1QwkSport2.5r

I ran this engine a couple weeks ago and forgot to post my findings.. I haven't seen any other tach readings for this engine on this forum, and I searched all 34 some pages.

72°F air temp, 75% humidity
Italian SuperTigre S90K with stock "swing" muffler, clamped the farthest away from the cylinder, and stock ST carb with flat spraybar.
APC props
McCoy MC59 glow plug
5% nitro 20% castor

13x6 = 12,700rpm slightly rich of peak
13x4W = 13,400rpm slightly rich of peak as well (This prop had some major balance problems, so I will retest with a different 13x4W prop)

I have a mousse can for this engine that I'd like to try but need a header for it.

airraptor

My Feedback: (66)

http://www.rcfaq.com/RPMSTATS/RPMINDEX.ASP

it might be in here

1QwkSport2.5r

Macs has a header for $40.. For that price, I'm better off getting a Jettstream for twice the cost and 1/4 the work.. A bigger carb is good for a 1000rpm gain, and the exhaust could see 1000rpm gain.. I guess 15k isnt out of the ballpark for this engine on a 13x6 APC.

codycarlisle25

A ST 90 turning high rpm like that it will use some serious fuel. Please post your findings.

1QwkSport2.5r

I get about 15 minutes run time on a 16oz tank running on my airboat. I run 5%nitro 20%castor. Break in used about 2oz/min. I will try testing this engine over the weekend again if I have time.

airraptor

My Feedback: (66)

12x10 APC 12,200 on muffler with minor mods

1QwkSport2.5r

I wonder if it could do that with a mousse can and a bigger carb. I've heard swapping in an ASP 108 carb is good for a 1k increase, as is a mousse can of the right size being good for another 1k gain. I have it bolted to the stand, I just have to get around to running it.

airraptor

My Feedback: (66)

not sure on the OS carb. I just open up the stock carb. Some of the stock carbs can be opened up a lot others cant. If i get another one i will try another carb just to see what the carb swap will offer but to me a 1,000 seems like a very large gain but the engine is a torqer so the small carb may play in to that.

1QwkSport2.5r

The Italian mag carb is roughly 9.3mm and the ASP 108 carb is about 11mm. The G90's gain 1k on the 108 carb, so the S90 should do that or better. The S90 is stronger than the G90's from all I've read.

airraptor

My Feedback: (66)

I will look at mine tonight I dont know which one i have. I got the engine in a large batch of engines from chip hyde. It says made in Italy. its pretty old but has great compression.

1QwkSport2.5r

I went through and rebalanced all of my props, blades and hub. I decided to re-run them on the engine and see what it felt like turning today.

71°F / 42% humidity
5/20 fuel, MC59 plug, APC sport props, stock Mag V carb w/ spraybar "straight in".
12x7 - 2100 lowest idle rpm / 12,810rpm
13x6 - 1950rpm / 12,700rpm
13x7 - 2000rpm / 12,330rpm
13x8 - 1890rpm / 11,300rpm

Much less vibration than the last time it ran and the throttle transition is superb.

1QwkSport2.5r

Added a Jettstream muffler to the S90, and new bearings. The flogging follows.
5% nitro 20% castor fuel, McCoy MC59 plug, APC props.

69*F and 64% humidity
11x8 13,800/2,500
11x9 13,650/2,500
12x6 13,900/2,250
12x7 13,300/2,200
13x6 13,300/2,200
13x7 12,600/2,200
13x8 11,800/2,200

computermonkey

My Feedback: (90)

Hello 1QwkSport2.5r,

What Jettstream muffler are you using? I have the red 90 size on mine. Turning the same rpm with 0 and 5 percent nitro, Thurder bolt R/C long idle bar glow plug. Engine runs extremely good. Super Tigers are excellent engines.

1QwkSport2.5r

I have the red .90 size muffler as well. I have a bolt-on/bolt-through muffler adapter from Jett on it but I think the adapter is limiting power a bit so I think I'm going to drill the threaded holes out and all the way through on the engine case to use the Jett muffler without the adapter. My .90 runs pretty well on 5% nitro fuel as well. During the first gallon or two after the bench runs it didn't like even 5% nitro so I ran FAI fuel for awhile initially. I had to clock the spraybar about 35* to lean the midrange. After a couple gallons, I had to reset the spraybar to straight in. Runs great now, and the compression is incredible. All of my ST engines run really well.

computermonkey

My Feedback: (90)

I ended up moving the spray bar down also, but haven't moved it up leaving the mid range a little on the rich side. I drilled my engine mount through added a spacer and bolted without the adapter.

1QwkSport2.5r

I won't need the spacer myself but I'll be doing the same thing. I just need to get a vice for my drill press before I drill the engine case.

1QwkSport2.5r

I pulled this engine out of the drawer and decided to chuck the stock ring and put the Bowman ring in it that I had. After 2 tanks of FAI fuel and 3 tanks of 5% nitro fuel, I peaked it for just a second to grab a tach reading of 14,100rpm on a 12x6 APC and red Jettstream .90 muffler. After another 5-6 tanks, I'll see where it ends up. So far it's +200rpm from the stock ring and it runs fantastic. Better than it did with the stock ring and it's not even completely broken in yet. I look forward to seeing how it runs after its more broken in.

spaceworm

I have a Como S90K that has great compression and runs very well, but I would like to get a Bowman ring for it for the future. Do you have a spare, or a source for same? I also have an ASP 108. I never thought of using it's carb on the Como, but I may now that I have heard of it's giving 1K more revs. Thanks.

Vbr, Richard

1QwkSport2.5r

I don't have any spares. The one I had I'd gotten to have as a spare to replace the factory ring. Contact Gavin Carter on eBay. His username is gaviscool. He makes rings of good quality in much the same fashion that Frank did. He is in the UK though. His prices are around $13 for the ring and about $4 for shipping.