1QwkSport2.5r

I did a quick search and didnt see any posts about the Thunder Tiger Pro .91BB 2-stroke engine. Has anyone ran this engine and have any RPM numbers? I'm between this engine and a Super Tigre .90 (probably S90K if I can find one) but the price difference between the TT .91Pro and even a ST G90 is over $100. I want to know if the $100 price difference is worth it or not. Looking to spin up to 13" props, no larger. Current engine is turning a APC 13x6 at 10,400rpm and I'd like to turn this prop (or higher pitch) at 12,000rpm or so. (This is for an Airboat, not a Plane.) I'm not opposed to spinning a smaller prop faster if it will move the boat faster. I get 32MPH with 13x6 at 10,400rpm.

Thanks in advance
Tim

MartyH

My Feedback: (16)

As long as you know how to tune the Super Tigre carbs it is not worth the difference. If ST carbs give you nightmares, the Thunder Tiger is always a good way to go. I have owned a number of Thunder Tiger engines and every one of them have been the most user friendly in their respective size. I am certain the TT-91 will be no different. The Super Tigre will typically make a little more power but may be a little finicky relative to a Thunder Tiger.

Ernie Misner

I ran my ST 90 with a mousse can it man did it come alive! (and mac's header) Just made a huge difference over the stock muffler. Also I use a carb off of a Tower .75 engine. Lots of carbs drop right in if you don't like the ST carb.

Ernie

1QwkSport2.5r

Is that a g90 or s90k?
I'd put a Jett pipe on it since most stock mufflers suck by comparison. I need more thrust and speed (RPM!) than my K&B Sportster .65 can muster.

Ernie Misner

It is the newer Japanese made ST 90, must be the S-90 if I remember right.

Ernie

Ernie Misner

Here is a shot of the mousse can setup on the ST 90. You can't believe how this thing came alive. And INSTANT throttle response!

Ernie

Sport_Pilot

I recall the TT being more powerfull with smaller props.  Not sure about larger ones.  The new SuperTiger's are now made in China.  That now means I would not buy one.

airraptor

My Feedback: (66)

put a Jett muffler on that engine you have for around 80-90 dollars and have that 12,000 rpm

1QwkSport2.5r

I have a lead on a S90K Super Tigre - I think the S90K's are made in italy. Probably going to start with a 13x8 or 13x7 and tach it. Of course this would be after break-in. At this point, anything is better than the temperamental K&B. If anyone has a K&B Sportster .65 early style non-bushed crank version with "91" stamped in the backplate thats gotten the engine to run reliably and transition good, tell me your secrets. I almost pulled the carb off and tossed it in the lake.

The engine I have (as mentioned above) is nowhere near worth putting a Jett muffler on. If I had 80-100$ laying around, I'd invest in a pair of perry carbs (or K&B carbs that worked right) for both sportsters I have. Max RPM according to Mecoa (modern versions with remote needles mind you..) is 12,800rpm. The highest RPM I've gotten with this engine is 12,400 on a 11x5 or 11x6 prop but my boat only went about 15mph. If I had a good carb to put on it, I'd probably be perfectly happy with it. Only problem is 1 carburetor is $50 new (perry) and so I'd probably want to get 2 and maybe sell the other NOS engine with a good carb.

OR just buy a new engine, shelf the K&B until I come across a couple of used carbs for the right price and maybe revive both sportsters on a Twin engine Airboat...

airraptor

My Feedback: (66)

well the any of the other 90's will get the boat moving better than now. you still want to stay low on your pitch. something in the 5-6" range. try to run the APC props. A 14x6W cut down might give you some good trust to get the boat moving.

1QwkSport2.5r

I've been using APC props. I cannot use anything bigger than 13" diameter so if I cut a 14x6 down, I'm left with a 13x6 which I already have. Moreover, I got a significant boost in speed going from a 12x8 to a 13x5 and now 13x6. Since the k&b gave me such a fit, I'll just shelve it until the s90k comes. The carb is just crap on the k&b.

scooterinvegas

My Feedback: (1)

Dah!! There is no prop on it!

airraptor

My Feedback: (66)

you need max trust to get this boat moving.

i think this will be a very good prop for you with one of those 90 engines
http://www.apcprop.com/ProductDetail...tCode=LP14040W

just cut it down till it clears the boat.

it is a 14x4W the W stands for wide blade which will move alot of air.

next prop might be a Master airscrew 13x7 3 blade

Sport_Pilot

You haven't seen the boat, he needs a bit of speed.  NOT the typical air boat.  Was it a hydrofoil?

QwkSport.  I think you would be happy with a Jett.  If too expensive perhaps you can get a used Rossi or NoviRossi 90.  K&B and OS used to make .90 ducted fan engines that would probably do the trick.

airraptor

My Feedback: (66)

no i have not seen the boat but in his first post he was talking of only getting 32 mph. yes he wants more speed and a 5" - 6" pitch will get him to 45-50 with one of the 90's he is talking about and the props i talked about.

he doesnt want to spend a lot of money either so all of your engine suggestions are out of his limit.......

1QwkSport2.5r

Here's my two boats. That rule laying between them is 18" long - only there for reference. The flatbottom boat (32" long x 18" wide) is the one in question here. It moves pretty well with the K&B but for what it would cost to buy a new carburetor for this engine as well as the other one I have, I may as well buy a new one and stick this one in the drawer with the other one for future usage. (I wouldnt buy just one carb for the one engine since the other one is of the same batch - "91" backplate stampings = military drone engines. Pretty much only ran WOT and shot down thus the crappy carb)

I have a lead on a S90K for $75+shipping which I think is more than fair. It ran one time, the ring hasnt even seated yet. I think this is a good deal and I trust the seller. I think this engine (based on the threads I have read) likes to turn up some, and benefits from a pipe. I dont think I'll need a pipe as I think this boat will be ballistic with a .90ci engine no matter the prop. I just want something that will be more reliable and not "deadstick" on my in the middle of the pond as its done so many times up to this point. Who knows, it might be way too much and I fix the K&B and build something for the S90K.. Not sure right now. Just want the thing to run, and go fast.
The other boat is a fresh build - currently running a TT .46 Pro/Jettstream. This boat (39" long x 24" overall width) will get a Jett .56lx after I've flogged the TT enough and learned how to drive the darn thing. I'm already set on the Jett, and who knows... I may put the Jett on the flatbottom just for a try. If I do, I'll bring a canoe because I know it'll flip under that much power.



Since the flattie isnt a speed demon anyway, I dont need a $400 engine on it. I was looking at $200 or less.

Thanks for your input folks... I do appreciate it.

DarZeelon

Quote:

ORIGINAL: Ernie Misner

It is the newer Japanese made ST 90, must be the S-90 if I remember right.

Ernie

Ernie,


The Super Tigre line of engines are now made in China; not in Japan.

And yes, it is their S series.