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. :confused:

[Danny Pigott]

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. :confused:

Remember the Yamato is a 20 cu. looper the 20 H is not, it is 1950's design . The other thing is no (offence) but the 20H's running to day or not as good as in there hay day.

[champ20B]

Remember the Yamato is a 20 cu. looper the 20 H is not, it is 1950's design . The other thing is no (offence) but the 20H's running to day or not as good as in there hay day.

Well, its just all in fun and interest....but Rumley says 24HP and I estimate 26-27HP. Yet, 29HP might be a stretch based on the stats I mentioned since it is still raced. I guess we can say that the Mark 20H Conversion is 24-27 horsepower respectively. There are still some good engine builders out there though that are still messing with these motors, and the other kinds are old engines just the same. One can still build a fresh 20H or any thing else as good as ever if desired I think. If anything isn't as good, maybe its just the fuel. But that would effect anybody with any engine regardless. Anyway, I wish that there was an actual manufacturers rating for this engine just for history sake. I always wondered for years what it really made, being that it was such a favorite in racing history. Ill bet a lot of enthusiasts have.

[JohnsonM50]

It seemed in the time that Mercury had an odd rating system. Of course HP is just a # & only one of the factors in what makes speed. In fun & interest, somewhere in the AOMCI links I read a converted 20H produced 45hp, hard to believe of course. I also heard of a mod that should do 72mph ??, doubtful. There are some racing locally that do ok considering the A-mod competition [converts]. All in all, from an AOMCI point of view the most over rated motor going & one of the most collected & over priced.

[zul8tr]

Since popper Hp officially unknown look at it this way as an estimate. Power is proportional to V^3. From what I recall when racing in the 70's my unconverted 20H in BSH would run about 61 mph, a 20H popper about 66 set up for circuit on a hydro. Running the numbers and assuming 20 Hp for the 20H gives 20 Hp x (66/61)^3 = 25.3 Hp for the popper all else on the hydro being constant including rpm except speed. You can play with other numbers and get maybe 26-27 hp because some of the real good poppers set up right would tic at 67 mph and that gives 26.5 Hp.

All this assumes 20 Hp for the 20H standard so the real answer is?

[champ20B]

Since popper Hp officially unknown look at it this way as an estimate. Power is proportional to V^3. From what I recall when racing in the 70's my unconverted 20H in BSH would run about 61 mph, a 20H popper about 66 set up for circuit on a hydro. Running the numbers and assuming 20 Hp for the 20H gives 20 Hp x (66/61)^3 = 25.3 Hp for the popper all else on the hydro being constant including rpm except speed. You can play with other numbers and get maybe 26-27 hp because some of the real good poppers set up right would tic at 67 mph and that gives 26.5 Hp.

All this assumes 20 Hp for the 20H standard so the real answer is?

The Mark 25 fishing motor was 20 actual HP. But the 20H was dynode at 23 by Hubbel I think. Doing this formula, that means that the 20H converted makes 29.13 HP.

[rumleyfips]

I heard that the 25SS was a 25 hp engine. The 25SS and converted 20H were interchangeable to me. Same boat, same prop, same setup, same speed 64mph . Your 25 hp figure makes sense.

Your calculation doesn't explain the KG4H. In ASH I read between 61 and 61 on the same Keller. This 16 hp motor was an anomaly that shouldn't have been able to run that fast.

[zul8tr]

I heard that the 25SS was a 25 hp engine. The 25SS and converted 20H were interchangeable to me. Same boat, same prop, same setup, same speed 64mph . Your 25 hp figure makes sense.

Your calculation doesn't explain the KG4H. In ASH I read between 61 and 61 on the same Keller. This 16 hp motor was an anomaly that shouldn't have been able to run that fast.

The world is full of anomalies isn't that interesting! The relation (really a proportionality) is just that and estimate so don't expect a fit for everything. BTW what is the Hp of a stock KG4 at the reduced RPM that it was rated at compared to the 'H' engine at 7000 rpm or so on a race boat? Remember all the calc is doing is comparing the relative change in Hp for a relative change in speed (as stated rpm is not in the comparison and everything else is unchanged except speeds).

[zul8tr]

The Mark 25 fishing motor was 20 actual HP. But the 20H was dynode at 23 by Hubbel I think. Doing this formula, that means that the 20H converted makes 29.13 HP.

"I think are" the operative words, so base 20H Hp still unknown. I doubt the 29 Hp unless a popper was modded someway. BTW are all these dyno tests mentioned done at the prop shaft, or at the crank w/o the tower or with the tower and no gear foot :confused:

[rumleyfips]

Frank Volker posted pictures of the Quincy dyno ( looks to be powerhead only ) in a thread called " Quincy Dyno and Pipe Stuff" here. I don't know what Hubbel had.

