flyboy2

My Feedback: (1)

I am ready to purchase my first 4-cycle engine and I am considering:OS FS-70 II; YS 63 FZ;or Saito FA-80. I would appreciate your comments on the pros and cons for each of these engines.

Hobbsy

My Feedback: (102)

I can only speak about the Saito .80, I have the older high compression version. It has been totally reliable running on 10% Wildcat Premium Plus, Fox Miracle Plug and turning a 13x6 Scimitar at 9,800. Very light for the power it has.

Mode1

My Feedback: (10)

My son had an OS 70. Nice little engine. Well made. A little heavy for the power output(ours anyway). We have a YS 63 in a 40 sport model. Very powerful, dependable, a little on the heavy side, likes high nitro (20/30%). Personaly, if I was thinking of a Saito 80 I would jump to a Saito 91 or 100. Cost a little more, lots more power. We have two in World Models 40 size Cap 232s and one in a Thunder Tiger 40 size Giles 202. Ours took several tanks of fuel to "break in", lightweight for their power, easy on fuel. Nice engine for the 40-60 size models if you like lots of power to weight. All our little 4-strokes like the OS type F plug. Bob

GUNSHIPGUNNER

If you want the best engine with the most power go with the YS.

The initial investment is greater but is well worth it in the long run.

And the YS will run circles around the other engines you mentioned.

BTW: The YS has just about the best fuel delivery system in the industry AND they LOVE 30% Nitro fuel and will run for years using it.!!

pault

My Feedback: (34)

IT IS HARD TO PICK THE BEST ONE,BECAUSE THERE ALOT OF GREAT ENGINES OUT THERE.I REALLY LIKE THE 72 SAITO.IT PACKS ALOT PUNCH FOR ITS SIZE.IT HAS A NARROW BEAM WIDTH,SO IT CAN FIT IN NARROW SPACES.
I ALSO HAVE SEVERAL MAGNUM 91 MOTOR.THEY ARE OS 91 CLONES AND HAVE BEEN VERY RELIABLE(HAVE GOOD POWER AND ARE CHEAP)
THE 70 OS I HAVE IS A SUPER RELIABLE MOTOR ALSO,BUT DOESN'T HAVE THE POWER THE SAITO 72 HAS(ALSO HEAVIER)
MY ALL TIME FAVORITE IS THE SAITO 91. TONS OF TORQUE,AND THE MOTOR IS VERY LIGHT COMPARED TO THE OTHER 91'S I MENTIONED.
HOPE THIS HELPS IN YOUR SELECTION
MERRY CHRISTMAS
PAULT
PS. I FORGOT ONE...THE NEW MAGNUM 61 MAKES A GREAT 4 STROKE FOR TRAINERS.ITS VERY SMALL...IT DOESN'T HAVE GOBS OF POWER,BUT STILL A GOOD MOTOR

cascar38

pault:

PLEASE DON'T SHOUT !!!!!!!!!!!!!!!!!!!!1


dj

maverick

My Feedback: (12)

Hey pault there is no need to SHOUT!

Anyway, the OS FS-70 II may be heavier than the Saito .72 but it actually puts out more power. Don't believe me? Check out Clarence Lee's reviews of both engines in issues of RCM from this year.

His testing results show the OS FS-70 II is slightly heavier, but is more powerful than the Saito .72

ShempHoward

My Feedback: (3)

Maverick is dead on with his comments regarding the Saito 72 vs the OS 70 MKII.
Both the 70 Surpass and the 70 Surpass MKII put out the same power which is noticeably more power than the Saito 72. The 72 is only slightly lighter than the older 70 Surpass which is slightly lighter than the MKII version. Smaller mounting dimensions is where the 72 pays off. BTW the Saito 91 is only 1.2 ounces lighter than the 91 Surpass and does not have more power - this is an old wives tail at best.

Tex Pilot

Awwwwww. Lighten up guys. I know pault and he's usually a fairly friendly fellow......... maybe he's just tired of puttin up with the rookies he helps out at the field........ like me. Really...... I just bet paul didn't even know that all caps is like SHOUTING. Hey pault......... I still love ya buddie....... you can yell at me all day long........... as long as you keep teaching me to fly them there air vehicles the way their supposed to be flown........... no upside down landings. See you at the field Paul. Yep its me..... that Cub flying fool..... almost have my floats covered.

