I have ever come across. The runs were erratic in the extreme. I have tried all (and I do mean all!) the suggested tweaks, fuel, glow plugs and props, with very little improvement. It has been run so much, that the ring is starting to lose some compression! So Brian's new liner is my last hope.
Seriously these conversion sets are worth every $Aud asked! The chrome bores are the best I have seen. I have sneeked the use of a scanning electron microscope and have done some comparisons with other manufacturers chrome bores. Whoever does Brian's honing is a real craftsman!

Andrew.
rme

proparc · « **Reply #7 on:** March 10, 2016, 06:48:31 PM »

Quote from: Chris Wilson on March 10, 2016, 03:35:20 PM

Brilliant use of a plastic bread board as your test stand mounting plate! (In the original post's attachments.)

You have just solved a problem for me.

Thanks

Glad I could help. That is what we are here for, ( By the way, it is a common kitchen cutting board).

Steve Helmick · « **Reply #8 on:** March 13, 2016, 01:56:41 PM »

Brian says he has 30 packages ready to to mail "Monday", which is actually today (Sunday), so some of us will be getting ours in another week or so.

Steve

Andrew Tinsley · « **Reply #9 on:** March 18, 2016, 03:37:22 PM »

Hello ,
Mine turned up today and included a head which I don't remember ordering. Everything was to Brian's usual high standard. So tomorrow I will put my death row ST51 on trial and see which bit has been guilty of tormenting me with runs ALL over the place!
Seriously I will let you know what happens. If anything like previous BG P/Ls, it will run beautifully.

Regards,

Andrew.

Steve Helmick · « **Reply #10 on:** March 19, 2016, 08:45:15 PM »

Mine still haven't arrived. I've been good about checking the mailbox ASAP after delivery. Maybe Monday!

Steve

Dan McEntee · « **Reply #11 on:** March 19, 2016, 09:46:31 PM »

Mine is supposed to be in the batch that is in transit. Can't wait to try it out. I have a couple of R/C versions that will be the recipient of the new parts. I'll put it in my #2 Shark.45 that has a well used ST.51 in it that has so many runs on it I think it's due for a ring change. I'll get it down off the wall, put a few more flights on it to refresh my memory of how it performs (been a while since I have flown it) and then drop the new engine in it.
I don't understand the problems some have had with the ST.51. I have run them stock out of the box and T&L versions with much satisfaction and success. If Brian's parts are an improvement over what I have become used to, I will for sure be impressed! If anyone out there decides that they won't be using their's due to going electric or whatever, I would be interested in another one or two sets. I only ordered one set at the time due to now really knowing what my job situation would be when they were finsihed.
Type at you later,
Dan McEntee

proparc · « **Reply #12 on:** March 20, 2016, 08:06:07 AM »

Quote from: Dan McEntee on March 19, 2016, 09:46:31 PM

If anyone out there decides that they won't be using their's due to going electric or whatever, I would be interested in another one or two sets. I only ordered one set at the time due to now really knowing what my job situation would be when they were finsihed.
Type at you later,
Dan McEntee

Slapping Brian's parts in, will be well worth it for ANY ST51. If you are looking for serious power in a small light weight package, I don't see how you can go wrong. I especially see it having potential where, you may have been using an LA46 but, you want a LOT MORE juice, without having to go to something big and heavy.

Another scenario I see is where, maybe you were on 65ft lines and you want to get that profile out to say, 69-70ft this package is what I would reach for.

Dan McEntee · « **Reply #13 on:** March 20, 2016, 08:56:10 AM »

The ST.51 that I have in my #2 Shark45 was first used in a SIG Magnum that I let the weight get out of control on. Long story short is, the final weight with clear was 72 ounces, and ST.51 pulled it along just fine. I had to be gentle with the heavy beast like you would with any heavy airplane no matter what the power plant, but the engine never skipped a beat. I was just a half point out of making the Advanced top twenty at the NATS with the combination and I think the lines were in the 66 to 68 foot range, handle to model center. I hope to recreate that model but finish the weight tin the 60 ounce range next time. Anyhow, after I retired the Magnum I finished up the #2 Shark just in time to leave for VSC and used the tank and engine in the Shark so I wouldn't have any "new engine teething" issues while in Tucson trimming out the airplane. The poor engine has just been worked to death! I'll be watching the mail box every day for the coming weeks!

