Anyone ever dynoed a 20H conversion?

[champ20B]

I was wandering about the 20H popper, conversion, toilet, whatever one wants to call it, if one was ever dynoed......If so, what horsepower did this engine actually make? I know for sure that a true stock 20H made about 23-HP off the cuff...

I am thinking about building a 20H popper later on for A-Mod class....THANKS!!

[JohnsonM50]

That is a good question, somebody's got to know.

[champ20B]

I figure it may be maybe 26-27hp? The reason I think this is that the 15ss Hot Rod is reportedly about 25hp at 8500+RPM.

The 20H popper is only no more than equal to a 15cid Hot Rod performance in 250cc Modified where the HR is allowed pipes. The "A" Mod runabouts are only one or two mph faster than the "B" stock 15ss HR runabouts and slightly less on the kilo record! I figure that pipes on the "A" Mod is at most about 1-2 more hp than stock is @ 25hp. So the 20H popper is maybe 27 at best. The 20H conversion wont beat a 20cid HR with pipes without extensive mods to the power head and running 20lbs lighter, so the "B" deflector merc is at to much disadvantage for B mod. But since I actually have 20cid merc powerhead parts I figure "why not" for an "A" mod? I could probably come across a conversion tower and header as cheap as buying a new 15HR cylinder block, pistons, rings, and pins to swap on my 20HR... and just having another engine would a lot more convenient.

[rumleyfips]

Here's my recollection from a fading memory. KG4H 16hp, Quincy dyno. KG7H 18 hp Hubbell dyno. 20H 20 hp reference unknown. Converted 20H 24 hp , reference lost in the sands of time.

[smittythewelder]

I heard 29hp at 7200, but forget the source.

[champ20B]

I heard 29hp at 7200, but forget the source.

That's a good bit! But the 20H popper runs AMH at only 365lbs, and its still not quite as fast any faster than a 20SSH that runs 400lbs minimum. The 20SS are no more than 30 hp with a blunt gearfoot with greater drag too.