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Author Topic: Thunder Tiger 46 PRO Marine  (Read 8455 times)

RC John

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Thunder Tiger 46 PRO Marine
« on: December 23, 2006, 05:11:04 PM »

Attached is a picture of a modified aircraft engine.
It started off life as a Thunder Tiger 46 Pro but has now been marinised.
By removing the original head and replacing it with the head from a Leo 46 Marine minimal machining was required. All that was needed was to reduce the spigot on the Head Button by 0.2mm to achieve the conversion.
The propeller drive collar was removed and an SC46 flywheel was re-cut with a larger taper to suit the Thunder Tiger's Split Collet.
In the Just Engines catalogue it does say that the Thunder Tiger company is owned by the "Uncle" and the Leo company by the "Nephew" - that does seem to be born out by this conversion.

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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #1 on: December 27, 2006, 09:20:14 AM »

look good but dont expect great performance from a plane engine they dont have the rpm of a boat engine,a better conversion is to use a car motor as they have high rpm !!.i have a 61 sc plane engine i converted to marine use using a cooling coil on the head.it was quick easy and cheap and it works great.the engine is reasonable for a fun boat but compaired to a boat engine its slow.
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OneBladeMissing

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Re: Thunder Tiger 46 PRO Marine
« Reply #2 on: December 27, 2006, 11:53:14 AM »

I used to run aero engines in race boats with KoolKlamps around the head. OPS Ursus .60 and OPS .40. They worked fine. I won many races, including a national championship title. Mind you, that was in the days before everyone had to use CMBs!
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cbr900

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Re: Thunder Tiger 46 PRO Marine
« Reply #3 on: December 27, 2006, 12:40:14 PM »

Sorry Marty you are very wrong mate, I have a converted aircraft motor in a speedboat that revs out to 32,000 rpm and its an OS 90....]





Roy
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #4 on: December 27, 2006, 01:05:30 PM »

Sorry Marty you are very wrong mate, I have a converted aircraft motor in a speedboat that revs out to 32,000 rpm and its an OS 90....]


roy i am not wrong look at the numbers of a marine motor compaired to an aieo engine and you will see what im talking about.32,000 rpm is not high a small 20 marine engine gives out 35.200 (cmb) 2.9 hp, os and many more give similar numbers.plane motors are meant to spin large props not small boat props,they just dont have the rpm.theres a reason all race boats have marine engines and not aero and its not just the water cooled heads they are a totally different animal.the car motors give a similar rpm to a marine motor and convert much better!!.look at these engines first one is a 25 os aero engine 19,000 rpm
second a 21 marine os 25,000 rpm thats the difference between marine and aero the second one on that list gives 40,000 rpm and no aero engine is going to match that.nobody races aero engines in boats anymore that went out 20 yrs ago.things have moved on massively in the last few years with boats reaching well over 100 mph .with a plane engine youd be lucky to get anywhere over 35 mph.


]]

http://www.sussex-model-centre.co.uk/shopexd.asp?id=984

http://http://www.sussex-model-centre.co.uk/shopexd.asp?id=994
Roy
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BobF

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Re: Thunder Tiger 46 PRO Marine
« Reply #5 on: December 27, 2006, 01:23:56 PM »

Hi all,
What an interesting topic this could turn out to be.

I had never realised that there was any difference between motors, other than the fact that the head or the cylinder was water or air cooled. I have never compaired the revs or output against one another.
I used to run an aeroplane Merco 35 with a water cooling coil and a water cooled crank housing in the mid sixties. I tried the same boat with a brand new marine version of this motor which I had never used until last year, and it appeared the same to me. I just assumed that some motors were more highly tuned than others. Sport verses Compotition motors etc.

I will watch this thread with interest.

