gunnarmm

Just graduating up from my trainer and I could use a bit of advice!

I am about to start construction on a BTE Venture 60 (think Sig Four Star 60) and I initially intended to install a two stroke OS .65 AX. I noticed on the Tower Hobbies site that Magnum engines are about half the cost of comparable OS engines, and that for the price of a O.S. 65 AX I could nearly buy a Magnum XL 70 four stroke and an XL 91 four stroke is only $30 more!

Does anyone have any experience with Magnum engines? I assume they aren't as good quality as OS but if they are reliable enough for easy sport flying I may just buy the Magnum four stroke.

Would you rather have an OS two stroke or a Magnum four stroke?

I understand that an OS or Saito four stroke would be ideal, but I am simply not going to spend $350+ on an engine just because it sounds better than a $180 two stroke OS. The only way I'm going four stroke is if it is around the same price as the OS two stroke.

j.duncker

My Feedback: (2)

I would go for the Magnum.70.

Over the years I have seen quite a few and they have preformed well.

Sound good when they burble past on a slow fly bye.

JollyPopper

My Feedback: (6)

Of the choice between an OS two stroke and a Magnum four stroke, I would take the Magnum four stroke every time. The Magnums are virtually clones of the OS four strokes and seem to run fine. I have several. The same can be said of ASP four stroke engines. This is not to say that I don't like OS engines. I do. But I like four stroke engines a lot.

52larry52

My Feedback: (1)

Another "yes' on the Magnum 4 stroke, but I would go for the XL91. It will be the best extra 30 bucks you spent on this project.

blvdbuzzard

I too would take and have taken Magnum over O.S. I have a .70, (2) .91's and they just put along. I had one of the 91's in a Formula 3D. Hovered at just a touch over 1/2 throttle. Never had a flame out, idled great, just a nice running engine. 70 was in a Goldberg Cub. Flew around at 1/4 throttle and sounded good going by low and slow.


Buzz.

gunnarmm

Thanks for all the advice! Sounds like the Magnums are good engines.

CESSNA 421

My Feedback: (17)

I have never used a Magnum engine only OS however all of my OS engines are more than 25 years old and I believe the OS engines are not nearly as good as they were in the 1980's.

bikerbc

I believe todays OS engines are just as good as the older ones . I have had very good experience from all the Magnum engines that I have used as well as the ASP engines . The only ASP I have that gives me a bit of grief is my 160 twin . Its a bit hard to set . I bought it with hope that it would perform as well as my OS 160 twin . I Would rather have a 2 stroke engine in something I wanted lots of speed out of and a four stroke in something a bit slower like a Cub . I would rather have an OS engine over a Magnum or an ASP if somebody else was paying but if I was paying I would be quite satisfied with a Magnum or an ASP .Magnums and ASP are basically OS clones . They are great little engines .

jester_s1

You've asked 2 questions here- OS vs Magnum, and 2 stroke vs 4 stroke.
On the former question, the Magnum engines won't make as much power as a comparable OS, they'll take longer to break in, and they'll be more finicky to tune. Not impossible, but don't expect to have it running right in 10 minutes like you can an OS. Quality control is also spotty with Magnum, so you may get a great engine and you may get a temperamental one that takes some work to get flying. People buy OS engines because they don't want to have to spend their flying time jacking with their engines. They are as trouble free as anything in our hobby, and the warranty service on those rare occasions that there is a problem is top notch.
On the latter question, engine type depends on what you want out of the plane. 4 strokes have instant torque for acceleration and can swing really big props to improve your vertical performance and pull draggy planes through the air. They run at a lower RPM than 2 strokes, so you lose top end speed and you lose some of the speed range. You can get speed out of them by running more pitch, but the cavitation you'll get during acceleration can hurt your acceleration. On the downside, 4 stroke valves must be adjusted during the initial break in, they are more complicated so there are more things to go wrong, and if you leave them sitting for a while there will be a lot more cleanup of castor gum to get the engine running again. For that reason, it is generally recommended to run full synthetic fuel in 4 strokes to keep the varnish to a minimum.

For your application and at your level of experience with the hobby, I'd go for the OS .65 AX. It will let you fly fast if you want, pull big verticals with a low pitch prop if you want, and will give you many hours of trouble free operation.

bingo field

you will really enjoy the Venture 60. I had the Saito 91 on mine, until it met it's demise while inverted. It is an excellent move up from a trainer, and the build is really uncomplicated. It is a enjoyable flyer, and you will do a lot with it. I also have a magnum engine on an old Alpha trainer, and it ran really well until last year, when I didn't get drained well enough, and the bearings got really gritty. I have to replace them. The biggest difficulty you will have is really 2 fold , you will be spoiled by the quality of the finish of the parts for the kit, and a scheme to finish covering it with. My advice, would be to just go simple, mainly so you can get it in the air. Good luck!

bingo field

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JPMacG

My Feedback: (2)

Very good advice in post #9 from Jester_s1.

Clay Walters

I've had good luck with my Magnum engines; both two and four strokes. But the Magnum or ASP 91 four strokes are special. Run great, great sound.

Joe Fisher

My Feedback: (4)

Another thing I never buy new engines. All of my engines were used when I got them. That is one thing about this site you just have to watch the adds and every thing comes up for sale eventually. I like the Satio the best and I get them for half price or less and I haven't gotten a bad one yet.

J330

My Feedback: (3)

I never buy new engines either, not in 10 years anyway. Get the Saito .91, weighs about the same as a .70 Magnum. I also owned and flew the BTE Venture. Nothing like a Four Star at all except for it's looks. Does everything better than a SIG Four Star except you must come in hotter on the landing.

Saito. The right engine for any plane.

hugger-4641

My Feedback: (6)

Can't argue with Saito, love my .82 and 120. But, I also can't complain about my Magnum's either. I've got a couple .46 two strokes, a .60 two stroke, and a .91 four stroke, also have an ASP .60 , all have been great engines. I probably have at least one of every O.S. engine smaller than 120 and half of them were used when I bought them. If you are going to go with a new 4 stroke, the Magnum .91 is your best bang for the buck. Not saying it is better than O.S. or Saito because it is not, but for the money, it is not that much worse for power and no more finicky to tune than the O.S. or Saito. It is slightly heavier, but in that plane you will not notice.

JollyPopper

My Feedback: (6)

I have always thought that I liked Saito engines better then OS engines, but if I look at my collection of engines, I seem to have acquired more OS than Saito four stroke engines, so who knows? I also have Magnum and ASP four stroke engines and they all run and sound great.

J330

My Feedback: (3)

I have Rossi, OS, HP, Saito. I have them because I found them cheap here or on another forum. I have had dozens of other engines that simply didn't bench run in the manner that I wanted them to. I have no idea what has improve on the new stuff, but I read often it's improved greatly. ASP from Hobbyking, I hear is good stuff.
Maybe try that, I might also. It's cheap for 2 strokes too.