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Engine basics => Four strokes only => Topic started by: Dennis Toth on May 05, 2021, 08:33:53 AM

Title: Smallest 4 stroke glow available?
Post by: Dennis Toth on May 05, 2021, 08:33:53 AM
Just wondering what is the smallest commercially available 4 stroke?

Best,   DennisT
Title: Re: Smallest 4 stroke glow available?
Post by: Robert Zambelli on May 05, 2021, 11:42:16 AM
As far as I know, OS made the smallest 4S engine, a Non-Surpass .20.
I have a few of them and they're great little powerplants.
One of them is in my Cardinette* and besides pulling the plane quite well, it requires around 1 1/2 ounces of fuel for the pattern.
No muffler required, unbelievably quiet.
9-6 Master Airscrew plastic prop, Brodak 10-23, 50/50 castor synthetic, 55 foot .012 lines.
It was replaced by the Surpass 26 which appears identical in size and weight and has a tad more power.

Bob Z.

* plans may be available from Brodak.
Title: Re: Smallest 4 stroke glow available?
Post by: GERALD WIMMER on June 18, 2021, 06:08:46 AM
Hello Small Four strokes that are currently available (and stocked) are the Saito 40A and the H.P.21 see:
http://www.mecoa.com/hp/vt/21.htm?id=2111
Regards Gerald
Title: Re: Smallest 4 stroke glow available?
Post by: Dane Martin on July 31, 2021, 07:43:50 PM
Correct! OS made the smallest production 4 stroke,  the .20 . It was only produced one year, and it's actually not included on the official OS timeline. It was quickly replaced by the .26. Then, of course due to demand, tooling and general one-upsmanship, the .30 replaced the 26.

So that leaves the HP 21 as the current smallest production 4 stroke. It is, however, a little heavier. Very very cool engine though.
Title: Re: Smallest 4 stroke glow available?
Post by: Robert Zambelli on August 05, 2021, 07:16:11 AM
We tested the OS 304S when it first came out and were very disappointed. Despite claims, we could tell no difference between it and the Surpass 26.
In my opinion, OS does not always get it right.
I've owned and flown ever OS four stroke from the 20 up to the 70, both Surpass and non-Surpass.
The .20 (non-Surpass) and .26 were very good, the 30, well, see my comment.
The Surpass 40 was the WORST 4S engine I've ever owned - JUNK in my opinion.
The Surpass 48, 52 and 70 were also fine but I had decided to stay with the smaller engines.
Regarding the non-Surpass engines, I also had the 40 and 60 - both were smooth and very quiet but not up to the performance of the competitors.

The photo shows the latest OS 30S and this was quoted by the retailer, Mainhobbies: "This item is discontinued and no longer available for purchase."

My advice: If you want a 4-Stroke engine, buy a SAITO.

Bob Z.






Title: Re: Smallest 4 stroke glow available?
Post by: Dennis Toth on August 28, 2021, 09:27:58 AM
Has anyone tried one of the HP VT FC.25 or 21's? They seem like a nicely built engine with simple direct drive overhead ports. The smaller size is only one I see available right now, seems the Saito 30 isn't available any longer, seems neither is the small OS 26. Any thoughts?

Best,     DennisT
Title: Re: Smallest 4 stroke glow available?
Post by: Dane Martin on September 21, 2021, 12:00:06 PM
I have an HP 21fs somewhere. I think they run VERY well. However, the case seemed a little large for the displacement and I felt it was a little heavier than needed. But, a strong little engine.