Bass-Tohatsu D-Engine Performance

[nbass]

Bass-Tohatsu Test Results
November, 2004

Power head: The center crank pins are spot welded in two places per Tohatsu America recommendations. A throttle connection and a plug for the kill switch are installed. Larger Tohatsu carburetor jets are installed and the timing is set at 25-26 degrees advanced at full throttle. The power head is otherwise stock.

Tower Housing and Lower Unit: An adapter for the Bass Machines tower housing allows the use of the Tohatsu stock saddle and clamp system. Water supply is routed within the tower housing to the stock connection at the power head. Water is pumped to the power head through the Bass Machines standard pump system. The lower unit is a standard Bass Machines with Bass Machines 17:17 gears. Bass Machines standard 16:17 under drive or 17:16 overdrive are also available.

A&H 250cc hydro: The boat has a 35-inch wide bottom, 77-inches after plane, and approximately 2-inches lift. This boat has previously performed well as a 250cc at 85 MPH, and served as a test bed for D-mod R&D work. This hull was chosen for the first part of the season’s testing because it is available (Sid owns it) and is a safe ride for different drivers. The boat and engine weighs approximately 325 pounds.

D-stock hydro: A four point lay-down D-stock hydro owned by D-stock driver, Rick Keller, was used as a test platform for competition races at the end of the season. See the attached photograph.

Setup: The propeller shaft is set at the bottom of the boat per DSH rules. A slight tuck was tried, but level worked best with both boats. Overall handling was rated very good by drivers.

Propeller: Various types and sizes of propellers were tried. The best propellers include:
· 7-3/8 diameter three blade, round blade shape with a medium cup at the trailing edge. The mid section of the blade has a pitch of 11/11.5/13 inches and at the tip of the blade has a pitch of 9/9/11 inches. Max speed 74.6 @ 6800 RPM. Good corner speed and acceleration.
· A D-stock three blade, round blade. Max speed 75.4 @ 6500 RPM. Good corner speed and acceleration.
· A Hopkins 45 SS cleaver. Max speed 75.8 @6950 RPM. Good corner speed and acceleration.

Speed & RPM: The engine has a wide RPM range running well at top speed between 6,500 to 7,000 RPM. Speeds of about 73 to 76 MPH is easily obtained, depending on the weight of the driver. Acceleration is overall very good.


Performance under Competition:

Banks Lake (NBRA), June 19 and 20, driver Sid Bass placed second three heats and first one heat in a combination of mod, stock and pro boats. Close competition was provided by one competitive D-stock.

Cullaby Lake Regatta (APBA), DSH - June 26, driver Rick Keller finished D-stock in second and third place. Rick started with the pack both heats, lanes two and three. He drove it hard. June 27, Driver Jon Steen finished D-stock in second place both heats. Jon started with the pack in lanes two and three and pushed it real hard, only as Jon can do. There was good competition in D-stock both days. There was a three boat race out front and Jon Steen drove the boat hard competing well with the other two boats. He would have placed third in the last heat except that the second place boat missed a buoy in the last turn. Jon and the boat weighed approximately 500 pounds.

Cullaby Lake Regatta (APBA), DMH - June 27, driver Rick Keller finished second place both heats in D-mod. There was only one true D-mod that started out front both heats but did not finish. The wining boat both heats was a 44xs D-stock.

Silverlake Eatonville (APBA) - August 22, D-stock Driver Zack Maholt took first place the first heat, third or fourth the second heat, August 22nd, driver Rick Keller placed 4th D-stock, 3rd D-mod, & 3rd FEH

Waits Lake (AOF) - September 11 & 12 D-stock

Yelm, Lawrence Lake (APBA) September 18, 5th D-stock hydro, September 19th Howard Shaw 6th place D-mod Hydro

[csh12M]

Commisioners

So what say you commissioners?

12

[Matt Dagostino]

Ddddddddddd......

As a "D" person at heart what a strange site to see a Tomastushi (or however you say it) in a class that has been ruled by the american outboard high performance legend "MERCURY".................

What a bummer...................

Good luck

[ANZANI-QUINCY FREAK]

Tohatsu D-stock engine has spot welded crankpins nothing new and a good idea

The fact that the Tohatsu D-Stock has spot welded crankpins is not uncommon for some engines even years past. The practise is a reliabel way of keeping a high perforamance motor's hydralically pressed together component replaceable crankshafts from going out of phase causing rotating binding and weird binding. It all depended on crankpin end size, shape (tapered or straight end pin to crankarm input hole and end through thickness of the crankarm hole. Crecent 500 Alkys ands Super Cs of yesteryear were so heavily built and with straigtht pin ends, they just pressed together and stayed there without problems. British Anzanis on the other hand with tapered pin ends first generation type frequently threw their cranks out of phase through water ingestion or even too much fuel pored in them to start them so, they got welded like the Tohatsu D is now. Later second generation Anzani crankshafts were straight pinned corrected that and needed no spot welding to keep the crankshaft in phase. Konig crankshafts were good until you got to the Ds and Fs and those cranks needed attention time and time again to re-adust the crankshafts back into phase due to operations caused drift. When most of these engines dumped real bad with water ingestion, if they didn't blow up or cracked blocks and crankcases they would bend or alter the crankshafts significantly.

