I am fairly new to the hobby ,All I have flown is 2 Strokes .Just bought Hanger 9 F6F Hellcat and it looks like I will Probebly be putting a 4 stroke in it .Just want some impute on what to by (Saito vs OS)

Thanks Rob

well, you started out making the two of the four best choices, what sizes are you interested in and we'll go from there. Laser and Enya would be good choices also.

I have a Saito 100 in my very similar sized H9 Mustang and it flys very well.

I was thinking of 100 to 125

Was just looking at 4 stroke HP ratings ,they seem to have a lot less hp the 2 strokes .Are 4 strokes able to swing larger props becaues of the torque they put out .

The Saito 100 has been a favorite in the 60 size warbirds for several years but now it seems as though the Saito 125 is being used. Both these engines are the same external physical size as the Magnum and OS four stroke 91s

Don`t forget the mighty YS 110, it will put a spanking on all the above

....Welcome to R/C Universe, justinkserv....[sm=thumbup.gif]

For your first 4-stroke I would recommend the Magnum 1.20 for that plane. While it
may be the least expensive of all the popular 4-strokes....it is also the easiest to tune,
one of the most reliable, and all the parts are available. As a side note, the parts cost
a fraction of what the parts cost for those other engines, usually 1/3 to 1/2.

I use one in my big Dragon Lady. It is not a racer, but it is a sweetheart.

http://www3.towerhobbies.com/cgi-bin...&I=LXRF37&P=SM

FBD.

If you have the money, then the 1.25 is a good choice as it is an easy engine to learn. After pricing some OS parts the other day, I have to agree with Dave about the parts issue and Magnums. When something goes wrong, it matters!

Any YS will not be economical with parts, or the fuel with high nitro content. I don't think I would recommend a YS as a first 4 stroke engine to anyone.

Jim is right about the Saito 1.00 too.

I would say that either the Saito 100 or 125 would be great choices. I'd probably decide between these two based on how much money I could spend, and how much power I felt like I needed. (Too much power is ALMOST enough!) The 125 is $60 more than the 1.00.

I know of a couple Magnum 4S engines out at my flying field that have been problematic for their owners this past year, but I don't remember EVER seeing a new Saito with an issue that couldn't be resolved with better tuning and/or adjusting the valve clearances. Since I haven't actually worked on those Magnums personally, it is possible that they just had tuning issues too. (I actually tried to volunteer to help the Magnum owners. However, in both cases, it seemed like my help wasn't really appreciated, so I didn't push it. They never did get them running well, and one lost his plane due to a dead stick just after take-off.)

I don't think that a YS is the best choice for a 1st 4S. They do have extreme power, but extreme power comes with a price! If nothing else, just the extra cost for high nitro %.

I have just been SO happy with my Saitos, it is tough for me to recommend any other brand of 4S. I really like my OS 4S engines too, but they just don't seem to have as much power to weight as the Saitos.

I would probably buy another Saito if I were in the market for another 4S right now, and that is why I recommend them to you.

Rob,

Rather than recommend my favourite engine, let's look at the model itself.

Hangar 9 specifies a flying weight of 8.25 to 9.5lb and recommends a .60 - .76 Two stroke or a .91 to 1.00 four stroke for that model. That information suggests that the model will balance with an engine weight of approximately 23 oz, give or take a couple.

A Saito 1.00 (21 oz) fits into this band and so does the OS .91 (24 oz). Both these engines, with this weight range, will provide adequate (for scale model flying) but not sparkling performance. For example, I doubt that the power will be sufficient with these engines to do large loops or any routine requiring a long upline.

If you are not looking at doing aerobatics or expecting lots of speed and are just looking at flying circuits, a few rolls and the odd small loop, the Saito 1.00 or the OS .91 will suffice. You can skip to the end of the post now...

If you want more than adequate performance, you have a couple of options.

Going with an traditional "big block" 1.20 engine like an OS Surpass, Magnum or other 32 plus ounce engine will probably require additional weight to be placed in the tail to balance the model. This additional weight may mitigate any performance increase the additional power may promise. This option is therefore not recommended.

A Saito 1.25 (25 oz) does not weigh much more than the .91/1.00 engines and is still in the acceptable weight band, yet it should get closer to providing enough power for some reasonable aerobatics. It should be very user friendly just like the OS and Saito engines mentioned above.