The KG4 ( and ,I think, KG4H ) faceplate read 7 1/2 hp. Understating the hp rating helped sell motors on lakes with horsepower restrictions.

[champ20B]

"I think are" the operative words, so base 20H Hp still unknown. I doubt the 29 Hp unless a popper was modded someway. BTW are all these dyno tests mentioned done at the prop shaft, or at the crank w/o the tower or with the tower and no gear foot :confused:

I took a look at an old archive from boatsport about the services offered by Randolph Hubbel. According to the Hubbel service add, in the earlier times (1950s) they claimed that an "up front" stock "A" motor should do 15hp, and a "B" should do 21hp, a "C" do 30hp, and a "D" at 40hp all around 6000rpm.

Now, in a 1961 add they changed the needed output for the "B" stock front runner up to 23HP with all others still the same. I assume that this was going from a KG7H to a 20H in true stock form. They did not mention or acknowledge the conversion kits as far as I could see. It was just either stock tuning or their pipes and mods alone.

[rumleyfips]

Speed and Spray #8, June 1953, page 37. Hubbel dynoed a stock KG7 stock at 18 hp. The curves for 3 different modifications are also shown.

It says he dynoed the powerhead so he must have used a powerhead dyno too.

[zul8tr]

Speed and Spray #8, June 1953, page 37. Hubbel dynoed a stock KG7 stock at 18 hp. The curves for 3 different modifications are also shown.

It says he dynoed the powerhead so he must have used a powerhead dyno too.

As we all know the Hp at the crank is much higher than at the prop shaft. This was the reason Mr. K and C. Strang developed the tuned pipe popper tower to beat the Champion which had less Hp at the crank than the Merc 20H. Apparently the tower on the Champ didn't loose as much Hp as the 20H tower so the popper was born to beat the Champ. They never did figure out what advantage was in the Champ tower.

Hp/torque at the prop is what the water reacts to.

[A/B Speedliner]

If some one could ask John Timmons to inquire of Charlie Strang (sp) we might get a factory tested HP rating for the 20H conversion.

In my 20H Book I have a letter from Strang while he worked at OMC written in 1992. He does not quote a horse power number but he does state the original number for the 20H was measured at the crankshaft with no exhaust cover in place and that the 20H powerhead did have more power then the Hot Rod but at the propshaft the Hot Rod with both mid sections installed had more power then the 20H. This is what he said about the power after the initial fabricated steel design was installed. Quote "The welded steel prototype pulled plenty of power on the dyno, well above the Hot Rod."

In this letter he also stated that Edgar Rose was given the job to develop the conversion so no doubt he would also know what the power numbers were.

David

[champ20B]

As we all know the Hp at the crank is much higher than at the prop shaft. This was the reason Mr. K and C. Strang developed the tuned pipe popper tower to beat the Champion which had less Hp at the crank than the Merc 20H. Apparently the tower on the Champ didn't loose as much Hp as the 20H tower so the popper was born to beat the Champ. They never did figure out what advantage was in the Champ tower.

Hp/torque at the prop is what the water reacts to.

I know that that is how the story goes. But Ive got to say, though I truly like Mercs and am working on building one, I do believe that a 20H may have had better low/mid torque on the dyno. But there is no way on earth I can believe it was more powerful than any good running Hotrod. And that's either one at the crank overall. My old "B-U" 6NHR is much faster with the open straight exaust, and that would take away any tuning if it really had it to start with. We have to remember that C.K got pi$$ed and called the final shot on that, and we know what that means. :rolleyes:

[zul8tr]

We will never know completely what took place at the time between Mr K, Charlie Strang and Edgar Rose only what is recalled. John Timmons has direct access to Charlie Strang, I will ask him to see what Charlie recalls about the 20H Hp vs the Hot Rod and if he has any factory dyno test papers hanging around.
Did find this thread by John Timmons over at Johns Merc site and includes letter on the 20H and the Hot Rod issues by Charlie Strang hope it opens to non members, no Hp numbers:(

http://johnsoldmercurysite.com/phpBB3/viewtopic.php?f=9&t=7790

[Ron Hill]

The Mark 25 fishing motor was 20 actual HP. But the 20H was dynoed at 23 by Hubbell I think. Doing this formula, that means that the 20H converted makes 29.13 HP.