Spot welding the Tohatsu probationary D-Stock crankshaft is a good idea, makes perfect sense and gives more reliabilty to the engine product. Nice engine Bass bros! Your at the same place with that engine's introduction as was the MErc/Mariner 44X engines against their stock for-runners from the 1950s, the Merc 55H and 55H-1s. It was not long after the 44Xs introduction that they started bumping off all the early engines where those oldies were dropped off to become collectors items for preservation of what was against what is. I think that Tohatsu will soon enough do that too the Merc and Mariner 44Xs but for a while they will really mix it up.

[Cameraboy]

Norm, didn't Brian Palmquist take a very short run in the Tohatsu rig at Lawrence?

[dwestby]

palmquist and rick keller both ran the motor at lawerance it is amazing the only person we have heard from is the bass bother. I am impressed with the motor and think it would give the mer a good run with some set-up and prop work, but what do I know. It would be interesting to hear from all of the crash test dummies what they though, or maybe they just want the bass brother to do all the work for them and others and be cool being a boat racer. It is hard to figure out sometimes would you like to race a full field of boats and be able to buy a new motor and have all new part , or race a few boats and look for used rewind and other parts go figure SPUD.

[pops67g]

Lay down your money!

I hope to hear soon that racers on the west coast are standing in line at Mr. Bass' door with money in hand to launch this motor. So far all I hear is several people encouraging others, but with no intent to join in the fun. It is always more fun to have more than one motor in a class, but someone has to start the ball rolling. My 44xs can use more company, so bring 'em on.

[nbass]

A few in line for a legal Tohatsu

We have had several drivers suggest that they would purchase one if it goes off probation and becomes a legal competition engine. All it takes is a few in 2005 and the ball will start to role. Until then, nothing will happen.
Neil Bass

[R13racer]

Tohatsu D

I was one of the lucky ones to get to race the new engine. I think that with a little bit of setup work it will be right up in the running. It seemed to have great corner speed and punch. I won when I ran it on Saturday at Silver Lake. It wasn’t the fastest but with some work I can be a contender. If DSH wants to grow (and I think every class does) then they need to have an engine that is being produced and one that you can get parts for. The last few years in my region there have been less and less interest in this class and everyone would rather have a ten boat field instead of a three or four boat field. So write to Santa and wish for a Tohatsu on Christmas morning. Zach (Rrrr13) Malhiot

[pro350hydro]

Exactly!

We have had several drivers suggest that they would purchase one if it goes off probation and becomes a legal competition engine. All it takes is a few in 2005 and the ball will start to role. Until then, nothing will happen.
Neil Bass

No one is going to buy one UNTIL it become a legal motor. With the lack of available parts for the 44xs, I'm not sure why they wouldn't make it legal. Unless of course they don't want new technology in racing. If that's the case, they might as well start running Antique C's. At least they run alcohol. But why do that when the Tohatsu D will go faster and start easier.

I vote for the Tohatsu

Just my 2 cents, which ain't worth schit!

Mike

[jeff55v]

As a "D" person at heart what a strange site to see a Tomastushi (or however you say it) in a class that has been ruled by the american outboard high performance legend "MERCURY".................

What a bummer...................

Good luck

Yes, times do change. For better or worse, depends on a persons perspective I guess. I was stunned when OMC went out of business and was bought out by that French sounding company Bombardier!
I bet I could go down a list of outboard motor names that shook things up a bit during their "phasing in" to APBA.

[csh12M]

East of the Mississippi.....

I think the reason they would not approve it in 2005 is because no one East of the Mississippi has even seen it. Send it east this year or at least bring it to the Nationals so we all can see how well it performs. As a former commisioner I would have a hard time approving something I had never seen run.

Just my two cents...

12

[sponsonhead]

I wonder....

How many people east of the Mississippi...or for that matter, WEST of the Mississippi (you know, we do have flush toilets, electricity and everything, Dean and right now, only one active volcano) got to see the Mercury 15 tested as an "A" engine before it was approved?

R-19

[dholt]

What's to lose?

Pat,

Excellent point about the Merc 'A' and the Tohatsu 'D'. I was on the commission when we approved the Merc 'A' for 'A' stock. I hadn't seen one run either. No need to. The data is all that you need.

Who cares if you haven't "seen" it. The facts are in. It's almost 5-7 mph off the top 44XS speeds...so what's it gonna hurt to allow the motor into the dying 'D' classes????

One thing past history has pointed out. When you tinker and R&D and drag your feet with new equipment, it disappears without anything happeing.

Anyone remember the Tohatsu 'B' of a few years ago?

Oh the humanity!...will current 'D' drivers be upset if there are actually more than 12 boats at upcoming Nationals?? I don't think so.


Dana

[epugh66]

From the PRO perspective.

I will say first that comparing the two divisions is kinda like apples to oranges, but....

When Dieter or World Engines(Yamato) had new engines to test, they would bring about three engines and let racers use them for the year. Sometimes the the engine would become a production engine, or just a conversation piece. APBA has allowed the Tohatsu to be a probationary engine just so racers can test it in competition. From a racers point of view, shouldnt it be the manufactures expense to develope the engine.

I can imagine that the Bass brothers are more like Pugh Boat Works than World Engines, or König for that matter, but if they want the engine to be seen, build several and let racers campaign for a year.