Type at you later,
Dan McEntee

Andrew Tinsley · « **Reply #14 on:** March 20, 2016, 02:11:34 PM »

Hello Dan,
I I too have seen box stock ST 51s fly faultlessly, in fact I have had one. In fact they are an excellent stunt engine. This one was near new and was castored up. A quick clean up and unsticking the ring was all I had to do to it. It has been a fiendishly difficult engine to use, every run different. I was sure I had an air leak somewhere, but I went over it with a fine toothcomb and nothing. I have done ALL and I do mean ALL suggestions here on Stunthanger for recalcitrant ST 51s. Brian 's P/L is my last chance. No improvement and it gets thrown in the landfill!

Andrew.

Dan McEntee · « **Reply #15 on:** March 20, 2016, 06:42:45 PM »

Hi Again Andrew;
Sounds like the engines was previously used when you got it. They did make an R/C version of this engine and it has a different cylinder liner and is timed different. I've never compared and measured them side by side to say what the difference is, but it must be substantial for the factory to make two different parts. I'm wondering if somewhere along the way the wrong cylinder liners got used, or someone converted an R/C engine not knowing it was different, then sold/gave away his troubles to someone else? I know Tom Lay used to rework R/C versions for certain customers who thought they put out a bit more power. When my parts get here, I'll have to clear the decks and do some measuring and what the difference is. If this would be the case with your example, you should definitely see a difference.
Good luck and have fun,
Dan McEntee

Andrew Tinsley · « **Reply #16 on:** March 23, 2016, 03:39:39 PM »

Hello Dan,
The awkward ST51 is in fact a converted R/C engine. The one that ran well was also an ex R/C engine. I believe that one of the custom reworkers for the ST 51 (Tom Lay?) in fact preferred the R/C timed version to the stunt timed cylinder. So I am certain this isn't the cause of my problems.
It is just as though I have a variable needle valve leak, or something moving around in the spray bar and altering the flow delivery. Perhaps even a leak in the backplate. It is none of these as I have thoroughly checked everything by substitution. But the symptons could well be caused by variables like this.
Tank is not a problem, I fitted the bad ST51 in the plane that I had my good ST 51 in. The bad habits followed the engine! I can't see how a new P/L set will cure the problems, but if they do I shall be mystified!

Andrew.

Brian Gardner · « **Reply #17 on:** March 24, 2016, 01:54:30 AM »

This is great to read. I'm glad you guys like em.

If anyone wants extras just shoot me a message and I'll start building another waiting list.

Steve Helmick · « **Reply #18 on:** March 24, 2016, 01:44:19 PM »

So they've all been mailed out? I haven't gotten mine, and I figure it's 1.5 weeks...mail came today already. Maybe the box went to Western Australia, as I feared?

Steve

RandySmith · « **Reply #19 on:** March 24, 2016, 02:17:43 PM »

Quote from: Andrew Tinsley on March 23, 2016, 03:39:39 PM

Hello Dan,
The awkward ST51 is in fact a converted R/C engine. The one that ran well was also an ex R/C engine. I believe that one of the custom reworkers for the ST 51 (Tom Lay?) in fact preferred the R/C timed version to the stunt timed cylinder. So I am certain this isn't the cause of my problems.
It is just as though I have a variable needle valve leak, or something moving around in the spray bar and altering the flow delivery. Perhaps even a leak in the backplate. It is none of these as I have thoroughly checked everything by substitution. But the symptons could well be caused by variables like this.
Tank is not a problem, I fitted the bad ST51 in the plane that I had my good ST 51 in. The bad habits followed the engine! I can't see how a new P/L set will cure the problems, but if they do I shall be mystified!

Andrew.

The C/L version is better, but both work, the C/L version produces more power at lower RPMs, and more torque
They are also much better with a true venturie rather than the "stuck out da top" restrictor

Randy

Brian Gardner · « **Reply #20 on:** March 24, 2016, 03:18:35 PM »

There are just a few left waiting for payment. as of now there is just one "spare" set.