When the Mark 20-H came out, Stu Downs bought a new one. My dad, Stu and I went to Hubbell's to run this 20-H on the dyno. I remember the "Cussing" getting the cowlings off. I also remember that ONLY the powerhead was on the dyno. I can't recall the HP rating or how we started it without a rewind started.

I do remember that my dad and Pep didn't like the "Wobble" in the flywheel at high RPM's and they all kind of "DUCKED" when Pep ran the engine up to wide open throttle.

I guess you could say I was there when it happened.

[zul8tr]

When the Mark 20-H came out, Stu Downs bought a new one. My dad, Stu and I went to Hubbell's to run this 20-H on the dyno. I remember the "Cussing" getting the cowlings off. I also remember that ONLY the powerhead was on the dyno. I can't recall the HP rating or how we started it without a rewind started.

I do remember that my dad and Pep didn't like the "Wobble" in the flywheel at high RPM's and they all kind of "DUCKED" when Pep ran the engine up to wide open throttle.

I guess you could say I was there when it happened.

To bad a hp rating is not available from Hubbell's shop. Wobble is not good, what kind of wobble motion: up and down or side to side, or both? Good thing they ducked.

[champ20B]

To bad a hp rating is not available from Hubbell's shop. Wobble is not good, what kind of wobble motion: up and down or side to side, or both? Good thing they ducked.

That sounds wild! I wouldn't expect a bent crank on these engines. I figure they had some of the best one piece cranks made in outboards. Those Phelon wheels could get distorted or bent though, being they were forged steel. Sometimes they could get pitted in places from rust/corrosion and that could throw them off balance too.

[DeanFHobart]

Your calculation doesn't explain the KG4H. In ASH I read between 61 and 61 on the same Keller. This 16 hp motor was an anomaly that shouldn't have been able to run that fast.

The A Stock Hydro Kilo Record I set in 1974 was 60.884 mph....... One way at 61.8. My motor was a KG4, Serial No. 506879, and totally stock..... No Blueprinting and No Squished Block. I still have this motor... Green Gas Tank and Bottom Cowl and all...... Bendix Mag, by the way. I had always heard that the KG4 was about 15 - 16 HP. The olny thing that was done to this motor was to re-build it with pistons, rings (2 dead ones), bearings, seals, put in a sand cast reed cage, .010" (thin) reeds, and the Bendix Mag. It was fast right away. I ran it for at least 10 years, only putting on new top rings. After it wore out, I started to run a Mark 15.

[zul8tr]

The A Stock Hydro Kilo Record I set in 1974 was 60.884 mph....... One way at 61.8. My motor was a KG4, Serial No. 506879, and totally stock..... No Blueprinting and No Squished Block. I still have this motor... Green Gas Tank and Bottom Cowl and all...... Bendix Mag, by the way. I had always heard that the KG4 was about 15 - 16 HP. The olny thing that was done to this motor was to re-build it with pistons, rings (2 dead ones), bearings, seals, put in a sand cast reed cage, .010" (thin) reeds, and the Bendix Mag. It was fast right away. I ran it for at least 10 years, only putting on new top rings. After it wore out, I started to run a Mark 15.

Dean

When you set the ASH kilo record back in 74 did you have to be not less minimum weight for ASH of 330 lbs back then?
What was the prop shaft height you ran and rpm if you recall of course?

[rumleyfips]

ASH was 330 lb and ASR 345 if I remember rightly.

With the hydro you went up until it stopped pumping water then backed down 1/8. With the runabout you went up till it wouldn't get on plane and backed off 1/8. In fact we had our own version of height restrictions.

[DeanFHobart]

Dean

When you set the ASH kilo record back in 74 did you have to be not less minimum weight for ASH of 330 lbs back then?
What was the prop shaft height you ran and rpm if you recall of course?

The A Stock Hydro weight was in that range.... 330 - 345 if I recall. I was always not more than 5 pounds over..... Just to be safe.

The prop shaft height was at least 1" above the bottom of the boat. Kicked - in just a bit. I ran the 'Scoop Skeg" type Gear Case with the water inlet that was on the bottom of the bullet..... Allowing more "Jack Up". Best of all.... It was a R. Allen "Papa" Smith propeller, made from a Kamic 48-23636. The boat was an Ed Karelsen built for the Kilos. I could read about 62, on the Keller Speedometer.

[zul8tr]

The A Stock Hydro weight was in that range.... 330 - 345 if I recall. I was always not more than 5 pounds over..... Just to be safe.

