Saito .56 Information

I have recently purchased a Saito .56 ( my first 4 stroke) and have about 30 minutes breakin time on it with an R/C carb. Today I put on a Pat Johnston manifold kit from Ultra Hobbies. Due to a rain filled day, I could not get out to try my new set up.
My two questios are 1- The Duke of Dirt said in a past Stunt News report that Godzilla was writting an artical for Flying models about 4 stroke engines. Anybody know in what month the artical appeared?
2- Mr. Dirt also said he uses a Tettra tank in his Impact with a Saito .56. What is a Tettra tank and where do you get one?
So far the engine is running great, and the new experience is exciting.
Just looking for more info on 4 strokes to help in the future.

LAST EDITED ON Aug-30-03 AT 09:01 PM (CDT)
 
The entire FM article PLUS much more has been posted to the Ultra Hobbies Website, so you can go there and read the whole thing, and save it to your own computer. Good stuff, very worthwhile reading.
http://www.egpworld.com/ultrahobby/teamuhp/4stroke.htm

The Tetra fuel tanks are available from Central Hobbies in Billings, MT. They have props, glowplugs, etc. for the 4 strokes, but be aware, they are an R~C outfit. http://www.centralhobbies.com

There is nothing at all wrong with the Sullivan clunk tanks as recommended by Mr. Godzilla, aka "Theo(ther) Walker". Most the guys up here in the PNW run much bigger venturis in their Saito's than the Ultra kit, which in turn allows much bigger props. Maybe just the thing for your altitude. Steve

I'll chime in to say that a clunk tank is fine and only The Dirt would use a Tettra tank (Well, maybe Rich McConnell). The size if the venturi will regulate the rpm range and the available juice, but the ones that come with the Ultra Hobbies units are fine. I use a very large venturi to squeeze all the power I can out of the engine. Pat Johnston, the guy that designed the setup tha Ultra Hobbies markets, uses a much smaller one. But work fine. Mine puts out more power, but Pat's is very consistent...an important trait.

Pat loves the APC 13x4 prop and his Saito 56 runs in the 9500 to 9800 range. I like use a reworked Eather 12x4 3 blade flat back prop and run in the 9800 to 10,000 range. Both setups have considerable power, but Pat's plane is a feather and mine is, ah, much more substantial.

You have to mess with it a bit to decide what sort of run you're comfortable with. But I'd suggest stick with the stock Ultra Hobbies setup to start.

Thanks for all the information men, I'm starting to feel like I know what I'm doing. I am going with the smaller venturi, .265, because the manifold kit came with an OS needle valve assy. I have a Super Tigre assy, but didn't want to mess with the new manifold, perhaps at a later date. Guess I can try the larger venturis even with the OS N/V assy. Thanks again, Jerry

Jerry,

You don't have near enough run time on your 56. I would not consider bolting one in a model until it has at least an hour on the bench.

While I did use a Tettra tank last year and early this season, I have since switched to a 4-ounce Pylon (Sullivan) plastic tank, RST-style, I believe. The Tettra tank was/is a very nice and reliable setup. It's just that as I began flying more frequently the minor additional hassles involved in filling the thing were beginning the get annoying. Were the Pylon (and Du-Bro) tanks not available there would no hesitation in going back to a Tettra.

Amazingly, and thanks to Godzilla for the tip, the standard venting shown in instructions supplied with Pylon thanks works superbly. The only change I make it to use a Du-Bro sintered-bronze filter/clunk. This eliminates any need for an extranal filter and they are quite good at sucking up the very last bit of fuel in the tank.

As Steve notes, Tettra tanks--and a whole bunch of other Cool Stuff--are available from Central Hobbies, premier supplier to the RC Pattern community. Buy your four-stroke plugs from these guys, just specify the YS plugs; they are made by O.S. but are a lot cheaper. You won't need many spare plugs...

Steve's comment about CH being an RC outfit and so beware must be tongue in cheek. Over the years I have had nothing but excellent service from them, they offer some products with an application in CL Stunt that are not available from any of our traditional suppliers. Look to the Tettra remote plug attachment as only one example. And a whole slew of APC props...

Speaking of which, while Pat is liking the APC 13-4W, and I used one for a time, I am now flying with an Eather 12.5-5 three-blade. When I get the time I will try a 13-4W with another inch of pitch cranked in. And a 14-4W with more pitch plus being cut back slightly or to
13.0. Like Randy, I think a huge reason Pat likes the 13-4W is that his plane is very light. My converted Impact is not as heavy as Randy's current model but still heavy enough to keep that particular prop from being Killer.

