martenson

Hi.

I'm looking for the lightest 2 stroke 25 size engine.
I hope to build a Baby Curare and would like a light and reliable engine.
My OS 25 FSR is worn out.

I have a Super Tiger 29 NIB that I have to weigh first.

I was thinking of a OS 25 LA?

Thanks.

ThumbSkull

My Feedback: (57)

If you can find a Norvel 25, they are great light engines.

earlwb

The .32 engines weigh less than the .25 engines, and the .36 engines weigh less than the .32 engines do.
So if you are going for a lighter engine, go for a .36.
What happens is they bore out the crankcase for the larger diameter cylinder and that automatically makes the engines weigh less as you have a bigger hole down the middle. less metal inside to add weight.
The .36 engines also have the same mounting holes as a .25 engine, so they wind up being a plug in hop up for more performance.

spaceworm

That is generally true, my Como (Super Tigre) 90 is based on their 61 which was first bored to a 75 and then to the 90. All this with very slight weight gain over the 61, due to the bigger piston. I think the ASP 60/90/108 were made that way also, by overboring the basic case. The Evolution 60 is a bored out 46, and very light.

However, the basic smallest size engine of the series is often heavy for it's size as they have allowed extra material in that casting for the future expansions.

Regards, Richard

jeffie8696

Ihear the OS40LA makes a great .25

blw

My Feedback: (3)

Not trying to doubt you here, but I know the 46NT is a bored out 40 Alpha with a different crankpin on the crankshaft. I don't anything about the new 60 Evolution.

I have an Evo 36 that looks good and has low time on it. I haven't run it yet. I got it cheap.

ThumbSkull

My Feedback: (57)

earlwb,

Show me a .36 that weighs less than 8.1oz with muffler........
That's what the BigMig sport .25 weighs.

Most of the other posts seem to ignore the original posters question.

jaka

Hi!
OS FP .20 and LA .25!

Sport_Pilot

The Fox .25 only weights 8 ounces. Not sure if it includes a muffler. No problem with parts as youmay have with a Norvell. You do have to use 100%castor oil though.

http://www.foxmanufacturing.com/inde...roducts_id=281

earlwb

Thumpskull,
Albeit it isn't perfect, there are exceptions to everything. I usually try to find something people can get the Norvel engines aren't exactly common or easy to get anymore.
heck I wasn't able to get a Norvell engine myself either.

When you compare a number of the 25, 32 and 36 engines, the 32's and 36's are typically bored out 25's where they went as large as they could and still have a engine that works. Granted they sometimes make the crankcase larger for various reasons.
For example a Thundertiger 36 pro weighs 11.4 ounces and a OS 25 AX weighs 12.4 ounces. of course this could vary depending on if the muffler is included or not. ( compared from Tower Hobbies engine specs.)
although no one can get them right now, their GMS 25 and 32 engines show a similar weight reduction with the larger displacement too.

Now using HobbyPartz website and engine info the ASP .32a weighs 325 grams whereas the .36A weighs 322 grams. The older design long stroke 28a weighs 292 grams whereas the ASP 25 weighs 300 grams.

A ThunderTiger Pro .36 engine specs:
Displacement: .365 cu in (5.98cc)
Bore: .8189" (20.8mm)
Stroke: .6929" (17.6mm)
Power Output: 1 HP @ 14,500 RPM
Maximum RPM range: 2,000 - 17,000
Practical RPM range: 2,500 - 14,000
Weight (w/muffler): 11.4oz (323g)
Crankshaft thread size: 1/4-28
Crankcase width (for engine mount): 1.22"
Overall height: 3" (76mm)
Overall width (w/mount flanges): 1.77" (45mm)
Overall length (backplate to front of drive washer): 2.95" (75mm)

A OS 25 AX:
Displacement: 0.248 cu in (4.07cc)
Bore: 0.709" (18mm)
Stroke: 0.630" (16.0mm)
Practical RPM: 2,500-17,000
Output: 0.8 ps @ 15,000 RPM
Weight: 12.6oz (357g) with muffler
Recommended Propellers: 9x5, 9x6, 9.5x5, 10x5
Crankshaft Size: 1/4-28

Mr Cox

Fox engines are listed without the mufflers, the same goes for the Green series from Thunder Tiger etc. So one has to be a bit careful when looking only at web pages.

Norvels are back now and are easy to get, both the engines and parts. So if weight is the most important, that would be the way to go.