The prop shaft height was at least 1" above the bottom of the boat. Kicked - in just a bit. I ran the 'Scoop Skeg" type Gear Case with the water inlet that was on the bottom of the bullet..... Allowing more "Jack Up". Best of all.... It was a R. Allen "Papa" Smith propeller, made from a Kamic 48-23636. The boat was an Ed Karelsen built for the Kilos. I could read about 62, on the Keller Speedometer.

Do you have any pics of that Karelsen?

The record set in 1999 with a better engine(?) isn't much different than what you set back in 1974.

Kilo* Straightaway APBA 62.163 3/6/1999 Oroville, CA Gooffy Shawn Love Jack Terrell Sorensen Evinrude

[Danny Pigott]

Dean I still have a un touched Kamic 48 - 23636 prop. My Dad bought it new in the 50's

[champ20B]

Do you have any pics of that Karelsen?

The record set in 1999 with a better engine(?) isn't much different than what you set back in 1974.

Kilo* Straightaway APBA 62.163 3/6/1999 Oroville, CA Gooffy Shawn Love Jack Terrell Sorensen Evinrude

62+ isn't bad for a 15hp OMC outboard at all, even with a racing foot ! I wonder though, how those KG4 mercs would work with the conversion stack as a mod? I suppose it could be used just the same.

BTW, I read where the ASH guys in region 12 are bailing out because somebody bought a new engine (a sidewinder), and are regrouping as ACH ( "A" Classic Hydroplane) so they can just run OMCs. Since it is a classic division they want to start up, maybe they might let the KG4 stockers back in too? That would be interesting. I feel bad though, that someone invested in a new engine just to have competitors walk out or not show up because of it. Doesn't say much for sportsmanship at all regardless. I hope this idea doesn't spread across the country. If it does then ASH will disappear with the new 15 SW all together. That aint good.

[smittythewelder]

Since popper Hp officially unknown look at it this way as an estimate. Power is proportional to V^3. From what I recall when racing in the 70's my unconverted 20H in BSH would run about 61 mph, a 20H popper about 66 set up for circuit on a hydro. Running the numbers and assuming 20 Hp for the 20H gives 20 Hp x (66/61)^3 = 25.3 Hp for the popper all else on the hydro being constant including rpm except speed. You can play with other numbers and get maybe 26-27 hp because some of the real good poppers set up right would tic at 67 mph and that gives 26.5 Hp.

All this assumes 20 Hp for the 20H standard so the real answer is?


How did you come up with the speed figures? If they were read off a speedometer in the boat, then they are low because of the drag of the pitot tube. Wouldn't that effect the calculations? Also, how do you factor in propeller efficiency percentage, hydrodynamic drag, aerodynamic drag? This is not to say that a calculation from velocity is necessarily less accurate than various peoples' dyno readings, which notoriously differ from dyno to dyno (they shouldn't, but they do, and this seems to be true all over motorsports).

[zul8tr]

How did you come up with the speed figures? If they were read off a speedometer in the boat, then they are low because of the drag of the pitot tube. Wouldn't that effect the calculations? Also, how do you factor in propeller efficiency percentage, hydrodynamic drag, aerodynamic drag? This is not to say that a calculation from velocity is necessarily less accurate than various peoples' dyno readings, which notoriously differ from dyno to dyno (they shouldn't, but they do, and this seems to be true all over motorsports).

Speed is from my 20H days testing notes, the popper speed is from when I tested with a fellow racer that had one, most likely a Keller or similar pitot device . But it doesn't matter here because the simple basic physics relation is a Relative Comparison of Hp needed to achieve given speed increase all else being equal on set up except the speeds. Not comparing to dyno readings that may be just the power head or whatever. Don't make the relation any more complicated than that.

I have used this relation on many applications to figure what relative change in power is needed to achieve a change in speed, not just engines but drag vs speed, etc, seems to work fairly well but forget getting absolute answers just relative changes knowing any 3 of the 4 values to get the 4th. The accuracy is in the known values to get the unknown. BTW this is the same physics relation that Ken Warby's technical adviser used to estimate the Hp needed to overcome the total drag on Sprite of Australia when Ken set the water speed record of 317.6 mph in 1977, it worked quite well for him.

http://en.wikipedia.org/wiki/Ken_Warby

[champ20B]

Well, whatever a 20H conversion makes.......one thing that can be pointed out, being that a factory spec conversion is allowed in A-MOD, is that a factory spec OMC 22cid/25hp powerhead with closed exhaust (on a stock racing tower of various choice) and racing lower, can easily compete with the merc in this category. Again, that's a 25 hp unmodified powerhead.

