hooker53

My Feedback: (106)

Just wondering if anyone has had both of these engines and could give there spoof on them?? I found a few specs on the OS- Fr5-300 but went to horizons site and could not find the specs on the Saito 325. Going just from the photo's I'v seen it looks like the Saito could be a few Ounces lighter. More importantly, I'm wondering about the running of the two. I know each one of them will have there own qwerks. Thanks for the help on the comparison between the two. Hooker53

William Robison

My Feedback: (3)

Hook:

The weight of the Saito FA-325 R5 is 84 ounces.

The OS is a normal four stroke radial, having steel sleeves with aluminum pistons running iron rings. It used a conventional "Ring" cam to operate the valves. Where it differs from "Ordinary" radials is its induction system, having no provision for maintaining the fuel mixture even to all five cylinders. Running at speed it works fine, but at a low idle the fuel tends to condense giving uneven mixture to the upper and lower cylinders.

The Saito FA-325 R5 continues Saito's way of combining what amounts to multiple separate engines using a common crank shaft. It is, in effect, five destroked FA-91 engines mounted to a single case. Each cylinder has its own cam, inside the front case are five separate cam shafts geared to the common crank. It does use the master rod/ link rod connection of the pistons to the crank pin, as does the OS.

The major difference in basic design of the two is Saito's use of a diffuser in the inlet tract, this looks like a centrifugal supercharger and is sometimes mistaken for one. What is does is keep the incoming mixture "Stirred" and ensures even mixture distribution to all five cylinders. This gives silky smooth running from idle to full throttle.

Other differences include Saito's use of inclined valves, allowing larger ports, and greater volumetric efficiency. Add the chrome plated aluminum cylinders and the consequent lighter engine weight, the power to weight ratio is much better with the Saito, and the greater volumetric efficiency gives a greater power increase than the mere 0.25 cubic inch greater displacement would make one expect.

And now, to bring more ^%$ in the game, if all you want is "Grunt" to swing a big propellor, consider the Magnum AR5 400 engine. A full third larger than the OS, and mechanically similar with a much lower price than either the OS or Saito engines.

Bill.

old-pilot

Bill; are you sure they are 91s rather than 65s....?? HA.

William Robison

My Feedback: (3)

Roy:

You could look at it either way.

The FA-65 is 0.97 x 0.86 bore and stroke, the FA-91 is 1.11 x 0.94, the FA-325R5 is 1.11 bore and 0.86" stroke. So, the radial has the bore of the 91 and the stroke of the 65.

The only obvious difference between the 91 and 325 cylinders is the threaded intake attachment on the radial, so I tend to think the 325 is a destroked 91 rather than an overbored 65.

But as I said, you can think of it either way.

Bill.

William Robison

My Feedback: (3)

Roy:

Apologies, sir. The dimensions of 1.11 x 0.86 would give 4.161 ci displacement, so I checked a little further. The FA-325 R5 uses the SAI6506A piston, same a the FA-65, so the bore has to be 0.97 inches, again, the same as the FA-65. My latest specifications list gives the 325 bore as 1.11" so it has to be in error.

All this means the FA-325R5 has to be 0.97 x 0.86 bore and stroke, and you are right to start with - it's five FA-65 engines rather than destroked FA-91 engines.

But putting FA-91 cylinders on the FA-325 R5 is an interesting thought. Or maybe the 1.24" bore cylinders from the new FA-125a. 5.193 cid, 85cc capacity. Hmm...

Bill.

hooker53

My Feedback: (106)

Bill, your answer is right in there. No doubt the Saito's are good and I have a few of them. The prices on the used one's will attest to the most sought-after and tells me something. I want to put one on a 1/4 scale Fleet bipe. I have sat here and ask myself would a Saito 170 R3 pull the darn thing. If it would I know it would be a long take-off run and flying on the wing at Min. I have just came into a 170 R3 the other day and hope that I will have good luck with it. I can see the OS's 300 for sell right often but trying to wait for a good deal in a 325 is like waiting for christmas everyday!! Ha. Ha. I think the Saito 325 would be the best match for that bird. Thanks for the in-put and mabey we will hear from some others.

hooker53

My Feedback: (106)

Bill, just came back and read the last input you gave. The only thing that came to mind up the thread is I have always thought a Squared stroke works the best. Now I know you can get into a whole new world with Sq. Ver. destroked but either way I think the 325 would be the most pleasing.

Kmot

My Feedback: (24)

Dude!! [sm=lol.gif]

That would rock!

old-pilot

hooker53;
I don't think the 170 would be enough for safe flying the Fleet, only my opinion, and depends on flying conditions. I like to fly scalelike also but the fleet is big and draggy. Now if 'they' would put six more cylinders on the 90r3 I would snap it up. My 170 sounds like an old out of tune VW Bug. It's great tho.

hooker53

My Feedback: (106)

old-pilot, Any wise words about the 170 before I fire it up the first time??? I really got it to put in a CG Sukhoi. I know it will do ok in it. I also know that It will not pull the way my Saito 180 is doing now, but I know I'm gonna like the sound. Ha. Ha. I have heard that after you get the 170 broke in (about 5 gals) that it runs right well as far as keeping that 7 oclock cyl lit. The man I bought it from was taken-a-back with it because he could not get it to break in after only 1/2 gal. Ha. Ha. Thanks for your help. I'm a Roy C also!! Hooker53

old-pilot

hooker53;
I should have said the Fleet flies nicely with a Saito 180 at about 18 Lbs. The Saito 170r3 really sounds great in the Goldberg Sukhoi, but the plane didn't perform as well as with a 180 of course. We have guys here (I think jealous) that don't like Saito.