That big bunch was posted on the 14th of March which is only 11 days ago. I wouldn't expect them to be arriving till next week to the US guys. The Uk is sometimes quicker and to Brazil another couple of weeks.

Quote from: Steve Helmick on March 24, 2016, 01:44:19 PM

So they've all been mailed out? I haven't gotten mine, and I figure it's 1.5 weeks...mail came today already. Maybe the box went to Western Australia, as I feared? Steve

Steve Helmick · « **Reply #21 on:** March 25, 2016, 12:04:50 AM »

Ok. It's been a long time since I've had a package go walkabout, but it has happened to me, thus the anxiety attack! I'll spend some idle time thinking about Andrew's problem G.51.

I'm organizing my shop, moving my rollaway into the shop, moved the lathe, pitching some stuff, and finding all sorts of neat lost stuff, too! Found the missing ignition wrenches and now have at least 2 complete sets of SAE and 2 of Metric. Renewed my fishing license, too. That may become a problem...

Steve

phil c · « **Reply #22 on:** March 25, 2016, 07:43:19 PM »

Andrew, ringed engines can develop lots of problems due to a faulty ring/piston/liner. Many more fits/finish and tolerances to be off. If the case is machined squarely and shaft OK I'd be really surprised if Brian's setup doesn't fix it up.

Just as an aside or what if, I had one Fox 35 that started easily every time but I never got a complete flight out of it. Start it up in a weak, spitting 4 cycle. Lean it out a bit nothing happened. Lean it more nothing. lean it more it would start sputtering, and then quit. Any setting that would keep it running on the ground would sputter and go lean in the air and quit. Never any 2 cycle, the motor just came down blazing hot. I gave up on it. Probably the case was fit too tight to the shaft, maybe a tight rod or the case wasn't square. Who cares?

Carl Cisneros · « **Reply #23 on:** March 25, 2016, 08:12:20 PM »

one thing to check for are the bearings.
I have seen these things do strange and wierd things to motor runs. not just in CL motors.

Carl

Brett Buck · « **Reply #24 on:** March 25, 2016, 10:11:42 PM »

Quote from: phil c on March 25, 2016, 07:43:19 PM

Andrew, ringed engines can develop lots of problems due to a faulty ring/piston/liner. Many more fits/finish and tolerances to be off. If the case is machined squarely and shaft OK I'd be really surprised if Brian's setup doesn't fix it up.

Just as an aside or what if, I had one Fox 35 that started easily every time but I never got a complete flight out of it. Start it up in a weak, spitting 4 cycle. Lean it out a bit nothing happened. Lean it more nothing. lean it more it would start sputtering, and then quit. Any setting that would keep it running on the ground would sputter and go lean in the air and quit. Never any 2 cycle, the motor just came down blazing hot. I gave up on it. Probably the case was fit too tight to the shaft, maybe a tight rod or the case wasn't square. Who cares?

Liner is backwards, probably. Relatively easy to do on the Fox since there isn't much difference between the intake and exhaust - but it's certainly enough to matter.

Brett

Andrew Tinsley · « **Reply #25 on:** March 26, 2016, 05:23:16 PM »

It most certainly is not the liner in back to front. First thing I checked, when the problems started. Bearings are fine as I changed those too, just in case. The ring is not giving its best seal now, as it has had considerable running, trying to find the problem! It is a slide fit in the groove and it started off with a 4 thou gap. It is now out to 6 thou, so I don't think the wear is too much yet. It had first class compression and first flip starts to begin with. The compression is now merely good and sometimes needs a second flip to start I did hone the cylinder half way thro my troubles just in case the ring was not bedding in. But still the runs are inconsistent. I did a review of ST 51 problems and worked my way through them. Oil content and type, glow plugs and compression ratio, fuel with and without nitro. Still have the same problem. There is no overheating in either the head or crankcase areas. The inconsistency can be seen in bench runs, let alone in an aircraft.
This one has me beaten and I don't give up easily. The good news is that Brian's P/L set has turned up. I am recovering from flu and it will be a day or so before I feel up to installing the set

Steve Helmick · « **Reply #26 on:** March 26, 2016, 06:40:22 PM »

1) How do you measure the ring gap without taking the ring off the piston? Doesn't that pretty much mean you need to install a new ring?

