Dear all,

I am looking at a Phoenix Tiger 60 with compatible engine. Considering OS75AX and OS91FX. Of these, the 91FX is ringed while 75AX is ABC engone. Can someone explain to me the merits and demerits of each?

Ameya

Well, I had a Goldberg Tiger 60 and originally had an OS 61 SF. I later on changed it out for a Super Tigre 75 with a tuned pipe. But, I would highly recommend an OS .75 AX engine. I have two on similar sized planes. It adequate for that plane. Very much so.

CGr.

Dear CGRetired ,

the 75AX is certainly adequate for the Tiger60. But I am looking at the future from the durability point of view. I am wondering whether the 91FX ringed will last longer and be more maintainable than the 75AX ABC

Ameyam

As I said, I have two OS .75 AX engines and have had no problems with them. Longevity wise, I don't think any one can tell you much about them because they have not been on the market for that long.

If you believe the .91 is better, well, I guess you've already made up your mind.

I fly the tiger 60 with a 75 on it and it is plenty strong.

Actually, I was told by some of the more experienced guys on field that they found the 75AX difficult to tune, especially on cold days. The price difference between the two is about $10 here and it gives me the option to move to a 90 size plane, provided it lasts for more than 1.5years. My concern is, will the Phoenix tiger60 take the 91FX?

Ameya

yes it will take it, i have e a ST 90 on a 4* 60 and it flys it very well, im sure your Tiger 80 will appreciate a 90 on it.. 61 and 91s weigh virtually the same

Difficult to tune? Hmmm.. never ran into that. Once I set it, it needed one or two clicks either way at the beginning of the day and it was set to fly, all day. Even when new, any of the OS AX series both tune easily and start very quickly. In fact, a hard slap in the reverse direction on the prop will start it up even when cold. Subsequent tuning often is not even necessary.

CGr.

Of course you always have some people that have to fiddle with the tuning every time they start the thing. We have one in our club that spends more time tuning than flying. The funny thing is, it is never right. Then someone else will tune it for him and then when he starts it again, back to turning the screws.

My original Goldberg Tiger 60, which was heavy, by the way, flew just fine, aerobatic maneuvers and all, with that old .61 SF. Then, when it needed bearings (I bought it used), I put in that Super Tigre 75. And because of problems with the muffler falling apart on the inside (baffle plate kept coming undone), I put a MACS Tuned Pipe which REALLY woke it up. However, this was my second plane after my trainer (this was, oh, 8 or 9 years ago) and acutally both engines were more than adequate. Now, that was the Goldberg Tiger 60. I don't know much about the Phoenix Tiger 60 other than what I saw in a picture when Google'ing it.

CGr.

Just confirming whether there is no "technological innovation" in ringed engines. I mean most commercial pistons are ringed, so what is the advantage?. I always thought that using non-ringed ABC engines was a method of saving production costs at the expense of engine life. Also want to know how long do these engines last anyway..I am using 20%castor, no nitro.

Actually ringed engines have been around for a longer time than ABC, and ABN engines. Pinch vs Ring is just how we create compression. A ring engine uses
the ring to form a seal beween the piston and cylinder wall during the compression stroke. A pinched (non ringed) engine uses a tapered cylinder so the piston
squeezes into the "pinch" creating compression. both engines run equally well and will last a long time if treated properly. I have an OS 1.20 AX that runs
flawless and is simple to tune, My .91 FX is a great runner and likewise easy to tune, and The .61 SF (formerly in CGretired's tiger 60 is) a great engine also.

Depending on the weight of your tiger and what you plan to do with it is going to determine what engine you want. I fly my CG tiger .60 like a pattern plane, so
I use a .91 fx with 20% nitro and a 15x8 apc prop. this combination in a 7.5 Lb airplane gives me unlimited vertical. also because of the modifications
made to my tiger the plane came out tail heavy and required almost 1lb of nose weight with a .61. I opted for a heavier engine and moved my RX battery
directly against the firewall. With the added weight in the nose I was able to get away with no other weight in the plane to make it balance.

I don't think the ring VS ABN, ABC is even worth worrying over, OS is a great engine and if you care for it right it will last a long and fun time.

Thanx for then confidence, Overbored77.

Can you tell me regarding the Thunder Tiger engines and how they are as comparde to OS. TT is cheaper but there are zero TTs on my field...primarily why I was warned against taking it as it sounds different and hence no one would touch it.

Ameyam

Thunder tiger engine are very good and are inline with OS quality.
I only have experience with their .46 and 1.20 airplane (great quality)
engines, but I have owned about 15 of their car engines over a 10
year period and was very pleased with the performance.

I have both engines TT and OS and have had no problem with them. We have 4 Tiger 60 aircraft at my field. 2 fly with 91 four strokes and one with an OS 61 fx and another with a 75 fx. They all fly very nicely.

Not sure about a 91 two stroke in this plane but if you wanted to fly a rocket ship am sure that would be adequate

What is a tuned pipe and what will it do for a engine