If power to weight ratio is the most important then the new Magnum .25XLS, sounds pretty good. Runs stronger than an OS .25 FX from what I've heard.

earlwb

Has anyone actually bought a new Norvell, from the business that says they have them to sell yet?

I saw where someone had a engine for sale on ebay, but they stated it had a teflon coating inside. I thought I remembered reading about them using a ceramic coated cylinder liner instead.

Mr Cox

Yes, I have bought both engines and parts without any problems. Others have similar experiences and there is a thread on that in the 1/2a forum, look for "Norvel engines and parts are back" or something similar.

The cylinders are made from aluminum and the bore is oxidized aluminum which is the ceramic part.

CustomPC

Enya engines are typically lighter than equivalent OS.

The Enya SS .25 with AAC (Aluminium Piston, Aluminium Liner with Chrome Plating) is 2.5oz lighter than the OS .25, and that's before i include muffler weight in the equation. The Enya muffler will be lighter too.

earlwb

Thanks Mr Cox.

buzzard bait

I don't think you can get lighter than the Enya, and you might as well get the 30ss rather than the 25. With the muffler, mine (I have three) weigh barely 9 oz. Drawback is they are VERY noisy and the air bleed throttles are extremely non-linear. They weigh the same as my OS 25 FP, but put out way more power. However, the OS is quieter and the throttle works better. Even if you put an OS 40 FP muffler on the Enya it is still noisy.

You can get the Enyas with 2 needle carbs now, and I think they increased the size of the muffler. Those are both much needed improvements; the new muffler probably weighs a bit more but it will still be a light engine compared to the others. You can also get them plain or with ball bearings, and the weight difference is very small.

Jim

turbo.gst

My Feedback: (8)

Another thing of note with the Enya SS series is the fact that engine can set further back in the mount as there are no rear screws / back plate. I switched a OS 25fsr / Webra 32 / and Enya30SS and felt the Enya had the lightest weight of those three.

martenson

Thanks, I really appreciate all answers.

In fact I have a nice Enya SS 25 in my Flip 3D, I will compare that to my NOS Como/Super Tiger 29.

And Jaka I was thinking of the OS 25 LA.

Thanks.

johnvb-RCU

My Feedback: (1)

I just went through the same exercise for a MEN 15 Trainer. I weighed up all my .25s (OS LA25, Enya 25SS, Fox .25, GMS .25, Thunder Tiger .28, Super Tigre .34) and the lightest was the OS LA, it was the most compact too. Ended up using the TT GP28.

Hobbsy

My Feedback: (102)

Here you go Hugh, with muffler, I tookd a picture of the scale and engine separately because its difficult to get the whole engine and the scale. I wanted to show that the weight included the props nuts etc.

JPMacG

My Feedback: (2)

The TT GP-28 is a nice running engine and you might save some weight over an OS 25LA if you can use the cast-in engine mount on the GP-28.

martenson

Okey I only messure in "grams" so please bare with me.

*Old Enya plain bearing 29 with muffler and all 311 grams
*Old HP 40 ball bearings 40 with muffler and all 335 grams
*Worn out OS 25 FSR with muffler and all 269 grams
*Old Fuji plain bearing 19 with muffler and all 248 grams
*NIB Como ball bearing 29 with muffler and all 307 grams
*NIB MVVS 2,5 G7 with pipe and rc carb 199 grams
*Old OS 26 fourstroke with muffler 278 grams

And now to the winner (I think) my only chinese engine a ASP 15 with muffler 180 grams, and this baby really screams

Thanks.
Joakim[8D]

buzzard bait

I was thinking 25s. A very powerful engine for it's size in your range is the ASP .21. It's an 8 oz engine and it turns a 9x4 prop at 13,800 to 14,000. That's way better than an OS 25 LA, and it's lighter.

Are you sure about 180g WITH muffler? I thought the ASP 15 xls was about 7 ounces, which would make it only an ounce lighter than the 21.

Jim

martenson

Buzz, I will check in the morning again(with picture)
It's late and time for whiskey

Take care[8D]

freakingfast

My Feedback: (3)

A little screamer is the Webra 32 with muffler, it weighs 310g (10.9 oz.) and puts out about 1.2 hp for $124.00.
http://www.swanyshouse.com/engines/engines.aspx (good people). It likes low nitro, 10% or less.