2) I seem to recall that somebody recommended .001" ring gap for a new ring. Can't recall if it was Tom Lay, GMA, or Randy Smith, however.

Steve

proparc · « **Reply #27 on:** March 26, 2016, 06:42:37 PM »

Quote from: Andrew Tinsley on March 26, 2016, 05:23:16 PM

The good news is that Brian's P/L set has turned up. I am recovering from flu and it will be a day or so before I feel up to installing the set

Take your time and, have some Q tips and lubricant handy for installation. Wait till you crank it up!H^^

Dan McEntee · « **Reply #28 on:** March 26, 2016, 07:12:54 PM »

My set and head arrived today and are they a thing of BEAUTY! Hope to build up the engine soon and get it run in, then do the flight tests.
THANKS A LOT BRIAN!
Dan McEntee

Andrew Tinsley · « **Reply #29 on:** March 29, 2016, 03:42:36 AM »

Hello Steve,
Simple answer, I took the ring off the piston, slotted it in the bore and trued it up with the piston and then used a feeler gauge to measure the gap. I cannot see why you should not reuse the ring. As long as you don't put it in upside down and ruin the fit, then the only thing that cam happen is that the ring is sprung out a little more than normal and that is too the good! I long ago learnt how not to break the ring when taking it off! I seem to remember that the gap for full size pistons should be 1 thou per bore inch. How that translates to small toy engines, I don't know, but I would be a little uncomfortable with only a one thou ring gap, I suspect it may start to bind when it gets hot.
The good news is that I have installed Brian's P/L and the problem has gone. I have only bench run it so far, but it behaves unlike the old ringed set up.
So it must have been a ring bore problem, but what I don't know. Everything looks good on the removed P/L, so I shall use it as a paperweight to remind me of the "troubles".
Thanks Brian for such a great piece of work, to say I am impressed is an understatement.
Anybody out there use the MVVS stunt 49? If so, anyone interested in joining me, to start a new list for an MVVS 49 P/L from Brian? I am in for 3 sets and Brian reckons he needs 20 for a run of P/Ls

Regards,

Andrew.

Steve Helmick · « **Reply #30 on:** March 30, 2016, 06:15:08 PM »

My ST G.51 (Gardner .51?) came in today's mail. So much for the Western Australia conspiracy theory.

Still working in the shop. Moving some electrical outlets, so wishing J. Leidle would stop by. He could at least supervise. I did turn off that circuit. Gotta get it done tomorrow, because Friday = Fishing.

Steve

Brett Buck · « **Reply #31 on:** March 30, 2016, 06:28:41 PM »

Quote from: Andrew Tinsley on March 29, 2016, 03:42:36 AM

Hello Steve,
Simple answer, I took the ring off the piston, slotted it in the bore and trued it up with the piston and then used a feeler gauge to measure the gap. I cannot see why you should not reuse the ring. As long as you don't put it in upside down and ruin the fit, then the only thing that cam happen is that the ring is sprung out a little more than normal and that is too the good! I long ago learnt how not to break the ring when taking it off! I seem to remember that the gap for full size pistons should be 1 thou per bore inch. How that translates to small toy engines, I don't know, but I would be a little uncomfortable with only a one thou ring gap, I suspect it may start to bind when it gets hot.
The good news is that I have installed Brian's P/L and the problem has gone. I have only bench run it so far, but it behaves unlike the old ringed set up.
So it must have been a ring bore problem, but what I don't know.

It could be one of a few dozen problems. Ringed engines are random number generators, for the most part.

Brett

Andrew Tinsley · « **Reply #32 on:** March 31, 2016, 01:44:22 AM »

Hello Brett,
I could not agree more, which is why I don't like them overmuch. They usually give problems when you least want them. Having said that when they are good , they tend to be very good.
I always like to understand why trouble occurs and on ringed engines, I have never had much luck in diagnosing faults, except when they are obvious like a worn out ring. This particular ST 51 looked good in the ring department, still a good fit and springy too. As a last resort I did hone the bore, just in case the ring had not settled in, still no joy.
Some people claim that when the ring has bedded in sufficiently then it has also worn out. I am not sure I agree with this, otherwise we would have millions of motorists complaining everyday! Surely there is not much fundamental difference between our toy engines and full size practice?