John Leidle reports good results in his use of an APC 14-5N. While I have a couple they have not been flown.

I continue to like the .281-bore venturi with an ST NVA; as soon as I find my spare PA needles I will be switching to PA assemblies. With the low flow rate of a 56 the ST units are just slightly too touchy, even if only a mild annoyance.

Like most everybody else I am using YS 20/20 fuel from Powermaster. Good fuel, although not the step up in power from SIG 10% Champion that one would envision when going from 10% to 20% nitro.

There is news--well, it's news to me; original as well--with fuel blends and the Saito 56: Use varying mixes to fiddle with lap times and power levels. Using YS 20/20 as a pre-mix, and having on hand the other stuff, I have hotted some of it to 25/20 and 30/20. Have also mixed, from ingredients, some 20/20. You will find results from taching the motor on various blends to not show significant improvement, so I have learned--once the needle is set for the day--to simply ignore the ground rpm and fly. For example, going from YS 20/20 to my altered mix of 25/20 is good for knocking 0.12 to 0.15 off the lap times, an attendant increase in power. But one doesn't always want more speed, so I begin a practice session with standard 20/20 and go from there.

"There" being the fuel to use on that day, it turns out that my home-brew 20/20 is slightly stronger than off-the-shelf YS 20/20. I don't think there is any mystery to this, the reason (probably) being that I am mixing with 99%-pure nitromethane where Powermaster might well be using the more commonly available 90/10 stuff. The 10% is methanol; there is ALWAYS some methanol in all nitromethane or it gets real sensitive to shock. Since the NHRA changed their rules to a maximum of 90%-nitro fuel this has become the defacto standard with many suppliers, although I must emphasize that I have no way of knowing what PM uses to mix any of their high-quality fuels.

The really cool thing about fiddling with the blends note above is that one first takes the time to get a real good setting, whether you can do it on the ground or need a couple flights. Once the needle is set you can simply choose one of the blends mentioned and fly; no need whatsoever to play with the needle valve. Just get a feel for how the model flies, maybe take a peek or two at the stopwatch, try a different blend next flight.

Dan, I read in one of your 4 stroke articals in Stunt News, last years edition, that you drilled out the baffle in the muffler. I took mine apart and found several small holes in the wierd looking baffle. Could you explain exactly what you drilled.
Is PW still using Sig Champion fuel?
Appreciate yor reply to my post.

>You don't have near enough run time on your 56. I would not
>consider bolting one in a model until it has at least an
>hour on the bench.

I like a full gallon. There are a lot of moving parts in a Saito.

>Like most everybody else I am using YS 20/20 fuel from
>Powermaster. Good fuel, although not the step up in power
>from SIG 10% Champion that one would envision when going
>from 10% to 20% nitro.
>
>There is news--well, it's news to me; original as well--with
>fuel blends and the Saito 56: Use varying mixes to fiddle
>with lap times and power levels. Using YS 20/20 as a
>pre-mix, and having on hand the other stuff, I have hotted
>some of it to 25/20 and 30/20. Have also mixed, from
>ingredients, some 20/20. You will find results from taching
>the motor on various blends to not show significant
>improvement, so I have learned--once the needle is set for
>the day--to simply ignore the ground rpm and fly. For
>example, going from YS 20/20 to my altered mix of 25/20 is
>good for knocking 0.12 to 0.15 off the lap times, an
>attendant increase in power. But one doesn't always want
>more speed, so I begin a practice session with standard
>20/20 and go from there.

>The really cool thing about fiddling with the blends note
>above is that one first takes the time to get a real good
>setting, whether you can do it on the ground or need a
>couple flights. Once the needle is set you can simply choose
>one of the blends mentioned and fly; no need whatsoever to
>play with the needle valve. Just get a feel for how the
>model flies, maybe take a peek or two at the stopwatch, try
>a different blend next flight.
>
>
>Dan Rutherford

Wow, Dan I think you've got it! I actually dope my fuel on the fly in my RO-Jett tanker syringe. I use a can of 20-20 and a can of 30-20 and just change the ratio in the syringe. For example, this weekend I was flying 1.5 oz of 30-20 and the rest of the 3.75 oz of 20-20. The air was really horrible for power. The notri is really more for cooling in my mind, and it pushes the torque curve peak up a might.

Interestingly, I am currently working on a version of PW Saito 72 setup. I really, truly love his propellor recommendations and am currently working on a method to run them consistently. Using his props has put my run RPM's right at 10,000 RPM. I will not go into detail yet about my settings, as I have not decided on what works the best.

My next session I will be trying the big UHP venturi just for kicks.