Now being that the 15ss Hotrod is officially dynode at between 25 and 26 hp stock, that kind of denotes the point of running pipes or chambers on this engine since again, a 25hp OMC fishing powerhead mounted on the same mid and lower can compete. But maybe its the torque of the 25 that makes up for it if the 15 HR is making more hp with pipes. But the same may not be as prevalent comparing the 20H, so maybe it is about 26HP.

[champ20B]

Well, whatever a 20H conversion makes.......one thing that can be pointed out, being that a factory spec conversion is allowed in A-MOD, is that a factory spec OMC 22cid/25hp powerhead with closed exhaust (on a stock racing tower of various choice) and racing lower, can easily compete with the merc in this category. Again, that's a 25 hp unmodified powerhead.

Now being that the 15ss Hotrod is officially dynode at between 25 and 26 hp stock, that kind of denotes the point of running pipes or chambers on this engine since again, a 25hp OMC fishing powerhead mounted on the same mid and lower can compete. But maybe its the torque of the 25 that makes up for it if the 15 HR is making more hp with pipes. But the same may not be as prevalent comparing the 20H, so maybe it is about 26HP.

Basically what I mean is that if the 25OMC A-mod is 25hp, the 20H popper is 26hp, and the 15ssHotrod is 27+hp, the difference in torque on each motor is what evens them out.....

[DeanFHobart]

Dean I still have a un touched Kamic 48 - 23636 prop. My Dad bought it new in the 50's

Danny,

I still have one also...... Cool.

[DeanFHobart]

Do you have any pics of that Karelsen?

Yes I do..... However, they are stored away and not accessible at the moment. I only tested it once before going to Modesto, California for the Kilos. And just ran it two one way runs to break the record. Ed Karelsen sold the boat right after. I had no desire to do it again. The boat was definately fast in a straight line.
At the time, I had both the 1 - 2/3, 5 mile Competition and Kilo records..... The only records that were available at the time.

[rumleyfips]

All the speeds I quoted were dragging a Keller tube. I set it down as far as I could to get a steady needle. Over the years I bought and sold a bunch of Kellers to get one where the needle didn't wiggle. When trying different parts etc , a quarter of a mile was important and the speedometer had to show it. 4 I/4's was 1 mph.

In the 70's ASH was the only class that ran at it's full potential in competition. Racing speeds were close to kilo speeds. I never figured out why.

[DeanFHobart]

In the 70's ASH was the only class that ran at it's full potential in competition. Racing speeds were close to kilo speeds. I never figured out why.

It was because we ran "Jacked Up" even in competition... By the end of the KG4 / Mark 15 era, I was running between 1" and 1 - 1/8" above the bottom with a three blade all the time. Three blade propellers allowed us to do that.

[rumleyfips]

There were some good ASH's in Region 2 in the 70's; France,Marcell,Webster and more. I don't think I ever saw any of them run a 3 blade, but they all ran real high.

[DeanFHobart]

There were some good ASH's in Region 2 in the 70's; France,Marcell,Webster and more. I don't think I ever saw any of them run a 3 blade, but they all ran real high.

I started running 3 blades, approximately 1977 - 78 time frame. Made from again 48-23636 Kamics, Dick Fickett cut them apart and welded them back into a 3 blade and Papa Smith worked it. Then later Craig Dewald was making 3 blades from castings similar to these original ones.

[rumleyfips]

Was that one of the three blades that had about a 1/8" weld then a 3/8" air gap. We were throwing blades off 2 blade ASH whels at the time and I wondered how those things held together. Then I remembered that Dick could weld a fart to a cloud.

I sent a box of one and 2 blade stuff to Czblewski (sp? ) in 79 but he died and I never did get a 3 blade.

[rumleyfips]

We still don't know the dyno reading for a 20H, but the conversion made so much more power the original 20H cranks would break.

[DeanFHobart]

Was that one of the three blades that had about a 1/8" weld then a 3/8" air gap. We were throwing blades off 2 blade ASH whels at the time and I wondered how those things held together. Then I remembered that Dick could weld a fart to a cloud.

I sent a box of one and 2 blade stuff to Czblewski (sp? ) in 79 but he died and I never did get a 3 blade.

Yes, Dick Ficket was very good....... Never threw any blades. They were welded on the hub cut into 120 degree wedges.

[rumleyfips]

I just found where Hubbell's dyno figures were. His 60's catalogues advertised dyno testing for stocks and said that decent engines read as follows : KG4-16hp, Kg7-18 hp, unconverted 20H-21 hp, 30H-30 hp and 40H-40 hp. Even if the conversion added 15% that would only be 24 hp. Although dynos differ the Champion claim of 26 hp for a B stock seems like damn good advertising to me.