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Building What I called The 56 Package

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 PostPosted: Yesterday, 7:06 am   
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Most will say what the hell is he talking about. But now those T850 OMC racers who have been building several powerheads and testing them will now realize what I am talking about. If you haven’t experienced it you don’t understand it.

My learning started when we joined APR Superleaque and raced SST 60. It was very competitive. The best boats in North America raced . There were over 20 entries every event. There were detailed inspections on the top 3 finishers and one random pick every event, plus every boat was safety inspected before it was allowed in the water.

It was an equal playing field for all competitors yet there was a vast difference in performance in the group. Everyone raced similar equipment yet there were 4 to 5 boats that were always at the top, then a group of 5 or 6 and then the rest of the field.
It was a challenge to be in the top 10 finishers. The Haraway “Hooters” sponsored ($25,000. a year) hadn’t lost a race in two years and was clearly superior to the rest of the boats.
It passed every inspection at every event and was legal.

Why the difference?? It’s a stock class with measured engine and boat specifications you must adhere to. They DQ’d cheaters. You know the performance of your boat by testing and you can see how competitive you are watching the race.
The key was the time trials where each boat ran the course by itself to see who could run the quickest lap time. You couldn’t see much difference in speed, but the sound was different with the top boats as they started the lap. We made videos of those time trials.

Then I got lucky. I purchased a top 5 finisher powerhead. We couldn’t believe the difference. It did everything better. Next race without any boat setup changes we finished 4th. At the next race in Pittsburgh we were running a strong second behind the Hooters boat. They’re powerhead failed in the last heat race and they ran the number two powerhead in the final. We won the final. The Hooters boat never was superior without their original powerhead.

I had all our test data from testing various powerheads with exactly the same setup. Very similar to what the Gordon Group has done on their videos. You get the best setup on the boat first then you try powerheads and props.

Inspecting our number one powerhead and comparing it to the others , you couldn’t see any differences. Yet it had better acceleration and was 4 mph faster top end with exactly the same props.

Developing the package:
Initially you can’t mess or change the internal parts of your number one motor. But you can switch the external parts ignition, fuel system etc. off it and try those parts on other powerheads to see if they make a difference. On one they did and on the other no difference. It was the CDI box that wasn’t as good, so I replaced it on that powerhead and put the other original parts back on.

Once you sort out the add on parts then you need to check the internal parts. Why did our number one powerhead turn 8100 rpm and the others 7600-7700 rpm? Best test is to put a smaller pitch prop on to see if the powerhead can turn 8000 plus. Neither our number 2 or 3 could. So it’s either the air flow characteristics or the crank.
Best test would be to try the crank out of the number one in the other two powerheads. But you don’t want to risk hurting number one.
I contacted another top racer and asked him who had a perfect crank they would sell. I managed to get one and installed it in the number 2 motor. It became our number one motor with that crank.

Now when I went back and watched the videos of the time trials I could see what those racers did. They took advantage af their higher rpm motor at the start of the lap by going to the farthest point on the course to get the longest run to the starting line so the motor was at its maximum speed. You listen to the motor and you can hear the higher rpm. The sound is different. Just like Eric heard with Chris testing.

The fact is some of these 56 powerheads are just better to begin with and those are the ones that make a difference in Racing. You don’t need to have the same type powerhead on a lake boat where your main concern is top speed and it doesn’t matter if it takes a few more seconds to reach that speed. Nor do you need to run 8000 rpm. You can run more pitch and get the same top speed at less rpm and that increases engine life.

So this is what you need in the package.
A complete lot of add on parts of tested components carbs, ignition, fuel system, flywheel .
You need a perfect crank.
If you remove the sleeves, do the port work, balance the rods and pistons.
You will build the best powerhead out of that assembly.

But remember just like Mike Wienandt would tell you when he built your motor. “ I will build the best motor I can from these parts.” With all his experience his results varied. Some powerheads are just better. Sam Haraway would say the same thing, as would Paul Hickey, Cam Morley ....


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 PostPosted: Today, 12:02 pm   
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Quote: But remember just like Mike Wienandt would tell you when he built your motor. “ I will build the best motor I can from these parts.” With all his experience his results varied. Some powerheads are just better. Sam Haraway would say the same thing, as would Paul Hickey, Cam Morley

A few takeaways:
I am talking Stock legal powerheads not modified motors.

The APBA 1 mile speed EP record is held by Smoken Joe running a 49 OMC. The record is approximately 71 mph. The Canadian record is held by a 650XS at approximately 70 mph.
The UIM T850 record is held by a Yamaha 70CES at approximately 68 mph.
Those are the yardsticks for the original classes.
The Canadian version for T850 has a maximum 60 cubic inch displacement limit. We don’t have any records.