'zilla

>>My next session I will be trying the big UHP venturi just for kicks<<

What constitutes "big"?

Careful, 'Zilla. Randy is challenging you to a "Mine is bigger than yours," confrontation.

Jerry Bohn,

I forgot that you may have one of the Saito mufflers designed and produced by Briggs & Stratton. What I did in drilling out the baffle required no disassembly and it is readily apparent as to what to do and how to do it.

To my knowledge, PW is using YS 20/20 exclusively. If you've got SIG Champion 10% fuel, use it. Especially during run-in and early flights.

Dan, Yes I have the stock Saito muffler. It has a screw running from front to back holding on the rear section of the muffler. Inside is the baffle which looks like a sprinkler spigot from an industrial coffee pot. It has about 4 or 5, approx. 1/8" holes in it. Think I'll use it till somthing gives me reason to change.
This is a good post for me, reading the other stuff Randy and Godzilla are discussing. Good start to 4 strokes by the folks who know what their doing, helps a lot.
Thank you also and keep on keeping on.
Think I'm the only one in the Denver area trying to run a 4 stroke, didnt see any at the Denver contest last week-end. Jerry

LAST EDITED ON Sep-04-03 AT 05:36 PM (CDT)
 
Dan,

It's just what comes from being too stubborn to check out what others had done when I first started using the Saito.

I figured at the time that the first order of business was to figure out how big I could go on venturi size before the engine didn't develop enough fuel draw to keep it running during a pattern. That turned out to be about .338. The biggest venturi I could get to run reliably was a .327. And a .320 was a sort of compromise as far as not having to go down too ridiculously on prop pitch. My hypothesis was that the more fuel and air you can pack into the thing, the more power it would produce (to a point). That turned out to be the case. Make the thing produce as much power and torque as possible (without changing compression, cam lift or other hot-rodding areas requiring vast machining experience), then prop it to get the sort of lap times and tractoring you're looking for.

I've considered comming up with some sort of pressurized fuel system to allow a bigger venturi, but I haven't really seen the point. My current favorite prop is one of Eather's 13.5 x 4 3 blade, flat back props cut down to 11.75". This give a huge amount of blade area, seems to be keeping GP under some sort of control and produces more vertical and above 45 degrees performance than should be legal without killing the "steerability" of the thing.

But what do I know, I'm just a local scum sucker expert.

>'zilla
>
>>>My next session I will be trying the big UHP venturi just for kicks<<
>
>What constitutes "big"?
>
>

Randy Powell

The big UHP venturi is the .285". The UHP system uses the small OS needle though, which makes the cross section equal to a .305" with a ST needle.

'zilla,

OK. I'm using a .320 (my own venturi design) with ST NVA. probably why it takes me 4.5oz for a pattern using 10/23 fuel. Close to 5.25 with YS 20/20.

LAST EDITED ON Sep-04-03 AT 05:08 PM (CDT)
 
Jerry,

What you are describing sounds like the new and devolved muffler, what we refer to as the Briggs Option. Ugly. Even uglier than the muffler/header pipe on my 2003 vintage Saito, and that is going some with dog-peeing look it has.

You're on your own as far as getting rid of some restriction in the exhaust. I think it only helped my motor respond to needling a little bit more aggressively; but so long as one only needs to set the needle once a day with these things it's not a big deal.

Godzilla,

Gotta admit that I wimped, hoping someone else would challenge your statement. Plus the "Vote for My Guy" threads have been so entertaining lately...

It is hard to imagine more nitro leading to improved cooling. I am seeing more power as the percentage of pop goes up. I may be simplistic about this, but the added power would seem to be coming from a bigger bang (okay, better/bigger burn). Bigger bangs mean more power, more heat. Pretty basic stuff.

While I like your mix 'n match approach to fueling the model, currently I am not cutting it quite that close as to exact percentages of pop. And the ketchup-pump things are just so handy.

Might be a different deal for contest flights, especially if I can simply dial away--or add--.05 to .10 in lap times; I certainly see the potential for such trickery in that coarser adjustments to power and/or lap times has so far proven to be quite effective. And I still have my Secret Stash of Commie Syringes (150ml capacity, aluminum tube, teflon piston, O-ring seals--High Zoot) from which to select a graduated unit. So I can be just like 'Zilla, donchaknow?!

'zilla,

And having procured such a unit from one Mr. The Dirt, I can say that the commie syringes are very slick.

>'zilla,
>
>And having procured such a unit from one Mr. The Dirt, I can
>say that the commie syringes are very slick.
>
Randy Powell

Yes, and no longer available we should add. In particular, the one that went to the last W/Cs with PW and The Bomber is certainly not available.