For a very high level of performance, the YS 1.10 (27 oz) is the ticket. Power-wise, it will pound any other brand of four-stroke up to 1.50 into the dust and, contrary to the naysayers' assurances, is very economical on fuel. It's only a couple of ounces outside the band, so it could possibly be accommodated and balance achieved by moving the battery and/or receiver around a little. Once set in accordance with instructions, it should be a set-and-forget engine like the others mentioned. It doesn't care where the tank is situated either - a huge bonus for an ARF Warbird application.

Ain't it great to have choices...

Quote:

ORIGINAL: justinkserv

Was just looking at 4-stroke HP ratings ,they seem to have a lot less hp the 2 strokes. Are 4 strokes able to swing larger props because of the torque they put out?

Justin,


For one, IGNORE (!!!) the HP rating nearly all engine manufacturers state.

I and several other members here keep repeating this statement in this forum, for all newbies to see.


This is mostly true for two-stroke engines...

Example:

The OS.46AX is 'rated' by its manufacturer's advertised specs, at 1.65 HP at 16,000 RPM...

In reality, it spins a 10x6 APC, on 15% nitro fuel, at 14,200 RPM, which is calculated to 1.08 HP... This is the output required to spin this prop at this RPM! Period.

So you ask "But what does it put out at 16,000 RPM?..."

It spins an APC 8.75x8.25NN 'toothpick' pylon racing prop at just over 16,000 RPM (with the restrictive baffle removed from the 'PowerBox' muffler)...

This calculates to... 0.91 HP...The manufacturer is still looking for those 1.65 HP, since the engine is already 'over the hill' at this RPM, making more noise, but less power and a much lower torque output...


So, don't give any credit to those lies disguised as "specs"...


My Saito .72 four-stroke engine, on the other hand, spinning a four-blade APC 11x6 prop, manages 10,850 RPM, which is in effect 1.19 HP...
This is very close to what the manufacturer claims.


A four-stroke engine produces a much higher combustion pressure than a two-stroke engine, but since it fire only on half the revolutions, a four-stroke makes less HP and less torque than a two-stroke of the same displacement. ...At any RPM!


Most four-stroke engines run better at lower RPM levels; not needing to 'unload' like two-strokes, so a slightly larger prop is recommended.
...Even though a two-stroke engine of the same displacement would spin that same larger prop faster...

While Saito, Magnum, and O.S. Max all make fine 4-stroke engine products, don't overlook Thunder Tiger's wonderful F-91s four stroke engine. This engine may provide the ideal fit for most .60-sized warbirds. The TT F-91s is real stump-puller of an engine and its 25.7 ounce weight will help balance out models that might otherwise tend to be a touch tail-heavy.

The Thunder Tiger F-91s comes with a 3-year warranty and will provide many, many years of powerful and reliable service. The only disadvantage to using the F-91s on your F-6F Hellcat instead of a Saito or O.S. Max 4-stroke is you'll have to figure out what to do with all of your leftover money. The folks at www.thundertiger4u.com sell the F-91s for $194.99 and will provide free ground shipping within the contiguous United States. The folks at www.infinitehobbies.com offer the F-91s for $184.99 and ship all orders over $100 via ground for free.

Good luck and good shopping!

Oooops, I would have to agree on that one[sm=red_smile.gif]

has anyone ordered from infinitehobbies.com i just looked at their site for 20 min and couldnt find the thunder tiger engine

Mr G. Stockton,


[link=http://www.infinitehobbies.com/moreinfo.php?pid=2120]Here[/link] you are.

Search 'engine', 'show all' and just scroll down until you get there...

I've ordered from Infinite Hobbies on a couple of occassions. The part number for the F-91s is TTR9801, if you enter it in the "search" tool it will pop right up.

The Infinite Hobbies website is pretty poorly designed, but they ship quickly and I've been happy with their service.

Thanks I still have a lot to learn . Mr DarZeelon what is your thought on the tt75

Mr Stockton,


I really don't know much about the TT .75, but it seems to have a reasonable price and it is as light as the Saito .72, which I do own.

Previous knowledge about the TT .91 reveals the following:

1. It was a real elephant weight-wise... not true of the new TT .75.

2. It had all sorts of issues people began threads here about, involving the choke mechanism and assembly, which the engine cannot be run without... I don't know how and if it applies to the TT .75.

3. It is dead reliable and last very long, with no other problems I can recall.

4. It has a nice actual purchase price.


Maybe it is time for you to begin your own thread here, asking specifically about this engine...