The 170 takes a little getting used to and a long breakin, run it (slightly) rich for a while and it keeps getting better and better. I always use only OS 'F' plugs, fortunately only 3. It's a fun engine and sometimes aggravating. Mine was dropping a cylinder for a while and that's bad so I ran it in a cheaper plane for a while. Tuning is more or less a feel and a learning experience; I'm sure William Robinson can explain it much better than I can. Sorry I can't help more..I don't push my engines and I don't use 30% Nitro .

I am recovering from a major LiPo fire which took out my better airplanes. I've got a picture of a J3 with a 50 hp 3 cylinder on it so I am now putting my 170 on an old SIG quarter scale Cub.

hooker53

My Feedback: (106)

Roy, I agree with ya on the "some folks don't like Saito". I didn't at first but I learned as you have that they do have to be broke in the right way. The first Saito I ever had was a .65 four stroke and I thought I would wind up turning it into a paper Wt. I kept at it and after about three gal's of 15% it changed into a wonderful running engine just as if you had cut on a switch. I'm sure the 3 and 5 cyl are the same way. The only prob I ever had was stripping out the glow plug hole in the little .65. That was a heart breaker as I am a Machinist and sould hav eknown better. It was a very hot day and wet all in the face and just messed up. Ha. Ha. Sorry to hear of that fire. I have heard some bad story in the new Lipo's and having been safety Officer at our club field have had to watch the lipo's that come in. You are right I know that the 170 R3 will not pull like the 180 single is now in the Sukhoi but just got to get that radial sound in her one time. Ha. Ha. Have a good one and thanks for all the info. Hope you get everything back to normal after your fire. Thanks Roy Aka Hooker53 AMA 42938 IMAA (i forget) KC4CTU

Flugmax

Hallo, i had to change the main-bearing of the Saito 325 radial and so had to dissambley the engine including all cams....
i noticed the positon of the cams on a sheet.
but this sheet of paper cant be found anymore....
so could you give me help about the cam-timing of the 325? I know, one master rod#1, and firing time should be # 1 3 5 2 4 in flight-direction
but i dont know the correct position of the cam-timing-stamp,

next problem: if the engine was just started rpm and throttle -rpm increase was ok, when engine got warm, rpm did not increase 2000 , and than stopped;
so this is maybe the rusted main beraring; could it also bee some rusty valves or the crank?

thanks for your info
Nice greetings from SALZBURG, AUSTRIA mfc-lungau.at

NM2K

My Feedback: (14)

----------------


I'm not capable of answering your question, sorry.

But just out of curiosity, could you tell me how much total run time you think you have on your 325?

I bought mine a few weeks ago and haven't ran it yet. Just fishing for conversation about the engine. TIA


Ed Cregger

Flugmax

my Fa 325 has beeen standing in a glas vitrine for a couple of years, so i bought it New, but with rusty ball bearings from standing around.....

break in will last at least 5 hours up, the high speed needle should be 5 full turns out for break in, do not exeed 3500 rpm the first 2 liters.
there are many moving parts, who have to be harmonised to each other during break in, take a good Akku (min. 3000 mah for 45 minutes of runing) and a goodGlow-processor(for example www.microsens.at) glow 5,
use 15% Nitro, the first 2 hours you will have to let the glow permanently on, and the first hours, engine will quit sometimes, due to breaking in; use a heavy Spinner and Prop for good rotation mass and an electric starter.....

dont forget to oil the inner parts of engine with high quality oil, you can insert it throug thecrankcase breather nipple undersides of engine, after 2 hours running, check valve-tolerance ;

exciting hours and fascinating sound with your saito 325
Greeting from SALZBURG, AUSTRIA, mfc-lungau.at

hooker53

My Feedback: (106)

OK Guys, have my Saito 325 R-5 on a fleet bi-plane and having a little bit of trouble with it running well. I know with it being brand new I will have to work with it for a gal. or too but I think it's the kind of plugs I have in it. I'm running on-board glow with it cutting off at 50%. On the last run it cranked good but just saged out after about 5 mins. I had it plenty rich (5 turns out) so i'm ok there. I blew the 5 back plugs out and switched them with the front good one's I think it must have to have all ten plugs in good order rather than just the five back one's. Thinking about trying a set of O.S. F type plug. Any word from you radial pro's what type of plug runs the best in these Saito 325's?? thanks for your help. Hooker53

NM2K

My Feedback: (14)

Old Pilot, what are you using for break-in fuel, if I may ask? I'm trying to learn here, not gather information to criticize.


Ed Cregger

hooker53

My Feedback: (106)

Ed I have broken all my Saito's in on Power Master YS/SAITO 20/20 with 20% oil and I dose an oz or two of Byrons four stroke oil for the first Gal. or two. Thanks for reading. Roy Hooker53

blw

My Feedback: (3)

I have a 170R3 and I consider it to be 3 .56s which are great engines. You could look at your 325R5 as being 5 .65s. After I break mine in I'll use Saito SS plugs. They are good plugs and cheaper than OS Fs.

NM2K

My Feedback: (14)

I've been fooling with glow engines since 1958 or so, but recently acquired my first radial engines. Never thought that it would happen in a million years.

Just when you think you've done it all...<G>


Ed Cregger

hooker53

My Feedback: (106)

BLW, Ya gotta lovw that sound. I have a 170 R3 as well but have not fired it up yet. getting back to my Prob with the 325. I still think I have to have all 10 plugs in good shape. Five good in the back and five bad in the front I don't think will get it. I have soom of the new hanger nines comeing for it. They are duppose to be as good as the O.S. f's. Thanks for reading Hooker53

Bandicoot52

Hi all does anyone know how to do the timing on a 170r3 as I want to change the bearings.