CrateCruncher

My Feedback: (1)

I've got about 60 hours on my G61 ringed now and was considering purchasing something with more power in that displacement. Then I remembered that ST has 3 different engines that use basically the same case. I've started looking more closely at purchasing a larger displacement version of the G61 for a Dirty Birdy or Tiporare. My question is are they as reliable as the G61? Are there any problems with overheating or vibration? What are some performance numbers, etc. Has anyone tried the larger engines in .60 size pattern ships?

daveopam

My Feedback: (9)

The 75 is every bit the engine the 60 is. It will turn a 13x6 the same rpm as the 60 turns a 12x6. The size is identical. I have several of the 90s. They have the same bolt pattern but are taller. the 90 does have a little more vibration then the other two. It's not out of line though. I have had trouble on two of the 90 during break in. They would overheat on me in the air. Some of this is my fault. I don't break them in on a bench. I run two tanks on the ground and fly em. The 90s seem to take longer to break in. Once broken in they are very strong and reliable.I don't fly pattern but a 13x8APC is a good prop on a 90.

david

beppeVRCS

[:-] Please remember that ALL the Supertigre engines are designed for a country/continent where Nitro is difficult to find and, in case, extremely expensive. When Garofali started to export them to the US he decided not to modify the compressio ratio. Additonal head gaskets have never been popular in the Supertigre spares line. End of the story: 5% nitro is more than adequate for a correct performance of the engine. Some smaller engines can stand 10% (I occasionally use 10% in my GS 45 or 51), but for the larger engines 5% is the norm. Some vibe in the 90 might have been caused by pre-ingnition following too high Nitro content...
What kind of G60 have you been using, the Blue Head with Perry porting? In this case you might see a significant difference just with the "new" ST 61K or the GS 61: for the same displacement they are at least 15% more poweful, especially when used in conjunction with the latest ST muffler, the one with an almost cylindrical shape and a flat end.
Enjoy!
Beppe

Hobbsy

My Feedback: (102)

Bep, where in Va., I'm in Colonial Beach about 35 miles east of Frederickburg on Rt 3. I fly in Waldorf, Md at CCRCC. You're very right about the nitro, I have several European brands of two atrokes plus Fox two strokes and none likes more than 5% nitro.

w8ye

My Feedback: (16)

As a measure of power

61 = 12 X 6
75 = 13 X 6
90 = 14 X 6

All these Super Tigers last well

Beckster2008

I LOVE My ST 90.

CrateCruncher

My Feedback: (1)

Thanks for the info everyone. Just to be clear I'm only speaking of the Chinese built engines in the G61 crankcase. I tend to run a smaller steeper pitch prop for speed. I'm currently running an 11x7 APC on my G61 at about 12,600.

Can the 90 run say a 12x8 or 12x10? I'll have some ground clearance issues with 13" props.

Is there a performance benefit to running higher nitro if one lowers the compression? BTW, I can't even find 5% locally, 10 is the lowest stocked in Austin, TX.

w8ye

My Feedback: (16)

I ran 15% in my 61 and 90 engines with no problem

The 90 is a little more efficient down around 10,000 rpm. You'll have to try the 12-8 and 12-10 props and see which one you like.

captinjohn

I had a SuperTiger .75 on a Extra 300 and it was just as fast as my friends .90 SuperTiger powered Extra 300. He built both planes. Mine flew crummy...but fast!

rainedave

My Feedback: (1)

I don't mean to get off topic, but is there an optimal distance to set the muffler on the header for the S.61K? I'm guessing that moving the muffler in or out would effect performance to some degree. I could figure it out myself using a tach, but I thought I'd ask. The distance I'm referring to is indicated by the two red lines in the photo.

Thanks,
David

Cyclic Hardover

My Feedback: (3)

G90 is my favorite sport engine in most 60 size planes. Other engines i have like Jett etc are for a specific purpose. Have one in this Shoestring for 6 years now

anuthabubba

My Feedback: (102)

rainedave,

Never tached mine at different muffler settings. My guess is that farther out on the header will give the best power due to having the max volume in the muffler. Anyway, that's how I've run 'em.

Terry in LP

w8ye

My Feedback: (16)

The further out the better they ran for me

NoOneFlysAtMyClub

My Feedback: (32)

I have a ST 90 on my DC F-18. Running a Zinger 12 X 8, Mac's header,[uncut so far] and a Mac's Quiet pipe on 15% Powermaster. This thing ROCKS!!!