On this site there is a thread where we posted the GPS speeds submitted by TBoat owners. The GPS speeds are very accurate and compare well with the speed records.
We had lots of OMC 49 speeds posted. The speed range was between low 60 and high 60 mph.
Then two years ago Matt recorded a 72 mph run. That was impressive! When I questioned Matt about the motor...”lt is not rebuilt, its stock, a bit tired and I think there is more in it maybe 73 on a cool day.”
So this bone stock motor is 4 mph faster compared to similar combinations.

I have mentioned several times on this site that its best to rebuild a motor that hasn’t blown up rather than a blown one. If you can test it first then you have a good indication as to how good it will be rebuilt. Again some as just better to begin with. Those are the motors you want to start with.
It’s a learning experience. Most think they have a great motor and can’t believe similar motors are faster. That is common in boat racing especially at lower levels where there aren’t good inspections and racers assume the winners are cheating. I good example was the SST 60/90 class in CBF. The class was dominated for years by the Mercury SST 90 triple. The OMC SST 60 racers continually complained . Blair Kant’s decided to race his SST 60 in APR Superleaque. After a couple of years racing APR, Blair came back to race the Canadian Nationals and beat the SST 90 Mercury’s. After Professional Powerboat Racing finished there were no SST 60 races in Canada. The Canadian SST 60 went to race APR and every powerhead failed inspection.
Blair beat the mercury with a legal motor. The Canadian SST 60 guys got so locked on the thought that the mercury was cheating that they cheated. But the lesson is...their cheater motors were not a good as a stock one!

Also remember...the SST 60 powerhead is ported for a tunnel. A tunnel at top speed has less drag resistance than a TBoat. Rpm X pitch equals speed. The speed record for an SST 60 tunnel is 96 mph. That’s about 10 mph faster than you would ever see one run even on a mile and quarter race oval. A test was done and at 90 mph the weight of the boat was 25 lbs. that’s one reason why they blow over

If the basic components of the motor you are rebuilding aren’t good it becomes very frustrating trying to figure out why it doesn’t perform like you thought it would. It is even more frustrating if you have modified the porting.


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 PostPosted: Today, 6:07 pm   
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Question: How many horsepower can you get out of a 56 OMC?

I can only answer that based on my own observations. There is prop shaft horsepower and crank shaft horsepower ratings. But, what I found most important were the characteristics on the Dyno sheet as to how the motor performed thru it’s complete rpm range. Equally important was the seat of the pants feel when driving the boat.

Prop shaft horsepower
Bridgeport 70 hp ....71 to 72
Oval port 70 hp ......70 to 71
SST 60...................90

Crankshaft horsepower based on Mike Wienandt dyno sheets I have actually seen.
Race prep SST 60 ......97 to 105
Mod production block tiller SLT.......115

Crankshaft dyno characteristics ..Mike Wienandt motors
SST 60 sleeves........most had a maximum hp over a limited rpm range of 500 rpm. The horsepower was quick to fall off above that range. It didn’t matter what the top hp was they all had the same characteristic. You would see some that developed maximum hp at 7000, while another were maximum at 7400. In the 6000 to 6500 range none of them made big horsepower....maybe 75. So the motors build power with rpm, max out and lose power at 7500 to 7700 in most cases.

Mike Wienandt SST 60 sleeves
The ramp angles on the ports is the only difference. The sleeves passed inspection and were sold to selected successful SST racers. Those Mike Wienandt motors in SST 60 were the best. They cost $5000.00 US . I am not sure if any more were built after 2010 and they’re rare now.
The powerhead (dyno sheet I saw) made 100 hp at the crank. That was less than the stock SST 60 sleeves which could be 103 to 105 hp. Scott Whittington had one of each.
The big difference was the power curve....the powerheads developed maximum hp and held that maximum for 900 to 1000 rpm. Example Blair Kant’s 2006 motor made 100 hp at 68-6900 rpm and it was still 100 hp a 78-7900 then the hp dropped. The advantage was noticeably on the race course. They had stronger midrange and sooner top end speed.

Seat of the pants feel:
You notice the torque difference when driving the boat. One reason why Chris Gordon was interested in the 50 to 70 acceleration time is that is an important number when racing. On a race oval the TBoat speed exiting the corner is about 50 mph. If the straightaway is 14 seconds to the next turn you want to be at 70 mph as quick as possible. Once the water gets rougher this becomes more important because you can’t run full throttle all the time. That’s another reason why raceboat setup is difficult to a lake boat. The raceboat needs to react and accelerate quicker .

The oval port
The only experience I have had was putting SST 60 carbs with 74D jets on a stock 70 hp long shaft booked up to a prop dyno. The motor was making 71 hp with the stock plastic top carbs and just switching to my carbs it made 76 hp at the prop.


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