CaptainHook

My Feedback: (80)

Geez, now flyboy2 and I are all confused on what to buy. I , like him, are in the market for a similar sized 4 stroke. Great topic, I do like the cheap comment , got a budget to work with. Had Saito's and O.S. but the Magnum I might just have to try.

Tex Pilot

Pault and another friend have many different engines...... mostly 4 stroke. They have been in the hobby for a *while*. They convinced me to try Magnum 4 strokes......... I am not dissapointed. They have not let me down yet. Excellent reliability..... idle, economy etc. Just can't say anything bad about them. I will admit I have never owned any other except for Super Tigre 2 strokes. I like them also. I guess it's what ever flips your prop Saving money and getting quality flips my prop Tex

pault

My Feedback: (34)

Maverick and Cascar............
Please accept my apoligy for offending you by writing in capital letters. I was unaware that writing in capital letters was considered "shouting"
We are all entitled to our opinions. As far as RC eguipment goes,I base my opinion on personal experience not just what I read in magazines.
Merry Christmas to all
Pault

CaptainHook

My Feedback: (80)

Any info on the Magnum 1.60 twin? I am considering it for the new H-9 Taylorcraft. Less $ than the O.S.

maverick

My Feedback: (12)

Hey pault,

No problem. I just like to let people know when they type in 'caps' it is referred to as shouting. I guess we learn something new every day.

Also on the power figures reported in RCM, if you have a different experience then that is fine too.

Just because one person has a certain experience, does not necessarily mean that it will hold for every person.

Whatever you choose is right for you. Don't let anybody else tell you what is 'right' for you.

pault

My Feedback: (34)

ShempHoward,
Your reply to my comments on 4 strokes definitly fits into the "Old Wives Tale" catagory.
One of the best ways to compare the performance of different engines is by the power to weight ratio.
All specs are taken from the OS and the Saito advertisments.
OS 70- 20.4oz- 1.1hp- power/wt. ratio=.053hp/oz
Saito 72- 16.6oz-1.2hp- power/wt. ratio= .072hp/oz
Advantage Saito

OS 91-22.6oz- 1.6hp- power/wt. ratio = .070hp/oz
Saito 91- 19.6oz- 1.7hp-power/wt. ratio=.086hp/oz
Advantage Saito

You wrote the saito was 1.2 oz lighter then the OS
recheck the numbers...its really 3 oz! Big difference
No wives tales here,just the facts

Pault

maverick

My Feedback: (12)

I think the bottom line here is that you can't compare claimed horsepower ratings by manufacturers! They vary wildly due to the way they are calculated.

Also you need to verify if those weight figures are for engine only or engine and muffler.

To get real data for a comparison, you really need to compare rpm figures using the same fuel, plug, prop, break-in procedure and ambient weather conditions.

Then you will have a meaningful comparison.

If you look at Clarence Lee's reviews of both the OS FS-70 II and the Saito .72 you will see that he used the same plug, fuel and prop and the same break-in procedure. So this would be good data to work off for a comparison.

You are right about the weight advantage going to Saito, but based off the data presented in the above mentioned reviews, you would be wrong about power output.

Now when calculating the power to weight ratio, the lighter weight of the Saito may contribute to it having a better ratio.

But it does not seem to have more 'outright' power than the OS.

Also there are some cases where the little extra weight of the OS may be to your advantage. e.g. When using it in a warbird that may be tail heavy. Better to add the weight to the nose with something that is usable, than to add lead weights.

Also remember that the OS engine uses a sleeve in the cylinder whereas the Saito has no sleeve and the cylinder is machined from the cast block. This may be an advantage to the OS also in that it would allow a new sleeve to be fitted to the engine after the old one is worn to add more 'life' to the engine.

The Saito also has a plastic backplate which some view as inferior to a metal one.

The bottom line though is that whether you choose the Saito or the OS, you will have one fine engine and in the real world you will probably notice very little difference.

Hobbsy

My Feedback: (102)

In actuality the plastic back plate on the Saito is a non issue it's not something one would ever notice or have any occasion to be concerned with. I have Irvines that are several years old with plastic back plates with never a problem.

