gregusan

My Feedback: (2)

I see these engines are both the same wieght, and been hearing that Magnum's reputation has been improving. They are also similar price, except when the Magnum is on sale, it's cheaper.

I'm wondering if the Magnum's extra displacement will give it the edge over the Saito, especially if comparing 12x6, 12x7, 13x5, 13x6, or bigger prop sizes.

If anyone has any figures, or experience which is more powerfull, please post them here. Or, can email: [email protected]

futaba1024

hi.
Friend of mine has an ASP61fs (Magnum) which on our tests will pull 10100 on a Graupner 12x6, which is about the same as an OS52 (got 3 of these) however my Saito 56 will make 10700 on the same prop.
cheers.

gregusan

My Feedback: (2)

I just found other posts on these two (we really need some more figures on the Mag 61, especially with 13x6 & bigger):

Mag 61: 12x6 APC 9,500
Saito 56: 12x6 APC 10,000
Both engines; same owner.

Then, another post, different person:
Mag 61: 12x6 APC 10,500 (BIG DIFFERENCE!)

Some more Saito 56 readings:

12x6 Master Airscrew...10,200 rpm
13x6 Rev-Up...9300 rpm
14x4 Zinger...9300 rpm, and JUST to see "how it would do",
14x6 Zinger...7200 rpm.

Graupner 12x6 10700
APC 12.25x3.75 11700
APC 13x4w 10000

12 x 6 Master Airscrew black glass prop-10,200 rpm
13 x 6 Rev-Up wood prop-9200 rpm

APC 10X6 making a reliable 10,400 on Wildcat 10% with OS 'F' plug in 90%humidity at temps over 100 degrees

11400 on 11x7 apc


It looks like the Saito 56 maybe more powerfull, with the exception of the one Mag 61 turning the 12x6 apc at 10,500. maybe that was a fluke, or his tach was wrong?

futaba1024

Hi Gregusan.
Think the 13x6 and larger will kill The Mag61, it's too much prop, we tried a few on pals motor, we didn't log the rpm but they were quite dissapointing.

gregusan

My Feedback: (2)

Hmmm.. that's a little disappointing..... I was thinking since the smaller motors were more powerfull on a 12x6, perhaps the Mag 61 was tuned more for torque at a lower RPM, and would do better with a 13x6.

I'm tempted to get one, and figure why it's slower, when it should really trounce an OS 52, and top a Saito 56 by at least a small margin, if not more.

That single post (above) of 10,500 with a 12x6 APC seems like what should be normal for the 61, stock. I think it could be capable of a reliable 11,000 with the same prop, if tuned for it.
Unless the camshaft is really small, then there's not much one can do.

DarZeelon

Some four-stroke people want to overload their engine.
Propping an engine BELOW its torque peak is not recommended, It could kill your engine.

You can identify the torque peak by trying increasingly higher load props on an engine, until a large loss of RPM results.

Example: a four-stroke 60 shows the following RPM readings on XXX brand props:

12x4 - 11,500
12x5 - 11,000
12x6 - 10,600
12x7 - 10,100
12x8 - 9,100
12x9 - 8,500

The engine's torque peak is between 9,200 and 10,100; closer to the higher value.
Between 12x4 and 12x7, the engine lost 400-500 RPM.
This is because as load increased and the RPM decreased, the engine produced more torque, to produce a smaller loss of RPM.

When changing to the 12x8, the loss was significantly more marked, at 1,000 RPM. This is because the increase in load was joined by a marked reduction in torque.

I would not use a 12x8, or heavier prop on this engine. It could get the "death rattle" as it is, or it could unload at speed and then become too lean and get the "death rattle"...

Always prop ahead of the big drop.

Sincerely,

RCAddiction

My Feedback: (87)

I have Magnum 52 and 61 as well as have had a particularly strong running Saito 56 that I recently sold with my Cub.

When I initially received my Mag 61, it was frankly not much more powerful than my older Mag 52. Both were 500-600 rpm weaker than the Saito 56 on a 12x6. I checked timing, which was correct.

Why the weakness? The 61 initially shipped with a much more restrictive muffler to reduce noise in Europe. It is short and fat in shape with a very small outlet. Magnum has since revised the muffler (at least for the US Market) to look externally more like the older style, which was a long skinny type similar to the OS 52 . By swapping the 52 muffler onto the 61, I found that it gained a lot of performance. I contacted Global.