I am so happy with the this combo that I bought another ST 90 and a Juno F-18[same plane] for my winter project.

Best engine for the price on the planet. Period!!!

Tony

Kweasel

My Feedback: (29)

I have been able to run all three of these engines on the same plane. I found that the 60 needed high rpm (11-7) for good power and fuel draw. The 75 was absolutely wonderful, you can relieve the stock muffler and use 12-6 or 7 props for great performance. The 90 with an APC 12-10 performed the same as the 75 with an APC 12-8. The 75 was the best handling of all three by far. I think the best one overall is the 75, the 90 would be better if big props were required but this advantage fades as rpms increase.

XJet

The trouble with fitting bigger displacements into a .61-sized crankcase is that the only way to raise the capacity is to increase the bore. This means that the transfer ports become shallower and that almost always makes the engines far more sensitive to having a good air/fuel ratio.

The G90 seems pretty normal in this retard and this helps explains why they don't have as good a mid-range/transition as other .60/.75 engines (the ports choke at certain RPMs and the crankcase seems to load up). Fitting a better carby (such an OS or Perry) significantly reduces the problem but the G90 simply doesn't throttle or have as good a mid-range as many other engines.

The 90 of choice for me right now is the SK90. Mine's currently happy swinging a 13x10 prop - something my ST90 wouldn't do too well and the SK90 has a much nicer mid-range to boot.

However, if I were going for a "bored .60" engine these days I think (from all reports) that the Tower 75 is the engine of choice. I think it has even more power than the G90 and better throttling to boot.

asmund

I had the TH .75 for a while, but it fell badly short of power to my ASP XLS .91 and OS .91 FX and wasn`t all that much lighter either, so I sold it. The TH .75 will propably not match the ST .91 either unless the ST is a weak .91 (which I doubt )

ricardinho

hey guys just retired my supertiger 75 after 3 hard years of flying. i had it on a 60 size big stik and loved it. it started getting alot of dead sticks and was losing power. so i took it apart and seen lots of metal in the cylinder and the piston looked beat. i have been training a new guy on this plane so i want it to be reliable. so i ordered a super tiger g 90. tower was out of the 75 so i went for the next one. if this one is as reliable as my 75 then my friend should be very happy training. after all 3 years is a long time for running something to death. as cheap as these engines are why not buy one every couple years. question been running 10% in the 75. is 10% ok in the 90 as well... thanks guys if you can answer..

w8ye

My Feedback: (16)

Yes, it will be fine. Enjoy, they are a bolt on exchange

XJet

That's none too impressive - three years?

Even if that was a lot of hard flying I'd expect at the most to be looking at a new ring and bearings. That there's obviously been some serious issues is pretty poor.

My oldest engine has five years worth of flying on it (and I fly *really* hard) totalling some 400+ hours. It's still almost good as new - but it's not a SuperTigre.

Edwin

My Feedback: (2)

I've got 200+ hours on my St.75. Been flying it in a Supersportster 60 for about 8 years. Been two years since the last time I flew it. My ST90 only has about 40 hours on it.
Edwin

ricardinho

have you priced parts for the engines. a new carb is 50.00 a piston is 48.00 a head is 48.00 .rings i dont believe you can purchase alone. it makes more sense just to buy a new one. they robb you on parts so you do that..

anuthabubba

My Feedback: (102)

My Momma told me...You better shop around.

New parts can be found for less than that. I've recently seen ST carbs for around $30. Pistons for $24. Rods $19. Bought a ST 90 liner for $17. Rings can be bought as after market reproductions for about $12. Have never had the need for a new head.

Used parts are even less expensive. A 'parts' engine that someone gave up on 'cause they couldn't adjust the carb could supply some or all the needed parts for cheap.

But, hey. I understand the 'need' to buy a new engine.

Terry in LP

ricardinho

you are right but the engine looked bad inside. i really didnt want to fool to much with it. i have a new guy i am teaching so i wanted to get a new motor for him to be reliable so we dont have to do alot of tinkering and more flying. like i said that engine was trouble free for the past 3 years until this past month when it started acting up. oh well . thanks for the info...... pat

misterpanda

I've clearly established that my Super Tigre G90 definitely runs best and smoothest with an APC 14x8 on zero nitro and K&B plug. It pulls and transitions extremely well with this prop. If you opt for the G90 give this setup a try.

Regards,
Misterpanda