Bob
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #6 on: December 27, 2006, 04:30:45 PM »

mate try this site for all you will ever need to know about boat engines!! if you or anyone says plane engines are the same as marine engines performance wise dont say i didnt warn you !! just kidding this site is a great source of info for anything rc related.try the home page for all the different forums available.you are right about sport versus race motors been different but most marine engines are race type motors apart from the sc range and a few others.how old is the merc engine?the rpm of older engines versus modern ones ,the gap is massive.as i said things have moved on a long way since the sixties  ;).
http://http://www.rcuniverse.com/forum/default.asp?fh=1&forum=229
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Re: Thunder Tiger 46 PRO Marine
« Reply #7 on: December 27, 2006, 07:02:20 PM »

Hi martno1fan,
The Merco was purchased in 1963 I believe and had a red head. It was the same year the Cachalot by Vic Smeed was a free plan in Model boats Mag. The marine version had a Black head, but I can't remember the exact date, it was probably 1976/7. I know I was using a bicycle with a light weight side car frame attached to get to the pond with my models, so it was before 1965.

Bob
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #8 on: December 27, 2006, 09:37:11 PM »

Hi martno1fan,
The Merco was purchased in 1963 I believe and had a red head. It was the same year the Cachalot by Vic Smeed was a free plan in Model boats Mag. The marine version had a Black head, but I can't remember the exact date, it was probably 1976/7. I know I was using a bicycle with a light weight side car frame attached to get to the pond with my models, so it was before 1965.

Bob
hi mate thats what i meant engines now are totally diferent the marine engines are designed specially to produce very high rpm as are car motors.in the 60s they just used the very same engines for both.yes you can marinise a plane engine and it will work well but if you buy a marine engine the same power etc the difference in a boat will be astounding.a size 40 plane engine might give you say 30 to mid 30 s ,a marine one will give you 60s to 70 mph or more.a lot depends on the boat and set up but the marine engines are so high revving compaired to a plane engine .i have a 60 plane engine in a boat and its fast, so i thought but a marine engine the same size would be twice as fast no problem so in comparison its slow!!.my advice is rather than spend money marinising a plane engine save the money and buy a marine engine .some guys use open top boats and run car motors with no problems the open top keeps them cool enough for engines say upto 20 size.anything over that should be water cooled.heres mine shes 36" size 60 sc engine submerged drive.most race boats have surface drive so the engines need to rev very high as only one blade is in the water at one time.plane engines dont rev high enough which is why i did mine submerged drive.the fsrv boats use submerged drive but though fast they are not as fast as surface drive boats.all the speed records are held by surface drive boats running marine engines.
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retro boats

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Re: Thunder Tiger 46 PRO Marine
« Reply #9 on: January 02, 2007, 01:13:53 PM »

hi 
 just thought i would say that over the last 35 years i have seen & used many types of ICC motors. some of the modified aero/car engines can be quite fast i would say as a direct drive sport engine your thunder tiger will be fine . i did see a marineised rear exhaust 6.5cc tinder tiger on a gearbox in a fsrv boat about 15 years ago that was quick then but probably not now! also my friend runs a modified  novarossi 3.5 car engine in his boat & when not braking con rods is as quack as my CMB valvoa engine boat.
as  most larger glow ICC motors start off as designed as aero engines which need torque & to throttle well. there port timimg is adjusted for that  with  the smaller 21 size are modified car motors. most manufacturers do not develop porpoise built marine engines anymore due to the cost. CMB  the only ones that do (but even they still blow up) the smaller engines high reving motors all run on gearboxes to use the rpm properly.
 
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #10 on: January 03, 2007, 05:41:41 PM »

like i think i said car motors high rpm airplane low rpm.os make marine engines as do a few others.and they rev much higher than plane engines out of the box.some run gear bixes some dont.my point was yes a modified plane engine will work maybe even quite well but no where near as well as a propper marine engine or a modified car engine.they just dont have the rpm look at any race motor in a boat and look at the rpm and the difference is there to see.
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ids987

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Re: Thunder Tiger 46 PRO Marine
« Reply #11 on: January 12, 2007, 01:04:59 PM »