My 61 is now outfitted with the latest (3rd generation?) Magnum muffler, which looks like the original long skinny style, but with different baffles. It is both less restrictive and quieter as well. Performance increased and became noticeably stronger than my Saito 56. Honestly, it is even more even-tempered than the Saito, and is just super reliable with terrific transition.

Current performance:

13x6 APC 9500-9700 (depending on weather), Wildcat 15% nitro, 18% synthetic, OS-F plug.

This is in my 3D Magic which makes for incredible performance. I strongly prefer it to my Saito 56 with all else being equal. With a price advantage and great product support, it is an easy choice.

gregusan

My Feedback: (2)

Thanks Lee, that was the most helpfull post yet. Perhaps that explains the 1000 RPM difference between the two 61's I found posts on. I almost bought one on sale 129.00 yesterday, but hated to risk getting a "doggy" one. No point if it's not more powerfull than my 56.

I'm curious, would your Saito 56 turn a 13x6? Do you know the RPM? I think I ran one on mine, but it's not in a plane now & I forgot. I know I did fly it with an old wide blade (rounded tip) TF 13x5, and it ran fine & pulled strong with that. It would have almost unlimited verticle on take off in a 4 1/2 lb Sig clipped wing Cub. But with the Cub's fat body (I suppose), it seemed to eat up a lot of thrust & want to roll out of it after 130' or so.

How much does your Magic wiegh with the Magnum 61, RTF (less fuel) ??

gregusan

My Feedback: (2)

Dar: That seems like a handy & valid way to check for the torque range, if someone doesn't already know where it is.

From reading many posts here on people testing four strokes, I think many people are too afraid of "over revving" their engine, rather than over-propping it. Perhaps I'm wrong, but I haven't heard of anyone damaging their engine from valve float, etc, from over revving. And if they did, we would need to know how much it was over revved. Of course there are limits. If I'm not mistaken, I even saw 15,000 mentioned as the upper limit on a YS63, on their website.

However, regarding the quote above, it's been my experience with every engine I've tested, that the more you load the RPM down with bigger props, the richer you have to set the needle. Therefore, as it unloads in the air, it would seem to me that the setting would be richer than it would have been, had you a smaller prop on it.

Also, from Lee's post, it would seem the 13x6 is fine on this engine, at least with the "new" muffler. Even the guy at Hobby People yesterday said he's running a 13x6, but I think he was maybe wrong on the rpm (?). He had trouble remembering but, mentioned he thought it was about 8900 or so with a 13x6. According to ThrustHP, a 13x6 & 12x8 have about the same load factor.

How's things in Israel? I was there in 95.

Thanks for the posts.

DarZeelon

Gregusan,

How was your visit here? Memorable, I hope.

Now we just have to make sure no one is there to blow up, right next to us... Scary. But we manage.


When you adjust the mixture strength on your engine, what you are actually doing is to adjust the effective ignition TIMING...

Explanation:

A rich mixture burns more slowly than a lean mixture.
A lean mixture is also more volatile and will ignite earlier than a cooler, rich mixture.

As a result of these factors, maximum cylinder pressure will happen earlier when the mixture is leaner. If that maximum is reached just as the piston passes TDC, maximum power will result. If it happens later, less power is generated and more heat, but this is counteracted by the methanol's cooling effect.

If it happens too soon, you get detonation, which can do much more than throw-off your prop and break your spinner...

The pressure build up from the combustion and the compression simultaneously, causes spontaneous detonation; dieseling, which generates pressures and temperatures high enough to perforate the piston, cup the valves, break the con-rod and too many other damages.

When the unloading is large, like when propping an engine just below its peak torque, the needle is not opened enough to supply fuel at the unloaded engine speed. So the mixture can become lean and detonation could result.

At higher engine speeds you do need slightly more ignition advance, but not beyond the 50-60% of the maximum RPM, where mixture swirl does the job just as well. So as engine speed increases and mixture strength decreases, you are getting more ignition advance than you bargained for.

You know the result.

Sincerely,

RCAddiction

My Feedback: (87)

I'm running to catch a (full scale) plane, so this will be quick.

Yes, I ran a 13x6 APC in the Saito 56, and my records show it ran approx 9600 on YS20/20 fuel last time I checked. It was running approx 9300 or so on 15%. I'd just say that the Saito was great, but the Magnum turned out to be a bit more consistent day to day in performance.

Magic all up weight is 4lbs, 8.5 oz. That includes a bolt-on wing conversion, carbon fiber landing gear, Dave Brown 3" foam tires and a steerable tailwheel.