Tex Pilot

Hello Chook. Sorry...... I only wish I had experience with that engine...... I'd really like to have one. You may just want to look up the specs and see if it has the power etc.... that you need. If it is a Magnum and a 4 stroke...... I'd say you are ok on the purchase. Let me know what you decide. Merry Christmas, Tex

ShempHoward

My Feedback: (3)

Pault: I have all those engines mentioned, except the 72 (plus a few more) sitting NIB waiting for planes that I have yet to build. I have weighed them and used this info and what RCM and MAN wrote in my posting comparison. Many of us in the Hobby are well enough informed to know that HP ratings vary widely (Thanks Maverick) and should be used as a guide only. The weights listed by the manufacturers and/or distributors are rarely correct and often fudged somewhat to their advantage. I and many others discovered this fudge factor a long time ago. Get a scale and check it yourself but make certain the engines are NIB first. The proof is in the pudding when Clarence Lee posts RPM figures and its no wives tale when comparing the Saito 72 vs the OS 70 as the 70 is clearly more powerful. Lee's weight of the 72 was 17.8 ounces, the 70 Surpass 9plain first version) weighs 20 ounces exactly (my scale and USPS's as well) and the Surpass 70 MKII weighs 20.4 per C. Lee. The OS 91 Surpass (the plain first version) weighs 22.1 ounces (my scale and USPS's) with the Saito 91 weighing 20.9 ounces (my scale and USPS's). Do the math.

John B

My Feedback: (1)

The os 70 is a great engine , have not owned one ,but, everyone I have seen is a great runner. Myself, I have a habit of overpowering, if I was going with the wieght of the 70 I would install the saito .91 instead. Put one on a Skytiger and it turned it into a animal. It's all what you are after. My vote would be the Saito 91. Easy to pull back the throttle,tougher to crank power out of a engine when it is'nt there.

caf2461

My Feedback: (6)

I have the 91 Saito and the os 70 surpass. I actually swapped the 0s 70 in my p-47 with the Saito 91 and noticed no concernable power difference between the two other than the saito seems to handle the bigger props a bit better dut to its displacement. Having 3 Saito's and 2 os's I would recommend either. If weight is a primary issue go for the Saito. If ease of use is the primary issue go with the os. They seem a bit less sensitive to proper adjustment. Both will last forever.

desmobob

Good point John!

I was just messing around with choices of power for the Kyosho P-51D ARF I'm assembling right now. It requires an inverted engine mounting, so I wanted to run a four-cycle in it. I bought a new O.S. .70 Surpass II. I brought a pile of engines over to my scale and started comparing them. The O.S. .70 weighs ONE FULL OUNCE MORE than my Saito .91! (Both ready-to-run with mufflers attached.)

There was some debate in this thread about the merits of the .70 Surpass vs. the Saito .72. The comparison should be between the .70 Surpass and the Saito .91 or Saito 100!

Anyway, sometimes the extra weight is not a bad thing. I have The World Models Super Frontier Senior (a SIG Senior copy). It doesn't need much horsepower to fly. It came out pretty tail-heavy and I had to stick a bunch of lead all over the firewall and engine mount and use a heavy hub to get the balance right with a Saito .56. Later on, I picked up a new Saito .65 cheap. This engine is a lot heavier than the .56 but only makes a fraction more horsepower. It was the perfect solution for the Frontier Senior. It's extra mass even makes it a little smoother.

I'll hang on to my O.S. .70 until I build something that needs some nose weight.

Happy New Year!

ShempHoward

My Feedback: (3)

Bob: The Saito 91 weighs 20.9 ounces with the OS 70MKII weighing 20.4 ounces. How do you arrive at the 70 MKII weighing one full ounce more than the Saito 91??

desmobob

Easy... I put one engine on my scale, read the scale, took it off, then put the other on and read the scale again.

My scale is a big table-mounted meat scale from a now-closed grocery store. (It was inspection-stickered by the dept. of weights and measures.) My Saito .91, wet with after-run oil, and with a short piece of fuel tubing plugged with a machine screw attached to the crankcase vent, weighs a tiny smidgeon UNDER 20 oz.. My O.S. .70 Surpass II, dry, fresh out of the packaging, weighs exactly 21 oz..

Funny thing about manufacturer's specifications changing when you actually measure them! Thank goodness it's not easy to measure horsepower at home...

Happy New Year!

John B

My Feedback: (1)

Checked the stats on the 91 Vs the 70
Saito91.......520 g
OS 70 II......560 g
when I bought my saito that was my reasoning, after a couple 100 flights I am sure it was the right decision for me.
Im sure there is differances in the wieghts of the engines nib.
Just no way I'll pay the same amount ($10 diff) for a .70 when I can have the .91.