In my humble opinion (as a newby here), it's more the case that the SC / ASP (call it either, it's the same engine) engines are sport engines - whether you put them in a plane or a boat. There are still quite a large number of people flying I/C powered planes for sport and aerobatic use (aerobatics obviously requires plenty of torque), whereas I would say that the balance in boats for sport use is much more biased towards electric. So the market dictates supply. There is still some call for marine sport engines though, so they make marine versions as well. Having said that, the performance of the SCs and ASPs can cause some surprises if set up right - but that's a different discussion....
Racing engines for aero use develop much the same RPM (size for size) as racing engines for boats or cars. They are just not very common. OPS and Rossi are good examples of aero racing engines which were converted for marine use. Even though these are old designs, the acheivable RPM is in the same ballpark as current marine racing engines. Metallurgy etc has progressed considerably in the las thirty years, however, so a CMB .45 stands a better chance of finishing a race when running at a sustained 25 - 30K RPM than the older .40 or .45s would.
More modern examples of aero racing engines would be Nelson and Cyclon - primarily for Pylon Racing. These are even more of a niche product than marine racing engines though. As an aside, Novarossi still produce the RX21 in an aero version - again much the same as the car and boat versions. Ducted fan engines for aero use are also often high RPM types (eg OS VR-DF and VX-DF, Rossi, Picco etc).
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #12 on: January 12, 2007, 04:07:18 PM »

of course you have a point there but lets see some prices of those engines? i bet they are expensive? i can pick up a car motor for the same price as a sports plane engine or marine for that matter that will blow its socks off lol.of course you can get high rpm plane engines if you want to spend like 300 to 400 pounds and yes some boat engines are dear like cmb and lots of others.fact is a normal sports use plane engine wont give the rpm a car motor of similar price will.
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ids987

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Re: Thunder Tiger 46 PRO Marine
« Reply #13 on: January 12, 2007, 05:46:19 PM »

of course you have a point there but lets see some prices of those engines? i bet they are expensive? i can pick up a car motor for the same price as a sports plane engine or marine for that matter that will blow its socks off lol.of course you can get high rpm plane engines if you want to spend like 300 to 400 pounds and yes some boat engines are dear like cmb and lots of others.fact is a normal sports use plane engine wont give the rpm a car motor of similar price will.
Car engines have made great progress. Market forces dictate, and car engine sales eclipse all the others put together - many to one, so they have had far more development. Hence the reason why we have such high performing .12s and .21s now.
From what I've seen though, the high power, high RPM car engines (eg Novarossi, RB, Rossi, Picco, OPS) cost as much as, and in some cases more than similarly sized boat engines. And they only come in small sizes. I know there are some relatively cheap (eg Chinese) car engines which carry great claims for RPM and BHP. Interestingly, Leo make a high revving, high power .21 in Car and Marine versions 7220S (car), 7220M (marine).
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glennb2006

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Re: Thunder Tiger 46 PRO Marine
« Reply #14 on: January 13, 2007, 02:13:39 AM »

I am not quite getting this.

Maybe it is just me.

However - here goes. RPM is pretty much irrelevant, just so happens to be a side effect of high performance small motors. What does matter is the output of the motor,IE: HP / CC.

It stands to reason that higher power to weight (size) ratio motors have higher optimum RPM speeds, that's just the way it is. Interestingly enough, in the motorcycle world what has happened is that maximum power has been sacrificed for more "driveability", so power output has reduced (slightly), and lap times have tumbled in the last two years as a result.

Strange. Or not really.

So, back to the point, it really does not matter what RPM an engine is doing in a car / boat / aircraft or whatever, it does matter how efficiently that power can be transmittted to the ground / water / air.

It is all about power and useability.

That's why four strokes now are the fastest motorcycles around, on lap times, because their riders have an easier time and can use all the power.

My contri anyway's.