Andrew.

Lauri Malila · « **Reply #33 on:** March 31, 2016, 10:56:46 AM »

Hi.

I think that big part of ringed engine's bad reputation comes from bad metallurgy, bad workmanship and from an era when people used castor based oils.
I feel that a well made ringed setup can be better than lapped in a stunt engine. But a lapped setup is easier to mass produce.
With our integrated AAC-R, I have found no measurable wear after over 1000 flights, and no carbon buildup in critical places (Std 1mm high ring).
For the latest engines I made Dykes rings, after first 50 flights they feel better but there are also other changes in the packet so I cannot say for sure what causes what. Time will show..

Lauri

Andrew Tinsley · « **Reply #34 on:** March 31, 2016, 12:22:52 PM »

Leaving aside the fact that automotive engine technology has moved on from that of the 1970s. I used to get about 80,000miles before the engine needed a rebore. That was using a cast iron block and steel piston rings. As long as oil changes were as specified then it was usually the cast iron block that had worn beyond limits.
So if the cast iron wears faster than steel in this application, it is hardly surprising that our cast iron rings wear so quickly in our model application. Maybe we should make the cylinder cast iron and the rings steel. Just an idle speculation with a little baiting thrown in.

Andrew.

Lauri Malila · « **Reply #35 on:** March 31, 2016, 12:47:41 PM »

No, surface related problems are more like a rule with ferritic/ferritic metal sliding pairs, as with most pairs of similar composition. Grey cast iron ring is close to ideal when it is well made, and it's allways good to have the dominant wear in a part that is easier to replace. Good chromed cylinder - Problem solved.
Harder rings are possible but but then seating becomes more difficult, just as hard chrome can be too hard.
Quality and long life comes from correct material pairs, tolerances, surface quality and geometry, not straight from hardness.
Other than the ring, we use exactly the same piston/cylinder materials that are used in the best lapped engines (in F3D). That allows the use of much closer fits than in traditional ringed engines, and together with the integrated construction it gives so good stability and cooling that the usual ring-related issues don't exist.
But this is getting a little far from the original topic..

L

Brett Buck · « **Reply #36 on:** March 31, 2016, 01:01:16 PM »

Quote from: Lauri Malila on March 31, 2016, 10:56:46 AM

Hi.

I think that big part of ringed engine's bad reputation comes from bad metallurgy, bad workmanship and from an era when people used castor based oils.
I feel that a well made ringed setup can be better than lapped in a stunt engine. But a lapped setup is easier to mass produce.

   Hmm, I couldn't disagree more. A lapped system requires extremely precise machining and very careful control over the materials. A ringed system seems to be almost entirely dependent on the particular batch of iron you get, and the rest of the piston/liner, etc can be extremely crude by comparison. It seems to be a complete crap-shoot when it comes to batch-to-batch variations. Ringed systems were designed in the steam engine era when it was literally impossible to hold tight tolerances, and thus you added a spring element that conformed to whatever machining inconsistencies were present.

   But the trump card for a lapped system is that it's extremely unlikely to suddenly go over the hill like ringed systems do routinely. Even with iron liners/iron piston systems, crudely made (like the Fox and McCoy), you almost never have it suddenly change in the course of a few minutes or a few flights. Slightly too much castor, and all of a sudden, in the middle of a flight, the ring gets glued to the groove with varnish, and it goes off the rails. Or you get a sufficiently shiny spot in the liner, the ring starts to hydroplane, and boom, completely different. That was even evident in bench testing by Scott Bair, and matches pretty much right down the line with what we found in flight.

   I agree that people were making a mistake with all-castor or at least too much castor, which does lead to some of the problems with ringed engines. But removing the castor only fixes a few of the problems, and the others remain. We knew what to do and we had ST46s with good rings that provided acceptable repeatability, but we still ended up taking them apart on a regular basis just to keep them going. That stopped dead when we went to ABC and later AAC cylinder/pistons.