Glenn
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #15 on: January 13, 2007, 10:13:19 AM »

all i know is this the only way to beat high rpm or hp is higher torque,a lower reving motor may be able to get some speed back on a higher reving motor by using a larger prop as they can have more torque.but high rpm equals high hp from what i know?and more straight line speed too , higher torque can exellerate quicker out of corners and starts but on a long straight the high rpm comes into its own as the top speed will be a lot more.in a race there is allways the drivers ability too and im sure a good driver with a good boat can beat an average driver with a great boat.also on bikes my mate used to race 2 strokes and he has a 2 stroke 125 asprilla putting out 35-39 bhp he says try and get a 4 stroke to beat that?the only reason they stopped using 2 strokes for gp was for polution and a 500cc 2 stroke 8 yrs ago was doing the speeds the four stroke 1000s are doing now ,if they built a 1000 2 stroke they would do 250 mph easy a four will do 200 with mods..by the way his daughter races the asprilla and it beats 500 four strokes easy ,eats em in fact lol 130+ mph in case you were wondering. four strokes are heavy so the liter 2 strokes have the advantage weight wise if the hp is there.hes been modding race engines for bikes for years both for himself and others so he knows his stuff .
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ids987

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Re: Thunder Tiger 46 PRO Marine
« Reply #16 on: January 13, 2007, 10:18:18 AM »

I am not quite getting this.

Maybe it is just me.

However - here goes. RPM is pretty much irrelevant, just so happens to be a side effect of high performance small motors. What does matter is the output of the motor,IE: HP / CC.

It stands to reason that higher power to weight (size) ratio motors have higher optimum RPM speeds, that's just the way it is. Interestingly enough, in the motorcycle world what has happened is that maximum power has been sacrificed for more "driveability", so power output has reduced (slightly), and lap times have tumbled in the last two years as a result.

Strange. Or not really.

So, back to the point, it really does not matter what RPM an engine is doing in a car / boat / aircraft or whatever, it does matter how efficiently that power can be transmittted to the ground / water / air.

It is all about power and useability.

That's why four strokes now are the fastest motorcycles around, on lap times, because their riders have an easier time and can use all the power.

My contri anyway's.


Glenn
Very true. The pursuit for power usually leads to high RPM though - because BHP is directly related to the product of RPM and torque. Increasing RPM is usually the easiest way to increase BHP, but usually leads to less torque and a narrower power band. In the real world torque is a major consideration, and performance is very much application dependent. You can easily tune an engine that produces phenomenal power at phenomenal RPM, but will never acheive it in reality because there is a big hole in the torque curve, and it doesn't have enough torque to drive the given load up to the power band. In your motorcycle example, highly tuned engines require lots of gears, and constant gear changes to stay "in the zone".
In the R/C model world, boats - due to hydrodynamic drag, obviously require more torque than planes or cars (it's obviosuly dependent on type and individual model as well though). Throttling in boats is usually more of an issue than with planes, but less of an issue than with cars etc. So a boat which requires to throttle, and overcome all the drag could not be as highly tuned (RPM and BHP) as an engine for a plane designed just for flat out speed etc, etc......
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cbr900

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Re: Thunder Tiger 46 PRO Marine
« Reply #17 on: January 15, 2007, 10:15:24 AM »

all i know is this the only way to beat high rpm or hp is higher torque,a lower revving motor may be able to get some speed back on a higher revving motor by using a larger prop as they can have more torque.but high rpm equals high hp from what i know?and more straight line speed too , higher torque can exellerate quicker out of corners and starts but on a long straight the high rpm comes into its own as the top speed will be a lot more.in a race there is allways the drivers ability too and im sure a good driver with a good boat can beat an average driver with a great boat.also on bikes my mate used to race 2 strokes and he has a 2 stroke 125 asprilla putting out 35-39 bhp he says try and get a 4 stroke to beat that?the only reason they stopped using 2 strokes for gp was for polution and a 500cc 2 stroke 8 yrs ago was doing the speeds the four stroke 1000s are doing now ,if they built a 1000 2 stroke they would do 250 mph easy a four will do 200 with mods..by the way his daughter races the asprilla and it beats 500 four strokes easy ,eats em in fact lol 130+ mph in case you were wondering. four strokes are heavy so the liter 2 strokes have the advantage weight wise if the hp is there.hes been modding race engines for bikes for years both for himself and others so he knows his stuff .