   Getting rid of ringed engines like the ST46 and ST60 was a huge step forward in reliability and repeatability, even over very good ringed engines. That alone would have made me want to switch, and if this was 1985 and such a thing as a Brian Gardner piston/liner was available it would have been the greatest breakthrough in stunt since the early 60s. I even asked if someone could *make me* something like that at the time.

   The fact that the replacements for the STs also provided greatly improved performance was just gravy. I would have switched even if it reduced the performance. In fact I was running a OS35FP with an iron liner as a potential replacement for exactly this reason when the real solution was discovered.

   Brett

Lauri Malila · « **Reply #37 on:** March 31, 2016, 03:21:13 PM »

Quote from: Brett Buck on March 31, 2016, 01:01:16 PM

Hmm, I couldn't disagree more. A lapped system requires extremely precise machining and very careful control over the materials. A ringed system seems to be almost entirely dependent on the particular batch of iron you get, and the rest of the piston/liner, etc can be extremely crude by comparison. It seems to be a complete crap-shoot when it comes to batch-to-batch variations. Ringed systems were designed in the steam engine era when it was literally impossible to hold tight tolerances, and thus you added a spring element that conformed to whatever machining inconsistencies were present.

Hmm, I should think longer to be able to say what I have in mind but I'll try anyway:)
Yes, lapping and honing needs extreme precision, but that kind of precision is difficult to specify. It's a bit more artistic than usual machining. But in mass production, average results are acchieved more easily than in making of good ringed setups, with machine grinding and hand finishing.
I fully understand your thinking but still, the faults and failure modes that you describe are largely results of bad metallurgy, materials, tolerances etc, as I wrote earlier.
Why would you not put the same extreme precision and correct metallurgy into a ringed setup? Because that's what was missing in the time when you got your traumas.
Another thing is that the very basis of a modern lapped engine technology is largely a result of tinkering of the other guy behind our little engine, Rob Metkemeijer. So technically we could do whichever, lapped or ringed.
I think that by choosing the ringed, Rob eliminated lots of variations that may occur with lapped geometry, certainly it would take much longer to find the optimal geometry. And the integrated cylinder structure, close to ideal metallurgy and piston porting eliminates quite well the hot spots that are a main reason behing instability.
I have had similar discussions with Yuriy Yatsenko, he is also quite interested in ringed engines but he can't make them with the required repeatability and precision.
In ST etc. era, manufactury costs were certainly less than costs of producing lapped engines, but if you want to do it well, it becomes very time consuming and cost-ineffective.
L

Chris Wilson · « **Reply #38 on:** March 31, 2016, 11:56:49 PM »

From what I understand about ring setups its the bore that has to be absolutely parallel.

Otherwise the ring will assume the 'middle' road or average size of the bore as it really doesn't want to expand and contract to follow every nuance thrown its way.

Ensuring that the bore stays perfectly parallel may well be more difficult than tapering it due to port cutouts and heat zones.

Casey · « **Reply #39 on:** July 21, 2016, 09:24:13 PM »

Hello proparc

In the picture you posted, your engine have a white venturi. Do you know where I can get one?

proparc · « **Reply #40 on:** July 21, 2016, 10:11:01 PM »

Quote from: Casey on July 21, 2016, 09:24:13 PM

Hello proparc

In the picture you posted, your engine have a white venturi. Do you know where I can get one?

Eric Rule at RSM. Tell him Milton sent you.

Andrew Tinsley · « **Reply #41 on:** July 28, 2016, 07:11:55 AM »

Hello.
Brett's remark about "if the Brian Gardner P/L were around in 1985 it would have been a revolution", rings a bell. Long before Brian had his accident, which has severely reduced his mobility, he used to run a setup called Bristunt. One of the offerings was an ABC P/L for I think the ST60. By the time I noticed this, stocks had long since been sold. Brian has started to produce ABC P/Ls again for various engines, to relieve the boredom caused by his injuries. I would like to know when the original ST 60 ABC P/L were produced? I think it must have been before the millennia?

EddyR · « **Reply #42 on:** July 28, 2016, 10:11:57 AM »

I believe the ST/46 came first. I have the first two sets and did a lot of testing and feedback for Brian. We found the stock head had to much compression. He then offered a hemi head. The stunt run is better with the hemi head. Must be almost ten years now.
Ed