Marty
just to set the record straight, the bikes name is Aprilla not asprilla, the 500 cc GP bikes have never been as fast as the 990 Not 1000 Gp bikes as can be seen by the fact that all track records are now held by four strokes, the two stroke was dropped because no one wanted to buy two stroke motorcycles and they had virtually reached there use by date and it was no longer a valid machine, as for doing 250 mph with a thousand cc twostroke yes easily but with the same technology now being used in four strokes 250mph is also easily achievable, the only reason the GP bikes do not reach that figure now is gearing as it would then be to slow out of corners, the only real advantage a two stroke has is weight, but that does not compare with ridability of a four stroke
As for the use of aircraft engines in boats the engine I was talking about was 15 cc not a piddling little 21 sized motor so please show me a 15 cc boat motor that will rev better than 32,000 revs out of the box......

Please mate get your facts correct before typing..............


Roy
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DickyD

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Re: Thunder Tiger 46 PRO Marine
« Reply #18 on: January 15, 2007, 10:29:50 AM »

Calm down Roy, it's not good for you at your age ! ::)
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #19 on: January 15, 2007, 01:54:06 PM »

yea roy calm down sorry i spelt it wrong but my keyboard is playing up a bit,my mate mods two strokes so ill leave it for him to put you straight mate .as for the 15 cc cant help you there but you show me yours thats running those numbers . the cmb engines run 23,000 rpm and they are one of the best so what engine do you have running 32,000?if you have one im sure you will be breaking world speed records soon?also the torque of a plane motor is not as high as a boat motor either maybe thats the big difference here.you may be running those rpm on a plane but no way in a boat on the water.
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glennb2006

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Re: Thunder Tiger 46 PRO Marine
« Reply #20 on: January 15, 2007, 08:20:06 PM »

Oops,

sorry, did not mean to light any blue touch papers!!

It does not really matter you know.  :D

Enjoy,

Glenn
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #21 on: January 15, 2007, 11:03:57 PM »

Oops,

sorry, did not mean to light any blue touch papers!!

It does not really matter you know.  :D

Enjoy,

Glenn
lol i think its a brit ausie thing lol
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cbr900

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Re: Thunder Tiger 46 PRO Marine
« Reply #22 on: January 16, 2007, 12:45:44 PM »

The engine I was talking about is an OS 90 two stroke or 15cc and with the modifications that were performed by a friend on his OS he obtained 35,000 rpm on the ground and it also developed 14.5 lbs of thrust in a 9.8 lb aircraft, it was electronically timed at Leeton in NSW at 346 kph....


Roy
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martno1fan

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Re: Thunder Tiger 46 PRO Marine
« Reply #23 on: January 16, 2007, 01:11:53 PM »

roy big difference between air and water"" also boat motors have better torque thats why they move that prop faster on the water than any plane engine !!.buggy motors have high rpms but less torque also so need smaller props to work in a boat.the highest reving petrol marine engine i know of the zen 7 hits 18,100 rpm and puts out 7.3 hp its 26 cc.its faster than the qd 25 cc and 35 motors and the cmb gass ones too.but it hasnt the torque for bigger boats that they do.but it beat them by 3 laps last year in a 48 inch mono(dave marles)running against bigger boats ,race was for 15-35 cc boats. check this link out this is what marine engines do.
http://http://media.putfile.com/WC2006-15-35-FSRV
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Re: Thunder Tiger 46 PRO Marine
« Reply #24 on: January 16, 2007, 01:34:00 PM »

Oops,

sorry, did not mean to light any blue touch papers!!

It does not really matter you know.  :D

Enjoy,

Glenn

I reckon its got something to do with the cricket results   ::)

Richard ;)

PS

Nice to be on the outside for a change
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